Key result
Diphenhydramine overdose caused sustained torsades de pointes with a markedly prolonged QT interval requiring cardioversion in a 26-year-old man.
Why the study?
Can diphenhydramine overdose cause torsades de pointes?
Case Report (n=1)
Can diphenhydramine overdose cause torsades de pointes?
This first reported case demonstrates that high concentrations of drugs with weak I(Kr)-blocking effects, such as diphenhydramine, can cause lethal proarrhythmia like torsades de pointes.
Monitor QT in diphenhydramine overdose; single case leaves open proarrhythmic risk of weak IKr blockers.
This is the first reported case of torsades de pointes attributable to diphenhydramine, a drug with weak I(Kr) effects. A 26-year-old, healthy man was admitted to intensive care after a diphenhydramine overdose. Results of physical examination, ECG, and electrolytes were normal at admission. Despite supportive care, he developed typical, sustained, torsades de pointes with a markedly prolonged QT interval requiring cardioversion. Drugs with weak I(Kr)-blocking effects may cause lethal proarrhythmia in susceptible individuals when delivered in high concentrations. This case illustrates the variation in repolarization reserve that exists in a free-standing population.
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Joshi et al. (2004) conducted a case report in Diphenhydramine poisoning (n=1). Diphenhydramine overdose was evaluated on Torsades de pointes and prolonged QT interval. Diphenhydramine overdose caused sustained torsades de pointes with a markedly prolonged QT interval requiring cardioversion in a 26-year-old man.
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