Effects of age on the elimination of labetalol

Labetalol is an alpha 1- and beta-adrenergic antagonist currently used in the treatment of hypertension. Studies which have evaluated the effects of age on its pharmacokinetics have yielded conflicting results. The purpose of this study is to comprehensively re-evaluate the effect of age on the elimination of labetalol. Data were obtained from 4 single-dose and 3 multiple-dose studies of the pharmacokinetics of the drug. An analysis of covariance was performed on the single-dose data to determine whether the type of subject evaluated (normotensive vs hypertensive), type of assay methodology used and/or age were significant factors affecting labetalol clearance estimates. A similar covariance procedure was used for the multiple-dose data, to assess whether the type of subject, duration of treatment and/or age were significant variables affecting labetalol elimination. Subsequent to the analysis of covariance, linear regression and correlation analysis was used to evaluate the effects of age on labetalol clearance. A modest though significant relationship was observed between the apparent oral clearance of the drug and age; it appeared slightly stronger when clearance was normalised for bodyweight. No relationship was found following multiple doses of the drug. Hence, age does not appear to be a significant factor affecting the oral clearance of labetalol, particularly in individuals receiving the drug in the long term.