Pharmacokinetics and pharmacodynamics of two morphologically homogenous forms of famotidine per os in Chinese healthy volunteers

The lg C of famotidine (Fam) A and B forms in plasma vs time curve following a single oral dose of 40 mg showed an one-compartment open model in 5 healthy volunteers. The T1/2Ke of Fam A and B forms = 3.06 and 3.48 h, Tmax = 2.96 and 2.68 h, The Cmax = 115 and 145 ng.ml-1, AUC = 811 and 1190 h.ng.ml-1, respectively. No significant difference was found in the pharmacokinetic and pharmacodynamic properties between Fam A and B forms. The mathematical model describing the whole course of blood concentration of Fam A and B forms in relation to inhibiting effects on gastric acid were: E (A) = 100.C2.04/(C2.04 + 15.0(2.04)) and E (B) = 100.C1.67/(C1.67 + 14.0(1.67)). Predication of blood drug concentration from pharmacodynamics or vice versa became possible using the mathematical equations.