Pathology Handbook

Carbamazepine

Synonyms

Tegretol

Clinical Indications

Carbamazepine (CBZ) is an anti-epileptic drug, used for tonic-clonic seizures.  Monitoring may assist dose changes. Concomitant therapy may affect levels by inducing liver metabolism.

Request Form

Request on ICE

Availability

On request

Specific Criteria

Patients on carbamazepine therapy

Patient Preparation

Time of collection is not critical but due to the relatively short half-life CBZ levels can vary quite markedly across the dosage interval; collection at a similar time, usually before next dose, may help long-term monitoring

Turnaround Time

Same day (Monday to Friday)

Specimen

Serum

Volume

1 ml

Container

Vacutainer gold top

Lab Handling

Samples should be analysed same day if left on gel.

Causes for Rejection

Unlabelled or incorrectly labelled sample; not meeting specific criteria for analysis; inadequate clinical information.

Target  Range

3.8 - 11.8 mg/L

(Molar units: 16-50 µmol/L)

Toxicity

Dizziness and visual disturbances are increasingly frequent at CBZ levels above 42 umol/L. A generalized erythematous rash may occur in 3-5% of patients. Long-term effects are few but water retention and hyponatraemia may occur as a late complication