SNRI toxicity
Mechanism of toxicity
- Na channel blockade
- serotonergic effects
clinical presentation
C: hypertension, tachycardia, Torsades de Pointes
D: seizures - usually short lived; coma not a feature - see alt diagnosis; agitation and anxiety; dilated pupils/mydriasis
E: rhabdo in massive overdose; Hyponatraemia, hypoglycaemia
pharmacokinetics
absorption
PO
distribution
large - 5-7L/kg
metabolism
hepatic metabs
elimination
Venlafaxine: t½ 15h
issues requiring resuscitation
circulation
- Arrest or prolonged QRS - bicarb
- QT prolongation - Mg 2g or 25-50mg/kg (max of 2g), avoid Amiodarone
disability
- Seizures - may be delayed
exposure
- Hyperthermia (as in Serotonin syndrome)
- Rhabdomyolysis
observation period
-
= 24h if
- symptomatic
- toxic dose of sustained release
- mixed overdose
- otherwise, minimum 8h (toxbase)