Psych Vivas · Emergency psychiatry
Overdose and toxicology — structured clinical viva
Fellowship viva on venlafaxine and SSRI overdose toxicity, the found-down approach, paracetamol and acetylcysteine timing, and relative lethal toxicity.
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Target exams
FRANZCPMRCPsychABPNMD-DNB
Prompt
You are the psychiatry registrar. ED asks you to review a 27-year-old after a large venlafaxine and possible paracetamol overdose. She had two brief seizures. HR 118, BP 100/62, GCS 13. ECG QTc borderline prolonged, QRS 98 ms. A junior doctor says 'SSRIs are safe in OD so she can go to the psych ward now.' Discuss relative toxicity, the approach to the poisoned patient, paracetamol, and the prescribing lessons.
Interpretation
Reveal interpretationShowHide
Venlafaxine is not an SSRI in overdose. Seizures occurred in 14% of venlafaxine overdoses, all at 900 mg or more, with an odds ratio of 4.4 against TCAs; venlafaxine was more likely to cause serotonin toxicity but less likely to cause coma than TCAs.[1]
References6ShowHide
- [1]Whyte IM, Dawson AH, Buckley NA Relative toxicity of venlafaxine and selective serotonin reuptake inhibitors in overdose compared to tricyclic antidepressants. QJM : monthly journal of the Association of Physicians, 2003.PMID 12702786
- [2]Isbister GK, Bowe SJ, Dawson A, et al. Relative toxicity of selective serotonin reuptake inhibitors (SSRIs) in overdose. Journal of toxicology. Clinical toxicology, 2004.PMID 15362595
- [3]Bateman DN, Dart RC, Dear JW, et al. Fifty years of paracetamol (acetaminophen) poisoning: the development of risk assessment and treatment 1973-2023 with particular focus on contributions published from Edinburgh and Denver. Clinical toxicology (Philadelphia, Pa.), 2023.PMID 38197864
- [4]Parris MA, Calello DP Found Down: Approach to the Patient with an Unknown Poisoning. Emergency medicine clinics of North America, 2022.PMID 35461619
- [5]Brett J, Wylie CE, Raubenheimer J, et al. The relative lethal toxicity of pharmaceutical and illicit substances: A 16-year study of the Greater Newcastle Hunter Area, Australia. British journal of clinical pharmacology, 2019.PMID 31173392
- [6]Smilkstein MJ, Knapp GL, Kulig KW, et al. Efficacy of oral N-acetylcysteine in the treatment of acetaminophen overdose. Analysis of the national multicenter study (1976 to 1985). The New England journal of medicine, 1988.PMID 3059186