New uses of anticonvulsant drugs in psychosis.

Psychotic patients not adequately relieved by neuroleptic drugs often improve when anticonvulsants are added. In bipolar disorders and organic psychoses, anticonvulsants can sometimes be used to replace neuroleptics. No individual anticonvulsant is clearly, consistently superior. Patients who fail on one agent may improve on the next. Clonazepam is an excellent adjunct to neuroleptic therapy, but there is little evidence that it is effective as monotherapy. However, it is safe, sedates rapidly, and has an excellent patient tolerability profile. Carbamazepine is the best established drug for patients with bipolar disorders, particularly for rapid cyclers, and is often effective monotherapy. The therapeutic profile of valproic acid (sodium valproate) is similar to that of carbamazepine, but its side effects are quite different and are often preferred. Other anticonvulsants are little studied, but might be chosen to avoid certain side effects, or after better-studied drugs have failed. The pharmacological basis behind using anticonvulsants in psychoses is primarily empirical. In almost every case it has been clinicians who have first noted the beneficial effects of these drugs. Theories such as that of Post have followed.