A study of drug-drug interactions in prescriptions received at selected community pharmacies in Tamil Nadu

Abstract

The main objective of the study is to assess the significance and severity of Drug- Drug Interactions (DDI) in prescriptions collected prospectively at selected community pharmacies in Erode and Komarapalayam, Tamil Nadu for a period of six months. All prescriptions with two or more drugs were included in the study and reviewed for drug interactions using Drug interactions software. A total of 2466 prescriptions were reviewed and assessed for the DDIs. A total of 1053 DDIs were observed in 696 (28.22%) prescriptions with frequency rate of 42.7%. Gender difference did not shown any significant influence on precipitation of DDIs. Prescriptions with one or more DDIs used a significantly large number of drugs with an average of 5.42 ± 1.26 (ranged from 2-10 drugs). Prescriptions with 7 or more drugs shown maximum incidence rate of DDIs (96%). Among the total number of prescriptions with DDIs, 64% prescriptions contain more than 4 drugs suggesting a direct relationship between the number of drugs prescribed and the incidence of DDIs (r=0.41). About 44.26% of DDIs found were due to pharmacokinetic, unknown. The main drug classes commonly involved in the precipitation of DDIs were Anti-TB (14.6%), analgesics & antipyretics (17.04%), bronchodilators (15.56%), and diuretics (12.46%). Commonly interacting drug classes involved in DDIs were anti-TB (20.92%), antiplatelets (15.63%), H2 blockers and ulcer healing drugs (16.46%), and bronchodilators (14.64%). The results of the present study show a high frequency rate of the DDIs in prescriptions received at community pharmacies. The occurrence rate is directly proportional to more number of drugs in the prescription.