Pharmacokinetic considerations relating to tacrolimus dosing in the elderly

Area of Science:

• Pharmacology
• Geriatrics
• Transplantation Medicine

Background:

• Solid organ transplantation is increasingly performed in elderly patients.
• Tacrolimus, an immunosuppressant, has a narrow therapeutic window and significant pharmacokinetic variability.
• Aging may alter tacrolimus pharmacokinetics due to physiological changes.

Purpose of the Study:

• To investigate the impact of aging on tacrolimus pharmacokinetics.
• To determine if age influences tacrolimus dosage requirements in elderly transplant recipients.
• To highlight the need for further research into tacrolimus use in older populations.

Main Methods:

• Review of existing pharmacokinetic studies, including population pharmacokinetic analyses.
• Analysis of age as a covariate in tacrolimus dosing.
• Consideration of age-associated physiological and clinical factors.

Main Results:

• Previous studies found no significant influence of age on tacrolimus bioavailability, volume of distribution, or clearance.
• The number of elderly patients in prior studies was often small and undocumented.
• Inter- and intraindividual pharmacokinetic variability of tacrolimus is likely increased in the elderly.

Conclusions:

• While age may not significantly alter initial tacrolimus pharmacokinetics, increased variability is probable in elderly patients.
• Factors like co-morbidity, polypharmacy, and altered immune response necessitate careful tacrolimus management in the elderly.
• More integrated pharmacokinetic-pharmacodynamic studies are needed, with frequent monitoring recommended for elderly transplant recipients.