Clinical implications of increased antipsychotic plasma concentrations upon anticonvulsant cessation.

Plasma antipsychotic concentrations were measured in five patients when their anticonvulsant medications were discontinued. Plasma antipsychotic concentrations increased by two- to five-fold at 4 weeks after cessation. All patients demonstrated either moderate or marked improvement as antipsychotic plasma concentrations increased. Four patients experienced extrapyramidal side effects within 30 days of anticonvulsant discontinuation. Careful monitoring of clinical symptoms, adverse effects, and plasma antipsychotic concentrations is recommended.