PITFALLS TO BEWARE IN IN-VITRO RELEASE STUDIES Presented by: Maneesha Pande Department of Chemical Engineering, Indian Institute of Technology Delhi 6th World Congress on Biotechnology October 6, 2015

CONTENTS INTRODUCTION SIGNIFICANCE OF IN-VITRO DRUG RELEASE STUDIES METHODS FOR IN-VITRO DRUG RELEASE STUDIES COMPENDIAL METHODS NON-COMPENDIAL METHODS METHOD DESIGN: IMPORTANT FACTORS PITFALLS TO BEWARE EXAMPLES/CASE STUDIES CONCLUSION November 29, 2018

IN VITRO DRUG RELEASE STUDIES: SIGNIFICANCE Objectives of in-vitro drug release studies: 1) At the formulation development stage – to assess the drug release characteristics of different formulations and relate them with in-vivo release pattern - here, efforts are to mimic maximum possible physiological parameters - in vivo – in vitro correlation is done as per established protocols 2) At the production stage - as a tool for quality control - after a specific formulation is selected, to ensure batch-to-batch uniformity - to establish bioequivalence November 29, 2018

IN-VITRO DRUG RELEASE METHODS: COMPENDIAL USP Apparatus 1: Rotating Basket USP Apparatus 2: Rotating Paddle USP Apparatus 3: Reciprocating Cylinder USP Apparatus 4: Flow Through Cell USP Apparatus 5: Paddle Over Disc USP Apparatus 6: Cylinder USP Apparatus 7: Reciprocating Holder Franz Diffusion Cell (Non-compendial apparatus) Apparatus for medicated chewing gums (Non-compendial apparatus) November 29, 2018

In-vitro drug release studies at the formulation development stage November 29, 2018

IN-VITRO DRUG RELEASE METHODS: NON- COMPENDIAL Sample and separate method Useful for microparticulate system Continuous flow method Useful for microparticulate systems Dialysis method Useful for micro/nanoparticulate system Useful for semisolid/gel systems November 29, 2018

POSSIBLE TO IN-VIVO CONDITIONS IMPORTANT PARAMETERS Release medium Composition Volume Maintenance of “sink” conditions Flow characteristics of release medium vis-à-vis the shape of container Stirring speed Sampling procedure Volume of sample Sampling interval Whether sample is replaced by plain release medium Concentration of drug CONDITIONS SHOULD BE AS CLOSE AS POSSIBLE TO IN-VIVO CONDITIONS November 29, 2018

PITFALLS TO BEWARE Interference of membrane used for retaining the sample Incomplete release of drug Inability of flow pattern to provide thorough mixing of release medium Causing resistance to mass transfer Influence of drug concentration November 29, 2018

CASE STUDY : EFFECT OF SAMPLE HOLDER AND FLOW PATTERN Magnetic stirrer blade Sample enclosed in dialysis membrane Release Medium Baffles Typical initial experimental set-up for in-vitro drug release studies using dialysis membrane Inadequate mixing of release medium Thorough mixing of release medium

MODIFIED EXPERIMENTAL SET-UP Baffles Release medium Sample holder covered with fine nylon cloth (to retain sample) Stirrer bar Modified experimental set-up November 29, 2018

RESULTS AND DISCUSSION Comparative release of sulfadiazine from plain solution and through MC-4000 gel (across a dialysis membrane, 12-14 kDa MW cut-off), at 400C) Comparative release studies of cisplatin from plain solution in normal saline and from 90:10 castor oil:water biliquid foam (across a dialysis membrane, 12-14 kDa MW cut-off) at 400C) November 29, 2018

RESULTS AND DISCUSSION continued…….. Drug release pattern at different stirring speeds Eliminating mass transfer resistance

RESULTS AND DISCUSSION continued…….. Effect of concentartion of drug (sulfadiazine) on in-vitro release of drug November 29, 2018

CONCLUSIONS Seemingly insignificant factors such as the selection of sample holder and speed of stirring play a very important role Amount of drug contained in the formulation (whether above or below saturation concentrations) is important Careful experimental design is of utmost importance in in-vitro drug release studies November 29, 2018

THANKYOU

QUESTIONS??? November 29, 2018

IN-VITRO RELEASE STUDIES: REPRESENTATIVE PLOTS OF SOME PUBLISHED WORK Zheng, et al., 2010. Oncology Reports 23: 717-724 Shikanov et al. Vol.2011. Chemotherapy Research and Practice Article ID 175054. November 29, 2018

CHEMICAL STRUCTURES Sulfadiazine, C10H10N4O2S MW 250.278 g/mol Cisplatin, H6N2Cl2Pt MW 300.01 g/mol

RELEASE KINETICS: DIFFERENT MODELS Zero order release First order release Higuchi Model Hixon-Crowell Model Weibull Model Korsenmeyer-Peppas Model Hopfenberg Model Baker-Lonsdale Model Gompertz Model November 29, 2018