Application of Oxidizing Properties of Permanganate to the Determination of Famotidine in Pharmaceutical Formulations

one titrimetric and two spectrophotometric methods are described for the determination of famotidine (fmt) in either pure form or in its pharmaceutical formulations. the methods are based on redox reaction between fmt and kmno4 in acid and alkaline media. in titrimetry, an acidified solution of fmt is titrated directly with permanganate. direct spectrophotometry (method a) involves treating the alkaline solution of the drug with permanganate and measuring the bluish green product at 610 nm. in indirect spectrophotometry (method .), the drug solution is treated with a fixed concentration of permanganate in h2so4 medium, and after a specified time, the unreacted permanganate is measured at 545 nm. the molar combining ratio in titrimetry and the optimum assay conditions are studied. titrimetry is applicable over 1-10 mg range and the calculations are based on a 1:3 (fmt: kmno4) molar-ratio. in spectrophotometry, beer's law is obeyed over 0.75-7.5 and 2.5-20 μg ml-1 for method a and method ., respectively. the molar absorptivity values are calculated to be 2.79 × 104 and 1.62 × 104 l mol-1 cm-1 for method a and method b, respectively, and the corresponding sandell sensitivity values are 0.012 and 0.021 μg cm-2. the limits of detection (lod) and quantification (loq) are also reported for the spectrophotometric methods. the applicability of the developed methods was demonstrated by the determination of fmt in pure drug as well as in commercial dosage forms.