DETERMINATION OF ASTEMIZOLE USING IODINE CHARGE-TRANSFER COMPLEXATIONAND HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Two analytical techniques are described for the determination of astem izole. A simple and rapid spectrophotometric method based on the direc t absorbency measurements of the formed charge-transfer complex betwee n astemizole and iodine at either 286 or 362 nm was used. The continuo us variation method indicated a 1/2 complex between the drug and iodin e. The concentrations were linear over the concentration range of 2 to 7 mu g/ml at both wavelengths. A full detailed investigation of the c omplex was made with respect to its association constant and the free energy change. The method is simple and sensitive and has been applied successfully to the analysis of commercially-available astemizole tab lets and suspension without any interference from the pharmaceutical e xcipients. To validate the proposed procedure, an high performance liq uid chromatography method in the reverse phase mode using C-18 column and a mobile phase of acetonitrile/water/triethanolamine in the ratio of 70/30/.5 with pH of 6.0, flow rate of 2 ml/min with UV detection at 286 nm was developed. Cinnirazine was chosen as the internal standard . The results obtained from both methods were statistically compared u sing the Student's t-test and F-variance ratio test.