Chemical Stability and a Novel Quinine Syrup Formulation for Pediatric Drug Use

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Malaria is a public health problem worldwide, especially in tropical Africa where it kills around a million of people a year, of which 75% are children under 5 years of age, drug assessment in this group is lower which complicate the choice of appropriate treatment. Quinine is re-emerging as an important drug in the treatment of multiple-drug resistant or severe Plasmodium falciparum malaria. Chemical stabilities of brands of quinine syrup on the market were studied as well as the formulated product. Changes in percentage contents and pH were used as a tool for the study. UV-spectrophotometer was used for the analysis. This was done by preparing different concentrations of pure quinine sulphate in 0.1 M HCl solution and their respective absorbance determined at 250 nm. A calibration curve was plotted and the equation obtained was used for the quantification of quinine sulphate syrups bought from market. Two sets of each brand were analyzed. The analysis was done for a period of one week on each set. Brands A and D passed percentage content of 95 – 105 % on first sets of analysis, however, failed on the second sets. Brand A had a percentage breakdown of 3.76 and D 0.81% with pH changing within a range of 2.50 – 2.94. Brands B and E failed percentage content and had 13.97% and 1.34% percentage breakdown respectively with pH range of 4.78 – 5.69. Brand C also failed percentage content with percentage breakdown of 8.87% and having its pH changing within a range of 2.50 – 2.94. Quantitative solubility of quinine sulphate was established in citric acid, citrate buffer and in water using UV-spectrophotometer at 250 nm. Quinine sulphate had a solubility of iii 20.20 mg/ml in citric acid, 2.20 mg/ml in water and 12.67, 5.00, 0.0563, 0.153 and 0.188 mg/ml respectively in citrate buffer of pH 2, 3, 4, 5 and 6. Quinine sulphate syrup was eventually formulated. The formulation was done in a citrate buffer of pH 2 as the vehicle. This was necessitated by the outcome of the solubility test performed on the salt. The product had a pH of 2.30 with syrup strength of 40 mg of quinine sulphate per 5 ml. Anise water prepared from anise oil was effectively used to mask the taste. The product had a better stability when packaged in amber bottle than in plain bottle. The amber bottled product passed percentage content on the two sets of its analysis with virtually 0% breakdown and had a pH changing within 2.30 – 2.40. Plain bottled product on the other hand, failed percentage content and had a percentage breakdown of 12.73% with pH range of 2.30 – 2.60. Comparatively, the syrup strength of the formulated product of 40 mg/5ml (amber bottled product) stands at advantage over the market products of a reduced toxic effect in case of accidental overdose and again its high stability will also ensure accurate dosage delivery to avoid underdose. Key words: Quinine sulphate, Citric acid, Citrate buffer, UV-spectrophotometer, pH, solubility, chemical stability, plain and amber bottled products.
A Thesis Submitted in partial fufilment of the requirement of the degree of Master of Philosophy in Pharmaceutical Chemistry.