| Status Epilepticus (Epilepsy)
| Coma management
| Epilepsy - General Management
| First Seizure
| Epilepsy in Pregnancy
| Febrile seizures
Signs of toxicity include ataxia, diplopia, nystagmus, sedation, dysarthria.
- Less popular AED used more IV rather than long term orally
- Blood levels Target Trough (before next dose) 10-20 mg/l (40-80 micromol/L)
Mode of action
- Inhibits Na+ influx into cells
- Zero order kinetics - small dose rises soon becomes toxic
- High plasma protein binding displaced by other drugs - Aspirin and Valproate
- Induces liver enzymes
- Epilepsy, Trigeminal neuralgia
- Porphyria, Bradycardia, Heart Block
- Signs of toxicity: ataxia, diplopia, nystagmus, sedation, dysarthria.
- Hirsutism, Coarsening of features, Gum hyperplasia, Greasy skin, Rashes
- Macrocytic anaemia due to folate deficiency
- Cerebellar symptoms, nystagmus, Lymphadenopathy
- Vitamin D deficiency - osteomalacia, Teratogenic
- High pH so extravasation will cause tissue damage.
- Reduced efficacy of OCP, Theophylline, TCAs, Thyroxine, Steroids
The following drugs reduce the breakdown of Phenytoin
- Acute Alcohol, Erythromycin, Metronidazole, Allopurinol
- Amiodarone, Omeprazole, Sulphonamides
Loading and Maintenance Dose
- Loading dose in Status Epilepticus is 20 mg/kg. This assumes the patient is not on Phenytoin. This is given with 0.9% N-Saline. Infuse into a large vein. Flush before and after. Ideally use an in line filter. Patient should be closely cardiac monitored.
- Infusion rates of more than 50 mg/minute. Use slower doses such as 25 mg/minute in elderly and with heart disease. Higher doses may be needed in heavier patients and the infusion time will be longer.
Emergency Loading Dose 20 mg/kg: Give over 30-60 mins with cardiac monitoring
||Dose in N-Saline (Do not give in 5%Dextrose).
||750 mg in 100 ml
||1000 mg in 100ml
||1250 mg in 250 ml
||1500 mg in 250 ml
|> 92 kg
||1750 mg in 250 ml
Maintenance Dose range