- Manuel Roman Pina-Monarrez added an answer:7Can any body help me to learn how to fit drug release data into Weibull Function in Excel?
Hi all. I need to fit my drug release data into Weibull function to know about the mechanism of drug release.
The formula for weibull function is F = 1 − exp(−atb). where F is the drug fraction released at time t, and a and b are constants. b, as a shape parameter, is characterized as exponential (b = 1), sigmoidal (b >1), or parabolic (b < 1).
Can some one help me HOW to fit or put my drug release data into this formula using microsoft excel sheet?
Nauman, I am familiar with Murat advised, Only, in the estimation of ln(-ln(1-F(t))), since F(t) is estimated by the median rank given by the Benard's approximation given by F(t)=(i-0.3)/(n+0.4), then the sample size n has big impact in the estimated b and a parameters. Thus, in order to select the right n, you has to determine first the desired or expected reliability percentile R(t), and based on R(t), determine n as n=-1/ln[R(t)]. (see eq.(35) of the reference paper given below).
In particular, since b is completely determined by the standard deviation of the lifetime data [eq.(41)], and a is completely determined by the mean of the lifetime data [eq.(46)], then, selecting the right n is determinant to accurately estimate the b and a parameters.
My paper where these issues are addressed and solved is "Weibull and lognormal Taguchi analysis using multiple linear regression". which is uploaded to RG. Please observe that in addition to estimate n correctly, the paper also gives the method to determine b and a for a desired combination of the factors that determine your life times. Thus, if you have the factors that determine the lifetimes you can use them in the estimation of the related Weibull family. Any question related to the paper content or how it could be implemented by using your data, please let me know.
- Sonal Mazumder added an answer:9What concentration of nanoparticles should be used for release studies - Is sink condition the determining factor?
How important it is to maintain sink conditions during drug release studies from nanoparticles? What should be the concentration of pure drug and drug in nanoparticles in the buffer to start with? Is there a way to decide that? I have drug incorporated in polymeric nanoparticles.
- Adeel Masood Butt added an answer:2Why is important to lyophilize drug-loaded micelles before drug release curves?
I have drug loaded polymeric micelles, and i read in some papers that lyophilized and other non-lyophilized before the drug reléase.
Usually we lyophilize the samples for stability and storage. As you can not keep the micelles in solutions for long time (for storage), so it is better to freeze-dry. Then you can use the freshly prepared micelle solutions for release experiments or for any other required assay.
Hope this helpsFollowing
- Poulami Majumder added an answer:8How do I assure a sustained release for a weakly basic hydrophobic drug?
I am trying to make a sustained release system of a hydrophobic drug (significantly soluble in DMSO only, not in methanol/acetonitrile/choloroform, etc). The drug is NOT aromatic but has a nitrogen and pka ~ 8.3. It always leads to a burst release when I tried to encapsulate within neutral liposomes composed of DOPC/DOPE/Cholesterol, etc. I dissolved the drug in DMSO, mixed app. amount (10:1 lipid: drug in w:w) with other co-lipids, swelled overnight with water and removed unentrapped drug by centrifugation. Encapsulation efficiency was ~50-60%. But it was released entirely within 3 h. Then I tried to use the citrate salt of the drug (water solubility ~ 1 mg/ml) for remote loading into the neutral liposomes (DOPE/DOPC in 1:1) after forming transmembrane pH gradient. Now, I found no encapulsation at all. Please suggest something so that I am able to reduce the burst release for the drug. Any help is appreciated. Thanks!
Many thanks for your extensive reply. My drug is a nitrogen base containing pyrimidine and piperidine rings with a mol wt of 313 for the free base form. The drug is really leaky because my first trial was to load it into a hydrogel for making a sustained release system and that too did not work for the drug, so I decided to load into the liposomes first and then put the liposomal drug into the hydrogel.
I tried the following:
1. to load the free base form in the lipid bilayer. It shows ~ 80% encapsulation.
2. Loaded an inclusion complex of the drug with beta-cyclodextrin into liposomal aq core with ee of ~ 60%
3. Loaded the water soluble citrate salt of the drug (solubility 1 mg/ml) into the aq core and had ee of ~ 50%.
But none of these does not lead to any improvement of the burst release profile when I put the liposomal drug into the hydrogel. So, I decided to check with transmembrane gradient.
Many thanks for your suggestions. Hopefully this time it would turn out well.Following
- Lefnaoui Sonia added an answer:13How can I increase solubility of my hydrophobic drug (Log P = 5.09) for in vitro drug release and permeation study?
I've prepared nanoemulsion and need to measure the release and permeation of that formulation using franz diffuiosn cell. I've found some of the researchers added SDS (sodium dodecyl sulphate, 2%) or ethanol in PBS 7.4? Which one is the best? Is there any guideline that I can follow for this experiment? My drug is very hydrophobic (0.039 ng/ml - solubility in water) and high solubility in methanol and ethanol. Thanks a lot.
L'ethanol est plus approprié pour votre étude.Following
- Çağla Çibuk added an answer:4What is the reason that the release does not continue? (controlled drug release, HPMC matrix, cefazolin)
I am working on drug delivery behaviour of cefazolin by using HPMC as a matrix. In vitro release of cefazolin from HPMC carried out at 37 C in SBF pH 7.4. 55% of the loaded drug was released within 6 hours and after that we did not observed any release. We did not explain this peculiar behaviour.
We think that either cefazolin are trapped within the HPMC matrix or it degrades and we can not observe the change in concentration.
Thanks to all of you for your answers, I will consider your thoughts.Following
- Nguyen Thuy-Duong Thi added an answer:4Ask for recommendation of using Tris-HCl solution for releasing test?
I want to check the releasing rate of Ca from my bio-material sample by using Tris-HCl solution (pH=7.4). However, I can not figure out which concentration of Tris-HCl solution is close to body fluid. Could you give me some recommendations?
Any help would be respected.
I want to detect the release of Ca from bioactive surface in physiological conditions without inorganic components. The release (dissolution) of Ca in SBF or other solution containing inorganic components effects on the release of Ca due to other phenomena: precipitation and ion exchange, Thus, Tris-HCl solution looks like to be suitable...Following
- Ahmed Agiba added an answer:3Can it be claimed that cyclodextrin based polymer shows enhanced drug release due to inclusion complex formation?
I have prepared a polymer using cyclodxtrin as a crosslinker. After loading of a drug into cyclodextrin based polymer matrix, the drug showed enhanced drug release as compare to polymer without cyclodextrin. There are reports which describes that my model drug forms inclusion complex with cyclodextrin.
inclusion complexation of a drug with B-cyclodextrin loaded into a hydrophilic mucoadhesice polymer is considered one of the methods to ehance solubility, bioavailability and stability of drugs, particularly poorly soluble drugs.Following
- Ashish Atodariya added an answer:4Can anyone suggest the best way for this study as i can't see the sirolimus peak after HPLC at 278 nm?
I coated the metal surface with a mixture of PLLA and sirolimus and i want to study the drug release in human plasma. The loading amount was 125 ug per sample. For the drug release, i immersed the sample in 1 ml of plasma solution and after predetermined time 1d, 3d, 5d, ....... i can't measure the amount of the released sirolimus. could you please inform me how to extract the sirolimus from the plasma solution or any other way?
Thank you in advance
you can go through following link too,
- Jeffrey J Weimer added an answer:3How can I determine the n exponent of korsmeyer peppas?
If I have an equation of korsmeyer chart ( log cumulative %drug release and log time) is y = 5.1 x + 3.2 and R2 = 0.8038
how can determine the n exponent to determine the mechanism of release ?
"You can take two points of time with their respective Mt to complete the equation and isolate the k in each."
Two points may give the slope and intercept of a line or solve two equations for two unknowns. It is however a sloppy approach to take in this case. The suggested method should be used only to obtain a first guess. The rigorous approach for a publication-quality report is to use non-linear regression fitting methods to get the parameters and their uncertainties.
We have inexpensive (free), intuitive, user-friendly desktop computational applications today that can perform rigorous data analysis and return fitting values with their confidence limits in the blink of an eye. Why do folks still insist on doing data analysis as though all they have with them is an abacas or hard-copy graph paper?Following
- Anu Rosina added an answer:27Can we crush a sustained release tablet?Is it possible for a person to crush a sustained release tablet for fast action?
crushing a sustained release tablet affects the drug release in which the drug is designed to release slowly in a specific period of time & results in rapid release of the drug and also affects site specific delivery of certain drugsFollowing
- Abbas Raza added an answer:5Does anyone know about silastic tubing for implants in mice?
i am looking for some guidelines to using silastic tubing for implanting hormones in mice. I need to provide 50ug of drug released every day. Has anyone worked with them and would be willing to guide me the required specifications for this dosage?
that's an excellent piece of info. thank you!Following
- Sree Gayathri asked a question:OpenHow do I analyze the mechanism of drug release-rate kinetics? Is it first order or zero order kinetic by looking at the drug release results?
How do I analyze the mechanism of drug release-rate kinetics? Is it first order or zero order kinetic by looking at the drug release results?Following
- kRISHNA CHAITANYA Telaprolu added an answer:7In drug release calculations, does dilution factor have any role in it?
nanoparticle drug release
yes that's correct and follow the same for entire drug release, notice down the conversion to mg or micro gram as per your std calibration curveFollowing
- Mohammed adnan Mezaal added an answer:6Whats the difference between cumulative drug release(%) and drug release(%)? How might I calculate drug release using a formula)?
I am studying nanoparticle drug release
You may read this article . I have explained in details the kinetics of drug release in the aquous media. If you need further help let me know please. Layered Double Hydroxides Nanohybrid Intercalation with Folic Acid Used as Delivery System and their Controlled Release Properties. DOI: 10.1007/s13369-012-0403-2. M A MezaalFollowing
- Sachin Surwase added an answer:4What would be the hydrophilic drug release pattern from PEG-PLGA polymer? Will it be decreasing since its very soluble in water?
Nanoparticle drug release.
You can say it as a "burst release" due to adsorbed or weakly bound drug.Following
- Cristian Hugo Gil added an answer:2Is there anybody working with Norgestomet / Altrenogest controlled release formulations?We are studying release profiles in PLGA and silicon implants. Any help would be great for us.
We think we understand shape and structure from carrier. Question is, we are not sure of amount and use of Propyleneglycol in matrix. As it is highly hydrophilic, maybe it is used to make device more hydrophylic, or to dissolve Norgestomet in it. Any help on this subject, I shall appreciate very much. Thanks a lot!Following
- Raphael Henrique Marques Marcilli added an answer:2What are the causes of burst drug release ??
i want to know the factors control the burst effect in a modified drug release systems ?
Temperature, pH or some reductor or oxidizing agente can promote the bust release for example, the critical point is to know the release mechanism of your drug. I've worked with S-nitrosothiol group releasing, in this case a reductor agents, like ascorbic acid, promote a bust release by the reduction of bond S-N.Following
- Shafi ullah Khan added an answer:5What will be the release mechanism of the drug and what will be the effect of pH on drug release?
If polyoxometalate (anion) is electro-statically binded with the a cationic polymer using acrylic acid as a monomer.
what will be the release mechanism of the drug and what will be the effect of pH on drug release?
Normally a drug is loaded in free form in polymeric network (hydrogel) and release mechanism is by diffusion process. Here the drug by itself is the part of hydrogel system and is electro-statically binded with the polymer.
Thanks Alot Raphael Henrique Marques Marcilli,Jeannine Coburn and Abdelkader BOUAZIZFollowing
- Saadi Bin Qasim added an answer:1Why do we take the absorbance of drug once during dissolution of capsule? What would be the equation for calculating the comulative % of drug release?
Why do we take the absorbance of drug once during dissolution of capsule? What would be the equation for calculating the cumulative % of drug release?
I did the percentage of drug release for amoxicillin capsule.
This is one of the most mindboggling questions I cracked, Preffered to stick to % recovery thoughFollowing
- Abbas Rahdar added an answer:2Drug Release ProfileI work on temperature sensitive liposomes and I encapsulate calcein to get the release profile. But each time I measure the dye release using fluorometer, the fluorescence intensity decreases as I increase the temperature.
Can someone suggest to me a better method to measure the drug release? How can I ensure that free calcein has been completely removed after purification? Gel filtration alone doesn't work for me.
please sugget me several fluorescent dye that be soluble in water and micelle systems.
All the best,
- Mala Menon added an answer:10How can I calculate the % of drug released during dissolution studies?
Can anybody provide me the equation by which i can calculate the percentage of drug release during dissolution of a solid oral dosage form?
1) You need to have a suitable analytical technique (UV spectrophotometry or HPLC) and standard plot of your drug in the dissolution medium you are using for the release studies.
2) During dissolution studies you will be withdrawing various aliquots and analyzing the drug content in them by your method.
3) From calibration/std plot find out amount in the withdrawn aliquots.
4) By simple mathematics you can calculate the amount in total dissolution medium (900ml). From 2nd reading onwards, you need to add the cumulative amounts released in the withdrawn volumes.
5) Then you can compute 5 released at each time point based on total drug (label claim) in your solid oral dosage form.Following
- Prabhanjan Giram added an answer:3How can I fix the concentration of alcohol/surfactant in a medium for drug release studies of a nanoformulation incorporating poorly soluble drug?
I have a nanoformulation of hydrophobic drug for which I have to study drug release using dialysis bag method. Can methanol be used (instead of surfactant) along with the buffer to maintain the sink condition? Does it has any effect on membrane permeability? Kindly advice.
GO FOR PREVIOUS REPORTED METHOD.Following
- Rajesh Kumar Gupta added an answer:2Can you suggest whether I should go for cumulative or simple drug release kinetics from nanoparticles?
Very good morning. I need your kind help. I am using following pilot experimental conditions for study of drug release kinetics.
a) Time points 0-96 Hrs (12 time points). Encapsulated nano-particles equivalent of 200 microgram BSA are incubated in 1 ml PPB buffer (pH 7.2)/ Acetate buffer (pH 5.0) for each time point separately. After fixed time points, supernatant is collected by centrifugation and estimated for BSA release via ELISA.
b) Time points 0-96 Hrs (12 time points). Encapsulated nanoparticles equivalent of 3000 microgram BSA are incubated in 15 ml PPB buffer (pH 7.2)/ Acetate buffer (pH 5.0) on a magnetic stirrer. After each time point, 1 ml sample is removed from the vial and supernatant is collected by centrifugation estimated for BSA release via ELISA. Pallet of the particles is re-suspended in fresh buffer and added back to 15 ml vial to maintain the constant volume.
I have some confusions regarding the BSA release kinetics calculations from chitosan nano particles. In the literature, people have used both the individual as well as cumulative methods of drug release study.
1) What is the basic principle of drug release calculations individually at each time point and cumulative drug release across different time points?
2) How do we calculate cumulative drug release and which one is better in terms of the amount of useful information?
(a) When known amount of drug loaded particles are individually incubated (in separate tubes) for different time points, in fixed volume of release buffer and buffer is not replaced by fresh buffer?
(b) ) When known amount of drug loaded particles are incubated (in one tube) for different time points, in release buffer and buffer is replaced by fresh buffer every time a sample is taken out?
3) Do we need to essentially calculate cumulative drug release across different time points? Or can we calculate drug release at each time point individually and then sum it up?
4) I will greatly appreciate if you could suggest me the stepwise calculations and explanation of critical steps (i.e. why we multiply each time point protein release amount by total volume of buffer or sample buffer) to calculate the drug release and a relevant book or other study material site or source.
Thanks in anticipation,
Regards and best wishes,
Dear Kishore, thank you so much for your kind help and suggestion in this matter. I greatly appreciate your thoughtful insight into this very matter.
Regards and best wishes,
- Elanthiraiyan Saravanan added an answer:2Is there anybody working with curcumin release from Nanoparticles in a dialysis tube?I am studying release profiles in MSN, but pure curcumin does not pass from a dialysis tube (12KD). Any help would be great for me.
hi, try soaking the dialysis tube in D.I for 10-12 hrs prior to release study this might help and check for the suitable buffer too.Following
- Kenneth M Towe added an answer:5Is there any formula for calculating the optimum concentration of drug release in superparamagnetic iron oxide nanoparticles?
I am working on polysacharide coated magnetic nanoparticles drug release. when the drug loading is 2% W/W, the release is around 67% but in higher concentrations it is reduced rapidly.The maximum MNP loading capacity is around 40 %W/W. is there any formlation for calculating the best loading percentage in pharmacokinetic field? Is there any role for selecting a concentration as the best for drawing release curve?Following
- Alessia Di Capua added an answer:8How can I study the release of curcumin in PBS or in a medium to simulate an human tissue?
I produced powder of a polymer and curcumin and I want to study the release of curcumin (or luteolin) by Uv-vis. Curcumin is hydrophobic, so I have some problem to built a calibration curve in PBS to know the concentration of my drug in the medium. when I prepare the samples a different concentrations I obtain sospension. How can I do?
si si! ho provato con del Tween 80 e non ho avuto dei grandi miglioramenti però posso provare con il SDS magari.Following
- Adam B Shapiro added an answer:4Do you know an efficient method to concentrate cells in solution that would be faster than centrifugation but would preserve cell integrity ?
I would like to make a kinetic analysis after drug release with short time points. We use RAJI cells that are not adherent, and we need a lot of cells (10xe8) for each time point (2', 5', 10', 15', ...). Centrifugation for the first wash is too long and we overpass the first time point. We thought on using filtration apparatus (the on we use for the serum). Does anyon have tried this yet ? Or have another idea to fastly concentrate cells ?
Thanks for you comments and answers
Perhaps you can pre-concentrate your cell suspension before beginning the treatment, in order to make the final filtration step faster.Following