A Massive Venlafaxine Intoxication: Evolution of Cardiac Toxicity with Venlafaxine and O-Desmethylvenlafaxine Elimination Kinetics: A Grand Round.

BACKGROUND: This study presents the case of a 19-year-old woman who attempted suicide by ingesting 11.25 g of venlafaxine (V). She was admitted to the hospital with severe biventricular dysfunction, progressing to cardiac arrest requiring extracorporeal circulatory life support for 11 days. The pharmacokinetics of venlafaxine during impaired cardiac output and the effect of its active metabolite, the O-desmethylvenlafaxine (ODV), are currently not very well understood.

METHODS AND RESULTS: Serum concentrations of V and ODV were monitored twice daily for 3 weeks. The maximum concentrations of venlafaxine and ODV were at 14 hours after ingestion, with 29,180 mcg/L for V and 5399 mcg/L for ODV. Half-lives increased, requiring 2 weeks to eliminate the drug. The left ventricular ejection fraction significantly improved when V + ODV was below 1000 mcg/L and remained altered until the ODV concentrations were lower than 400 mcg/L.

CONCLUSIONS: This report, with complete elimination kinetic of V and ODV in a monodrug intoxication, provides information about the modification of pharmacokinetics in the case of an overdose managed by extracorporeal circulatory life support, the cardiac toxicity of ODV, and the value of the toxic threshold for the active moiety.