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

Multicomponent crystals, essentially cocrystal engineering, comprise an emerging research area in pharmaceutical development which offer an easy solution to concerns with several drugs. Famotidine, a histamine H2-receptor antagonist drug, is commonly used for the treatment of gastroesophageal diseases, but it soon degrades at the stomach pH environment. The degradation kinetics of famotidine are studied by isolating the degraded product and proposing a plausible mechanism. As a remedy to such degradation, three cocrystals of famotidine with xanthine derivatives of active ingredients, i.e., theophylline, caffeine, and theobromine, are synthesized followed by phase stability studies under the same physiological pH environments. Formation of stronger hydrogen-bonded heterosynthons in cocrystal structures contribute to cocrystal stability and result in favorable conformation of the drug famotidine, concealing the process of acid hydrolysis at pH 1.2.