Carbamazepine

Related Subjects: | Status Epilepticus (Epilepsy) | Coma management | Lorazepam | Phenytoin | Levetiracetam | Epilepsy - General Management | First Seizure | Epilepsy in Pregnancy | Febrile seizures

Serious Skin reactions may be seen mainly in Asians with HLA-B1502 allele so caution before using on Hong Kong Chinese/Thai . Can worsen myoclonic/absence seizures.

About : Always check the BNF link here

• Induces the p450 enzyme system

Mode of action

• Blockade of Na⁺ and Ca++ channels, Enhances GABA transmission
• Liver enzyme inducer - reduces efficacy of other drugs

Indications/Dose

• Anticonvulsant - Partial and Generalised tonic-clonic seizures
• Trigeminal neuralgia, Mania and bipolar disorders

Dose range:You must check with BNF or drug datasheet

Monitoring

• Check compliance with random blood levels after several weeks
• Optimum 4-12 mg/L or 20-50 micromol/L
• Toxic > 12 mg/L or 50 micromol/L
• Monitor FBC, U&E and LFTs and levels

Side effects

• Nausea, Drowsiness, Ataxia, Headache, Diplopia, Dizziness
• Aplastic anaemia and agranulocytosis, blurred vision, rash
• Allergic skin reactions, including urticaria, may be severe.
• Fluid retention, Dry mouth, Leucopenia, Hyponatraemia (SIADH)
• Stevens-Johnson syndrome (SJS), Toxic epidermal necrolysis
• SJS is increasingly seen in Asians with the HLA-B1502 allele
• Pregnancy - Neural tube defects

Cautions

• Caution use in Chinese/Thai at risk of Stevens-Johnson syndrome
• Drowsiness may affect driving/machinery

Interactions

• Reduced Efficacy of Oral contraceptive pill, Ciclosporin, Warfarin
• Erythromycin, Diltiazem, Verapamil increase Carbamazepine levels

Contraindications

• Can worsen absence/myoclonic epilepsy
• MAOIs, Bone marrow suppression
• Porphyria, AV conduction disease

References

• Carbamazepine at BNF