In vitro-in vivo correlation and comparative bioavailablity of vincamine in prolonged-release preparations

Developing an in vitro dissolution test that gives good correlation with in vivo data for a particular drug product is an important objective. Available dissolution data of vincamine prolonged-release preparations show different in vitro release behavior at different pH using the conventional dissolution techniques. This does not allow development of an in vitro-in vivo correlation (IVIVC). In the present work, the flow-through cell (FTC) dissolution system (USP apparatus 4) was utilized to compare the release rate of three marketed prolonged-release oral formulations of vincamine; namely, a brand innovator formulation used as the reference and two formulations from different manufacturers as test products. Both the open and closed systems of FTC were used at variable pH. A comparative bioavailability study was then conducted in 16 healthy volunteers for a test versus the reference product by administering a single dose of 60 mg in a crossover design. Vincamine plasma concentrations were analyzed by a sensitive high-performance liquid chromatography (HPLC) method. This was followed by assessment of IVIVC according to level A as specified by USP 23; the absorbed fraction of vincamine was determined using the Wagner-Nelson method. The results indicated that the pH of the medium affects the release rate pronouncedly. The relative bioavailability based on Cmax and AUC0-12 were found to be 83.15% and 84.15%, respectively. Good correlation was obtained between fraction absorbed in vivo and fraction dissolved in vitro by applying the open system of the FTC. This technique gave the most favorable results with regard to the percentage vincamine released and the IVIVC.