Nigerian Journal of Pharmaceutical Research Vol. 7 No. 1 (2008) The Official Publication of Nigerian Association of Pharmacists in Academia 12 Nigerian Journal of Pharmaceutical Research Vol. 7, No. 1, 12 - 17 (September 2008) QUALITY EVALUATION OF SOME BRANDS OF VITAMIN C PREPARATIONS J.O. Soyinka 1,* , F.J. Faleye 2 and G.E. Adetogun 3 Departments of 1 Pharmaceutical Chemistry and 3 Pharmaceutics, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, 2 Department of Chemistry, University of Ado-Ekiti, Ekiti State, Nigeria. Abstract Ten brands each, of vitamin C tablets and syrups were evaluated for their quality using British pharmacopeia colorimetric and titrimetric analytical methods. Other characteristics assessed were uniformity of weight, friability, disintegration and dissolution rate. Sixty percent of the tablet and 40 % of the syrup brands had values within the BP specified range and were therefore chemically equivalent. The percentages of the tablet brands that complied with the official specifications for friability, disintegration and uniformity of weight tests were 100, 100 and 60 %, respectively. Seventy percent of the brands had above 70 % dissolution at less than 45 min. while 30 % failed to attain 70 % dissolution throughout the period of the determination. Although sixty percent of vitamin C tablet brands had ascorbic acid contents within the pharmacopoeial limits, some of these brands failed the dissolution profile and weight uniformity tests, indicating that they were substandard with consequent therapeutic failure. Therefore, in ascertaining quality of the brands of drugs, assays for active constituents should be combined with assessment of other pharmaceutical characters. Keywords: Vitamin C, tablets, syrups, titrimetric method, colorimetric method, quality evaluation * : Corresponding author E-mail: josandj@oauife.edu.ng Introduction Vitamin C or L-ascorbate (1) is a water-soluble vitamin that plays important role in human nutrition. It is a highly effective antioxidant and reduces oxidative stress (Padayatty et al., 2003). As an enzyme cofactor, it is important for the biosynthesis of many biochemicals such as collagen necessary for the building of blood vessels, tendons, ligaments, and bone. It is also essential for the synthesis of carnitine that is needed for the transport of fat in the production of energy (Levine et al., 2001), metabolism of cholesterol to bile acids and reduction of incidence of gallstone (Lee et al., 2001). The increased number of various brands of drugs from multiple sources in the developing countries was to improve their overall healthcare delivery systems. However, this was accompanied with increased number of fake and substandard drugs that make it difficult for healthcare providers to effectively select good products from among several brands containing the same active ingredient(s). The proprietary drugs must be identical in content, purity, uniformity of weight, disintegration and dissolution rates before they are considered chemical equivalents (Olaniyi et al., 2001). There are several reports of differences in clinical efficacies by these chemical equivalents that could only be due to the different manufacturers (Remington’s Pharmaceutical Sciences, 1990). Only sixty percent of brands of ciprofloxacin tablets (Adegbolagun et al., 2007) and 38 % of pyrimethamine tablets (Odeniyi et al., 2002) were found to be chemically equivalent while the others were substandard. Most of the counterfeits detected were largely by accident. It is conservatively estimated that more