First-Derivative Spectrophotometric Determination of a Mixture of Pirbuterol Hydrochloride and Butorphanol Tartrate

Abstract

Vierordt's method, its modified version and the first derivative method have been applied for the simultaneous determination of butorphanol tartrate and pirbuterol hydrochloride in laboratory mixtures of authemtic and dosage forms. The first derivative spectrophotometric method yields accurate and reprodeucible results for both drugs. Mean percent recoveries for butorphanol tartrate and pirbuterol hydrochloride in dosage forms were 100.54±0.84 and 100.42±1.27, respectively. Virrordt's method and its modified version have given unreliable results; the reasons behind have been discussed.