Comparative pharmacokinetic study of two lyophilized orally disintegrating tablets formulations of vinpocetine in human volunteers

Vinpocetine is a poorly water soluble drug, commonly used in treatment of various cerebral insufficiency conditions. The aim of this work was to formulate vinpocetine in the form of orally disintegrating tablets (ODTs) and enhance its solubility and dissolution rate. This objective was addressed using lyophilization technique of either solid dispersion using polyethylene glycol 4000 (PEG 4000) or inclusion complex with 2-hydroxypropyl β-cyclodextrin (2HP-β-CD). Differential scanning calorimetry (DSC) and fourier transform-infrared (FT-IR) spectroscopy were used to characterize the solid state of the prepared solid complex. Tablets were prepared by direct compression using 23 factorial design to evaluate the effect of formulation variables (Ac-di-sol concentration 5 or 10%, the ratio of soluble polymer 1:1 or 1:3 and binder type 6% w/w Avicel PH102 or 6% w/w carboxymethyl cellulose) on release characteristics. Results showed that lyophilized ODTs disintegrated within few seconds and had significantly faster dissolution rate (70100 % in 5 minutes) compared to the commercial oral tablet (Cavinton®). This was achieved at high content of PEG 4000 or 2 HP-β-CD in presence of 10 % w/w Ac-Di-Sol and 6 % w/w Avicel PH102. The extent of per oral absorption of vinpocetine was determined in healthy human volunteers using randomized crossover design. The relative bioavailability of selected solid dispersion and inclusion complex formulations were found to be 171.98 % and 196.06 % respectively. The study indicated that complexation of vinpocetine with 2-HP-βCD or dispersion in PEG 4000 followed by lyophilization are two successful strategies for enhancing the bioavailability of the drug from ODTs.