Drug Release

Drug Release

  • What are the causes of burst drug release ??

    i want to know the factors control the burst effect in a modified drug release systems ?

    Raphael Henrique Marques Marcilli · University of Campinas

    adicional information
    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.

  • Helmut Ritter added an answer:
    Can 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.

    Helmut Ritter · Heinrich-Heine-Universität Düsseldorf

    Dear Archana,

    Basicly, you are right. The size of the drug is a strong point: e.g benzene or cyclohenane rings fit into the cavity of alpha- or beta cyclodextrin. Plese check the inclusiion with ROESY NMR spectroscopy

    Kind regards


  • Abdelkader BOUAZIZ added an answer:
    What 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.

    Abdelkader BOUAZIZ · Univ. Ibn Khaldoun Tiaret

    Dear all,

    Thanks Dr. Jeannine Coburn for the nice contribution and coments. I would add a small concerning another factor that will contribute to the release, is the osmosis effect which operates and help in diffusion ones the drug is released first from the binding sites of the matrix towards another environment. As you have said, things sometimes do not go along with our thinking, but the experience is the only witness about any result and explanation. Regards

  • Saadi Bin Qasim added an answer:
    Why 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.

    Saadi Bin Qasim · The University of Sheffield

    Hi Rashaduz,

    This is one of the most mindboggling questions I cracked, Preffered to stick to % recovery though

  • Abbas Rahdar added an answer:
    Drug Release Profile
    I 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.
    Abbas Rahdar · Zabol University

    Dear Mercedes,

    please sugget me several fluorescent dye that be soluble in water and micelle systems.

    All the best,


  • Mala Menon added an answer:
    How 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?

    Mala Menon · Bombay College of Pharmacy

    Dear Ashraf,

    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.

  • Prabhanjan Giram added an answer:
    How 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.

    Prabhanjan Giram · CSIR - National Chemical Laboratory, Pune


  • Rajesh Kumar Gupta added an answer:
    Can you suggest whether I should go for cumulative or simple drug release kinetics from nanoparticles?

    Hi friends,
    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,

    Rajesh Gupta

    Rajesh Kumar Gupta · The University of Western Ontario

    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,


  • M. R. V. Sahyun added an answer:
    Is 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.

    I don't know anything about release from dialysis tubing, and only use curcumin when I'm cooking.  On the other hand the possibility of time-release of a seasoning molecule from any kind of host-guest system suggests uninteresting new tool for molecular gastronomy.

  • Kenneth M Towe added an answer:
    Is 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?

  • Alessia Di Capua added an answer:
    How 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?

    Alessia Di Capua · Università degli Studi di Salerno

    si si! ho provato con del Tween 80 e non ho avuto dei grandi miglioramenti però posso provare con il SDS magari.

  • Edward Russak added an answer:
    Can we crush a sustained release tablet?
    Is it possible for a person to crush a sustained release tablet for fast action?
    Edward Russak · University at Buffalo, The State University of New York

    I would not recommend crushing any SR tablet.

  • Adam B Shapiro added an answer:
    Do 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

    Adam B Shapiro · Entasis Therapeutics

    Perhaps you can pre-concentrate your cell suspension before beginning the treatment, in order to make the final filtration step faster.

  • Syaiful Choiri added an answer:
    Would cumulative drug release graph ever show a decrease ?

    Would Cumulative drug release graph show a decrease ? My understanding is that cumulative release should never go down simply because it is an addition process, so if no release then add zero, thus it will stay the same as previous level/time-point.. Figure 7 on the following paper shows a decrease in the cumulative drug release graph! Can anyone comment on this as is this even possible? and/or do the authores have an explanation for this ? "Preparation and Characterization of a Novel Smart Polymeric Hydrogel for Drug Delivery of Insulin " Link : http://bi.tbzmed.ac.ir/Portals/0/BI-2011-1-2/Jafari-BioImpacts-2011-1-2.pdf

    Syaiful Choiri · Universitas Sebelas Maret

    decreasing the drug release graph associate with some case e.g. error in analysis of samples or forget add correction of drug in every sampling, you must calculate the drug in the sampling using correction and you can add it in cumulative correction 

  • Do you have any methodology about the drug releasing study in plant extract loaded chitosan nanoparticle?

    details please! :)

  • Arpan Mahanty added an answer:
    Can anyone help me for using software for different kinetic models for drug release?

    Simple software for differnt kinetic modles like 1st order, zero order, higuchi model and peppas-korse mayer model etc

    Arpan Mahanty · China Pharmaceutical University

    I am using a Dissolution software Made from my Ex-institution using only for Dissolution for different order kinetic models. I attached it I think it will be helpfull for you.

  • What would a Peppas n exponential coefficient smaller than 0.3 suggest?

    release study of a water soluble drug from a very high viscosity hydrogel, % released is inferior to 60%.

    Adriana L. Navarro-Verdugo · Universidad de Sonora (Unison)

    Try using http://pubs.rsc.org/en/content/articlelanding/2011/sm/c1sm05252g#!divAbstract

    A modified Boltzmann sigmoidal model for the phase transition of smart gels
    Adriana L. Navarro-Verdugo, Francisco M. Goycoolea, Guillermo Romero-Meléndez, Inocencio Higuera-Ciapara and Waldo Argüelles-Monal
    Journal Article Soft Matter, 2011,7, 5847-5853
    DOI: 10.1039/C1SM05252G, Paper

    If you need more, please contact,

    give me regards

  • Robert A Bellantone added an answer:
    Any suggestions on In vitro release calculation of SLN?

    I am using dialysis bag diffusion technique for in vitro drug release of Solid Lipid Nanoparticle of my drug.My receptor compartment is 300 ml of  70% methanol.My question is when I will calculate percentage of drug release in different time interval, should I multiply my drug concentration with 300 ml every time? 

    Robert A Bellantone · Long Island University


    As Drs. Patel and Shapiro say, the amount of drug in the bag equals the concentration times the volume. (This comes from the definition... C=M/V).

    I don't know all of the details of your experiment, so I apologize if something is not relevant to your situation. There are a couple of other things to consider...

    First, the bag is initially 70% methanol, but methanol is a small molecule that will exchange across the dialysis membrane readily. If the experiment goes on for any length of time, this might require an evaluation of the drug solubility and dissolution, and the resulting effect on the accumulation in the bag.

    Also, depending on the relative volumes of medium inside and outside of the bag, and the sampling times, equilibrium may not be established between the medium in the bag vs. outside the bag... in that case, the dissolved free drug concentration outside the bag would not equal the concentration inside the bag. 

    Final though... I don't know what the sample volume is, or if you replace the volume inside the bag after each sample is taken, but that would affect your calculation of the mass dissolved as well.

    Hope this helps... good luck!

  • Jesus Rodriguez Pulido added an answer:
    What is the size of the pores formed in the chitosan and HPMC films made by casting?

    Hi. I am working with chitosan and Hydroxypropyl methylcellulose films for prolonged drug release. I am developing films with 1% acetic acid at 70ºC (according to the manufacturer HPMC for optimal homogenization of the mixture), but I would like to know the size of the pore formed in the film for drug uptake.

    Jesus Rodriguez Pulido · Autonomous University of Nuevo León

    Thanks, it was very helpful!

  • Ashraf Islam added an answer:
    Is 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.
    Ashraf Islam · The University of Asia Pacific

    Please specify what type of help do you need. Formulation, process, analysis??

  • Muhammad Sohail added an answer:
    2-acrylamido-2-methylpropane sulfonic acid based hydrogels have pH independent swelling but pH dependent drug release, why?

    AMPS (2-acrylamido-2-methylpropane sulfonic acid) based hydrogels swells at both acidic and basic pH, but shows significant drug release only at basic pH.

    Muhammad Sohail · COMSATS Institute of Information Technology

    Many thanks, Actually the dug is weakly acidic and is not soluble at acidic pH. 

  • Sachin Chauhan added an answer:
    What is the normal range of Entrapment Efficiency(%) in microcarrier Drug Delivery Systems?


    I have fabricated micro-carries and then soak them in the drug solution in order to loading drugs into the carriers. After loading I shaked the drug loaded micro-carries for 24hr to ensure that all of the loaded drug release from them, then I calculated the entrapment efficiency and it was 1.6% (!!)....is this percentages normal?? if it is not, where did I have done a mistake?


    Sachin Chauhan · Sumandeep Vidyapeeth University

    there is no any fix rule for percentage entrapment of drug. it can be anything from 0 to 100%. but in your case, there may be a chance of errors are more...for example, in calculation, the amount that you have load, or in your procedure for loading of drug, selection of solvent for drug etc.....

  • Victor Cojocaru added an answer:
    Does anyone have experience with DDSolver for office 2011 for mac os?

    I cannot seem to get to the bottom of this problem. I keep receiving an ”Automation error” when trying to install the DDSolver add-on for excel. Can anyone give me a suggestion on how to make this work?

    Victor Cojocaru · Carol Davila University of Medicine and Pharmacy

    thank you. I found out yesterday...

  • In the case of pH sensitive hydrogels that are used for drug release,how can I make sure that the drug releases at a particular pH?

    For example, pH of stomach is around 3, so how can I make sure that the drug doesn't get released at a pH 4? How can I make sure exactly that it gets released at a particular said pH, and not anywhere else?

    Christopher Daniel Duntsch · Hybrid Bioscience, Inc., Synthetic Investments, Inc., The University of Tennessee Health Science Center

    The question you are asking and the answers to it are far more complex and diverse than you might think. I would not venture an answer here if I had not had the same experience from a RD perspective, in a very different biologic, pharmacologic, and animal / disease modeling series of experiments for a specific project.

    The answer to the question regarding pH, drug release, timing, and presumably all other related pharmacobiology of said in vivo drug release modeling, is theoretical, anatomical, physiologic, pan-pharma biology and pharmacology of all types. Further, presumably, you are giving a drug for a reason, meaning in the context of some pathophysiology of gastric, or upper small intestine origin, and nature.  

    That being, said, the approach to working this out is hands on, and is easier to work through in the lab, than modeling this in theory.

    Step 1 - Create a series of in vitro experiments, where the drug, the pH and chemistry of the media, or chemical medium, and the solid phase tissue, gel, or otherwise organic or inorganic solid the drug is loaded into, the drug, and all the various pharma parameters, are addressed, and in some range or kinetic. Critical even here, is the type of matrix, polymer, gel phase, the drug is loaded into, before the  loaded drug polymer composite is loaded into the tissue or tissue surrogate. The rest is measuring, observing, recording all the various data types and data points that might come from this simple bench top series of experiments. The results will be useful, but by no means provide definitive or even significant information regarding how to proceed.

    Step 2 - Identify through physical, chemical, pharmaceutical means, some type of surrogate drug, that can be used in vitro as above, and in vivo as follows. For example, there are are many useful compounds that have the various pharma parameters similar to many series of molecular subtypes. Compounds that fluoresce, or that are dyes, that can be combined with radiolabling for tracing, or that have some other meaningful chemistry and biology for use in vitro, and in vivo, for pre-modeling the same with the drug of choice. Perform the same studies with the surrogate drug, in vitro, as above with the target drug.

    Step 3 - Create an in vivo model that approximates the intent and biology of the preclinical animal scenario. Thus, healthy controls, physiologic or pathophysiogic models, etc. Perform all in vivo experiments, studies, research, data collection, documentation, with the surrogate drug as follows. Included here is a biodistribution study over time, that might not be feasible with the target drug.

    Step 4 - Using all research and data from above, perform a safety study with target drug, where the target drug is given as indicated in a kinetic over time and dose range as indicated, with all appropriate cell and molecular tissue studies to follow.

    Step 5-Using all research and data, from above, perform an efficacy study, where the target drug is given as indicated in a kinetic over time and dose range, with all appropriate cell and molecular tissue studies to follow.

    Step 6 - As it is unlikely that all chemistry, dosing, time kinetics, formulation, safety and efficacy dose equivalents, biodistribution, will be adequate until many studies are performed, and the protocols, chemistry, dose, formulation, etc, are adjusted as needed, the last step, is perform a final study, where all previous studies are repeated, and all parameters are closed around a range, and nature, that approximates the best results found in the studies above. The goal here is to create a final common experimental series, where the outcome is drug, drug dosing, dose kinetic, safety, efficacy, and all other pharma as indicated.

    Attached is a PDF of several projects that collated over 18 months to reach a successful conclusion to the intent and end objectives. The data sets shown are the preliminary projects and experimental series, and are unpublished. These pdf files, are documentation of experiments, data, and other information as indicated, but all write ups are informal and were not meant to be definitive or conclusive as documented at that time, when these preliminary first look studies were done in 2004 - 2005.  All research was done at the University of Tennessee, Department of Neurosurgery, Molecular Neurosurgery Program, in my Academic labs. All research was done in collaboration with 1 several clinical neurosurgical faculty including Julius Fernandez, MD, 2 Faculty from the pharmaceutical science department ... Atul Shukla (Professor, medicinal chemist, formulation and drug polymer expert), Sun Yin, PhD (Assistant Professor), Yichun Sun, PhD (Assistant Professor), 3 Faculty from the College of pharmacy and George Wood, PhD (formulation expert), Divi Murali, Phd (student at the time), and 4 My group as follows in the academic neurosurgery research program … Zixiu Zhou, PhD (Assistant Professor, (Neuro) Electrophysiologist), Qihong Zhou, MD, PhD (Asst Professor), Sal Akbar, MD (Postdoctoral Fellow), Bing Teng, MD (Senior Research Technician), Xiofei Wang, MD (Senior Research Technician), Mariya Nazarova, PhD (Program Director for Department Technical Guidelines, Senior Research Technician).

  • Wei Guo added an answer:
    How do you calculate the cumulative drug release in percentage?

    I have the absorbance data as well as the corresponding concentration values at different interval for drug release study. Please help me to get the percentage of cumulative drug release at different times

    Wei Guo · Harbin Institute of Technology

    You can see this paper Dalton Transactions (Impact Factor: 4.1). 10/2014; DOI: 10.1039/C4DT02441A    Title: P(EO-co-LLA) Functionalized Fe3O4@mSiO2 Nanocomposites for Thermo/pH Responsive Drug Controlled Release and Hyperthermia

  • Wei Guo added an answer:
    Can anyone suggest a good polymer for sustained drug release?
    Wei Guo · Harbin Institute of Technology

    hyaluronic acid

  • Samir Haddouchi added an answer:
    How can I determine the cumulative drug release from microparticles?


    I study on a drug delivery microparticle which contain antibiotic for joint infections. To determining the in-vitro release  profile, I suspended microparticles in PBS at 37C and at each time points I withdraw 0.5ml of PBS and replacing with 0.5ml of fresh PBS. Then I calculate the concentration of released drug with UV-Vis,  My question is how can I determine the cumulative drug release? Any help will be appreciated. Thank you.

    Samir Haddouchi · SPS Pharma Services

    In response to Claudio Nastruzzi: All the reasons you indicated are valid to not use UV. I just wanted to point out that very often, people think that HPLC is the only way to obtain precise and valid results...

    Cheers. Samir

  • Gunawan Setiyadi added an answer:
    How can one measure the concentration of free drugs released from nanoemulsion droplet apart from the one in the droplets using UV spectrophotometer?

    If one measure the spectrophotometric absorbance for free drugs in nanoemulsion, is it obscured by the drugs in the droplets? If yes, how can one measure the concentration of the 'free' and the 'entraped' drugs using UV spectrophotometer?

    Gunawan Setiyadi · Universitas Muhammadiyah Surakarta

    Thank you, Tamer. At present, I have circumstances that make uv spectrophotometer the only tool I can use. Certainly, next time I should use HPLC. Thanks for the paper also.

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