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Anticonvulsant levels and reloading
From WikEM
Contents
Background
- IV load can be performed with phenobarbital, phenytoin, valproate, levetiracetam
- Oral loading can be spread over day or more to avoid GI upset
- May use IV vs PO reload at physican discretion[1]
Initial Loading[1]
| Anticonvulsant (brand name) | PO Loading Dose | IV Loading Dose |
| Carbamazepine (Tegretol) | 8mg/kg suspension in single oral load | NA |
| Gabapentin (Neurontin) | 900mg/day oral (300mg tid) for 3 days | NA |
| Lamotrigine (Lamictal) | 6.5mg/kg single oral load if on lamotrigine for >6 mo without a history of rash or intolerance in the past and only off lamotrigine for <5 days | NA |
| Levetiracetam (Keppra) | 1,500mg oral load | Up to 60mg/kg (rapid loading) |
| Phenytoin (Dilantin) | 20mg/kg divided in maximum doses of 400mg every 2 hours | 18mg/kg (max rate of 50mg/min) |
| Fosphenytoin (Cerebyx) | NA | 18 PE/kg IV (max rate of 150 PE/min) |
| Valproate (Depacon) | NA | Up to 30mg/kg IV (max rate of 10mg/kg/min) |
Reloading
- Dose (mg) = ideal body weight (kg) X Vd X [desired level - current level (mcg/mL)]
Volume of Distribution
| Agent | Volume of Distribution | Desired Level |
| Phenytoin (dilantin) | 0.8 | 20 mcg/mL |
| Carbamazepine (tegretol) | 0.8 | 12 mcg/mL |
| Phenobarbital | 0.6 | 40 mcg/mL |
| Valproate (depakote) | 0.2 | 100 mcg/mL |
