SPECTROPHOTOMETRIC DETERMINATION OF PYRITHIOXIN IN PHARMACEUTICAL PREPARATIONS

Rapid direct and induced difference spectrophotometric methods for determination of pyrithioxin in single dosage forms (tablets and syrups) are reported. The direct methods depend upon measurement of the absorbance of pyrithioxin in different media at lambda(max) i-e at 296 nm in 0.1 M hydrochloric acid, at 328 nm in citric acid-phosphate buffer of pH 7 and at 314 nm in 0.1 M sodium hydroxide. The mean percentage recovery of the authentic samples were 100.55 +/- 0.43, 101.21 +/- 0.58 and 100.29 +/- 0.64 respectively (P = 0.05). The absorbance difference methods are based upon either measurement of the difference between the acid and the alkaline solutions i-e. DELTA A (Alk-Acid) at 318 nm with an accuracy of 100.72 +/- 0.88 or the absorbance difference between the acid and neutral solutions i-e DELTA A (pH 7-acid) at 328 nm with an accuracy of 100.31 +/- 0.68.