Phenytoin toxicity: Difference between revisions
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==Background== | == Background == | ||
*Mortality is extremely rare after intentional overdose if good supportive care is provided | |||
*Rapid IV dosing carries greatest risk (due to propylene glycol constituent of IV form) | *Mortality is extremely rare after intentional overdose if good supportive care is provided | ||
*Rapid IV dosing carries greatest risk (due to propylene glycol constituent of IV form --> myocardia depression & cardiac arrest) | |||
*90% protein bound; dialysis ineffective | *90% protein bound; dialysis ineffective | ||
Revision as of 19:40, 5 November 2012
Background
- Mortality is extremely rare after intentional overdose if good supportive care is provided
- Rapid IV dosing carries greatest risk (due to propylene glycol constituent of IV form --> myocardia depression & cardiac arrest)
- 90% protein bound; dialysis ineffective
Clinical Features
- CV (only with IV form)
- Bradycardia
- Hypotension
- Asystole
- Neuro
- Nystagmus
- First only with forced lateral gaze; later becomes spontaneous
- May disappear at higher levels
- Ataxia
- Decreased LOC
- Nystagmus
- GI
- N/V
Diagnosis
- Phenytoin level
- Provides a rough guide only; neither sensitive nor specific
- Level >10: usually no symptoms
- Level 10-20: Occasional mild nystagmus
- Level 20-30: Nystagmus
- Level 30-40: Ataxia, slurred speech, N/V
- Level 40-50: Lethargy, confusion
- Level >50: Coma, seizure (rare)
Treatment
- Detoxification
- Activated charcoal PO
- Bradyarrhythmias
- Atropine, pacing
- Hypotension
- IVF
Disposition
- Cannot base on phenytoin level (erratic absorption after PO overdose)
- Consider discharge if pt has only mild symptoms and serial phenytoin levels decline
Source
Tintinalli