Purpose:  The aim of the present  study  is  to  investigate  the physicochemical  equivalence of eight  brands  of tablets containing  sulfadoxine-pyrimethamine  (antimalarial  drug  combination) sourced from different retail Pharmacy outlets in the Nigerian market.
Method: The quality  and physicochemical  equivalence of  eight  different  brands  of sulfadoxine-pyrimethamine combination tablets were assessed.  The assessment  included the evaluation of  uniformity  of  weight, friability,  crushing  strength,  disintegration and dissolution tests as well as chemical assay of the tablets.
Results:  All the eight brands of the tablets passed the British Pharmacopoeia (BP) standards for  uniformity  of  weight,  disintegration and  crushing  strength.  Three of the eight  brands  failed the  friability  test.  One of the brands  did not  comply  with  the  standard assay  of  content  of active  ingredients  while another  brand did not  comply  with  the  USP  specifications  for dissolution test for sulfadoxine-pyrimethamine tablets.  There were no significant differences in the amounts of pyrimethamine and sulfadoxine released from the different brands (P>0.05).
Conclusion:  Only  three brands  (registered by  NAFDAC)  out  of the eight  brands  of sulfadoxine-pyrimethamine  tablets that  were analysed passed all  the BP quality specifications and  were physically  and  chemically  equivalent.  This study  highlights  the need  for  constant market monitoring of new products to ascertain their equivalency to the innovator product.