A Prospective Analysis of Potential and Observed Drug-Drug Interactions, Adverse Events and its Associated Risk Factors in Hospitalized Cardiology Patients in Benin.

Background & Aims: The objective is to ascertain the pattern of potential drug-drug interactions (pDDIs) and record any observed DDIs and adverse events (AEs) in hospitalized Beninese cardiology patients from Sub-Saharan Africa and analyze all risk factors associated with DDIs and AEs.

Methods: It was a prospective study in which data including AEs were assessed from medical files and interview of patients and their relatives. Patients who were treated with more than two drugs and who remained in the hospital for at least 48 hours were included. A computerized database system Pharma IAM- VIDAL version 2011 was used to identify the pattern for potential DDIs.

Results: 156 patients were included in this study. The prevalence of potential DDIs was estimated at 93 % (145/156). Forty (5.1%) among 804 potential DDIs identified were observed clinically. The observed DDIs were attributable to low blood pressure (27.5%), hyponatremia (22.5%), hemorrhage (20.0%), hyperkalemia (17.5%) and nephrotoxicity (7.5%). The combination of spironolactone and furosemide resulted in hyponatremia while the combination of enoxaparin and potassium resulted in hyperkalemia. ACE inhibitor (or ARAII) in combination with furosemide resulted in the nephrotoxicity cases observed. Enoxaparin, Acetyl salicylic acid, Acenocoumarol and Clopidogrel were decreasingly involved in the pairs of drugs responsible for observed hemorrhages. 29 patients out of 156 (18.6%) had at least one AE. AEs were mainly (34.2%) of metabolic type. Severe AEs, which represented 18.4% was mostly from nephrotoxicity and metabolic disorders. More than 14 active substances multiplied the risk factor for AEs occurrence by 42, while more than 14 days hospitalization increased this risk by 42.

Conclusion: This study highlights the need to optimize treatments by strictly regulating blood pressure, serum sodium and potassium levels, coagulation parameters and looking for clinical signs of hemorrhage. Physician should be aware of certain drug associations that may carry a risk of severe adverse events.