The manufacturers predict that potent inducers of CYP3A4 such as
phenytoin (and therefore possibly fosphenytoin) may lower the
serum levels of
rimonabant. This is based on the fact that potent inhibitors of CYP3A4 increase
rimonabant levels (see under azoles).
Caution is recommended with concurrent use of
phenytoin. Patients should be monitored to ensure
rimonabant remains effective.