Effects of age on meperidine disposition

Area of Science:

• Pharmacology
• Geriatric Medicine
• Drug Metabolism

Background:

• Elderly patients often exhibit increased sensitivity to meperidine.
• The underlying pharmacokinetic and dynamic factors contributing to this sensitivity are not fully understood.

Purpose of the Study:

• To investigate age-related differences in meperidine pharmacokinetics.
• To compare drug disposition in healthy elderly men versus younger adults.

Main Methods:

• Seven healthy elderly men (60-79 years) received intravenous meperidine HCl (25 mg) and the same dose orally or intramuscularly.
• Blood and urine samples were analyzed using gas chromatography-mass spectrometry over 24 hours.
• Kinetic data were compared to a previously studied young cohort.

Main Results:

• Systemic clearance, apparent oral clearance, terminal half-life, and blood/plasma ratio did not differ between elderly and young subjects.
• The elderly showed significantly larger initial and steady-state volumes of distribution.
• No age-related differences in absorption or bioavailability were observed for oral or intramuscular routes.

Conclusions:

• Age-related changes in meperidine disposition do not fully explain altered clinical efficacy in the elderly.
• Increased volume of distribution in the elderly may play a role in altered meperidine response.