Evaluation of the Physicochemical Properties and Quality Indices of Multisource Tadalafil Drug Products Marketed in Nigeria

Abstract

The present study evaluates and compares the physicochemical parameters and cost of some multisource tadalafil products marketed in Nigeria. Six randomly selected products were analyzed for weight uniformity, friability, hardness, disintegration, dissolution testing and assay. The assay for chemical content was performed using RP-HPLC method with isocratic run using acetonitrile: acetate buffer pH 2.8 (45:55, volume in volume) as mobile phase at a flow rate of 1.0 mL/min and wavelength of determination of 283 nm. All the products passed the disintegration time and crushing strength tests with no significant difference in values (p<0.05), while all complied with the uniformity of weight specification except two products. The chemical content of the products was between 70.2 and 86.8% (weight in weight). The dissolution profile revealed that two products could not achieve 70% drug release after the 90 min dissolution time. The average shelf price of the originator product, for an equivalent pack of four tablets/capsules was N 8 000 (USD 45) while the other products were generally below N 2 000 (USD 11). The innovator as well as the two generic products that passed all the physicochemical tests can be regarded as pharmaceutically equivalent among the tadalafil drug products tested. There was an indication of high disparity in price between the innovator and the generics that is not justified by physicochemical test outcomes.