Assessment of the physicochemical and pharmaceutical properties of some brands of commercial tadalafil tablets in Nigeria

Abstract

Fake, sub-standard and counterfeit medicines are recognized as major threats to public health in both developing and developed countries. There are reports of the existence of fake and substandard medicines in the Nigerian pharmaceutical space and this spurred the present study which is aimed at evaluating the physicochemical and pharmaceutical properties of five brands of tadalafil tablets commercially available in Nigeria. Pharmacopoeial and non-pharmacopoeial tests such as uniformity of weight, hardness, friability, uniformity of diameter, disintegration time and in vitro dissolution rate were used to assess the physicochemical properties of the tablet brands. Assay of the brands for content of active ingredient was done using UV spectrophotometry at the maximum wavelength of 283.6 nm. The results obtained show that all the brands passed the test for uniformity of diameter, uniformity of weight, disintegration time and friability. Three of the tablet brands failed the hardness test, while only two of the brands passed the content uniformity test with their active ingredient falling within the limit specified by the pharmacopoeia (90%-110% of the stated content). All the tadalafil brands however failed the in vitro dissolution tests as they were all unable to release up to 70 % of the stated content within the 45 minutes limit. These comparative evaluations clearly demonstrate the need for routine quality surveillance of pharmaceutical products in circulation in order to detect and apprehend any fake and substandard products in the country.