Therapeutic Drug Monitoring of Antibiotics in the Elderly: A Narrative Review

Background: Antibiotic dosing adaptation in elderly patients is frequently complicated by age-related changes affecting the processes of drug absorption, distribution, metabolism, and/or elimination. These events eventually result in treatment failure and/or development of drug-related toxicity. Therapeutic drug monitoring (TDM) can prevent suboptimal antibiotic exposure in adult patients regardless of age. However, little data are available concerning the specific role of TDM in the elderly patients. Methods: This review is based on a PubMed search of the literature published in the English language. The search involved TDM studies of antibiotics in the elderly patients performed between 1990 and 2021. Additional studies were identified from the reference lists of the retrieved articles. Studies dealing with population pharmacokinetic modeling were not considered. Results: Only a few studies, mainly retrospective and with observational design, have specifically dealt with appropriate antibiotic dosing in the elderly patients based on TDM. Nevertheless, some clinical situations in which the selection of optimal antibiotic dosing in the elderly patients was successfully guided by TDM were identified. Conclusions: Elderly patients are at an increased risk of bacterial infections and inadequate drug dosing compared with younger patients. Therefore, the availability of TDM services can improve the appropriateness of antibiotic prescriptions in this population.