REVERSED PHASE LIQUID CHROMATOGRAPHIC DETERMINATION OF VINPOCETINE IN HUMAN PLASMA AND ITS PHARMACOKINETIC APPLICATION

Abstract

ABSTRACT A simple, rapid specific and reliable high performance liquid chromatographic assay of vinpocetine in human plasma has been developed. Reversed phase chromatography was conducted using a mobile phase of methanol : water (80 : 20 v/v), containing 0.1% triethylamine, pH 7, adjusted with glacial acetic acid. The flow rate was 2 mL/min, UV detection at 274 nm. The drug after extraction from plasma was chromatographed using a C18 reversed–phase column. The average recoveries of vinpocetine from spiked plasma in the concentration range from (0.01–0.1) µg/mL was 91.83% and the coefficient of variation was 3.03%. Regression analysis for the calibration plot for plasma standards obtained on three different days for the drug concentrations between (0.01–0.1) µg/mL indicated excellent linearity (r>0.999) and the coefficient of variation of the slopes of the three lines was <2%. Analysis of variance of the data showed no detectable difference in the slopes of the three standard plots (F = 3.2, P>0.01). The high correlation coefficients and the similarities in the slopes are good indication of the excellent reproducibility and linearity of the proposed method. The proposed method was applied to study the bioequivalence of a commercial product of vinpocetine using as reference standard the innovator drug product. The study was conducted on using two tablets (2 × 5 mg) of each of the commercial product and the reference standard in a two way open randomized crossover design involving twenty four volunteers. The criteria used to assess bioequivalence of the products were AUC (0–∞), C max, t max, t 1/2 and K. The obtained values for these parameters were 519.8 ± 8.2 ng h/mL, 64.3 ± 1.6 ng/mL, 1.5 h, 2.09 ± 0.27 h and 0.34 ± 0.04 h−1 for product A whereas, for product B they were, 514.6 ± 10.7 ng h/mL, 63.5 ± 1.3 ng/mL, 1.5 h, 2.2 ± 0.35 h and 0.32 ± 0.04 h−1 respectively.