Carbamazepine

Clinical Chemistry

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Description

Carbamazapine (brand name Tegretol) is used to control seizures and may also be used for other conditions. It is usually only monitored in patients with seizures. Where dose changes are being considered, the patient should ideally be at steady-state (a minimum of 20 days after initiation of therapy or for patients on established regimens, a minimum of 4 days after last dose change) prior to sample collection.

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Indications

This guidance concerns carbamazepine use to treat epilepsy. Guidance regarding carbamazepine use and monitoring pregnancy is outside the scope of this summary.

Use of carbamazepine to treat other conditions is outside the scope of this guidance.

Measurement of carbamazepine may be useful in the following circumstances;
- dose optimisation
- uncontrolled seizures or suspected toxicity
- in patient populations with greater metabolic variability/polypharmacy (children, pregnancy, elderly, severe intercurrent illness)
- where the formulation of the drug is altered
- where there is the possibility of drug interactions

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Sample Type

Serum, SST/Gel, minimum 2 mL (1 mL separated serum) ideally pre-dose.

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Reference Range

Reference ranges are provided on the report. Alternatively, please contact the laboratory for current ranges.

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Turnaround Time

Within 1 day

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Testing Frequency

Daily

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External Notes

Ideally sample pre-dose for therapeutic drug monitoring (TDM) purposes. In cases of suspected toxicity, please indicate time of last dose and sample collection. Blood carbamazepine concentrations may exhibit diurnal variation. When requesting for TDM purposes, consistency of sample timing is recommended.

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Patient Preparation

For TDM purposes, take samples pre-dose (ideally). Patients should have attained steady-state (see below) prior to sample collection.

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Please note: the above information is subject to change and we endeavour to keep this website up to date wherever necessary.