see also: [[Serotonin Syndrome]] [Austin tox Venlafaxine](https://www.austin.org.au/Assets/Files/Venlafaxine%20and%20Desvenlafaxine_Feb2023.pdf) [murray tox venlafaxine](x-devonthink-item://C8AE745C-C96E-4AEF-9010-D441840C6DF4?page=401&istart=2101&ilength=10&search=VENLAFAXINE) > [!Key Points] > - **risk dose:** [[Seizures]] likely >5g venlafaxine, can be delayed up to 16 hours. # Risk assessment - Toxicity is dose-dependent and can be delayed up to 16 hours post ingestion (current formulations are extended release) # Toxic Mechanism - SSRI + SNRI # Clinical features **Seizures** - likely in all ingestions >5g, delayed onset - usually short duration and self-limiting [[Serotonin Syndrome]] - increase risk wiht >5g or co-ingestion of other serotonergic agents (SSRI, MAOI, TCA) **Cardiotoxicity** - rare unless >8g - LV dysfunction - severe low BP - tachyarrhythmias - long QT, wide QRS ==note: coma is NOT a typical feature of venlafaxine toxicity== and suggests co-ingestion with something coma-inducing # Treatment ## Decontamination - 50g activated charcoal to patients >2g up to 4 hours post ingestion - Austin says 4 hours post, murrays says up to 2 hours - Austin >8g consider intubation to facilitate early decontamination - consider [[Decontamination#Whole bowl irrigation]] if >8g (speak with tox) *this is per Austin guideline; murrary’s does not advocate WBI as tx* - “Both single-dose oral activated charcoal and WBI reduce venlafaxine absorption, with the combination of both treatments producing the greatest reduction in maximal venlafaxine concentrations. However, the risk of seizures occurring *following delayed administration of activated charcoal or during WBI* means that a risk–benefit analysis does not clearly favour these interventions.” ## Seizures - benzos ## serotonin tox see [[Serotonin Syndrome]] ## cardiotox - usually only in doses > 7g - ionotropes, iCU # Disposition - <2g - home after 8h if asymptomatic and normal ECG - 2-5g - observe minimum 16h for seizure - \>5g - observe with cardiac monitoring and IV access for 24 hours - \>8g - high risk of precipitous deterioration, consider admission to HDU for 24 hours of monitoring