Oxcarbazepine
Introduction
Carbamazepine is an anticonvulsant medication used primarily in the treatment of epilepsy. It has been used both alone and as add-on therapy for partial seizures with or without secondary generalization.
| Generic Name 藥名 | HA Code 藥物代碼 | Classification藥物分類 |
|---|---|---|
| P1S1S3 |
Pronunciation
Oxcarbazepine 600mg
Mechanism of Action
Anticonvulsant medication. It is a sodium channel blocker. It binds to sodium channels and suppresses repetitive neuronal firing.
Dosage
1. Epilepsy
| Oral | initially 300 mg twice daily increased according to response in steps of up to 600 mg daily at weekly intervals; usual dose rage 0.6 – 2.4 g daily in divided doses. |
|---|
Administration in children
| 6 – 18 years | 8 – 10 mg/kg daily in 2 divided doses increased according to response in steps of up to 10mg/kg daily at weekly intervals, to a maximum dose of 46 mg/kg daily.
Usual maintenance doses in adjunctive therapy around 30mg/kg daily. |
|---|
Side Effects
Common side effects include:
- Drowsiness, dizziness and headaches
- Gastrointestinal disturbances, such as nausea and vomiting
- The loss of full control of bodily movements (motor coordination impairment)
- Increased risks of hyponatremia and SIADH
- Blood disorders (such as decreased white blood cell or platelet counts)
Serious side effects may include:
- Skin rashes, exfoliative dermatitis, epidermal necrolysis, Stevens-Johnson syndrome, and SLE
- Decreased bone marrow function
- Suicidal thoughts
- Abnormal heart rhythms
- Blurry or double vision, nystagmus
- Male infertility
- Osteoporosis
- Gynecomastia
- Galactorrhea
- Photosensitivity leading to severe sunburns as a result of sun exposure
Pharmacokinetics
| Oral bioavailability | Oxcarbazepine is a prodrug which is metabolized to its pharmacologically active metabolite licarbazepine. It has high bioavailability upon oral administration. |
|---|---|
| Onset of action | The half-life of oxcarbazepine is about 2 hours, whereas licarbazepine has a half-life of 9 hours. The latter provides most of the antiepileptic activity |
| Metabolism | Licarbazepine is metabolized in the liver |
| Elimination half-life | Excreted in the urine, with faeces accounting to less than 4%. |
Drug interaction
Monitoring
- signs of blood, liver, or skin disorders. Seek immediate medical attention if symptoms such as fever, rash, blistering, mouth ulcers, bruising or bleeding develop.
- Patients with heart failure should be weighed regularly to detect fluid retention.
- Patients with pre-existing cardiac conduction disorders should be carefully monitored.
- Hyponatremia (monitor plasma-sodium concentration in patients at risk).
Drug interaction Plasma concentrations of the active metabolite of oxcarbazepine may be reduced by strong inducers of cytochrome P450 isoenzymes, such as phenytoin, or phenobarbital. Oxcarbazepine and its metabolite also have the capacity to induce CYP3A4 and CYP3A5 with the possibility of reducing plasma concentrations of drugs such as dihydropyridine calcium-channel blockers, and oral contraceptives.
