Comprehensive and Validated Chromatographic Techniques for the Estimation of Lercanidipine Hydrochloride and Atenolol in Bulk and Combined Dosage Form in the Presence of Lercanidipine Degradation Products with LC/MS Characterization.

Two rapid, smart and validated stability indicating HPLC and TLC techniques were developed to determine atenolol (ATE) and lercanidipine HCl (LER) simultaneously in their pharmaceutical formulation. HPLC chromatographic separation was implemented by using Microsorb C18 (250 × 4.6 mm, 5 μm) column, with mobile phase of acetonitrile and 20 mM potassium dihydrogen phosphate buffer pH 3.5 adjusted by orthophosphoric acid in the ratio of (65:35, v/v) at a flow rate of 1.2 mL/min at 240 nm also the injection volume adjusted to be 30 μL. These selected conditions effectively separated ATE and LER at a retention time of 2 and 6.7 min, respectively, by isocratic elution mode without any interference from the obtained degradation products of LER. The densitometric determination was performed by using precoated silica gel 60F254 aluminum plates and chloroform, methanol and triethylamine (11.3:1.3: 0.3, by volume) as a developing system. The detection wavelength for simultaneous estimation of both drugs was 240 nm in the presence of the oxidative product of LER. The RF values for ATE and LER were 0.22 and 0.78, respectively. The calibration curves of both techniques were constructed with linearity ranges of (5-55) μg.mL-1 and (1-55) μg.mL-1 for both ATE and LER, respectively, for HPLC determination. While for TLC, the linearity ranges were (1-4) μg/band and (0.2-1.4) μg/band for ATE and LER, respectively. LER degradation products were characterized using UPLC/MS and the suggested mechanisms and degradation pathways were introduced.