Clonazepam appears to markedly raise the levels of
primidone in children, and
toxicity has been seen. The concurrent use of
primidone and clorazepate was thought to have caused irritability, aggression and
depression in a small number of patients. Note that
primidone is metabolized to
phenobarbital.
The
clinical importance of this interaction is unknown, but bear it in mind in case of an unexpected response to treatment. Indicators of
phenobarbital and
primidone toxicity include drowsiness, ataxia, and dysarthria.