A Rare Case of Junctional Bradycardia Secondary to Oral Phenytoin

Phenytoin is a commonly used anti-seizure agent, which stabilizes neuronal membranes by blocking voltage-gated sodium channels to inhibit the propagation of action potentials during convulsions. However, phenytoin has also been shown to have antiarrhythmic effects as it can prolong the effective refractory period of ventricular pacemaker cells. Adverse cardiac effects such as junctional bradycardia are usually seen with intravenous use. Cardiovascular dysfunction is not well recognized in oral phenytoin toxicity. Here we present a case of junctional bradycardia due to oral phenytoin toxicity, which resolved spontaneously with the discontinuation of phenytoin. This case report will serve to increase awareness of the adverse cardiovascular effects of oral phenytoin toxicity to improve the recognition and treatment of these adverse effects.