Abstract

Potential Drug-Drug Interaction in the Elderly Patients: Out-Patient Prescription Analysis from One Secondary Care Hospital

Piphat Janthapim

Sittikorn Wichairam

Peerawat Jinatongthai

 Sawaeng  Watcharathanakij 

drug-drug interaction, out-patient service, the elderly patients

Introduction:  Thailand becomes aging society. The elderly patients have many illness conditions that need different kinds of medications. Therefore, it is possible that they receive medications with potential drug-drug interaction (pDDI). This pDDI may lead to adverse drug event.  Objectives: To measure rate of pDDI in the elderly patients from out-patient prescriptions from one secondary care hospital.  Methodology: Cross sectional descriptive study identify drug pairs with pDDI from out-patient prescription from 2017 through 2018. Severity of pDDI was categorized by Lexicomp® Drug Interactions. Result: The elderly patients who received medical services accounted for 130,017 visits. Of these, 5.79% had pDDI. Patients with pDDI received an average of 8.65 ± 0.08 drug items Patients prescribed more than 5 items accounted for 49.05%. The rate of pDDI with major severity was 32.9 episodes per 1,000 prescriptions. The rate of pDD with moderate and minor severity were 9.2, 15.2 episodes per 1,000 prescriptions respectively. The most found pDDI pair was enalapril and amiloride combined with hydrochlorothiazide. The second and third pair found were calcium carbonate and ferrous fumarate, and simvastatin and gemfibrozil respectively. Conclusion: Drug pairs with pDDI were observed in the elderly patients.  Most are drug pairs with major severity that can lead to adverse reaction. Thus, they must be monitored and operations should be changed to promote patient safety.