. Monitor and adjust guanfacine dose, p. 352.

Theoretical

▶ Guanfacine increases the concentration of valproate. Monitor

and adjust dose.oStudy

▶ H2 receptor antagonists (cimetidine) transiently increase the

concentration of carbamazepine. Monitor concentration and

adjust dose.oStudy

▶ H2 receptor antagonists (cimetidine) increase the concentration

of antiepileptics (fosphenytoin, phenytoin). Monitor

concentration and adjust dose.rStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) decrease the concentration of

haloperidol. Adjust dose.oStudy → Also see TABLE 11

p. 1377

▶ Haloperidol potentially increases the risk of overheating and

dehydration when given with

r

zonisamide. Avoid in children.

Theoretical

▶ HIV-protease inhibitors are predicted to affect the exposure to

antiepileptics (fosphenytoin, phenytoin) and antiepileptics

(fosphenytoin, phenytoin) decrease the concentration of HIVprotease inhibitors.rTheoretical

▶ HIV-protease inhibitors are predicted to affect the

concentration of antiepileptics (phenobarbital, primidone) and

antiepileptics (phenobarbital, primidone) are predicted to

decrease the concentration of

Theoretical

HIV-protease inhibitors.r

▶ HIV-protease inhibitors are predicted to increase the exposure

to carbamazepine and carbamazepine is predicted to decrease

the exposure to HIV-protease inhibitors. Monitor and adjust

dose.rTheoretical

▶ HIV-protease inhibitors (ritonavir) slightly decrease the exposure

to lamotrigine.rStudy

▶ HIV-protease inhibitors are predicted to very slightly increase

the exposure to perampanel.nStudy

▶ HIV-protease inhibitors (ritonavir) are predicted to decrease the

concentration of valproate.rAnecdotal

▶ Antiepileptics (carbamazepine, eslicarbazepine, fosphenytoin,

oxcarbazepine, perampanel, phenobarbital, phenytoin,

primidone, rufinamide, topiramate) are predicted to decrease

the effects of hormone replacement therapy.oAnecdotal

▶ Hormone replacement therapy is predicted to alter the

exposure to lamotrigine.oTheoretical

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to ibrutinib. Avoid or adjust ibrutinib dose, p. 983.rStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to idelalisib. Avoid.rStudy

▶ Idelalisib is predicted to very slightly increase the exposure to

perampanel.nStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to imatinib. Avoid.oStudy

▶ Oxcarbazepine

o

decreases the exposure to imatinib. Avoid.

Study

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to irinotecan. Avoid.rStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to iron chelators (deferasirox). Monitor serum ferritin and

adjust dose.oTheoretical

▶ Isoniazid increases the concentration of antiepileptics

(fosphenytoin, phenytoin).oStudy → Also see TABLE 12

p. 1378

▶ Isoniazid markedly increases the concentration of

carbamazepine and carbamazepine increases the risk of

hepatotoxicity when given with isoniazid. Monitor

concentration and adjust dose.rStudy → Also see TABLE 1

p. 1375

BNF 78 Antiepileptics — Antiepileptics 1395

Interactions | Appendix 1

A1

Antiepileptics (continued)

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to ivabradine. Adjust dose.oTheoretical

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to moderately to markedly

decrease the exposure to ivacaftor. Avoid.rStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to ixazomib. Avoid.rStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to lapatinib. Avoid.rStudy

▶ Antiepileptics (fosphenytoin, oxcarbazepine, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to ledipasvir. Avoid.rTheoretical

▶ Carbamazepine is predicted to decrease the exposure to

ledipasvir. Avoid.rStudy

▶ Antiepileptics (carbamazepine, phenobarbital, primidone) are

predicted to decrease the concentration of

o

letermovir.

Theoretical

▶ Letermovir is predicted to decrease the concentration of

antiepileptics (fosphenytoin, phenytoin) and antiepileptics

(fosphenytoin, phenytoin) are predicted to decrease the

concentration of letermovir.oTheoretical

▶ Antiepileptics (fosphenytoin, phenytoin) decrease the effects of

levodopa.oStudy

▶ Antiepileptics (carbamazepine, eslicarbazepine, fosphenytoin,

oxcarbazepine, perampanel, phenobarbital, phenytoin,

primidone, rufinamide, topiramate) are predicted to decrease

the efficacy of levonorgestrel. For FSRH guidance, see

Contraceptives, interactions p. 794.rTheoretical

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to linagliptin.oStudy

▶ Antiepileptics (carbamazepine, oxcarbazepine) are predicted to

increase the risk of neurotoxicity when given with

r

lithium.

Anecdotal

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to lomitapide. Monitor and adjust dose.oTheoretical →

Also see TABLE 1 p. 1375

▶ Antiepileptics (fosphenytoin, phenytoin) decrease the effects of

loop diuretics (furosemide).oStudy

▶ Lumacaftor is predicted to decrease the exposure to

antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone). Avoid.rTheoretical

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to lurasidone. Avoid.oStudy → Also see TABLE 11 p. 1377

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to macitentan. Avoid.rStudy

▶ Macrolides (clarithromycin) slightly increase the concentration

of

r

carbamazepine. Monitor concentration and adjust dose.

Study

▶ Macrolides (clarithromycin) are predicted to very slightly

increase the exposure to perampanel.nStudy

▶ Macrolides (erythromycin) markedly increase the concentration

r

of carbamazepine. Monitor concentration and adjust dose.

Study

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to maraviroc. Adjust dose.rStudy

▶ Phenytoin

o

is predicted to decrease the exposure to melatonin.

Theoretical

▶ Levetiracetam

Anecdotal

decreases the clearance of methotrexate.r

▶ Antiepileptics (phenobarbital, primidone) are predicted to

decrease the exposure to metronidazole.oStudy

▶ Antiepileptics (fosphenytoin, phenobarbital, phenytoin,

primidone) are predicted to decrease the effects of

metyrapone. Avoid.oStudy

▶ Phenytoin is predicted to increase the clearance of mexiletine.

Monitor and adjust dose.oStudy

▶ Antiepileptics (phenobarbital, primidone) are predicted to

decrease the exposure to mianserin.oStudy → Also see

TABLE 11 p. 1377

▶ Carbamazepine markedly decreases the exposure to mianserin.

Adjust dose.oStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to midazolam. Monitor and adjust dose.oStudy → Also

see TABLE 11 p. 1377

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to midostaurin. Avoid.rStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to mirtazapine. Adjust dose.oStudy → Also see TABLE 11

p. 1377

▶ Mitotane is predicted to decrease the exposure to perampanel.

Monitor and adjust dose.oStudy

▶ Antiepileptics (carbamazepine, phenobarbital, primidone) are

predicted to decrease the exposure to modafinil.n Theoretical

▶ Antiepileptics (fosphenytoin, phenytoin) are predicted to

decrease the exposure to modafinil and modafinil is predicted

to increase the concentration of antiepileptics (fosphenytoin,

phenytoin)

Theoretical

. Monitor concentration and adjust dose.o ▶ Antiepileptics (phenobarbital, primidone) are predicted to

increase the effects of monoamine-oxidase A and B inhibitors,

irreversible.rTheoretical

▶ Carbamazepine is predicted to increase the risk of severe toxic

reaction when given with monoamine-oxidase A and B

inhibitors, irreversible. Avoid and for 14 days after stopping

the MAOI.rTheoretical

▶ Carbamazepine is predicted to decrease the effects of

monoclonal antibodies (brentuximab vedotin).rTheoretical

▶ Monoclonal antibodies (tocilizumab) are predicted to decrease

the exposure to antiepileptics (fosphenytoin, phenytoin).

Monitor and adjust dose.oTheoretical

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to montelukast.nStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to markedly decrease the

exposure to naloxegol. Avoid.oStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to slightly decrease the

exposure to nateglinide.nStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to netupitant. Avoid.rStudy

▶ Carbamazepine is predicted to decrease the effects of (but

acute use increases the effects of) neuromuscular blocking drugs,

non-depolarising (atracurium, cisatracurium, pancuronium,

rocuronium). Monitor and adjust dose.oStudy

▶ Antiepileptics (fosphenytoin, phenytoin) decrease the effects of

(but acute use increases the effects of) neuromuscular blocking

drugs, non-depolarising (atracurium, cisatracurium,

pancuronium, rocuronium).oStudy

▶ Nevirapine is predicted to decrease the concentration of

antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) and antiepileptics (carbamazepine,

fosphenytoin, phenobarbital, phenytoin, primidone) are

predicted to decrease the concentration of

Study

nevirapine.r

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to moderately decrease

the exposure to nilotinib. Avoid.rStudy

▶ Carbamazepine is predicted to decrease the exposure to

nintedanib.oStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to nitisinone. Adjust dose.oTheoretical

▶ Antiepileptics (carbamazepine, eslicarbazepine, fosphenytoin,

oxcarbazepine, perampanel, phenobarbital, phenytoin,

primidone, rufinamide, topiramate) are predicted to decrease

1396 Antiepileptics — Antiepileptics BNF 78

Interactions | Appendix 1

A1

the efficacy of norethisterone. For FSRH guidance, see

Contraceptives, interactions p. 794.rAnecdotal

▶ Carbamazepine potentially decreases the exposure to

olanzapine. Monitor and adjust dose.oStudy

▶ Phenytoin is predicted to decrease the exposure to olanzapine.

Monitor and adjust dose.oStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to olaparib. Avoid.oTheoretical

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin) are predicted to decrease the exposure to

ombitasvir. Avoid.rTheoretical

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to ondansetron.oStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to opioids (alfentanil, fentanyl).oStudy → Also see

TABLE 11 p. 1377

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to

Theoretical

opioids (buprenorphine)

→ Also see TABLE 11

. Monitor and adjust dose.

p. 1377

o ▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) decrease the exposure to opioids

(methadone). Monitor and adjust dose.rStudy → Also see

TABLE 11 p. 1377

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to

Study

opioids

→ Also see

(oxycodone)

TABLE 11

. Monitor and adjust dose.

p. 1377

o ▶ Carbamazepine decreases the concentration of opioids

(tramadol). Adjust dose.rStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to moderately decrease

the exposure to osimertinib. Avoid.oStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to moderately decrease

the exposure to ospemifene.oStudy

▶ Oxybutynin potentially increases the risk of overheating and

dehydration when given with

r

zonisamide. Avoid in children.

Theoretical

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to palbociclib. Avoid.rStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to paliperidone. Monitor and adjust dose.rStudy → Also

see TABLE 11 p. 1377

▶ Valproate slightly increases the exposure to paliperidone.

Adjust dose.oStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to panobinostat. Avoid.oTheoretical

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone)

o

decrease the exposure to paracetamol.

Study → Also see TABLE 1 p. 1375

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to

Study

paritaprevir (with ritonavir and ombitasvir). Avoid.r

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to pazopanib. Avoid.rTheoretical

▶ Valproate increases the risk of side-effects when given with

penicillins (pivmecillinam). Avoid.rAnecdotal

▶ Phenothiazines (chlorpromazine) decrease the concentration of

antiepileptics (phenobarbital, primidone) and antiepileptics

(phenobarbital, primidone) decrease the concentration of

phenothiazines (chlorpromazine).oStudy → Also see

TABLE 11 p. 1377

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to

r

phosphodiesterase type-5 inhibitors (avanafil, tadalafil). Avoid.

Study

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to

o

phosphodiesterase type-5 inhibitors (sildenafil, vardenafil).

Theoretical

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to moderately to markedly

decrease the exposure to pibrentasvir. Avoid.rStudy

▶ Antiepileptics (eslicarbazepine, oxcarbazepine) potentially

decrease the exposure to pibrentasvir. Avoid.rTheoretical

▶ Antiepileptics (fosphenytoin, phenytoin) are predicted to

decrease the exposure to pirfenidone.oTheoretical

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to moderately decrease

the exposure to pitolisant.oStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to ponatinib. Avoid.oTheoretical

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to markedly decrease the

exposure to praziquantel. Avoid.oStudy

▶ Antiepileptics (carbamazepine, phenobarbital, phenytoin,

primidone) are predicted to increase the risk of

hypersensitivity reactions when given with

r