Solid State Photodegradation Study of Fexofenadine Hydrochloride

The photodegradation of solid-state fexofenadine hydrochloride, H1 receptor antagonist, was investigated under UV light conditions as per option 2 of ICH photostability testing guidelines. The amount of drug remaining intact after photodegradation was estimated using a newly developed and validated HPTLC method employing ethyl acetate: methanol: ammonia (30%) as a mobile phase in proportion of (6:3.5:0.5v/v/v). In solid state, after 1800watt.hrs/m2 of UV light illumination, fexofenadine hydrochloride concentration was reduced to 57% following a first-order kinetic with t1/2 of 2221.5watt.hrs/m2 and a degradation rate constant (k) of 3.12(watt.hrs/m2)−1. The results indicate that fexofenadine hydrochloride should be protected from light.