Plasma Levels and Effect on Heart Rate and Blood Pressure of Metoprolol after Acute Oral Administration in 12 Geriatric Patients

Abstract

Metoprolol, a cardioselective .beta.-blocking agent, was given orally to 12 geriatric patients with moderate hypertension. Drug levels of metoprolol and the effect of the drug on resting heart rate and BP [blood pressure] were studied. Metoprolol was given in a dose of 20 mg, and 8 of the 12 patients also received a 50 mg dose. After the 20 mg dose the peak drug plasma concentration varied between 5 and 80 ng/ml (mean 33), and after the 50 mg dose between 14 and 212 ng/ml (mean 111). This variation is much greater than that seen in earlier studies on healthy volunteers and on a group of non-geriatric hypertensive patients. Plasma half-life of metoprolol averaged about 3.5 h after both the 20 mg and the 50 mg dose; this does not differ from the plasma half-life in earlier studies in younger age groups. The variability observed in the study might be explained multifactorially, e.g., by different body weight, absorption and/or first-pass effect of the drug.