Potentially inappropriate medications (PIMs) can predispose geriatrics to adverse drug events. Additionally, WHO prescribing indices can help to determine the rationality of administrations. Using the prescriptions, rather than the insurance claim data, can provide a more precise picture that can help to identify the prescribing problems and target the interventions more effectively. →What this article adds: Almost one-third of the patients received at least 1 PIM based on the Beers Criteria in Tehran, and general practitioners prescribed PIMs more frequently. On average, patients received 3.57 medications per prescription. Only 76.77% of all drugs were prescribed by generic names. Vitamins and corticosteroids were among the top injectable medications in this study.

The high prevalence of concomitant chronic illnesses and the resulting higher number of medications in the elderly population increase the risk of adverse drug reactions due to drug-drug interactions (DDIs) and potentially inappropriate medications (PIMs). Therefore, the aim of this study was to investigate the prevalence and factors associated with DDIs and PIMs in outpatient geriatrics. In this cross-sectional study, 1512 prescriptions belonging to patients aged ≥65 years from five public pharmacies in Tehran were evaluated. Clinically relevant (C, D, and X) and significant DDIs (D and X) were documented according to the Lexicomp ® . Additionally, Zhan criteria were used to detect PIMs. At least one clinically relevant DDI was detected in 61.7% of the prescriptions containing ≥2 medications. The largest percentage of prescriptions with DDIs was prescribed by cardiologists (74.3%). The number of medications in prescriptions and the specialty of the prescriber significantly affected both clinically relevant and significant DDIs in a logistic regression model. At least one PIM was identified in 16.3% of the prescriptions. General practitioners (GPs) were the largest prescribers of PIMs. The mean number of medications was significantly higher in prescriptions with PIMs. In conclusion, clinically relevant DDIs are frequent in the elderly. In terms of PIMs, more attention should be paid to the education of GPs.