Background: Drug–drug interactions (DDIs) are very common and responsible for 6%–30% of the adverse drug events that will increase healthcare cost and patient outcome. Polypharmacy significantly contributes to DDIs.
Aims and Objective: To assess the DDIs in the outpatients in the medicine department in a tertiary-care hospital.
Materials and Methods: The prescription of patients attending OPD of medicine department were analyzed for demography of patients and potential drug–drug interaction (pDDI). pDDI were checked by freely available drug interaction checker on Internet. pDDI were classified major, moderate, and minor according to severity and, by its mechanism, as pharmacokinetic, pharmacodynamic, or pharmacokinetic + pharmacodynamic. Statistical analysis was done using appropriate statistical software (MS Excel, Epi info, etc.).
Results: Of the 300 patients who attended the medicine OPD during the study period, 253 patients were included in our study. From these, 128 (50.59%) were men and 125 (49.41%) women. Among these 253 patients, 147 (58.27%) patients had at least one pDDI and 106 (41.9%) patients had no pDDIs. The incidence of pDDI per patient was 1.68 ± 2.68 in our study. Average number of drugs prescribed per patient was 4.4 ± 1.48 in our study. A direct correlation was observed between the age of the patients and the number of pDDIs (r = 0.35, P < 0.01), between the age of the patients and the number of the drugs prescribed (r = 0.18, P < 0.01), and between the number of drugs prescribed and the number of pDDIs (r = 0.69, P < 0.01). Among 423 pDDIs, 215 (50.83%) were pharmacodynamic drug interactions, 163 (38.53%) pharmacokinetic, and 45 (10.64%) showed both kinds of mechanisms. Interactions with major severity accounted for seven (1.65%) of the total pDDIs, while those with moderate and minor severity accounted for 321 (75.87%) and 95 (22.46%), respectively.
Conclusions: In our study, we found that most common pDDIs were pharmacodynamic in nature and of moderate severity. The number of pDDI increased with increase in the age of patients and the number of drugs prescribed.
Potential Drug–Drug Interaction (pDDI); Pharmacokinetic Drug Interaction; Pharmacodynamic Drug Interaction; Severity of Drug Interaction