Three new bromimetric methods for the estimation of famotidine.

摘要

Three methods, titrimetric, spectrophotometric and kinetic, are described for the detn. of famotidine in bulk drug and in formulations. The methods involve the use of bromate-bromide reagent and methyl orange dye. In titrimetry, the sample is treated with a measured excess of bromate in the presence of a large excess of bromide and in hydrochloric acid medium, and after the reaction is judged to be complete, the unreacted bromine is detd. iodometrically. Spectrophotometry comprises of addn. of a known excess of bromate-bromide mixt. to the sample soln. in hydrochloric acid medium followed by the estn. of surplus bromine by reacting it with a definite amt. of methyl orange dye and measuring the absorbance at 520 nm. The reacted bromate amt. corresponds to the sample content. Kinetic method is based on bromination-oxidn. of famotidine by the bromine generated in situ by the addn. of acid to bromate - bromide mixt. With small amts. of drug in soln., the rates of bromine generation and consumption are roughly equal. Under these conditions, bleaching of added methyl orange by bromine will occur only after the bromination - oxidn. is complete. The time required for bleaching of the dye is measured and related to sample concn. The working conditions of the methods were optimized. Titrimetry is applicable over 3-15 mg range whereas spectrophotometry permits the quantitation of famotidine in the concn. range of 0.50-2.25 μg ml-1 with an apparent molar absorptivity of 8.97�104 l mol-1 cm-1 and Sandell sensitivity of 3.76 ng cm-2. The kinetic method allows the detn. of 10-50 μg ml-1 of famotidine with reasonable accuracy and precision. The methods have successfully been applied to the detn. of famotidine in several com. formulations with a recovery of 97.79 - 102.21 %. [on SciFinder(R)]