Kinetics of pentoxifylline release from hydrophilic, lipophilic and dual matrix tablets

The aim of this study was to evaluate the possibilities of using matrix tablets and dual matrix tablets containing hydrophilic and/or lipophilic retardant for extended release of pentoxifylline.  Polyvinyl alcohol (Parteck® SRP 80) and hypromellose with different viscosity grade (Methocel® K4M, K15M a K100M) were used as hydrophilic retardants and Compritol® 888 ATO was used as a lipophilic retardant.The matrix tablets were prepared by direct compression method using Prosolv® SMCC 90 as a binder and magnesium stearate as a lubricant. The tablets were of cylindrical shape without facets of a diameter of 13 mm and weight of 0.5 ± 0.0010 g.Dissolution testing was carried outaccording to the European Pharmacopoeia 9th using dissolution apparatus SOTAX AT7 Smart. As the dissolution medium was used aqueous solution of HCl with addition of NaCl(pH 1.2). Other experimental conditions: 900 mL of the dissolution medium, temperature 37 ± 0.5°C, 100 rpm. Released amount of pentoxifylline was determined by UV/VIS spectroscopy. Obtained dissolution profiles were evaluated by non-linear regression analysis and fitted to the first order kinetic model, Weibull model, Korsmeyer-Peppas and Higuchi models. The mechanism of drug release was studied and the drug release rate constants and other kinetic parameters were evaluated.
    Based on the results of fit to the Korsmeyer-Peppas model, it was found the anomal transport is major release mechanism. The higher release rate of pentoxifylline was found for tablets containing Compritol® 888 ATO in comparison with hydrophilic matrix tablets.
Audience take away:
• The presentation brings to the audience comparison of kinetics of pentoxifylline release from different types of matrix tablets and a clear summary of kinetic parameters for different retardants used
• The audience can learn about evaluation of drug release mechanism using different mathematic models.
• This study can make a designer’s job more efficient because  thanks to knowledge of the kinetic parameters is possible to obtain required drug dissolution profile 
(in vitro).
• Knowledge of the kinetic parameters is important for in vitro/in vivo correlation.