Analysis of nifedipine-acebutolol hydrochloride binary combination in tablets using UV-derivative spectroscopy, capillary gas chromatography and high performance liquid chromatography.

Three methods are described for the simultaneous determination of nifedipine and acebutolol hydrochloride in combined pharmaceutical tablets. The first method depends on first-derivative ultraviolet spectrophotometry, with peak-to-base and zero-crossing measurements methods. The first derivative amplitudes at 400 and 352 nm were selected for the assay of nifedipine and acebutolol hydrochloride, respectively. Calibration graphs follow Beer's law in the range of 4-12 and 44-132 micrograms ml-1 and the linearity was satisfactory (r = 0.999) for nifedipine and acebutolol hydrochloride, respectively. The second method was based on the separation of nifedipine from acebutolol hydrochloride, with an internal standard thymolphthalein, using capillary gas-liquid chromatography with a programmable temperature change. The third method was based on high performance liquid chromatographic separation of the two drugs on a reversed-phase, C18, column using a mobile phase of methanol-water (55:45, pH 4.5) with a programmable flow rate of 1 ml min-1 for 4 min which changed to 2 ml min-1 for the rest of the run. The detection was done at 260 nm using oxprenolol hydrochloride as an internal standard. Both chromatographic methods showed good linearity, precision and reproducibility. No spectral or chromatographic interference from the tablet excipients were found. The proposed methods were successfully applied to the assay of commercial tablets and a content uniformity test. The procedures were rapid, simple nondestructive and suitable for quality control application.