Development and validation of two chromatographic methods for the simultaneous determination of raubasine and almitrine besmesylate in pharmaceutical dosage form

A binary mixture of almitrine besmesylate (A) and raubasine (R) was determined by two different chromatographic methods. The first method was based on HPTLC separation of the two drugs followed by densitometric measurement of their spots at 245 and 285 nm for A and R, respectively. The separation was carried out using HPTLC silica gel F254 nanoplates with methanol: ammonia (10:8, v/v) as developing solvent. The linearity was achieved over concentration range of 0.5–8 μg/spot and 0.5–10 μg/spot with mean accuracy 100.79± 1.58 and 100.68± 1.78, for A and R, respectively. The second method involved the determination of A and R using reversed phase high performance liquid chromatography (HPLC) on C18 column using acetonitrile:potassium dihydrogen orthophosphate buffer pH= 4.7 (70:30, v/v) as mobile phase with flow rate at 2 ml/min. Quantitation was achieved using UV detection at 220 nm. A linear relationship was obtained over a concentration range of 0.75–105 μg ml^-1 for both drugs with mean accuracy 100.85± 1.74 and 98.82 ±1.31, for A and R, respectively. The methods were successfully applied for the determination of the cited drugs in dosage forms. The proposed methods were validated according to USP and were found to be valid and suitable for the assay of the cited drugs in dosage forms in quality control laboratories.