Antiepileptics(continued)
▶Antiepileptics(fosphenytoin, phenytoin)slightly decrease the
exposure toefavirenzandefavirenzaffects the concentration
ofantiepileptics(fosphenytoin, phenytoin).rTheoretical
▶Carbamazepineslightly decreases the exposure toefavirenz
andefavirenzslightly decreases the exposure to
carbamazepine.rStudy
▶Phenobarbitalis predicted to decrease the exposure to
efavirenzandefavirenzaffects the concentration of
phenobarbital.rTheoretical
▶Efavirenzis predicted to affect the efficacy ofprimidoneand
primidoneis predicted to slightly decrease the exposure to
efavirenz.rTheoretical
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the exposure
toelbasvir. Avoid.rStudy
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the exposure
toeliglustat. Avoid.rStudy
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the
concentration ofelvitegravir. Avoid.rTheoretical
▶Enteral feedsdecrease the absorption ofphenytoin.r
Study
▶Enzalutamideis predicted to slightly decrease the exposure to
brivaracetam.oTheoretical
▶Enzalutamideis predicted to decrease the exposure to
perampanel. Monitor and adjust dose.oStudy
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the effects of
ergotamine.oTheoretical
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the exposure
toerlotinib. Avoid or adjusterlotinibdose.rStudy
▶Antiepileptics(carbamazepine, eslicarbazepine, fosphenytoin,
oxcarbazepine, perampanel, phenobarbital, phenytoin,
primidone, rufinamide, topiramate)are predicted to decrease
the efficacy ofetonogestrel. For FSRH guidance, see
Contraceptives, interactionsp. 497.rTheoretical
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the efficacy of
etoposide.oStudy
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the exposure
toetravirine. Avoid.rTheoretical
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the
concentration ofeverolimus. Avoid or adjust dose.rStudy
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)moderately decrease the exposure to
exemestane.oStudy
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the exposure
tofesoterodine. Avoid.oStudy
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the exposure
tofingolimod.oStudy
▶Fluorouracilincreases the concentration ofantiepileptics
(fosphenytoin, phenytoin). Monitor concentration and adjust
dose.rAnecdotal
▶Folatesare predicted to decrease the concentration of
antiepileptics(fosphenytoin, phenobarbital, phenytoin,
primidone). Monitor concentration and adjust dose.r
Study
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the exposure
tofosaprepitant. Avoid.oTheoretical
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the exposure
togefitinib. Avoid.rStudy
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to moderately decrease
the exposure toglecaprevir. Avoid.rStudy
▶Antiepileptics(eslicarbazepine, oxcarbazepine)potentially
decrease the exposure toglecaprevir. Avoid.rTheoretical▶Valproatepotentially opposes the effects ofglycerol
phenylbutyrate.oTheoretical
▶Grapefruit juiceslightly increases the exposure to
carbamazepine. Monitor and adjust dose.oStudy
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the exposure
tograzoprevir. Avoid.rStudy
▶Antiepileptics(phenobarbital, primidone)decrease the effects of
griseofulvin.oStudy
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the
concentration ofguanfacine. Adjustguanfacinedose,p. 231.
oStudy→Also seeTABLE 11p. 849
▶Oxcarbazepineis predicted to decrease the concentration of
guanfacine. Monitor and adjustguanfacinedose,p. 231.
oTheoretical
▶Guanfacineincreases the concentration ofvalproate. Monitor
and adjust dose.oStudy
▶H 2 receptor antagonists(cimetidine)transiently increase the
concentration ofcarbamazepine. Monitor concentration and
adjust dose.oStudy
▶H 2 receptor antagonists(cimetidine)increase the concentration
ofantiepileptics(fosphenytoin, phenytoin). Monitor
concentration and adjust dose.rStudy
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)decrease the concentration of
haloperidol. Adjust dose.oStudy→Also seeTABLE 11
p. 849
▶Haloperidolpotentially increases the risk of overheating and
dehydration when given withzonisamide. Avoid in children.
rTheoretical
▶HIV-protease inhibitors(ritonavir)slightly decrease the exposure
tolamotrigine.rStudy
▶HIV-protease inhibitorsare predicted to affect the exposure to
antiepileptics(fosphenytoin, phenytoin)andantiepileptics
(fosphenytoin, phenytoin)decrease the concentration ofHIV-
protease inhibitors.rTheoretical
▶HIV-protease inhibitorsare predicted to affect the
concentration ofantiepileptics(phenobarbital, primidone)and
antiepileptics(phenobarbital, primidone)are predicted to
decrease the concentration ofHIV-protease inhibitors.r
Theoretical
▶HIV-protease inhibitorsare predicted to increase the exposure
tocarbamazepineandcarbamazepineis predicted to decrease
the exposure toHIV-protease inhibitors. Monitor and adjust
dose.rTheoretical
▶HIV-protease inhibitorsare predicted to very slightly increase
the exposure toperampanel.nStudy
▶HIV-protease inhibitors(ritonavir)are predicted to decrease the
concentration ofvalproate.rAnecdotal
▶Antiepileptics(carbamazepine, eslicarbazepine, fosphenytoin,
oxcarbazepine, perampanel, phenobarbital, phenytoin,
primidone, rufinamide, topiramate)are predicted to decrease
the effects ofhormone replacement therapy.oAnecdotal
▶Hormone replacement therapyis predicted to alter the
exposure tolamotrigine.oTheoretical
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the exposure
toibrutinib. Avoid or adjustibrutinibdose.rStudy
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the exposure
toidelalisib. Avoid.rStudy
▶Idelalisibis predicted to very slightly increase the exposure to
perampanel.nStudy
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the exposure
toimatinib. Avoid.oStudy
▶Oxcarbazepinedecreases the exposure toimatinib. Avoid.
oStudy
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the exposure
toirinotecan. Avoid.rStudy
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the exposure866 Antiepileptics—Antiepileptics BNFC 2018 – 2019
Interactions|Appendix 1A1