Three sensitive spectrophotometric, spectrofluorimetric, and densitometric methods are described for the determination of indapamide. The first and second methods are based on the oxidative coupling reaction of indapamide with 3-methyl-2-benzothiazolinone hydrazone HCl (MBTH) in the
presence of cerium(IV) ammonium sulfate in an acidic medium. The absorbance of the reaction product is measured at the λmax, 601 nm. With the same reaction, indapamide is determined by its quenching effect on the fluorescence of excess cerous ions at the emission λmax,
350 nm, and the excitation at λmax, 300 nm. The reaction conditions were optimized, and Beer's law was obeyed for indapamide at 1.2–9.6 μg/mL with mean recoveries of 99.92 ± 0.83 and 99.97 ± 1.11%, respectively. The third method, a stability-indicating
densitometric assay, was developed for the determination of indapamide, using toluene–ethyl acetate–glacial acetic acid (69 + 30 + 1, v/v/v) as the developing system and scanning at the λmax, 242 nm, in the presence of the degradation product and related substance;
for the indapamide concentration range of 0.6–6 μg/spot, the mean recovery was 99.73 ± 0.71%. The proposed methods were successfully applied to the determination of indapamide in bulk powder and commercial tablets, and the results of the analysis agreed statistically with those
obtained with the official method. Furthermore, the methods were validated according to the guidelines of the U.S. Pharmacopeia and also assessed by applying the standard additions technique.
Document Type: Research Article
National Organization for Drug Control and Research, 6 Abo Hazem St. Pyramids Ave, PO Box 29, Cairo, Egypt
Publication date: September 1, 2003
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