DEVELOPMENT AND VALIDATION OF SPECTROPHOTOMETRIC METHODS FOR DETERMINATION OF CERTAIN PROTON PUMP INHIBITORS

Two simple, sensitive and economic spectrophotometric methods, A and B, were developed for the determination of certain proton pump inhibitors. Method A is based on the reaction of esomeprazole (EMZ), lansoprazole (LNZ), and pantoprazole (PNZ) with molybdenum(v)-thiocyanate ion to form stable orange red colored ion pair complexes extractable selectively with methylene chloride. The orange red colored complexes showed maximum absorption at 468-470 nm. Method B is based on formation of colored products between the three studied drugs EMZ, LNZ, PNZ and 4-chloro-7-nitrobenzofurazan (NBD-CI) in methanol medium at 70 ± 2 °C. The absorbence of the yellow colored product was measured at 382-390 nm. Optimization of the various experimental conditions is described. Under the optimized experimental conditions, Beer's law was obeyed in the concentration ranges 5-60, 1-60 % and 6-60 for method (A) and 2 - 10 µg ml^-1 (methods B) for the three drugs. Results obtained by applying the proposed methods showed good recoveries of 99.86 ± 1.02 %, 99.66 ± 1.23 % and 100.1C± 1.10 % for method A and 100.24± 1.18 %, 100.03 ± 1.1.08% and 99.63 ± 0.61 %, method B, for the three mentioned drugs. Tae developed methods were applied for determination of the studied drugs in their pharmaceutical preparations with good accuracy and precision. The obtained results were compared favorably with reference spectrophotometric method indicating no significant d fference between the methods compared. Thus, the proposed spectrophotometric methods can be applied as inexpensive, rapid, easy, accurate and precise methods for the routine analysis of the three proton pump inhibitors in pharmaceutical preparations.