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Controlled Drug Delivery - Science topic

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I am looking for a plain/empty gel system, which we can directly buy and load the drug for the purpose of transdermal delivery. Your kind help will be appreciated.
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generally, based on the nature of the drug we have to select the polymers to prepare any formulation .
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Hello, can anyone please named few potential drug delivery technologies that you think are novel and unique. Our comapny is looking to buy few drug delivery technologies that can serve us to compete for now and few next years. Suggestions are highly appreciated. Thanks in advance.
Regards
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Current trend is Nanotechnology based drug delivery systems like nanogels, Hydrogels for wound healing, surgical sprays, Monoclonal antibodies are in high demand in this covid state and many companies are even having patents.
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Hi to all!
I am currently working on sequential glucose and oxygen delivery in tissue engineering field and I need to choose specific tissue and cells to work on. I wonder that which tissue need the highest amount of glucose during the first days of implantation. is there any valid reference reporting concentration of normal glucose consumption rate in different tissues?
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As for as the oxygen demand is concerned the heart, followed by kidneys, brain and liver tops the list. The glucose demands is high for the brain. The demand is dependent upon the metabolic rate. The cancerous tissue also has higher demands for the glucose.
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I have collected 6h to 96h drug release data for unilamellar liposomal vesicle by using spectrophotometer. According to data, we have encapsulated chemotherapeutic agent in 80% efficiency. But when we look at the release profile, liposomes do release the drug at minimum level even at the 96h. Is it possible ? What are the reasons behind that ? Is minimum releasing okay ? What are the consequences of this thightly encapsulation ?
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Hello,
The release profile of the encapsulated drug in strongly influenced by the characteristics of the release medium. For instance, low solubility of the target chemotherapeutic in the employed release medium might be the reason for your observations. Several other factors such as stability of the carrier and interactions between drug and carrier could also affect the release profile. Overall, all of these factors must be carefully considered in order to draw an accurate interpretation.
Furthermore, drug encapsulation efficiency and release profile are two independent factors and in some instances, one might not even be affected by the other, therefore, it is best not to use one of these factors for interpretation of the other one.
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The main (and generalistic) advantages and disadvantages of each type of nanosystem have been widely pointed out in literature. However, the advantages and disadvantages stated are too broad and sometimes overlap. Of course, it can depend on several factors: the targeted tissues; the loaded compounds; the type of administration; the final formulation; industrial scalability; among others. This way, this question aims at opening a debate to untangle and explore further the potentialities of each nanosystem and, more specifically, the (1) differential and (2) more specific applicabilities of each one towards the right final choice for the preconized biomedical application. Personal experiences and opinions are deeply welcomed!
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Choose polymer based systems as they are more stable than lipid based.
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These days the hottest news of the world is about the rate of the victims of Coronavirus disease (COVID-19). It is very interesting if you share your valuable experiences here. Let's help each other.
Regards,
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During this Coronavirus (COVID-19) epidemic, we remain at home, avoid to visit crowded areas, use of face mask when going out for purchasing essential items (medicines, milk,fruits, vegetables etc.), immediate washing of hands with soap and water after coming in contact with symptomatic person or surface, eating of foods rich in antioxidants to increase the immunity, and greeting the person with Namaste (Indian way of greeting) instead of hand shaking.
I recommend the use of Vaseline in both nostrils whenever one goes out of home, daily drinking of one lemon juice in one glass of water in morning, and taking Vitamin E and Omega fatty acids -3 .
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There are two samples for comparison against same cell line.    
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The one with low IC50
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There are several phytochemicals and natural products reported for having good anticancer or antiviral activity.. but problems like low solubility and degradation on first pass metabolism make them unsuitable for oral administration..
Please share your ideas about compounds belonging to this category
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I try to encapsulate a drug (Diclofenac pot.) into a micelle and study its release.
Firstly I use thin film hydration method is this method suitable? Since both drug and polymer are soluble in water.
Secondly; calibration curve of the drug done in solvent or in a buffer (7.4 for example). Because I read many papers and confused which is correct?
Third; how to calculate amount of drug encapsulated and then % of drug release ?
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I will study the release in pH=7.4 so calibration curve done in pH7.4
THANKS
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Controlled drug delivery
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Hi,
There are many target sites for nanoparticle drug targeting. These depend on many factors such as disease in question, or in vitro (e.g. industrial) applications. I am attaching one of our publications to this message in which we used nanoliposomes to target and eliminate pathogenic bacteria in vitro.
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Electrospun fiber mats are normally highly porous. During electrospinning process one can control the pores on individual nanofibers which depends on operating parameters such as relative humidity. How can you benefit from these pores while the average pore size and pore size distribution of the fiber mat is considerably high compared to the individual fiber strands?
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Hi Lizo,
I think it depends on the application. From a tissue engineering perspective, a large average pore size would be beneficial for cell migration and mass transfer. But from my short experience, the pore sizes of random electrospun nanofibers with an average fiber diameter of approx. 300 nm would give less than 1 micrometer average pore size. But having additional "porous individual fibers" might facilitate in increasing the surface area of the fibrous mat. This will probably increase the adhesion of cells or biomolecules onto the surface, which is one of the important functional features targeted in the development of biomaterials.
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I am preparing temperature responsive in situ forming hydrogel loaded with Dox-Liposomes. i need to measure the particle size and zeta potential of hydrogel loaded Dox-Liposomes. I also  need to determine EE% of drug from Hydrogel loaded Dox-Liposomes. During particle size measuring, size of hydrogel particle was very higher as compare to Dox-Liposomes. i performed it with dilution of hydrgel -liposomes suspension. Is dilution  require for particle size measuring? If require, then at which ratio?
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The entrapment efficiency (EE%) is measured by dialysis membrane method.
the percentage of drug encapsulated was determined after lysis of the prepared liposomes with absolute alcohol and sonication for 10 minutes. The concentration of drug was determined by suitable method in triplicate. The encapsulation efficiency expressed as entrapment percentage was calculated through the following relationship:
Encapsulation efficiency % =Total drug−free drug/
                                                      Total drug                                ×100.
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I am searching what is the maximum molecular radius for protein based drug and/ antibody related drug.
If any one know please let me inform.
Thanks in advance.
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Hi Sanat,
If it is protein bio-therapeutics, 6-7 nm is max. The glomerular filtration process cannot filter proteins above this hydrodynamic radius. But, in some cases such as PEGylated bio-therapeutic proteins have around 9 nm. However, this is in cases of one which cleared through receptor/ ligand binding.
kind regards
Praveen
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For injectable application, what is the maximum viscosity of the formulation either microemulsion, or in-situ gel allowed to use? Is there any reference for this viscosity range of injectables?
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You can check some publications here: http://www.rheosense.com/publications
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Do nanocomposite ethosome degrade in the blood? Do ethosomal nano carreier release the drug in the blood? Do these carriers bring the drug into the cells? What factors affect the degradation of ethosomal in the blood?
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Hi Mehrdad, as far as I know, most ethosomes are destroyed during or after skin penetration.
The main question that should be asked is whether drugs carried by ethosomes are supposed to act locally or systemically.
If the drugs are to act locally, then administration will be easy.
If the drugs are to affect the whole body then they have to bind serum albumin. Any drug that does not bind serum albumin is eliminated by the kidneys within minutes. 
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hello i have question regarding intranasal drug delivery as drug delivered to the brain through nasal route will either bypass BBB (olfactory region) and/or remaining drug will either cleared by mucocilliary clearance or will go into the systemic circulation so i have que that during in-vitro permeability study (franz diffusion cell) which media should i use in acceptar campartment in order to mimic its permeation in brain & blood as well.......
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Hi,
These references should be useful, you will find cell culture models or excised nasal tissue as well as buffer systems used for permeation studies. It seems that oxygenated phosphate buffered glucose enriched solutions are of interest.
 M.Christiane Schmidt, Hagen Peter,Steffen R Lang,Günter Ditzinger,Hans P Merkle. In vitro cell models to study nasal mucosal permeability and metabolism. Advanced Drug Delivery Reviews, volume 29, Issues 1–2, 5 January 1998, Pages 51–79
P.M. Reardon, In vitro nasal models, in: R.T. Borchardt, P.L. Smith, G. Wilson (Eds.), Models for Assessing Drug Absorption and Metabolism, Plenum Press, New York, 1996, pp. 309–323
Best regards,
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I would like to know about the issues related with the application of metallic nanoparticles in ocular drug delivery. Specially for the drug delivery to the  the posterior segment of the eye. Which path they usually follow to cleared out from the posterior segment. What about the toxicity issue due to their possible deposition in the posterior segment if they are not able to move out from there. 
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Hi,
These are some 2017 publications relevant to your query:
Positioning metal-organic framework nanoparticles within the context of drug delivery–A comparison with mesoporous silica nanoparticles and dendrimers
S Wuttke, M Lismont, A Escudero, B Rungtaweevoranit… - Biomaterials, 2017 - Elsevier
,.,.,.,.,.,.,.,.,.,.,.,.,.,.,
Hydrophilic polymeric nanoparticles prepared from Delonix galactomannan with low cytotoxicity for ocular drug delivery
AT Ogunjimi, SMG Melo, CG Vargas-Rechia… - Carbohydrate …, 2017 - Elsevier
,.,.,.,.,.,.,.,.,.,.,.,.,.,.,,.,.,.,.,.,.,.,.,.,.,.,.,.,.,
A novel nanoparticles impregnated ocular insert for enhanced bioavailability to posterior segment of eye: In vitro, in vivo and stability studies
LV Rathod, R Kapadia, KK Sawant - Materials Science and Engineering: C, 2017 - Elsevier
,.,.,.,.,.,.,.,.,.,.,,.,.,.,.,.,.,.,.,.,.,,.,.,.,.,.,.,.,.,.,.,,.,.,.,.,.,.,.,.,.,.,
Naked eye and spectrophotometric detection of chromogenic insecticide in aquaculture using amine functionalized gold nanoparticles in the presence of major …
C Loganathan, SA John - Spectrochimica Acta Part A: Molecular and …, 2017 - Elsevier
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I am doing an experiment where I am applying a drug 40 microMolar to the apical dissolved in HBSS (500mcl total), and no drug just 1.5 ml of HBSS to the basolateral and then I measure the concentrations in the basolateral taking 100mcl and replace it with 100mcl HBSS to maintain sink conditions at different time points. and finally get the concentration using HPLC.
now how to calculate the cumulative concentration in the basolateral?!
Thanks.
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Hi,
At each sampling time 15% of drug that reached the basolateral compartment is discarded  (100mic/1500mic) which is a significant loss. If you don't consider this, concentrations measured will decrease with time because  of the dilution but also because the release rate will slow down as basolateral concentration come closer to the apical concentration. To obtain a cumulative concentration, it is quite simple you have to add the quantity of drug (mass) removed in the basolateral compartment in all previous samples except the fisrt one (Q= concentration measured at each time x 100mcl).
Hoping this will help you!
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I want to know flow rates of drug delivery systems. for example, insulin delivery needs very low flow rate. I am trying to know the minimal flow rate for every microinjection. 
Thank you for your answers.
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Hi Jasti,
it depends very much on the application. A diabetic 80 kg human needs about 80 IE Insulin per day as basal rate. Insulin is available in concentration up to 500 IE/ml. That would mean a delivery rate of  0,16ml/day or  0,007ml/hour or 0,1µl/min. But you can play with the reservoir and use Insulin solutions less concentrated.
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I've been synthesizing PLGA particles for the controlled release of different drugs. I'm wondering what is the impact of using PVA of different Mw. I've read about the impact of PVA concentration, but is there a optimal Mw?
 thank you in advance!
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I have gathered hundreds of articles (reviews too) on the effects of formulation parameters on the release or degradation of the microparticles, and I´ve found ZERO reference to the Mw of the PVA..I´ll keep asking! but thank you very much.
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Is there any standard protocol that I can use? My antigen is a model protein
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10.1128/JCM.43.12.5873-5875.2005 this article may useful to u 
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I am looking for the answer how metabolic nanoparticle bind to targeted agent in drug delivery system,& what is the relation with the surface area?
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You may need to consider the surface membraneous charge of your target cell, which is usually negative. Hence a positive surface would give higher association. If the surface of nanoparticle is having a targeting ligand for which a corresponding receptor exists on the target cell...thn it is definitely going to enhance the uptake via receptor mediated endocytosis.
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Hi every body, I am going to work in Computational nanomedicine fields, but i do not have any information about it, where should i start? thank you
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Dear Vahid, I must say that your question is so vague that no direct answer can be given.
It sounds like "I have a computer. What software should I install?"
It depends on what you will be doing within the "Computational nanomedicine" which I guess involves the use of a computer and nanomedicine (or will it be nanomedicines, ie, nano particulate systems?). You may only need to use Word if you are just writing reports of the work of your "computational" colleagues or doing a literature revision. A hand calculator or Excel (or similar) may be enough for calculations or you may need to use specific software for specific tasks. The good suggestion given by Rakesh is one of the choices when it comes to design of experiments, optimization (Design expert) as well as the Minitab for general statistical use. However, none of these are tailored towards "nano-whatever" and I never heard of any software designed to "nano".
I've been doing optimization of process, formula and methods as well as modeling and simulation for years and the choice of the software that I use(d) was never based on the kind of item (nano, tablets, powders, analytical, etc) but on the task to be performed.
My advice is to first know what are you exactly going to do and then you may ask for some advice on the software.
I hope you succeed in the quest of finding the right software.
Kind regards
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The project is very innovative and promising for the current and future generations.  I appreciate your initiative and novel ideas. I am interested to work on such project as collaboration. 
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Dear colleague, thanks a lot!
My answer is yes, you are free to give your contribution  for this project.
You are wellcome to us!
Sincerely, Bashkim
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I recently read several articles on single walled carbon nanotube based drug delivery system. However, in this field, multi walled carbon nanotube is less frequently used.
Does multi walled carbon nanotube has any advantages over single walled carbon nanotube in constructing drug delivery?
OR is there any difference about using single walled carbon nanotube or using multi walled carbon nanotube as the carrier for drug delivery.
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easy-fabrication?
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What I think is centrifuge filtration would it be a good test for encapsulation efficiency.
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Dialysis method can be applicable if the formulations are nano size. Bioactive agents loaded particles were dialyzed to eliminate free drug. Perform suitable spectroscopic method (UV/HPLC) to quantify the encapsulated drug.  
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I want to evaluate particle size distribution of Naproxen using Malvern or DLS. Something suggests to perform the analysis? For example, which solvent can I use?
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Water plus surfactant would probably work as a dispersant liquid - that would be my first try (unless you have the sodium salt which I'd expect to be water soluble). Or measure dry, if in powder form.  According to Wikipedia: "The free acid is an odorless, white to off-white crystalline substance. It is lipid-soluble and practically insoluble in water".  Attached MSDS from SigmaAldrich.
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I am looking for 3D software to generate the 3D bio-images. Except bio-chemdraw software, does anybody know what software is appropriate? I would be so thankful if you provide me with the download link/ purchase link. 
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Adobe illustrator, inkscape, CorelDRAW....
All these mentioned above software are used for 3D structure annotation 
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I am preparing niosomes from mix of Span 40,60,80 and Cholestrol and I want to use them for drug delivery. It has been long I am struggling with the concentration of ingredients. As I use 100mg for 10 ml of hydration medium which is equal to 2 e-4 mol/L, but the amount is very small to manage ( when weighting) .
My method is thin film hydration method and for now the molarity of Span which I prepare at first ( 50 cc solution of Chloroform/methanol) is 2 e-4 . I just wonder how I can determine the range of concentration which I will have the niosomes.
Thanks,
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Use stock solution dilution (after dilution another dilution on the first diluted, mean multiple dilutions) and vesicle bleach or hydrolysis and UV (Spectrophotometric, concentration based, dilution curve estimation) or HPLC-based quantitations. 
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I want to check the dissolution behavior of a liphophilic drug particles and want to know:
1- The exact dissolution medium
2- Weather or not to use membrane filters (If yes, type and size)
3- Optimal conditions (If changed from normal)
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Dear Syed,
Please refer my following published papers on pulmonary drug delivery systems.....
1. Patil JS, Sarasija S.Physicochemical Characterization, in vitro Release and Permeation Studies of Respirable Rifampicin-cyclodextrin Inclusion Complexes. Indian J Pham.Sci. 2009; 71(6):638-43. 
2.  Patil JS, Devi VK, Devi K, Sarasija S.A novel Approach for Lung Delivery of Rifampicin-loaded Liposomes in Dry Powder Form for the Treatment of Tuberculosis. Lung India. 2015; 32:331-8.
3. 28. Formulation and Evaluation of Novel Spray-dried Alginate Microspheres as Pulmonary Delivery Systems of Rifampicin in Rats. Indian J Pharm Edu Res. 2015; 49(4): 320-328. 
Hope you will get some idea. Please upvote my answer.
with regards
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If I prepare Eudragit nanoparticles and later convert it to suspension and use it as nasal spray, would it be ok? Remember drug is neither for respiratory tract, nor it has to target brain. I have not seen any article so far in which eudragit alone has been used in the nasal route. 
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What is the intended use of your Eudragit nanoparticle?..afterthat I can tell whether you should deliver Eudragit NP or not to deliver..
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I'm doing drug release using Franz diffusion cell. The medium is PBS. I'm taking 900uL samples at predetermined times and replace the amount taken with fresh PBS to maintain the sink condition. I'm not sure how to do a cumulative release plot (amount permeated vs time) because the absorbance data that I've got is going up and down( is that normal?). 
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Hi.
You didn't say anything about the drug, its solubility in the donor or receiver and the quantity in the donor, so this answer may be a bit long.
First, it is possible for the concentration to go down in the receiver if the amount of drug in the donor is mostly released to the receiver before the experiment is done.  In other words, if there is no more drug (or almost no more drug) entering the receiver, then taking samples of 900 uL and replacing the volume with empty buffer will end up diluting the receiver. (Depending on the variation of Franz cell you have, 900 uL will be about 5-7% of the receiver volume.)  
As far as how to make the cumulative amount released vs. time plot, you have to calculate the amount of drug that permeated the membrane, which is equal to the amount of drug in the receiver at the sampling time plus the amount in the samples that you assayed then discarded. Again, taking 900 uL (0.9 mL) of sample is significant when compared to a receiver volume of 10-15 mL. If done for enough samples, will amount to a large quantity of drug not accounted for if you only look at the instant concentration in the receiver. (By removing a sample and replacing with fresh PBS, you are discarding the drug in each sample.)
To calculate the cumulative drug released, do the following.
1) For each sample, withdraw the 0.9 mL of receiver and determine the concentration.  Multiply the sample concentration by the full volume of the receiver, including the 0.9 mL.  This is the amount of drug in the receiver at the sampling time t (an instant before taking the sample.)  Next, multiply the sample concentration times 0.9 mL to obtain the drug amount in that sample. (This is the amount of drug that you took out at time t that will NOT be in the receiver when you take the next sample later on.)
2)  At the next sampling time, take the sample and obtain the drug concentration. Then multiply that concentration times the full receiver volume (before taking 0.9 mL) and by the sample volume of 0.9 mL.  
Keep repeating, and make sure you keep track of the amounts  in each sample (conc. times sample volume at each time.)
3)  The cumulative amount released at each sampling time is the sum of the amount in the receiver at that time (Conc x reciever volume including the 0.9 mL) PLUS the amount in each sample that was removed and replaced with empty buffer. (In other words, the amount in the receiver the instant before taking the sample plus the amount you discarded from each PREVIOUS sample.)  
By the way, for the first sampling time, since there is no previous sample, the cumulative amount released at that first sampling time is just the concntration imes the full receiver volume. 
Hope this helps!
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Spesifically, for encapsulation protocol of hydrophobic drugs into PAMAM dendrimers, I need to optimize the required/adequate time to remove the non-encapsulated drug by dialysis against DI water. I'm trying to understand how to set the time before the system starts to release the encapsulated drug.
I'd be very happy if you could help.
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I don't have an answer, but here are some things to consider.
Is this hydrophobic drug appreciably soluble in water? If not, it probably won't be removed by dialysis in any reasonable amount of time.
Dialysis is a slow process, taking several hours to reach equilibrium across the membrane for a freely diffusible solute. If this time scale is comparable to the rate of release from the dendrimer, then dialysis would not be a good method.
Can you use a faster method of separating unincorporated small molecule from high molecular weight dendrimer? I'm thinking of gel filtration (gel permeation) chromatography, which can be fairly rapid since the high molecular weight component elutes first.
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So, this is not evaporation, as the container is tightly closed. Was there any rupture in the parafilm(R)? Did the parafilm seem even a bit hazy, moist or decolored or loose?. The volume decrease is, in all likelihood, retained by the material. I guess the dialysis is also not complete. An unwanted equilibrium is reached and the membrane becomes dry! Try using a bit + volume of the buffer (may be +110 uL). I guess the look at the molar requirements ratio for other dialyzes of the same material may be helpful! There is nothing wrong with the dialyzer or the set-up.
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We need to inject drugs into rat brain regularly, but that would do too much damage given to the needed frequency. We tried nano particle strategy and  those commercial SR pumps, but they didn't work well in our experiments. So I wonder if there's any other validated ways to inject the drug once and let it perform sustained release itself. Many thanks.
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have you heard of the Alzet brain infusion system? We have used them in mice and it is basically an Alzet mini osmotic pump which you insert subcutaneously on the flank which is attached to a guide canulae inserted into which ever brain region is desired. The ones we have used give constant infusion but I think you can get ones where you can programme drug delivery at set time points. http://www.alzet.com/products/brain_infusion_kit/index.html
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I see some papers have 10% w/v tween 80 or even more, but if we increase the concentration to 10% doesn't the dissolved drug or the particle get adhered to the tube? and also that might have some effects on the dialysis membrane?
Please correct me if I am wrong.
Thank you
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The critical micellar concentration of Tween-80 is about 0.0013% and the micelle molecular weight is 76,000. This means that the Tween-80 is not going to dialyze out of the bag in any reasonable amount of time, using dialysis tubing with a typical molecular weight cutoff (e.g. 10,000) if the starting concentration is as high as 10%. If a small molecule drug associates with the micelles because of its hydrophobicity, it will also not dialyze. Nanoparticles are generally too large to dialyze in any case. Depending on what they are made of, they may be dissolved by the detergent or coated by it.
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Hi, I am working upon nano medicines. Drugs are made targeted to the site of action. So, I am wondering for how a drug can be made a targeted one. How does it reach to specific area without prior loss or being harmed?
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Hi,
Your question is based on an open research topic which needs a lot of explanations. but there are few important things to be considered.
1- specific site targeted drug.
2- Ideal polymers
3- if sustained release, then particle size is the most important.
You can find many papers on each site specific delivery system. I hope this will help.
Regards
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I'm curious about different delivery methods for chronic THC exposure in adolescent rats (3 weeks). Typically, intraperitoneal injections of THC are used, but I'm wondering if there is an easier/less stressful method.
Some ideas I'm considering include:
1. Osmotic minipump implants. This might be the simplest method.
2. Food delivery. Mixing THC with a palatable food like strawberry/chocolate milkshake, or jello, with appropriate pre-exposure of drug and vehicle to avoid conditioned taste aversion. I know jello has been used with alcohol studies.
3. Catheter implantation. Daily intravenous delivery of THC would allow for very precise control of drug delivery according to daily body weight. 
I'd be very curious to hear of any ideas others have tried.
Thank you!
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Thank you so much to Dr. Tatiparthi and Ms. Hampton for your suggestions. 
Indeed, the food delivery method is flawed, though enticing. I assume this is why others in the past have stuck with IP injections for reliable/efficient delivery of THC.
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Dear Folks, struggling for a good intra-nasal delivery of vaccine although my vaccine is working perfectly by SC and IM routes. Tried with same IN route but is not working. Could you please suggest about the possible excipients or compounding materials to formulate, so it will be staying into the nasal cavity or thereby lungs for a while. It's need to be stayed as well as uptaken by antigen presenting cells, macrophages or other immune cells for better IgA or IgG response. Do I need to think about something to be included in the vaccine that can help or enhance the penetration of intranasal membrane barrier or mucous around the nostril's or nasal cavity? Your advice or suggestions will be highly appreciated. Thanks.
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Hi
This two links I think help you, read carefully
Search Results
Strategies for intranasal delivery of vaccines
www.ncbi.nlm.nih.gov › NCBI › Literature › PubMed Central (PMC)
by M Zaman - ‎2013 - ‎Cited by 22 - ‎Related articles
Jul 12, 2012 - This review describes vaccine formulations designed for mucosal delivery to the nasal-associated lymphoid tissue, via intranasal administration ...
You've visited this page 2 times. Last visit: 6/11/16
Advantages of Intranasal Vaccination and Considerations on Device ...
www.ncbi.nlm.nih.gov › NCBI › Literature › PubMed Central (PMC)
by M Birkhoff - ‎2009 - ‎Cited by 6 - ‎Related articles
Oral and Intramuscular vaccination has been considered till date as the ultimate ways, but nasal route offers advantages such as ease of self administration and ...
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Attached Figure is showing the thermal release of entrapped drug. Free drug, Free nano-particle and entrapped drug (Np+drug) is determined at different temperature (25-300 C). Why the drug lose its UV-Vis absorbance when it was entrapped in nano-particle?!!?
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Hello Pashandi,
I saw that your nanoparticle doesn't absorve on UV-Vis, so I believe it is Silica or something like that.
If I undertood, the free drug is inside of nanoparticle. If it is inside, the free drug is not interacting with the light. The suface of nanoparticle is blinding it. 
And others cases, when a molecule adsorbs on nanoparticle surface, it may not appear on UV-Vis cause it's bonding properties may change.
It is just an Idea...
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The purpose of the mini-pump is to deliver in a sustained manner the compound known as 7-OHDPAT over a period of 2 months...
     Thanks in advance for your comments!!
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Dear Rafik and Anwar,
     Thanks a lot for your valuable advice and information supplied. The mini-pumps have been successfully implanted and work well hence no concern with unexpected blood flushes. We are going to determine the initial and final 7OHDPAT concentrations in the pump solutions and plasma by HPLC.
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Attempting to find the Encapsulation Efficiency%, by dissolving the drug loaded matrix in a suitable solvent,the color of the drug is visible on the matrix surface even after several washes.
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Start with known quantity-concentration of the drug and similar ratioed quantity-similar ratioed weight of the matrix (material need to be of same - structure and density also). If you used fresh curcumin - use fresh here too. Treat both -drug and matrix in the way it simulates or nearly simulates (especially pH care needed, solvents acidity-basicity at trace levels, temperature, shaking intensity and time etc.) your original experimental conditions. Run quantitative analysis for the simulated experiment recovered drug and compare to see how much drug is returned after retaining by the matrix. Both UV-Vis (not just UV) and HPLC can be employed to see concentration. 
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can anyone please mention a very simple method to study the drug release from an electrospun PLGA mesh by taking in conservation that it's hydrophobic
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You could use a dissolution medium at an adequate physiological pH (1.2 if the release is intended to be in the stomach; 4.5 if is in duodene; 6.8 if release is on lower intestine; or 7.0 for neutral environments) added with small amounts of Sodium Lauryl Sulphate (SLS, 0.1-1.0% p/p is currently used in dissolution tests) or Tween 80. Decide if mesh will be introduced into a rotating basket or will be submerged into the dissolution medium. I hope this helps you in some way. Best regards.
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Also tell how much volume of liquid should be used to redisperese them. How much amount of sample should be taken to redispere in liquid.  Kindly give a detailed reply
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You should strictly disperse them under conditions expected for further use, e.g. it does not make sense to disperse them in a special solvent if its application is in water buffered to a fixed pH value and defined electrolyte content.
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It will be done in mice
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I was more thinking on intracraneal injection but I don't know if delivering the drug into the ventricles would be fine or I should do the injection in the cerebellum directly. 
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How we can predict the "n" value in Korsmeyer peppas release model? 
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Take “ln” on both sides of the equation. Then your equation would be ln(Mt/Mi) = ln (k) + n*ln (t).
The plot the graph for ln (Mt/Mi) versur ln (t). Slope of that equation is “n”
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Dear all,
I have been trying to deliver a very small (# 3 kDa) and hydrophobic peptide into cells in order to study on its biological function in neurons and pc12 cells using different methods, but I found that the efficiency was very low <5%. Recently, I am advised to use micelles for that purpose, so I am just wondering if anyone has some experience about micelles and can give me some advice?
Thank you,
Khalil
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Dear Norbert, thank you so much for your kind advice. I really appreciate it. I am going to synthesize the peptide and test it. I let you know the result.
Thanks a lot:-)
Khalil
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i am preparing nanoparticles, drug is hydrophilic and entrapment efficiency is very low. If i find the drug release by dividing with the total drug taken its giving very low drug release so is it possible to find drug release by dividing with the total drug entrapped? Kindly send if there is any reference for it. 
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Along with all previous answers... consider correction factor every time if your are doing replenishment of your disso medium.
All drug may not be entrapped in carrier system during NP preparation hence its mandatory to find how much drug exactly incorporated in NP against total amount of drug added by you in preparation.
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We are working on an intracellular delivery technology and have verified cytosolic delivery of a membrane impermeable dye and dextrans, but are having trouble with GFP plasmids and need to check if we are getting cytosolic delivery. Any tips on how to do this?
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Dear Ryan S Pawell,
The following few publications may be helpful:
1- Research Article
Gene Therapy (2003) 10, 72–83. doi:10.1038/sj.gt.3301859
Enhanced cytosolic delivery of plasmid DNA by a sulfhydryl-activatable listeriolysin O/protamine conjugate utilizing cellular reducing potential
G Saito1, G L Amidon1 and K-D Lee1
1Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, MI, USA
Correspondence: K-D Lee, Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, 428 Church St., Ann Arbor, MI 48109-1065, USA
Received 1 March 2002; Accepted 16 June 2002.
Topof pageAbstract
Listeriolysin O (LLO), a sulfhydryl-activated pore-forming protein fromListeria monocytogenes, was tested and utilized for promoting plasmid DNA (pDNA) delivery into the cytosol of cells in culture. To render pDNA-complexing capability to LLO, the unique cysteine 484 of LLO was conjugated to polycationic peptide protamine (PN) at a 1:1 molar ratio through a reversible, endosome-labile disulfide bond. The sulfhydryl-oxidized LLO construct, LLO-s-s-PN, completely lacked its pore-forming activity, yet regained its original activity upon reduction. The enhanced cytosolic delivery using this construct therefore relies on the requisite reduction of the disulfide bond in LLO-s-s-PN by endogenous cellular reducing capacity. Condensed PN/pDNA complexes incorporating LLO-s-s-PN were tested for their enhanced gene delivery capability monitoring reporter gene expression in HEK293, RAW264.7, P388D1 cell lines and bone-marrow-derived macrophages in the presence of serum. Dramatic enhancement was observed for all tested complexes with varying weight ratios. The effect was most prominent at 0.64–0.80 (w/w) of PN/pDNA upon replacing 1–4% of PN with LLO-s-s-PN, resulting in approximately three orders of magnitude higher luciferase expression compared to PN/pDNA without apparent toxicity. These results demonstrate that incorporation of endosomolytic LLO into pDNA delivery systems in a controlled fashion is a promising approach of enhancing delivery into the cytosol of target cells in gene delivery strategies.
2-Angew Chem Int Ed Engl. 2015 Dec 7;54(50):15105-8. doi: 10.1002/anie.201505913. Epub 2015 Oct 30.
Detecting Cytosolic Peptide Delivery with the GFP Complementation Assay in the Low Micromolar Range.
Schmidt S1, Adjobo-Hermans MJ1, Wallbrecher R1, Verdurmen WP1,2, Bovée-Geurts PH1, van Oostrum J1, Milletti F3, Enderle T4, Brock R5.
Author information
 
Abstract
Transfection of cells with a plasmid encoding for the first ten strands of the GFP protein (GFP1-10) provides the means to detect cytosolic peptide import at low micromolar concentrations. Cytosolic import of the eleventh strand of the GFP protein either by electroporation or by cell-penetrating peptide-mediated import leads to formation of the full-length GFP protein and fluorescence. An increase in sensitivity is achieved through structural modifications of the peptide and the expression of GFP1-10 as a fusion protein with mCherry.
3- Metabolic instability of plasmid DNA in the cytosol: a potential barrier to gene transfer
D Lechardeur1, K-J Sohn1, M Haardt1, P B Joshi2, M Monck2, R W Graham2, B Beatty3, J Squire3, H O'Brodovich4 and G L Lukacs1,3,a
Inefficient nuclear delivery of plasmid DNA is thought to be one of the daunting hurdles to gene transfer, utilizing a nonviral delivery system such as polycation-DNA complex. Following its internalization by endocytosis, plasmid DNA has to be released into the cytosol before its nuclear entry can occur. However, the stability of plasmid DNA in the cytoplasm, that may play a determinant role in the transfection efficiency, is not known. The turnover of plasmid DNA, delivered by microinjection into the cytosol, was determined by fluorescence in situ hybridization (FISH) and quantitative single-cell fluorescence video-image analysis. Both single- and double-stranded circular plasmid DNA disappeared with an apparent half-life of 50-90 min from the cytoplasm of HeLa and COS cells, while the amount of co-injected dextran (MW 70000) remained unaltered. We propose that cytosolic nuclease(s) are responsible for the rapid degradation of plasmid DNA, since (1) elimination of plasmid DNA cannot be attributed to cell division or to the activity of apoptotic and lysosomal nucleases; (2) disposal of microinjected plasmid DNA was inhibited in cytosol-depleted cells or following the encapsulation of DNA in phospholipid vesicles; (3) generation and subsequent elimination of free 3'-OH ends could be detected by the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay (TUNEL), reflecting the fragmentation of the injected DNA; and finally (4) isolated cytosol, obtained by selective permeabilization of the plasma membrane, exhibits divalent cation-dependent, thermolabile nuclease activity, determined by Southern blotting and 32P-release from end-labeled DNA. Collectively, these findings suggest that the metabolic instability of plasmid DNA, caused by cytosolic nuclease, may constitute a previously unrecognized impediment for DNA translocation into the nucleus and a possible target to enhance the efficiency of gene delivery.
4-Detecting Cytosolic Peptide Delivery with the GFP Complementation Assay in the Low Micromolar Range
Transfection of cells with a plasmid encoding for the first ten strands of the GFP protein (GFP1-10) provides the means to detect cytosolic peptide import at low micromolar concentrations. Cytosolic import of the eleventh strand of the GFP protein either by electroporation or by cell-penetrating peptide-mediated import leads to formation of the full-length GFP protein and fluorescence. An increase in sensitivity is achieved through structural modifications of the peptide and the expression of GFP1-10 as a fusion protein with mCherry.
5-Cytoplasmic delivery of proteins and DNA by pH-sensitive liposomes
The technique of introducing exogenous DNA into living cells, known as transfection, is a commonly used and very important approach in molecular biology. A number of methods have been developed to achieve this, 1-12 but none of them can likely be used in vivo studies. In this paper we would like to introduce a pH-sensitive immunoliposome delivery system that can efficiently deliver such macromolecules in vivo in a target-specific manner.
Mechanism of delivery
Immunoliposomes are lipid vesicles coated with antibodies that have been attached with hydrophobic anchors.13 These surface antibodies direct the specific interaction of liposomes with antigen-expressing cells. Previous studies revealed that the bound vesicles are taken up by cells through a receptor-mediated endocytotic process.14 To prevent liposomes and their contents from being delivered to the lysosomes for degradation, pH-sensitive immunoliposomes are developed to enhance a prelysosomal discharge of the liposome contents into the cellular cytoplasm.
It was found for the first time in this laboratory that liposomes composed of unsaturated phosphatidylethanolamine and a weakly acidic amphiphile, such as fatty acid, become destabilized and fusion-competent when the pH of the medium is reduced to below 6.5.15 If these types of liposomes are endocytosed into endosomes that have a pH range of 5 to 6.5,16,17 they will release their contents into cell cytoplasm by fusing with the endosome membrane from within and/or rupturing the endosome membrane.18 The prelysosomal discharge of the liposome contents significantly enhances the cytoplasmic delivery efficiency of the liposome for anti-tumor drugs,19toxin20 and DNA.18,21
Hoping this will be helpful,
Rafik
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The use of Organic Solvents in performing the release studies for Hydrophobic drugs is commonly seen. The main aim of the study is to see the release pattern of the drug from the formulation and to have some correlation with its in-vivo behaviour.
Most of the time we see similar methods used in publications for performing the release studies, irrespective of the type of formulation and route of administration, which is not convincing. 
I would also like to know how we can design release studies in such a way that it mimics the in-vivo conditions. 
Finally, can we justify the use of organic solvents and surfactants for in-vitro release studies and correlate with in-vivo behaviour?
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In dissolution study, they are use for maintenance of sink condition. 
Similar justification was given in below article. They given good justification for Polymeric and Lipidic microparticulate systems.
Title: Accelerated in vitro release testing methods for extended release parenteral dosage forms 
link of article.
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I am wondering whether there are some experts in osmotic pump field who may kindly help me with the following questions:
What is the most important parameters involved in controlling the internal pressure? What kind of material could be used to make the "outer coat", only allowing for water to traverse?
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The outer, rate-controlling layer of the osmotic pump is basically a cellulose ester blend which forms a semi-permeable membrane. The rate of delivery is controlled by the water permeability of the pump’s outer membrane. The release rate for each pump model is fixed at manufacture (according to proprietary membrane formulations for each pump model), and cannot be changed. The pumps operate by osmotic displacement. The high osmolality of the salt sleeve (middle layer) causes water to flux into the pump through the semipermeable membrane. As the water enters, it compresses the flexible reservoir, displacing the test solution from the pump at a controlled, predetermined rate. Note that the outer semi-permeable membrane is selective to water and you do not need to make any modifications to his "outer coat". A video of the pump mechanism is available at this link...
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I have tried to separate it using centrifugation at 12000 rpm for 10 min. 
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Tangential Flow Filtration 
You can avoid dilution (which is happening during GFC/GPC) and you can further concentrate the liposomal solution (Ultrafiltration) and you can remove untrapped drug from liposomal solution and buffer exchange with final formulation buffer.
Advantages : 
1. Avoid dilutions and you can further concentrate the liposomal solution
2. Buffer exchange or Dia-filtration : When you select the right MWCO of your TFF membrane ( Cassette / Hollow fiber) , you can retain your desired liposomal solution in retentate side and untrapped drug and other low molecular weight impurities and salt will be removed in diafiltration. You can also use and customize dia-filtration buffer wisely.
Please write me on ymk108@yahoo.com if you need further support.
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Am currently working with NIVs and am struggling to understand why, if discovered in the 1970s and first utilised as a drug delivery system (DDS) in 1985 (Chemotheraphy), why has their use as a DDS not been more widely used? Only recently (2012), has their use as a DDS been a primary focus with intention to move into human trials. Has it been a technological barrier? (I.e. manufacturing at a commercial scale) or something else? 
Any answers or resource you can direct me to would be amazing.
Thanks in advance.
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Michael-Jon Rosslee,
FDA guideline M3(R2) states that:
In vitro metabolic and plasma protein binding data for animals and humans and systemic exposure data in the species used for repeated-dose toxicity studies generally should be evaluated before initiating human clinical trials.
The lack of comprehensive toxicity studies (pre-clinical) for non-ionic surfactants in the past, to warrant a clinical trial could be a reason for the lack of widespread NIV applications.
This might help:
(Yadav et.al, 2011)
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Greetings to everyone,
I want to deliver siRNA to Cardiomyocytes (Heart) using liposomes or polymeric nanoparticles or any other drug delivery vehicle.
For the targeted delivery to cardiomyocytes, I am looking for some specific protein which are specifically expressed or over expressed on surface of heart muscles. I would be glad to know the appropriate size of drug delivery vehicle to deliver the content in heart muscles. 
So please suggest me some appropriate marker to target the cardiomyocytes using drug delivery vehicles.
Thank you in advance :)
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You could try Integrins to target cardiomyoctes. But look for the specific one's which are overexpressed on them. 
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Nowadays so many research articles only indicate their compound treatment group only. they do not compare with any standard drug. kindly send the reasons
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Dear Arun,
Uusually, All of researchers use of Ctl + in their researches. As DR Béatrice Marianne Ewalds-Kvist  conveyed in drug treatments, the most researchers use of CTl + such as saline or anything else. also when we want to evaluate the effect of Sage "Salvia Officinalis" on reproductive traits we used of water as Ctl +
regards
Mehdi
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Thank you.
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No. You will place your nanoparticles in dialysis membrane available in the form of tubes and cassets. These nanoparticles filled systems will be placed in dissolution medium. If you place nanoparticles directly into disssolution medium, they will get removed when you take samples.
These are two examples. Please ask you supplier to find best options.
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There are many protocols available, but unfortunately the solvent used give a high background reading and therefore i can not detect my drug.
Which method is more useful when measuring the encapsulation efficiency using UV/VIS at 360nm?
Thanks in advanced!
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Crushed PLGA spheres are to be kept over night in a little amount of solvent in which drug is soluble. Next day the mixture is filtered and diluted with solvent, and absorption is measured. With the help of standard curve amount encapsulated can be calculated.  Otherwise, as Naga mentioned, dialysis is best method.
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I am working on Phytosomal drug delivery of herbal extracts. I am finding difficulty in getting phytosome using methanolic extract of plants. Please suggest the reference or your experience in Phytosomal preparion using Lecithin.
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Phytosomes can be regarded as liposomes of natural ingredients. On the other hand, liposomes with alcoholic core are called ethosomes. Please see following paper for methods of preparation.
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Water for injection, drug industry
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Mr Abhishek has quite clearly defined the differences. The basic purpose in industrial development process is regarding development in line with cost of raw material, such as here Water. A non-pyrogenic injectable would require especial care as also Mr David Bautista reflected. Thus injectable differ as LPN (long term / infusions) and SPN (active admin); nature of water selection is thus critical with respect to the exposure time of such pyrogens clinically.
Thus based on your formulation, requirements of particular water complying with monograph must be considered.
best regards
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I need to buy some transdermal patches for Nicotine, Fentanyl, Nitroglycerin, Scopolamine, Sumatriptan generic one for research purpose. Preferably want to buy from India as I am going to visit there. Also anyone has done any experiment on this type of patches will be appreciated to contact.
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Hi Rajesh and Kailash, thanks a lot. My friend is in India now. I will inform him.
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Kindly respond rapidly.
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It depends on what is the continuous phase used for fabrication of nanoparticles. Assuming, the NP are prepared in aqeous base system, with DCM as the solvent., then vacuum pressure of 300- 500 mBar should be more than sufficient. Also, temperature of the system will be very important. Adjust the temperature close to boiling point of DCM i.e. 40 C. As the tg for eudragits is close to 65 C it will not hamper the shape/ structure of formed nanoparticles. Time is a dependent factor and relies on pressure and temp as independent factors.
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Hi,
I am preparing nanoparticles by w/o/w double emulsion method.Firstly I am sonicating w/o emulsion at 70 % amplitude for 2 minutes by using sonics vibracell ultrasonic processor 500 W, 20 kHz and then again sonicating the w/o/w emulsion for 2 minutes at 70 % amplitude using sonics vibracell ultrasonic processor 500 W, 20 kHz. Is it right? 
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Mine is under review right now in JCR (hoping for the best (-:) but anyway it's based on the double emulsion method described in Saltzman paper: http://www.sciencedirect.com/science/article/pii/S014296120900115X
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To study release of a hydrophobic drug, I need a method that may to evaluate how much drug dissolves in PBS in time? I have some difficulties to obtain good results using UV-vis, can someone recommend any articles on this topic? 
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Dear Alessia,
First of all you have to choose the release medium according to the dosage form of the drug, IV, IM, SC, Solution, enetric coated tablets or regular tablets. For hydrophobic drugs, PBS with pH 7.4 with 2& surfactant such as SLS (you might change the percentage of the surfactant according to the solublity of the system) and mixing by shaker at 37 degrees is generally used.
The following links contain publications for the release of hyrophobic drugs incorporated in a variety of vehicles:
Hoping this will be helpful,
Rafik
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Transdermal drug delivery
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Dear Heba,
Please read the following text which contains the required equations along with an example:
One can estimate the skin input rate of a drug required from its transdermal system based on volume of distribution (Vd), total body clearance (ClT) and steady state or therapeutic concentration (CPss) under steady state conditions, the drug input rate from its transdermal system is expected to be equal to its output rate, determined by total body clearance multiplied by the therapeutic plasma concentration. This relationship can be expressed using following mass balance equation; input rate = dosing rate × bioavaliable factor (F), output rate = total body clearance × steady state plasma concentration and input rate = output rate or F × dosing rate = CLT×CPss….1, where CLT is total body clearance, CPss is average target plasma concentration. Since epidermis is metabolically inert, F = 1. For most drug compounds, total body clearance is the product of volume of distribution and total elimination rate (KE), CLT = KE × Vd….2. Thus the required flux from a transdermal patch can be calculated by normalizing the dosing rate Eqn. 1 for the surface area (A, cm2); Flux, Jss = CLT × CPss/A…3.
Here is an example to determine the feasibility of the anticonvulsant drug, primidone for 10 cm2 transdermal patch, currently administered 750 mg/day as a tablet. The required flux (Jss) or input rate can be calculated from the pharmacokinetic properties of the drug, therapeutic concentration 10 μg/ml, total body clearance and elimination half-life which was determined to be 0.78 ml/kg/min and 4 h, respectively, permeability coefficient is 5 × 10−3 and saturation solubility is 1 mg/ml5.
Since the drug is absorbed completely, F = 1, the required output rate of primidone can be calculated from Eqn. 3; CL = 0.78 ml/kg/min × 70 kg (normal body weight) = 54.6 ml/min = 3276 ml/h. Out put rate = (3276 ml/h×10 μg/h) ÷ 0 cm2 = 3276 μg/cm2/h. The input rate, transdermal flux in this case, is 3.3 mg/cm2/h is required from the transdermal patch of primidone. The mass of drug that can be delivered across the skin is M = Pestimate × Cs = 5×10−3×1 = 5 μg/cm2/h the area of the patch required to deliver therapeutic plasma level of primidone is Jss ÷ M = 3300 μg/h ÷ 5 μg/cm2/h = 660 cm2
For more details, use the following link:
Hoping this will be helpful,
Rafik
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After collecting supernatant which pore size filter is used to filter the supernatant? After filtration do we take its UV absorbance or to do anything in between? After taking its absorbance what to do next?
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I agree with Rafiq Karaman, you should construct a callibration curve.
For this purpose, you will make a number of dilution of known concentration and take their absorbance in UV-Vis spectrophotometer. Plot a graph in MS Excel between concentrations (x-axis) and their absorbances (y-axis). Then, you can take trend line to see if calibration curve is predictable  (R2 value is near to 1 i.e. 0.99) and show equation of graph.
In this equation, you will need to replace "y" with value of your absorbance of supernatant and you will find the the of "x", the concentration of drug in sample.
You can collect supernatant by centrifugation or by use of dialysis tube. Dialysis tube of differetn Molecular Weight Cut-Off are available that can retain nanoparticles but un-encapsulated molecules will come out of tube membrane due to smaller size. Usually we formulate drug loaded nanoparticle so that drug is released at desired rate. One disadvantage of using dialysis tube or similar membrane systems is that they need significant time for separation. During this time, a significant amount of drug is release which was actually encapsulated inside nanoparticles. Thus, you might find lower encapsulation than actual. Centrifugation may be less efficient in some cases but need relatively lower time.
Is this information helpful?
Regards, Mubashar Rehman
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Prompt response will be appriciated.
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First of all I would like to have a clear view about standard solution. What do you mean by standard solution?? A higher absorbance of drug in supernatant is generally observed when 
1. the centrifugation speed utilized is not sufficient enough to settle down all the drug loaded nanoparticles. This leads to presence of drug loaded nanoparticles in supernatant along with free drug. To confirm wheather all the nanoparticles have settled in form of pellet at particular centrifugation speed, you need to carry out mas balance equation. You have to collect the pellet after centrifugation. dry it and weigh it. now find the entrapment efficiency. Now calculate mass balance.
eg: If you took 100 mg polymer and 50 mg drug so total weight of nanoparticles will be 150 mg in case of 00% entrapment.
Now, if you get entrapment efficiency of 50 %..it means only 25 mg drug got entrapped. so weight of your NP will be 125 mg.. accordingly you can calculate mass balance. If its nt correct then you need to increase speed and time of centrifugation.
2. Second reason is related to interaction of drug with polymer leading to shift in absorbance which may b high or low. In that case u need to study compatibility of drug with polymer in form of solution. Drug polymer and solvent in which you are making nanoparticles. If same absorbance of drug is obatained in all cases then its okk or else you will have to go for derivatization method for estimation of your drug. 
You can cross check both the point by using HPLC for precise result.
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Using stealth liposome is one of the best option to target cancer cells but it also destroys host cells because liposomes are not able to differentiate exactly between cancer cells and host cells. Targeting through antibody mediated liposomal drug delivery specific for cancer surface receptors may have some immunological complexions. Is there any other method to avoid immune reaction from host? Or Is there any method to specifically target cancer cells? Any Ideas/Suggestions are welcome...
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Liposomes are a type of passive targeting since you can use the EPR. Also you can create immunoliposomes to active target receptor overexpressed in cancer cells. Since you have problems with that you can overcome the immunological problems of the immunoliposomes. Ligand-receptor approach is interesting if you can use the overexpressed ones in cancer cells.
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Need urgent reply. 
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Dear Pharmacis,
The answer is NO. You can not proceed without centrifuge and washing. Please follow the following steps:
Nanoparticle Collection
1-Split the hardened nanoparticles into two Oak Ridge centrifuge tubes (30 ml nominal volume) and balance to within 0.1 g.
2-Centrifuge nanoparticles in a fixed-angle rotor for 15 min at 17,000 x g. Longer centrifugation times will result in the collection of a higher fraction of smaller nanoparticles.
3-Discard the supernatant, being careful not to disturb the nanoparticle pellet (water may be poured orpipetted off). Add 15 ml diH2O and use a water bath sonicator and/or vortexer to completely resuspend the nanoparticles.
4-Combine the contents of the two centrifuge tubes into one and repeat steps 2.1-2.3 2x more, for a total of three washes in 30 ml of diH2O each time. The fluid volume of the last pellet resuspension should be 4-5 ml.
A weight ratio of 1:2 trehalose:polymer may be added at this point as a cryoprotectant (freeze a small aliquot of nanoparticles without trehalose for SEM imaging). Ice crystals that form during the freezing process may damage the particle surface and induce aggregation, and inclusion of trehalose has been shown to improve the uniform and complete resuspension of PLGA nanoparticles13.
5-Transfer the nanoparticles to a preweighed 5 ml centrifuge tube and freeze at -80 °C for a minimum of 30 min.
6-Moving quickly so as not to let the frozen contents melt, uncap the tube and cover the top by securing lab tissue across the top with a rubber band. **If any melting occurs, refreeze before placing in the lyophilizer.
7-Lyophilize 72 hr for a 5 ml volume. Store lyophilized particles in Parafilm-wrapped tube at -80 °C.
Hoping this will be helpful,
Rafik
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It has become very common practice with supplements to administer some through the Buccal delivery method (sublingually). In fact, Resveratrol is best absorbed when taken under the tongue and when bypassed the gastrointestinal tract totally.
My question, can you put cycloastragenol powder underneath the tongue for better absorption into the bloodstream and better activation of telomerase ? Is Cycloastragenol one of the supplements that can be absorbed through the lining of the mouth? Thank you, Brooks
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Thank you 
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Dear all, Are there anyone send me a standard (ASTM) procedure to determine the solubility of a prepared polymer at aqueous buffer solution?
We are trying to prepare an aqueous soluble polyimide for using as an enteric coating for controlled drug delivery.
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good answer, I would like to add: one should make 
a) particle size measurements (Laser-Doppler or Light diffraction)
b) determine concentration in the "solution" 
c) then filter using nanosized pore membranes (I don't remember how small they are available)
d) then measure concentration and particle size again
if you lost something, you did not have a true solution.
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Generally nanoemulsion is prepared by first calculating solubility of drug in oil phase then further titrating it using water and the system stabilized by a surfactant. I want to know the preparation procedure if i am using a drug that is in oily state (for example clove oil). Will i have to perform any solubility study when my drug itself acts as an oil phase? 
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Also, you can see my other newly published article in this area, from below link.
“Shahavi M. H., Hosseini M., Jahanshahi M., Meyer R. L. and Najafpour G. D. (2015) Evaluation of critical parameters for preparation of stable clove oil nanoemulsion. Arabian Journal of Chemistry, Elsevier, Impact Factor: 3.725, ISSN: 1878-5352, DOI: 10.1016/j.arabjc.2015.08.024”
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Many works have been reported so far on various drugs belonging to many categories like anihypetensives, anti-lipidemia, etc etc. But i want to know if any of the drugs have been marketed?
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THANK YOU SIR.
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Trying to develop a sub-lingual delivery system for free sterols without converting them to esters.
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Dear Mathhew,
HPMC will be fine,
HPMC is a very good and different grades viz Methocel E3, Methocel E5, Methocel E15 Premium LV, etc.are available. Other natural polymers starch and pullulan can also be a choice.
Regards
Dr Shuaib
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If I prepare Eudragit nanoparticles and later convert it to suspension and use it as nasal spray, would it be ok? Remember drug is neither for respiratory tract, or it has to target brain. I have not seen any article so far in which eudragit alone has been used in the nasal route. 
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You need to check the MSDS of the excipients and also need to check the drug interactions if any.
Information regarding the comprehensive characterization of the physical and
chemical properties of the drug substance should be known as it will be inhaled. 
Also acceptance criteria for physicochemical parameters of a qualified polymeric
excipient for nasal spray must be of concern (e.g., molecular weight distribution etc.
Kindly do check all the above and related parameters.
Good Luck
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Calculation of permeability
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Hello! 
I have the same question now.. Did you find your answear?
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load drug-silver nano particles composite inside superporous hydrogel structure. 
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May this review help you,moreover, there are some articles may help you. Good luck.
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