EPILPESY: 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
Apart from epilepsy, what else can carbamazepine be used for?
- Adjunct in acute alcohol withdrawal
- Diabetic neuropathy
- Trigeminal neuralgia
- Bipolar
Contraindications
- Acute porphyrias
- Hx of bone marrow depression
Can carbamazepine be taken in pregancy
Yes
* Adjust dose based on Cp
* Increased risk of congenital malformations
* For any other indications it is not recommended to take whilst pregnant
Carbamazepine in breast feeding
Amount too small to be harmful
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
* Hyponatraemia
* Low vit D
* Oedema
* Rashes - SJS
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
Pre-treatment screening
- Han chinese and Thai patients with HLA-B1502 allele = increased risk of Steven-Johnson syndrome
- Test for allelle
SJS
- Due to carbamazepine
- Rare but serious
- Circular patches can occur characterised by darker in the middle and lighter on the outside
1. Flu
2. Rash upper body -> spreads
3. Blisters + sores can occur on lips, genitals and eyes
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 1-2 weeks to ensure within
therapeutic range) - Manufacturer recommends:
* FBC
* LFTs
* Renal
Why does carbamazepine have so many interactions
potent INDUCER
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
Drugs that antagonise the anticonvulsant effect of carbamazepine
Quinolones
Mefloquine
SSRIs
Antipsychotics
TCA and related antidepressants
Drugs that increase the risk of hyponatraemia
Aldosterone antagonists
SSRIs
TCAs
Diuretics
NSAIDs
