ABSTRACT
A simple and sensitive reversed phase high-performance liquid chromatographic method was developed for simultaneous quantification of diltiazem HCl and its major metabolite N-demethyldiltiazem in human plasma. The method involves one step solvent extraction of diltiazem, N-demethyldiltiazem and the internal standard, verapamil with n-hexane and diethyl ether [50:50 v/v]. The mobile phase comprised 0.1 M ammonium dihydrogen phosphate-acetonitrile [62:38 v/v] and triethylamine [0.08%] was added before the pH was adjusted to 5.9 with 85% phosphoric acid. Analysis was run at a flow rate of 1.0 ml/min at a detection wavelength of 238 nm. The completion time for assay was not more than 10 minutes and lower limit of quantification was 5 ng/ml. The calibration curve for diltiazem and its metabolite was linear over a concentration range of 5-200 ng/ml and average recovery was about 90%. The coefficient of variation and percent error values of the assay method within and between days were all less than 10%
Subject(s)
Humans , Drug Monitoring , Chromatography, High Pressure LiquidABSTRACT
The effects of light, temperature, pH and additives on the stability of Sulphacetamide sodium in eye preparations have been studied. The Sulphacetamide eye drops are stable at room temperature and lose potency at elevated temperature. The stability is also affected by light and pH of the solution. The eye drops are more stable when Sodium mctnbisulphitc and Phenyl mercuric nitrate are used as preservatives