Avicenna Journal of Pharmaceutical Research

Background: Drug-drug interactions can often lead to preventable adverse drug events and hospitalization. However, the clinical outcome of a potential drug-drug interaction that may range from minor alterations to major toxicity or loss of effect is often unknown. Drugs with narrow therapeutic index are more susceptible to the outcomes of interactions. Anticoagulants are one of the drug groups prone to drug-drug interactions and have important side effects. in this retrospective study, the frequency of drug-drug interactions involving warfarin, heparin and enoxaparin was investigated.

Methods: Overall, 300 patients (including 55% males with an average age of 50.75 years) participated in this study, and for each anticoagulant, 100 patient orders were randomly selected from the hospital system. Drug-drug interactions were evaluated using the Micromedex drug interaction checker.

Results: A total of 1691 drug-drug interactions (306 major, 253 moderate, and 89 minor interactions) were recorded of which only 648 (average 2.16) involved warfarin, heparin, or enoxaparin. Most interactions were recorded in patients admitted to the cardiovascular surgery (n=312) and cardiology (n=119) wards. There was a significant relationship between the number of drugs and the frequency of interaction. warfarin had the highest number of interactions (n=388).

Conclusion: The frequency of drug interactions is high in patients on anticoagulant therapy. The efficacy and safety of these drugs can be affected by drug interactions. Accordingly, these interactions should always be considered, especially in patients with multiple drug use. Efficient monitoring strategies should be employed to optimize treatment while reducing adverse effects.