Clonazepam and lithium--a toxic combination in the treatment of mania?

Clonazepam, a benzodiazepine with anticonvulsant properties, has recently been found to be effective in the control of acute mania. Its use in combination with lithium has been advocated. Here 5 cases are presented in which the combination of clonazepam (2 mg-16 mg) plus lithium (900 mg-2400 mg) produced a neurotoxic syndrome with ataxia and dysarthria. In all cases the syndrome was reversible.