A COMPARATIVE STUDY OF THE QUALITY OF MULTISOURCE RISPERIDONE TABLETS MARKETED IN NIGERIA

*Ukwueze S. E. and Nkangwung M. J.

ABSTRACT

Recently, multisource psychotropic medications have become the mainstay of clinical management of psychotic and neurological disorders resulting in decreased treatment cost. The World Health Organization (WHO), however, had estimated that 30 % of the medicines in circulation in low- and middle-income countries, like Nigeria, are substandard and counterfeit, thus, posing serious public health challenge to patients. The objective of this study was to evaluate the degree of compliance of different brands of risperidone with pharmacopeia standards. Generic brands of risperidone were sourced from pharmacies in south-south states of Nigeria and analyzed for uniformity of weight, hardness, friability, disintegration, and dissolution profiles. The content of active ingredients and similarity factor (F2) of the dissolution profiles for the tablets were also determined. All the tests were done according to USP and BP specifications. Risperidone content was determined at a wavelength of 241 nm using UVspectrophotometer. The innovator brand (R1) was applied as the reference standard. All the brands, passed the content of active ingredients assessment (> 95%), weight uniformity test (< 7.5 mg coefficient of variation), friability test (< 1.0%), disintegration test (< 10 min) and dissolution test (> 85% at 30 min). Only R1 and R2 passed the hardness test (> 4 kg/f)), while the comparison of their dissolution profiles via F2 determination gave values greater than 50, suggesting good potential for interchangeability of the brands. The study therefore indicated that the brands of risperidone available in Nigerian market met most of the stringent quality and safety standards necessary to ensure efficacy and interchangeability, but, the slight variations in some of the assessment parameters must be taken into account when brands are switched to avoid inconsistency in treatment outcomes.

Keywords: Risperidone, Substandard, Counterfeit, Pharmacopoeia, bioavailability, Similarity factor.