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.

The volatiles of desert truffle: Tirmania nivea.

The volatile constituents of Tirmania nivea (white desert truffle) have been analysed, using gas chromatography/mass spectrometric technique. 11 compounds have been identified in the ascocarp volatiles. The major components were found to be unsaturated fatty acids; whereas hexadecanoic [correction of haxadecanoic] acid represented 49% of the volatiles isolate.

An approach to the treatment of vitiligo by khellin.

An anticipated effect of khellin, related to its chemical structure, in the photochemotherapy of amelanosis has been investigated. In a double-blind clinical study, khellin has been orally administered to 30 vitiligo patients for 4 months with subsequent exposure to natural sunlight. At the end of the trial period, 5 patients out of 30 (16.6%) repigmented 90-100%; 7 cases (23.3%) repigmented 50-60% of the vitiliginous areas treated; 11 (36.6%) repigmented 25% or less, and 7 subjects (23.3%) showed negative response. 30 control subjects failed to repigment at all. The achieved repigmentation was stable after drug cessation for a period of 1 year. These data add a previously unreported effect for the non-psoralen compound, khellin, in the therapy of vitiligo.