How much is too much? Oligosymptomatic presentation after 11.5 g of diphenhydramine.
We report the case of a 47-year-old male obese Caucasian patient presenting 2 hours after ingestion of 11.5 g of diphenhydramine. Despite this excessive overdose, he showed only a few hours of impaired consciousness and no further symptoms. A diphenhydramine plasma concentration of 15,352 nmol/L was measured 8 hours after the overdose ingestion. A heterogeneous CYP2D6 extensive metabolizer genotype excludes a pharmacokinetic explanation for this unusually oligosymptomatic presentation. However, the patient suffered from longstanding, refractory depression despite numerous treatment attempts with various drugs, pointing to the possibility of decreased pharmacodynamic responsiveness for therapeutic and toxic effects.
Frick
Sonia
S
Department of Internal Medicine, Stadtspital Triemli, Zurich, Switzerland. sonia.frick@triemli.stzh.ch
Roos
Markus
M
Fattinger
Karin
K
D018926:Anti-Allergic Agents / Q000097:blood / Q000493:pharmacokinetics / Q000506:poisoning; D004155:Diphenhydramine / Q000097:blood / Q000493:pharmacokinetics / Q000506:poisoning*; D004305:Dose-Response Relationship, Drug; D062787:Drug Overdose; D006634:Histamine H1 Antagonists / Q000097:blood / Q000493:pharmacokinetics / Q000506:poisoning; D006801:Humans; D008297:Male; D008875:Middle Aged
D018926:Anti-Allergic Agents; D006634:Histamine H1 Antagonists; D004155:Diphenhydramine