An in situ method to quantitatively determine dissolved free drug concentrations in vitro in the presence of polymer excipients using pulsatile microdialysis (PMD)

International Journal of Pharmaceutics
Charchil Vejani, Robert A Bellantone

Abstract

In drug formulations containing polymer excipients, the effects of the polymer on the dissolved free drug concentration and resulting dissolution or release can be important, especially for poorly soluble drugs. In this study, an in vitro method based on pulsatile microdialysis (PMD) was developed to quantitatively determine dissolved free concentrations of drugs in the presence of polymers in aqueous media in situ (e.g., in place within the system being characterized). Formulations were made by dissolving various ratios of the drug griseofulvin and polymer PVP K30 in water and allowing the mix to equilibrate. A PMD probe was immersed in each mixture and the dissolved free drug concentrations were determined in the PMD samples. The experimental procedure and the equations used for data analysis are presented. To assess the consistency of data, a binding model was fit to the data obtained using PMD by calculating the dissolved free drug fraction fD for each drug-polymer ratio in solution, and obtaining the product of the binding stoichiometry and binding constant (νK per mole of polymer) from the slope of a plot of (1-fD)/fD vs. the molar polymer concentration. For comparison, equilibrium binding experiments were also performed ...Continue Reading

References

Dec 1, 1967·Journal of Pharmaceutical Sciences·P SinghW I Higuchi
Jun 7, 2000·European Journal of Pharmaceutics and Biopharmaceutics : Official Journal of Arbeitsgemeinschaft Für Pharmazeutische Verfahrenstechnik E.V·N A PeppasH Ichikawa
Feb 19, 2002·European Journal of Pharmaceutical Sciences : Official Journal of the European Federation for Pharmaceutical Sciences·Claudia HerforthFrancesca T Aweeka
Mar 22, 2005·International Journal of Pharmaceutics·Mohammed A KabirRobert A Bellantone
Mar 31, 2005·Journal of Pharmaceutical and Biomedical Analysis·Zhongping John LinLinyee Shum

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Citations

Aug 31, 2016·European Journal of Pharmaceutical Sciences : Official Journal of the European Federation for Pharmaceutical Sciences·Chao LiuLiang Fang

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