The antifungal effects of
griseofulvin can be reduced (
serum levels reduced by about one-third) or even abolished by the concurrent use of
phenobarbital. Note that
primidone is metabolised to
phenobarbital and may therefore interact similarly.
Concurrent use should be well monitored to confirm that
griseofulvin is effective. If appropriate, a non-interacting antiepileptic such as sodium valproate may be considered.