Carbamazepine-10,11 epoxide has anticonvulsant activity similar to that of the parent compound. The half-life averages six hours and is 60% bound to protein.1 This heterocyclic (iminostilbene) compound has potent antiepileptic properties and is effective alone or with other antiepileptic drugs in partial seizures, especially complex partial seizures, generalized tonic-clonic seizures, and combinations of these seizure types. Carbamazepine generally is ineffective for absence, myoclonic, and atonic seizures. In children with symptomatic generalized epilepsy and continuous spike-and-wave discharge, these seizure types may develop (or tonic-clonic seizures may increase in frequency) with the use of carbamazepine.
Additional Test Information:
Leukopenia may be dose-related and necessitates stopping the drug if the absolute neutrophil count falls to <1000/mm³.2Hyponatremia may occur, especially in older patients. Patients in the first month of pregnancy are at increased risk of neural tube defects. Carbamazepine may interfere with the actions of theophylline, oral contraceptives, oral anticoagulants, or doxycycline.
Serum or plasma
Red-top tube or green-top (heparin) tube. Do not use a gel-barrier tube. The use of gel-barrier tubes is not recommended due to slow absorption of the drug by the gel. Depending on the specimen volume and storage time, the decrease in drug level due to absorption may be clinically significant. Transfer separated serum or plasma to a plastic transport tube.
Trough: immediately prior to net dose. Due to variability of absorption, the trough level may not represent the lowest drug level during the dosing interval; therefore, in some patients, multiple determinations may be necessary.
Room temperature 14 days
Refrigerated 14 days
Frozen 14 days
Freeze/thaw cycles Stable x3
Gel-barrier tube; gross lipemia; hemolysis; icteric specimen