Permaganometric determination of sumatriptan succinate in pure drug and pharmaceutical formulation

Abstract

Based on the reduction of permanganate by sumatriptan succinate (STS) in acidic medium, two simple, sensitive and cost-effective methods were described for the determination of STS in bulk drug and in formulation. In titrimetry (method A), STS was oxidized by a known excess of potassium permanganate (KMnO4) in H2SO4 medium followed by determination of unreacted permanganate by titration with ferrous ammonium sulphate. In spectrophotometry (method B), STS was treated with a measured excess of permanganate in acid medium and the unreacted oxidant was measured at 545 nm. The molar combining ratio in titrimetry and the optimum assay conditions were studied. Titrimetry was applicable over 1-7 mg range and the calculations were based on a 1:6 (STS: KMnO4) molar ratio. In spectrophotometry, Beerûs law was obeyed over 0.8-16.0 μg ml-1 concentration range of STS. The molar absorptivity and Sandell sensitivity values are calculated to be 1.39 × 104 l mol-1 cm-1 and 0.03 μg cm-2, respectively. The limits of detection (LOD) and quantification (LOQ) were also reported for the spectrophotometric method. The applicability of the developed methods was demonstrated by the determination of STS in pure drug as well as in commercial dosage form.