Abstract

The pharmacokinetic (PK) of omeprazole (OMP), 5-hydroxy-omeprazole (5-OH-OMP) and omeprazole sulphone (OMP-SUL), was investigated in healthy premenopausal and postmenopausal females. A single oral dose, open-label, non-controlled, pharmacokinetic study was conducted in healthy premenopausal (n = 16) and postmenopausal (n = 8) females. The samples were analyzed using reversed phase high performance liquid chromatography (HPLC), different pharmacokinetics (PK) parameters were determined and compared statistically to evaluate the difference between two groups. The activities of CYP2C19 and CYP3A4 were determined as AUC_OMP/AUC_OH-OMP and AUC_OMP /AUC_OMP-SUL, respectively. The significant differences (P < 0.05) between C_max, t_max, [AUC]^t_o,  [AUC]^oo_o, t_1/2 and metabolic ratios (MR) of OMP, 5-OH-OMP and OMP-SUL were observed between premenopausal and postmenopausal females_. The present studies showed the higher AUC and longer t_1/2 in postmenopausal subjects. The increase in MR for 5–OH-OMP and also OMP-SUL determined as AUC_OH-OMP/AUC_OMP and AUC_OMP-SUL/AUC_OMP, respectively, was also observed in postmenopausal females compared with the premenopausal females.

Key words: Omeprazole, pharmacokinetics, menopause.