Sobre-anticoagulación por warfarina ocasionada por múltiples errores de medicación

Warfarin is the most widely used anticoagulant in the world due to its convenience and low cost. However, its effectiveness and safety are determined by paraclinical INR monitoring, control of vitamin K intake, drug-drug interactions and pharmacogenetic profile, among other factors, which could condition the occurrence of thrombotic or hemorrhagic complications. We present the case of a patient with thigh hemorrhage secondary to warfarin, in whom the lack of adherence to the prescribed dosage schedule, the lack of follow-up and a possible interaction with omeprazole were identified by the hospital's Clinical Pharmacy service as determining factors of the adverse drug reaction. The pharmaceutical intervention consisted of suggesting the substitution of warfarin for apixaban, a drug of similar cost-effectiveness, which does not require paraclinical monitoring and lacks drug interactions in the patient.