A VALIDATED RP-LC METHOD FOR SALMETEROL AND FLUTICASONE IN THEIR BINARY MIXTURES AND THEIR STRESS DEGRADATION BEHAVIOR UNDER ICH-RECOMMENDED STRESS CONDITIONS

摘要

Simple, accurate, precise and fully validated analytical methods for the simultaneous determination of salmeterol xinafoate and fluticasone propionate in combined dosage forms have been developed. These drugs were exposed to thermal, photolytic, hydrolytic and oxidative stress conditions, and the stressed samples were detected by the proposed method. Additionally, pKa values of three ionizable drugs (salmeterol xinafoate, fluticasone propionate and thioridazine) were determined using by the dependence of the retention factor on pH of the mobile phase. The effect of the mobile phase composition on the ionization constant was studied by measuring the pK_a in different acetonitrile—water mixtures, ranging between 50 and 65% (v/v) using LC—UV method.