ABSTRACT
Artesunate is a semi-synthetic derivative of artemisinin used in the treatment of malaria. Artemisinin and its semi-synthetic derivatives have played a significant role in relieving the world‟s malaria burden since their discovery owing to their higher safety profile and tolerability. Several methods are available for the analysis of artesunate but majority of them involves the use of sophisticated equipment and expensive chemicals/reagents. This study investigates the use of 2,4-dinitrophenylhydrazine, in acidic medium, for the colorimetric determination of artesunate in bulk and pharmaceutical dosage forms. The method involves reaction of the acid degradation product of artesunate and 2,4- dinitrophenylhydrazine to form a yellow colour solution. The concentration of hydrochloric acid, concentration and volume of 2,4-dinitrophenylhydrazine, diluents, temperature and heating time were optimized. The stability of the product formed was observed. A calibration curve was prepared and recovery study for pure samples of the drug was done. The developed method was validated using the International Council for Harmonization of Technical Requirement for registration of Pharmaceuticals for Human Use (ICH) guideline and then used to determine the percentage content of the drug in pharmaceutical dosage forms. The results obtained for the analysis of artesunate in pharmaceutical dosage forms using the developed method were compared with those of a reported method. The wavelength of maximum absorption (λmax) of the product formed was 476 nm. The optimum reaction conditions were; 5 M hydrochloric acid, 0.02 M and 1 ml of 2,4- dinitrophenylhydrazine, ethanol as diluents and heating at 450C for 15 minutes. The complex was stable for 80 minutes after which degradation set in. The regression equation for the Beer‟s plot is A = 0.0183C + 0.0057 (R² = 0.9991). Both reactants produced maximum effect at mole ratios of 1:1 and linearity was established at the concentration range of 2.5 - 70 xix μg/mL. The percentage recovery of artesunate from standard solution is 99.593 ± 0.267 (mean ± relative standard deviation). At P > 0.05, there is no significant difference between the mean recovery of artesunate from standard solution using the developed method and the true value and the result of repeated measurement (n = 8) is 0.634 ± 0.230 (mean ± RSD), indicating that the method is accurate and precise. The intra-day and inter-day precisions at concentrations of 10, 20 and 35 μg/ml were 0.190 ± 0.430, 0.395 ± 0.139 and 0.634 ± 0.081; and 0.190 ± 0.440, 0.395 ± 0.113 and 0.635 ± 0.132, respectively, showing the reproducibility of the method. The limit of detection and limit quantification was 0.288 µg/mL and 0.960 µg/mL respectively. The molar absorptivity of the developed method was 7.0797 x 103 L Mol-1 cm-1 . The percentage contents determined for the nine brands of tablets and four brands of powder for injection assayed were within the specifications of the International Pharmacopoeia (98 - 102%). In conclusion, the developed method is simple, accurate, and utilizes readily available chemicals and equipment, and is inexpensive. The method could therefore be used for the routine analysis of artesunate
