Reports are inconsistent:
benzodiazepines can cause
serum phenytoin levels to rise (chlordiazepoxide, clobazam,
clonazepam, diazepam), occasionally resulting in tox- icity; or fall (clonazepam, diazepam); or remain unaltered (alprazolam, clonazepam). In addition
phenytoin may cause a fall in the
serum levels of clobazam,
clonazepam,
diazepam,
midazolam (see above) and
oxazepam.
Warn the patient to monitor for indicators of
phenytoin toxicity (blurred vision, nystagmus, ataxia or drowsiness). Take
phenytoin levels as necessary. Be aware that the benzodiazepine may be less effective than expected.