Interacciones

CLINICS 2006;61(6):515-20

CLINICAL SCIENCES

A PHARMACOEPIDEMIOLOGIC STUDY OF DRUG INTERACTIONS IN A BRAZILIAN TEACHING HOSPITAL

Joice Mara Cruciol-Souza, João Carlos Thomson

Cruciol-Souza JM, Thomson JC. A pharmacoepidemiologic study of drug interactions in a brazilian teaching hospital. Clinics. 2006;61(6):515-20.
PURPOSE: Although drug-drug interactions constitute only a smallproportion of adverse drug reactions, they are often predictable and therefore avoidable or manageable. There are few studies on drug-drug interactions from Brazil. This study aimed to assess the frequency of drug-drug interactions in prescriptions and their potential clinical significance in patients of a Brazilian teaching hospital. METHODS: From January to April 2004, a sample of 1785 drugprescriptions was drawn from a total of 11,250. Drug-drug interactions were identified by using Micromedex® DrugReax® System. Patients´ records with major drug-drug interactions were reviewed by a pharmacist and a medical doctor looking for signs, symptoms, and lab tests that could indicate adverse drug reactions due to such interactions. RESULTS: From the 1785 prescriptions examined, 1089 (61%) were fromthe male adult ward. Patients’ average age was 52.7 years (SD = 18.9; range, 12-98). The median number of drugs in each prescription was 7 (range, 2-26). At least 1 drug-drug interactions was present in 887 (49.7%) prescriptions. Regarding the severity of the clinical result, the interactions were classified as minor (20; 2.3%), moderate (184; 20.7%), major (30; 3.4%), and undetermined because ofan incidence of more than 1 interaction in a single patient (653; 73.6%). From the 30 patients with major interactions, 17 (56.7%) presented adverse drug reactions induced by exposure to a major drug-drug interaction. CONCLUSIONS: Patients did suffer adverse drug reactions from major drug-drug interactions. Many physicians may be unaware of drug-drug interactions. Education, computerizedprescribing systems and drug information, collaborative drug selection, and pharmaceutical care are strongly encouraged for physicians and pharmacists. KEYWORDS: Prescriptions. Drug-drug interactions. Teaching Hospital. Pharmacovigilance. Drug utilization.

INTRODUCTION Drug-drug interactions (DDI) are a cause of adverse drug reactions, resulting in adverse outcomes associated with drug therapy.1,2 Theliterature on drug interactions is generally related to DDI mechanisms, drug pharmacokinetic studies, and clinical cases.3,4 The pharmacoepidemiology of drug interactions has been less explored.

Hospital Universitário da Universidade Estadual de Londrina - Londrina/ PR, Brasil. Email: jcruciol@yahoo.com.br Received for publication on May 09, 2006. Accepted for publication on August 18, 2006.Hospital stay may be associated with relevant changes in patient care. In general, close monitoring of medical care is guaranteed during the hospital stay. Patients without therapeutic care are more exposed to drug-related problems that may include potential DDI.5,6 At least 15% of the patients admitted to hospitals have 1 DDI at admission.1,7-9 The risk of DDI can increase in the hospitalbecause new drugs are often added to an existing drug therapy.10 Drug-drug interactions are often predictable and, therefore, avoidable or manageable, but the reactions caused by them are mostly unknown. The present study aimed to assess the prevalence of DDI in the hospital prescriptions for adult inpatients and describe their characteristics and the adverse reactions caused by ‘major’ DDI.

515A pharmacoepidemiologic study of drug interactions Cruciol-Souza JM et al.

CLINICS 2006;61(6):515-20

METHODS A drug utilization study was carried out using data from the prescriptions of a Brazilian teaching hospital. The hospital is a 300-bed teaching public institution that is also a referral center for hospital care. During the period of this study, hospitalization length for inpatients...