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Ars Pharmaceutica (Internet)

On-line version ISSN 2340-9894


YEVSTAHIYOVYCH, Blazheyevskiy Mykola; YURIIVNA, Serdiukova Yuliia; PAVLIVNA, Karpova Svitlana  and  OSYPIVNA, Dubenska Liliya. Kinetic investigation of Famotidine S-oxidation reaction using potassium caroate. Development and validation of the titrimetric method for the quantitative determination of Famotidine in pure substance and medical preparation. Ars Pharm [online]. 2018, vol.59, n.2, pp.69-76. ISSN 2340-9894.


The kinetic studies of Famotidine (FMT) pure substance and medicinal preparation have been carried out in buffer solutions under second-order conditions at the temperature 293 K for the first time. New titrimetric procedures are described for the FMT determination.

Materials and Methods:

FMT pure substance and tablets have been used in analytical reaction with of KHSO5. The kinetic behavior has been studied by the iodometric method in different pH medium.


FMT oxidation reaction has been studied for the S-oxide product under pH=2.0-5.0 and Sulfone product under pH=7.0-8.4. The reaction studied corresponds to the total second order. The Sulfone formation from FMT S-oxide reaction rate constant is in the interval from 14.49 to 32 min-1 L mol-1. FMT has been treated with a measured excess of standard potassium caroate in buffer solution with pH 7, after a contact time of 20 min, the residual oxidant back has been determined by the iodometric titration method. The titrimetric method is applicable over 1-10 mg mL-1 concentration range and the reaction follows 1:2 (FMT:KHSO5) stoichiometry. The method has been validated for precision, accuracy, linearity, robustness and LOQ. The recovery percent ranged from 99.2 to 100.5%, RSD from 1.09 to 1.70 %, LOQ = 0.03 mg mL-1 for pure substance. RSD for tablet formulations has been in the limits from 1.17-2.87 %.


The conditions of FMT S-oxide and Sulfone formation have been optimized. The developed procedures are rapid, simple and inexpensive and could be applied to pharmaceutical preparation.

Keywords : Kinetics; Mechanism; Oxidation; Famotidine; Potassium caroate.

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