Carbamazepine Flashcards
Category
Category 1
High risk drug
Maintain on a specific manufacturers product (same brand or generic drug manufacturer)
What type of seizures is it used for?
1st line in focal seizures AND generalised tonic-clonic seizures.
What type of seizures should it NOT be used for?
Atonic
Clonic
Myoclonic
Exacerbates seizures
Therapeutic range
4-12 mg/L OR
20-50 micromol/L
Signs + symptoms of toxicity
IHANDBAG
* Incoordination
* Hyponatraemia
* Ataxia
* Nystagmus
* Drowsiness
* Blurred vision and diplopia (double vision)
* Arrhythmias
* GI disturbances
Side effects
MR preparations reduce the risk of SE
* Blood disorders
* Hepatotoxicity
* Hypersensitivity reactions
* Rashes
* Hyponatraemia
Blood disorders
E.g. Leucopoenia, thrombocytopenia
Report/look out for signs of infection
* Fever
* Sore throat
* Mouth ulcers
* Unexplained bruising or bleeding
Hepatotoxicity
- Dark urine
- N + V
- Abdominal pain
- Itching
- Jaundice
Hypersensitivity reactions (AHS)
- Fever
- Rash
- Lymphadenopathy
Rash
Rash
* Reintroduce if mild
* Discontinue if recurrence
* Han chinese and Thai patients with HLA-B*1502 Allele = increased risk of Steven-Johnson syndrome
Hyponatraemia
In rare cases, can lead to water intoxication.
Dose-related side effects
Some SE are dose-related and dose-limiting
More common at the start of treatment and in elderly patients.
* Headache
* Ataxia
* Droswiness
* N + V
* Blurred vision
* Unsteadiness
* Allergic skin reactions
Monitoring
- Plasma concentration
(measured after 2 weeks to ensure within
therapeutic range) - Full blood count, renal and hepatic function
(recommended by manufacturers)
Drugs that increase the concentration of Carbamazepine
Increased carbamazepine concentration = toxicity
Enzyme inhibitors
* Cimetidine
* Macrolides
* Fluoxetine
* Miconazole
Drugs that decrease the concentration of Carbamazepine
Decreased carbamazepine concentration = therapeutic failure
Enzyme inducers
* St. John’s wort
* Phenytoin
