Laryngeal dyspnea in relation to an interaction between acenocoumarol and topical econazole lotion.

Background: Bleeding is the most serious complication of oral anticoagulant therapy used for the prevention of thromboembolic complications. Drug-drug interactions are an important concern, as they may increase drug toxicity and, in the case of anticoagulant therapies, increase the risk of hemorrhage.

Case Summary: An 84-year-old woman presented to the emergency department with a bilateral cervical hematoma and symptoms of upper-airway obstruction that had been increasing for 72 hours, with dyspnea and difficulty speaking developing in the previous 24 hours. Transnasal fiberoptic laryngoscopy revealed a significant laryngeal hematoma, as well as a hematoma on the floor of the mouth and in the tonsil area. Laboratory abnormalities included a prothrombin time < 10%, an international normalized ratio exceeding the laboratory limits, and an activated partial thromboplastin time >120 seconds. The patient had been receiving acenocoumarol 4 mg/d for 10 years for episodes of atrial fibrillation and recurrent deep venous thrombosis. Seventeen days earlier, she had received a prescription for topical econazole lotion 1% to be applied 3 times daily for 1 month to treat a dermatitis affecting 12% of the body surface. The patient was admitted to the intensive care unit for treatment of respiratory failure, where oxygen was delivered by face mask. The coagulation disorders were treated with prothrombin complex concentrate 30 IU/kg IV and vitamin K1 10 mg IV, and values normalized within 36 hours. Surgical evacuation of the laryngeal hematoma was not necessary. After 48 hours, improvement in the patient's respiratory symptoms allowed transfer to the ear, nose, and throat unit, where daily endoscopic examination was performed. Aspirin was substituted for acenocoumarol, and the patient returned home after 10 days without sequelae. Based on a Naranjo score of 7, this episode was probably related to an interaction between acenocoumarol and econazole.

Conclusion: This report describes a case of a probable interaction between topical econazole lotion 1% and acenocoumarol that resulted in overanticoagulation and a life-threatening laryngeal hematoma in this elderly patient.