ADVERSE DRUG INTERACTIONS IN ELDERLY HOSPITALIZED PATIENTS: A PROSPECTIVE ANALYSIS

Objective: To determine the incidence, characteristics, predictors and cost associated with the management of adverse drug interactions (ADIs) in elderly population. Methods: The prospective, intensive and interventional study included all patients taking at least two medications who were elderly admitted to medicine or surgery wards of a tertiary care hospital and were followed untill discharge. ADIs were identified using standard references. Results: A total of 1992 drug-drug interactions were detected from 659 patients over the nine month study period. Incidence of Drug-Drug Interactions (DDI) and ADI was 59.05% and 7.34% respectively. About 5.9% of DDIs resulted in adverse reactions. Of the total Adverse Drug Reactions (ADRs) detected, 31.5% (89 ADIs in 82 patients) of ADRs were due to DDIs. Pharmacodynamic interactions accounted for 73.5% of DDIs. There was significant association between occurrence of ADIs with three or more diagnosed diseases, three or more chronic diseases, administration of >10 medications and >7 days of hospital stay. The total direct cost associated with the management of ADIs was INR 15, 638/- of which moderate interactions accounted for the maximum (INR 13, 572/-). Conclusion: Clinicians need to be aware of most common ADIs occurring in the clinical practice and should be cautious in using the medications especially in elderly patients as they are more susceptible to ADIs. Clinical pharmacist can play a vital role in the detection, prevention and management of ADIs which can result in improved therapeutic outcomes and decreased unnecessary healthcare expenditure.