First derivative potentiometric and spectrophotometric determinations of cimetidine in tablets

Abstract

Cimetidine is an imidazole derivative, which acts as H2-receptor antagonist to inhibit gastric acid secretion and is thereby useful in the treatment of ulcers and other hyperacidity stomach disorders. This study sets out to provide simple, inexpensive and sensitive analytical techniques for the assay of cimetidine in tablet dosage forms using first derivative potentiometric and UV-spectrophotometric techniques, with a view to providing simple, sensitive and cost-effective analytical methods. Ten brands of cimetidine tablets were purchased from pharmacies in Yenagoa and Port Harcourt, Niger Delta region of Nigeria. The samples were assayed by Potentiometric and UV spectrophotometric methods after a Thin Layer Chromatographic (TLC) fingerprint. The potentiometric assay results of the samples ranged from 92-100% of stated amount for 70% of the samples. The coefficient of variation for In-between run, Intra-day run and accuracy of the UV spectrophotometric method was within 3%. The percentage purity of cimetidine from UV determination at 260 nm ranged from 86 - 97%, showing that 50% of the samples conformed to the stated standard – ie: contain 95- 105% of stated amount. The TLC fingerprints of the samples were similar in many respects, including R_f values which ranged from 0.8 to 0.9 compared to the reference sample with R_f value of 0.9. The results suggest that either of the two methods can be fine-tuned for assay of cimetidine in tablet formulations.

Keywords: Potentiometry, ultraviolet (UV) spectrophotometry, analytical methods, cimetidine, Tablet Formulations, volumetric standard (VS)