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Abstract

The kinetics of hydrolysis of famotidine in aqueous solution was studied by isothermal and nonisothermal method over the pH range of 1.71 to 10.0. Nonisothermal kinetics was studied with the purpose of determining its use in the establishment of the expiration date of pharmaceutical preparations, particularly drugs in solutions and for assessment of stability characteristics of pharmaceutical formulations during the development stage. A comparison of isothermal (55, 70 and 85 degrees C) and nonisothermal kinetics was performed. Aqueous solutions of famotidine were buffered at pH 1.71, 2.24, 2.66, 4.0, 8.5, 9.0 and 10.0 were used. In the nonisothermal studies, the temperature rate of the reaction was continuously varied throughout the experiment. The energies of activation were found to be in close agreement for isothermal and nonisothermal studies, indicating that nonisothermal studies may save considerable amount of time in the early stages of drug development and stability testing. Logk-pH profiles were constructed for 55, 70 and 85 degrees C from the first-order rate constants obtained from isothermal studies at pH values ranging from 1.71 to 10.00. The pH-rate profile indicated that famotidine undergoes specific acid catalysis in the acidic region and general base catalysis in the alkaline region. Hydrolysis in the acidic and alkaline media resulted in the formation of four and five degradation products, respectively. A possible degradation pathway for the acidic and alkaline hydrolysis was discussed.

Design of 3‐aminophenol‐grafted polymer‐modified zinc sulphide nanoparticles as drug delivery system

“…Alkaline pH (pH > 7) was not studied, because in alkaline pH, famotidine was decomposed [ 29 ]. The kinetic of famotidine sorption at pH = 5 can be seen in Figure 8 and Table 1 .…”

Engineering a Remedy to Improve Phase Stability of Famotidine under Physiological pH Environments

“…The change in absorption spectra of FAM-A at pH 1.2 with the variation of time is shown in Figure A,B. It is reported that the degradation rate of FAM-A follows pseudo-first-order kinetics over the pH range of 1–11. , Under the thermal condition, i.e., at 50 °C, the apparent rate of degradation of FAM-A is reported to be 1.54 × 10 –3 min –1 at pH 2.2, whereas we calculated the rate constant ( k ) for FAM-A at room temperature to be 4.93 × 10 –3 min –1 at pH 1.2 (Figure B). The higher rate constant value of FAM-A reported by Junnarkar et al is mainly responsible for degradation of FAM-A at acidic (pH 2.2) condition …”

“…Famotidine is a histamine H2-receptor antagonist drug, marketed under the trade name Pepcid. − It is generally used for the treatment of various kinds of peptic ulcers like gastric and duodenal ulcers, deterrence of ulcer recurrence, treatment of gastritis, Zollinger-Ellison syndrome, prophylaxes and gastro-esophageal reflux diseases, and acute upper gastrointestinal hemorrhage, and also for protection against the pulmonary target of acid during anesthesia. − It is reportedly categorized as a BCS class IV drug due to its extremely low solubility and intestinal permeability . It is apparently an unstable drug, corroborated after detecting degradation products present in plasma, urine, parental nutrient solution and gastrointestinal tract. − Essentially, the drug is unstable in acidic environment and afforded three degradation products assessed as sulfamoyl amide, amide, and carboxylic acid . It degrades rapidly under acidic conditions, and the concentration is reduced to 33–88% famotidine within 1–3 h duration of time .…”

Determination of Chemical Stability of Various Famotidine Dosage Forms by UV –Visible Spectrophotometric Method and Data Analysis by R-GUI Stability Software

“…In concentration rangeof4-57 g/ ml coefficient of variation of assay method ranged from 0.2 to 5.1%. Junnarkar and Stavchansky, in 1995, studied Isothermal and nonisothermal decomposition of Famotidine in aqueous solution was over pH range of 1.71 to 10.0 for establishing expiration date of preparations [15]. In 2002, Degim and Agabeyoglu have compared isothermal and nonisothermal stability of nizatidine and Famotidine by using linear and logarithmic temperature programs rate constants and activation energies were calculated.…”