title: Study of warfarin utilization in hospitalized patients: analysis of possible drug interactions.
abstract: Background Drug-drug interactions in patients taking warfarin may contribute to a higher risk of adverse events. Objective To identify and evaluate the prevalence and characteristics of potential DDIs with warfarin. Methods A cross-sectional study was performed in a Brazilian tertiary hospital. The electronic prescriptions of the patients receiving warfarin between January 2004 and December 2010 were analyzed. Socio-demographic, clinical, and therapeutic variables were collected. Warfarin drug-drug interactions were classified as either risk A, B, C, D, or X according to the Lexi-Interact™ Online database. Results A total of 3048 patients were identified who were prescribed warfarin. Of the 154,161 total drug prescriptions issued, 42,120 (27.3 %) were for warfarin. Evaluation of the prescriptions showed that 63.1 and 0.1 % of patients received concomitant drugs classified as having class D or X risk. It was found that 20,539 (48.7 %) prescriptions had at least one drug with a D or X risk. Patients were prescribed an average of 1.4 (±0.4) concomitant medications with a class D or X warfarin-DDI risk, the most frequent being acetylsalicylic acid and amiodarone. Conclusion The results demonstrate a high prevalence of concomitant drug prescriptions with the potential for clinically relevant DDIs with warfarin, the most frequent being acetylsalicylic acid and amiodarone.
authors.affiliation: State University of Londrina, Londrina, PR, Brazil.
authors.forename: Camilo Molino
authors.initials: CM
authors.lastname: Guidoni
authors.affiliation: Department of Pharmaceutical Sciences, Faculty of Pharmaceutical Sciences of Ribeirão Preto, College of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo (USP), Avenue of Café, Ribeirao Preto, SP, 14040-90, Brazil. helen.miranda@hotmail.com.
authors.forename: Helen Palmira Miranda
authors.initials: HP
authors.lastname: Camargo
authors.affiliation: Department of Pharmaceutical Sciences, Faculty of Pharmaceutical Sciences of Ribeirão Preto, College of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo (USP), Avenue of Café, Ribeirao Preto, SP, 14040-90, Brazil.
authors.forename: Paulo Roque
authors.initials: PR
authors.lastname: Obreli-Neto
authors.affiliation: State University of Londrina, Londrina, PR, Brazil.
authors.forename: Edmarlon
authors.initials: E
authors.lastname: Girotto
authors.affiliation: Department of Pharmaceutical Sciences, Faculty of Pharmaceutical Sciences of Ribeirão Preto, College of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo (USP), Avenue of Café, Ribeirao Preto, SP, 14040-90, Brazil.
authors.forename: Leonardo Regis Leira
authors.initials: LR
authors.lastname: Pereira
mesh_terms: D000328:Adult; D000368:Aged; D000638:Amiodarone / Q000009:adverse effects / Q000378:metabolism; D000925:Anticoagulants / Q000009:adverse effects / Q000378:metabolism*; D001241:Aspirin / Q000009:adverse effects / Q000378:metabolism; D001938:Brazil / Q000453:epidemiology; D003430:Cross-Sectional Studies; D004347:Drug Interactions / Q000502:physiology*; D064420:Drug-Related Side Effects and Adverse Reactions / Q000175:diagnosis* / Q000453:epidemiology / Q000378:metabolism*; D005260:Female; D006760:Hospitalization / Q000639:trends; D006801:Humans; D008297:Male; D008875:Middle Aged; D062606:Tertiary Care Centers / Q000639:trends; D014859:Warfarin / Q000009:adverse effects / Q000378:metabolism*
chemical_list: D000925:Anticoagulants; D014859:Warfarin; D000638:Amiodarone; D001241:Aspirin
keywords: Brazil; Drug-drug interaction; Pharmacoepidemiology; Unified Health System; Warfarin