Objective
To determine the optimal therapeutic range of serum carbamazepine concentration in agitated brain injured patients.

Methods
Five traumatic brain injured patients exhibiting agitated behavior were treated with carbamazepine during acute rehabilitation. Carbamazepine dose was increased from 400 mg to 1600 mg gradually and blood samples were analyzed for serum carbamazepine concentration. The presence and degree of posttraumatic agitation was measured by the Agitated Behavior Scale (ABS) developed by Corrigan. Therapeutic serum concentration of carbamazepine was defined as serum carbamazepine concentration at a point of time maintaining the ABS scores below 21.

Results
After carbamazepine therapy, ABS score was changed from 36.2 to 19.8 and the therapeutic serum concentration of carbamazepine was 10.18 ug/ml on average. Experienced adverse effects were drowsiness, gastrointestinal trouble, slurred speech, headache, leukopenia, abnormal liver function test, hair loss, skin rash, and double vision. But most of these adverse effects were mild, transient, and reversible with an adjustment in dosage or rate of dosage increase.

Conclusion
In the agitated brain injured patient, success in controlling the agitated behavior requires raising the dose of carbamazepine to high serum concentration levels above 10 ug/ml, as long as adverse effects do not intervene. Therefore we suggest that the therapeutic range of serum carbamazepine concentration for agitated brain injured patients is above 10 ug/ml.