Development and validation of RP-HPLC,HPTLC and UV-visible spectrophotometric methods for simultaneous estimation of alprazolam and propranolol hydrochloride in their combined dosage form

Three accurate, sensitive and reproducible methods are described for the quantitative determination of alprazolam (ALP) and propranolol hydrochloride (PNL) in their combined dosage form. The first method involves an RP-HPLC separation on the C₁₈ column using acetonitrile-25 mM ammonium acetate buffer and 0.2% triethylamine (pH of buffer adjusted to 4 with glacial acetic acid) in the ratio of 35: 65 (v/v) as mobile phase. Symmetrical peaks with good separation, ALP at 9.3 min and PNL at 3.5 min, were achieved. Quantification was done with photo diode array detection at 255 nm over the concentration ranges of 0.5–50 and 10–250 μg/mL for ALP and PNL, respectively. The second method is based on the separation of drugs by HPTLC using chloroform-methanol-ammonia 7: 0.8: 0.1 (v/v/v) as mobile phase. Quantification was achieved using UV detection at 248 nm over the concentration range of 100–600 ng/spot and 5–30 μg/spot for ALP and PNL, respectively. The third method involves dual wavelength UV-visible spectrophotometric method. It is based on the determination of PNL at 319.4 nm using its absorptivity value and ALP at 258.2 nm after deduction of absorbance due to PNL. Quantification was achieved over the concentration range of 1–40 and 80–200 μg/mL for ALP and PNL, respectively. All methods were validated according to ICH guidelines and successively applied to marketed pharmaceutical formulation, and the results of all three methods were compared statistically as well. No interference from the tablet excipients was found.