The effect of age on the pharmacokinetics of pentazocine.

Pentazocine was administered intravenously to 18 subjects, surgical patients and volunteers, ranging in age from 22 to 90 years. When divided into a young group (10 subjects, age 22-48 years) and an elderly group (8 subjects, age 60-90 years), the total clearance decreased as function of age from 22.14 +/- 4.114 to 11.68 +/- 3.593 ml/min/kg, and the elimination half-life increased from 2.5 +/- 0.71 to 4.11 +/- 1.187 hours. No change in the apparent volume of distribution was observed. Implications of change in clearance and half-life on dosage regimen design are discussed.