Pharmaceutica Analytica Acta

Abstract

Development of Stability Indicating Densitometric and Enhanced sensitivity Spectrofluorimetric Methods for Determination of Zaleplon in Presence of its Acidic Degradation Products

Sawsan A Abdel Razeq, Suzan M Soliman and Amal S Mohamed

Zaleplon is easily degradable into its acidic degradation products, so two stability- indicating methods were developed for determination of zaleplon in the presence of these degradation products and are successfully applied to quantify zaleplon in pharmaceutical preparations. The first was a densitometric evaluation of thin-layer chromatograms of the drug using a mobile phase of ethyl acetate ? ammonia (33%) - methanol (8.5:0.5:1, v/v/v). The chromatograms were scanned at 338 nm, a wavelength at which zaleplon can be readily separated from its degradation products and determined in the range of 0.5-2.5 ?g/spot with mean percentage recovery of 100.79 ± 0.65%. The second method was based on measuring the fluorescence intensity of zaleplon at ?ex/?em =350 nm/460 nm. The effect of micelle medium on the fluorescence emission was studied which revealed that the anionic surfactant of sodium lauryl sulphate has strong sensitizing effect for the fluorescence. The fluorescence intensity plot was linear over the range of 0.1-3.6 ?g/ml with mean percentage recovery of 100.39 ± 1.12%. Determination was also successful when analyzing zaleplon in a formulation in the form of Siesta capsules. Results were statistically analyzed and found to be in accordance with those given by a reported method.