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Pharmacokinetics of amitriptyline in the elderly
International Journal of Clinical Pharmacology, Therapy, and Toxicology
|January 1, 1981
Summary
Elderly individuals absorb amitriptyline (AMI) slowly but efficiently. Lower clearance rates and altered ECGs suggest reduced or divided daily doses are advisable for older patients.
Area of Science:
- Pharmacology
- Geriatric Medicine
- Clinical Pharmacy
Background:
- Amitriptyline (AMI) is a commonly prescribed tricyclic antidepressant.
- Understanding its pharmacokinetic profile in elderly populations is crucial for safe and effective dosing.
Purpose of the Study:
- To evaluate the pharmacokinetics of amitriptyline in healthy elderly volunteers.
- To compare these parameters with those observed in younger subjects.
Main Methods:
- Single oral dose of 125 mg amitriptyline hydrochloride (AMI-HCl).
- Pharmacokinetic analysis in six healthy elderly volunteers (72-83 years).
- Assessment of amitriptyline (AMI) and nortriptyline (NT) plasma concentrations.
Main Results:
- Slow absorption (peak time ~10.4 hours) but high bioavailability (F: 0.59-0.75) of AMI.
- Significantly lower formation rate of nortriptyline (NT) and lower appearance clearance of AMI compared to younger subjects.
- Reversible ECG alterations observed in 5 participants coinciding with peak AMI plasma concentrations.
Conclusions:
- The pharmacokinetic profile of amitriptyline differs in the elderly, characterized by slower absorption and reduced clearance.
- These findings support the need for dose adjustments in elderly patients.
- Reduced and/or divided daily doses of amitriptyline are recommended for the elderly to minimize adverse effects.