Determination of nitrendipine in tablets by HPTLC-densitometry

A sensitive, selective, precise, and stability-indicating high-performance thin-layer chromatographic method coupled with densitometric analysis has been developed for determination of nitrendipine both as the bulk drug and in pharmaceutical dosage forms. The active substance was extracted from tablets with methanol (recovery from 97 to 105%) and chromatographed on silica gel 60 F 254 HPTLC plates in horizontal chambers with n-hexane-ethyl acetate-acetone, 6 + 3 + 2 (vlv), as mobile phase. UV densitometric analysis of nitrendipine was performed in absorbance mode at A = 335 nm. The calibration plot was constructed in the range 0.025 to 0.150 mu g mu L-1 (corresponding to 0.5-3.0 mu g spot(-1)) with good correlation (r >= 0.990) and expressed as a second-order calibration function. Determination of nitrendipine in tablets was characterized by good precision (1.94% < RSD < 6.62%) and accuracy (-3.0 < RSE < 5.12). The HPTLC-densitometric method was successfully used for identification of nitrendipine in the presence of its induced degradation products. Pure drug and tablet extract were subjected to acid and alkali hydrolysis, oxidation, UV degradation, and photodegradation. The degraded products were well resolved from the nitrendipine with different R-F values.