Electrochemical studies and differential pulse polarographic analysis of lansoprazole in pharmaceuticals

• Published in: Analyst (London) Vol. 126; no. 3; pp. 361 - 366
• Main Authors: YARDIMCI, C, ÖZALTIN, N
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 01.01.2001
• Subjects: 2-Pyridinylmethylsulfinylbenzimidazoles; Analysis; Anti-Ulcer Agents - analysis; Biological and medical sciences; Calibration; Capsules; General pharmacology; Lansoprazole; Medical sciences; Omeprazole - analogs & derivatives; Omeprazole - analysis; Pharmacology. Drug treatments; Polarography - methods; Sensitivity and Specificity; Spectrophotometry; Chemical analysis; Electrochemical method; Differential impulse voltamperometry; Enzyme inhibitor; Chemical degradation; Proton pump inhibitor; Chemical reduction; Cyclic voltammetry; Benzimidazole derivatives; Antisecretory agent; Dosage form; Electrochemical reaction; Lansoprazole; Quantitative analysis
• ISSN: 0003-2654; 1364-5528
• DOI: 10.1039/b008800p

The electrochemical reduction of lansoprazole was investigated by cyclic voltammetry and direct current and differential pulse polarography. The reduction potential was -1.32 V vs. Ag/AgCl with a dropping mercury electrode in a supporting electrolyte consisting of phosphate buffer (pH 9.0)-tetramethylammonium iodide (4 + 1). The reversibility of the electrode reaction and the type of limiting current were studied. The temperature coefficient and the diffusion constant were determined. A mechanism for the electrode reaction was proposed. A new simple and sensitive differential pulse polarographic method was also developed for the quantification of lansoprazole. A linear calibration graph was obtained in the range 0.04-11.35 micrograms ml-1. The limit of detection was 0.03 microgram ml-1 and the intra- and inter-day precisions were 0.84-2.32 and 0.72-3.09%, respectively. The developed method was applied to six different commercial pharmaceutical capsule preparations containing enteric-coated granules. The relative standard deviations ranged from 1.36 to 2.85%. Recovery studies for the accuracy of the method were performed by adding a synthetic mixture to known amounts of lansoprazole and the mean recovery was 100.45%. The data obtained from commercial preparations were compared with those from a published spectrophotometric method. No difference was found statistically.