Carbamazepine Unit Conversion

Carbamazepine is an anticonvulsant drug, used in particular for the treatment of trigeminal neuralgia, all forms of partial epilepsy, generalized tonic-clonic seizures, and simple and complex partial seizures. The specific mechanism of carbamazepine is proposed as a depressant action on transmission through the nucleus ventralis anterior of the thalamus. Carbamazepine, 5H-dibenz[b,f]-azepine-5-carboxamide, is an iminostilbene derivative also recognized by its common brand name, Tegretol. In the circulation, carbamazepine is approximately 70 % bound by protein. The drug is metabolized to carbamazepine-10,11-epoxide, which is pharmacologically active, and then to carbamazepine-10,11-dihydroxide, both of which are excreted in urine. The plasma concentration of the epoxide metabolite ranges from 15 to 48 % of the parent compound. The epoxide has a shorter half-life (5‑8 hours) than the parent compound (8‑60 hours). The epoxide and the 10,11-dihydroxide are excreted unaltered or after conjugation to glucuronic acid.

Monitoring carbamazepine concentrations is essential during therapy in order to provide the physician with an indicator for adjusting dosage. Serum and plasma levels show only a moderate correlation to dose, due to individual differences in absorption, metabolism and clearance. Moreover, co-administration of other antiepileptic agents can significantly increase serum carbamazepine levels. Toxicity of carbamazepine associated with therapy may or may not be dose-related. Nystagmus, blood dyscrasias, and gastrointestinal disturbances including nausea, vomiting, and anorexia are not related to dose. However, the central nervous system symptoms of vertigo, dizziness, and diplopia are dose-related with chronic therapy.

In combination with other clinical information, monitoring carbamazepine levels provides physicians with an effective tool to aid in adjusting dosage and achieving optimal therapeutic effect while avoiding both subtherapeutic and toxic drug levels.