Int J Clin Pharmacol Toxicol. 2016 May;5(3):209-215. Epub 2016 May 19.
Gender based Dosing of Metoprolol in the Elderly using Population Pharmacokinetic Modeling and Simulations.
International journal of clinical pharmacology & toxicology
Andy R Eugene
Affiliations
Affiliations
- Division of Clinical Pharmacology, Department of Molecular Pharmacology and Experimental Therapeutics, Gonda 19, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA; Joyner Lab: Integrative Human Physiology and Pharmacology Lab, Department of Anesthesiology, Rochester, MN, USA.
PMID: 27468378
PMCID: PMC4959610
Abstract
INTRODUCTION: This article seeks to clarify if gender-based differences occur in the pharmacokinetics of metoprolol in the elderly patients. There are a series of physiologic changes that occur in the elderly ranging from decreased hepatic blood flow to increased adiposity causing higher plasma concentrations at therapeutic doses as compared to the healthy young population.
METHODS: Population pharmacokinetic modeling were performed using MONOLIX and Monte-Carlo simulations were conducted using MATLAB. The data was based from a previously published dataset where elderly patients, having multiple comorbidities, were administered a 50mg dose of metoprolol.
RESULTS: Metoprolol was modeled using a one-compartment model and resulted in the following population pharmacokinetic parameters: volume of distribution, V=38L (CV=155%), clearance rates, CL-Men=105L/hour and CL-Women=59.1L/hour (38%), time lag, Tlag=0.469 hour (CV=17%), and the absorption rate constant, Ka=0.235 hr
CONCLUSION: Gender stratified doses resulting in an equivalent systemic metoprolol exposure in geriatric patients have been identified. Metoprolol doses resulting a similar AUC in a healthy young male administered 50mg tablet were 15mg for geriatric women and 25mg for geriatric men. Further, Metoprolol doses of 25mg for geriatric women and 50mg for geriatric men resulted in an equivalent AUC to a healthy young males dosed with a 100mg tablet. A 15mg Metoprolol tablet may need to be compounded to account for the gender differences in Metoprolol pharmacokinetics.
Keywords: dose; gender; geriatrics; metoprolol; monolix; population pharmacokinetics
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