Severe verapamil intoxication despite correct use of low-dose verapamil

We report a case of an adult patient using chronic low-dose verapamil who developed severe verapamil intoxication. A 57-year-old male patient was presented at the emergency room after a collapse of unknown etiology. The airway was compromised, and thus, an endotracheal tube was inserted. The patient deteriorated hemodynamically. Because of verapamil use and bradycardia, verapamil intoxication was suspected. The treatment was supported with intravenous fluids, calcium, inotropes, and a transvenous pacemaker. The patient progressively developed circulatory shock. Verapamil intoxication was confirmed, and therapy was adjusted accordingly. Insulin and calcium infusion were intensified, and glucagon and Intralipid® infusion were initiated. With this therapy, the patient's condition improved rapidly. We found different factors in this patient that could have precipitated this event such as diminished metabolism by cytochrome P450 iso-enzymes, a slightly diminished renal function with hypoalbuminemia, and interaction with other protein-binding drugs.