is predicted to increase the exposure to didanosine.

Study

▶ Leflunomide is predicted to increase the exposure to

ganciclovir.oTheoretical → Also see TABLE 15 p. 1378

▶ Mycophenolate is predicted to increase the risk of

Theoretical

haematological toxicity when given with

→ Also see TABLE 15 p. 1378

ganciclovir.o ▶ Teriflunomide is predicted to increase the exposure to

ganciclovir.oStudy

Gefitinib → see TABLE 15 p. 1378 (myelosuppression)

▶ Antacids are predicted to slightly decrease the exposure to

gefitinib.oTheoretical

▶ Antiarrhythmics (dronedarone) are predicted to increase the

exposure to gefitinib.oTheoretical

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to gefitinib. Avoid.rStudy

▶ Antifungals, azoles (fluconazole, isavuconazole, posaconazole)

are predicted to increase the exposure to

Theoretical

gefitinib.o ▶ Antifungals, azoles (itraconazole, ketoconazole, voriconazole) are

predicted to increase the exposure to gefitinib.oStudy

▶ Aprepitant

o

is predicted to increase the exposure to gefitinib.

Theoretical

▶ Bosentan is predicted to decrease the exposure to gefitinib.

Avoid.rTheoretical

▶ Calcium channel blockers (diltiazem, verapamil) are predicted to

increase the exposure to gefitinib.oTheoretical

▶ Cobicistat

o

is predicted to increase the exposure to gefitinib.

Study

▶ Gefitinib is predicted to increase the anticoagulant effect of

coumarins.rAnecdotal

▶ Crizotinib

o

is predicted to increase the exposure to gefitinib.

Theoretical → Also see TABLE 15 p. 1378

▶ Efavirenz is predicted to decrease the exposure to gefitinib.

Avoid.rTheoretical

▶ Enzalutamide is predicted to decrease the exposure to

gefitinib. Avoid.rStudy

▶ H2 receptor antagonists are predicted to slightly to moderately

decrease the exposure to gefitinib.oStudy

▶ HIV-protease inhibitors are predicted to increase the exposure

to gefitinib.oStudy

▶ Idelalisib

o

is predicted to increase the exposure to gefitinib.

Study → Also see TABLE 15 p. 1378

▶ Imatinib

o

is predicted to increase the exposure to gefitinib.

Theoretical → Also see TABLE 15 p. 1378

▶ Macrolides (clarithromycin) are predicted to increase the

exposure to gefitinib.oStudy

▶ Macrolides (erythromycin) are predicted to increase the

exposure to gefitinib.oTheoretical

▶ Mitotane is predicted to decrease the exposure to gefitinib.

Avoid.rStudy → Also see TABLE 15 p. 1378

▶ Netupitant

o

is predicted to increase the exposure to gefitinib.

Theoretical

▶ Nevirapine is predicted to decrease the exposure to gefitinib.

Avoid.rTheoretical

▶ Nilotinib

o

is predicted to increase the exposure to gefitinib.

Theoretical → Also see TABLE 15 p. 1378

▶ Gefitinib is predicted to increase the risk of bleeding events

when given with phenindione.rTheoretical

▶ Proton pump inhibitors are predicted to decrease the exposure

to gefitinib.rTheoretical

▶ Rifampicin is predicted to decrease the exposure to gefitinib.

Avoid.rStudy

▶ St John’s Wort is predicted to decrease the exposure to

gefitinib. Avoid.rTheoretical

Gemcitabine → see TABLE 15 p. 1378 (myelosuppression)

▶ Live vaccines are predicted to increase the risk of generalised

infection (possibly life-threatening) when given with

gemcitabine. Public Health England advises avoid (refer to

Green Book).rTheoretical

Gemfibrozil → see fibrates

Gentamicin → see aminoglycosides

Glecaprevir

▶ Antiarrhythmics (dronedarone) potentially increase the

exposure to glecaprevir.oTheoretical

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to moderately decrease

the exposure to glecaprevir. Avoid.rStudy

▶ Antiepileptics (eslicarbazepine, oxcarbazepine) potentially

decrease the exposure to glecaprevir. Avoid.rTheoretical

▶ Antifungals, azoles (itraconazole, ketoconazole) potentially

increase the exposure to glecaprevir.oTheoretical

▶ Bosentan is predicted to decrease the exposure to glecaprevir.

Avoid.rStudy

▶ Ciclosporin increases the exposure to glecaprevir. Avoid or

monitor.rStudy

▶ Cobicistat

o

potentially increases the exposure to glecaprevir.

Theoretical

▶ Combined hormonal contraceptives (containing

ethinylestradiol) are predicted to increase the risk of

increased ALT concentrations when given with glecaprevir.

Avoid.rStudy

▶ Crizotinib potentially decreases the exposure to glecaprevir.

Avoid.rTheoretical

▶ Glecaprevir (with pibrentasvir) increases the exposure to

dabigatran. Avoid.oStudy

▶ Glecaprevir (with pibrentasvir) increases the exposure to

digoxin.oStudy

▶ Efavirenz is predicted to decrease the exposure to glecaprevir.

Avoid.rStudy

▶ Enzalutamide is predicted to greatly decrease the

concentration of glecaprevir. Avoid.rStudy

▶ HIV-protease inhibitors (atazanavir, darunavir, lopinavir)

(boosted with ritonavir) increase the exposure to glecaprevir.

Avoid.rStudy

▶ HIV-protease inhibitors (ritonavir) increase the exposure to

glecaprevir. Avoid.rStudy

▶ Lumacaftor potentially decreases the exposure to glecaprevir.

Avoid.rTheoretical

▶ Mitotane is predicted to greatly decrease the concentration of

glecaprevir. Avoid.rStudy

▶ Nevirapine is predicted to decrease the exposure to

glecaprevir. Avoid.rStudy

▶ Rifampicin markedly affects the exposure to glecaprevir.

Avoid.rStudy

▶ St John’s Wort is predicted to decrease the exposure to

glecaprevir. Avoid.rStudy

▶ Glecaprevir (with pibrentasvir) markedly increases the

exposure to statins (atorvastatin). Avoid.rStudy

▶ Glecaprevir (with pibrentasvir) is predicted to increase the

exposure to statins (fluvastatin).oTheoretical

▶ Glecaprevir (with pibrentasvir) increases the exposure to

statins (pravastatin). Use with caution and adjust pravastatin

dose.oStudy

▶ Glecaprevir (with pibrentasvir) increases the exposure to

statins (rosuvastatin). Use with caution and adjust rosuvastatin

dose, p. 204.oStudy

▶ Glecaprevir (with pibrentasvir) increases the exposure to

statins (simvastatin). Avoid.oStudy

BNF 78 Frovatriptan — Glecaprevir 1459

Interactions | Appendix 1

A1

Glecaprevir (continued)

▶ Glecaprevir (with pibrentasvir) slightly increases the exposure

to tacrolimus. Monitor and adjust dose.nStudy

Glibenclamide → see sulfonylureas

Gliclazide → see sulfonylureas

Glimepiride → see sulfonylureas

Glipizide → see sulfonylureas

Glucagon

▶ Glucagon increases the anticoagulant effect of coumarins

(warfarin).rStudy

Glucosamine

▶ Glucosamine potentially decreases the anticoagulant effect of

coumarins (acenocoumarol).oAnecdotal

▶ Glucosamine potentially increases the anticoagulant effect of

coumarins (warfarin). Avoid.oAnecdotal

Glycerol phenylbutyrate

▶ Antiepileptics (valproate) potentially oppose the effects of

glycerol phenylbutyrate.oTheoretical

▶ Corticosteroids potentially oppose the effects of glycerol

phenylbutyrate.oTheoretical

▶ Haloperidol potentially opposes the effects of glycerol

phenylbutyrate.oTheoretical

Glyceryl trinitrate → see nitrates

Glycopyrronium → see TABLE 10 p. 1377 (antimuscarinics)

ROUTE-SPECIFIC INFORMATION Since systemic absorption can

follow topical application, the possibility of interactions

should be borne in mind.

Golimumab → see monoclonal antibodies

Granisetron → see TABLE 9 p. 1377 (QT-interval prolongation), TABLE 13

p. 1378 (serotonin syndrome)

▶ Dopamine receptor agonists (apomorphine) are predicted to

increase the risk of severe hypotension when given with

granisetron.rTheoretical

Grapefruit juice

▶ Grapefruit juice is predicted to increase the exposure to

abemaciclib. Avoid.oTheoretical

▶ Grapefruit juice moderately decreases the exposure to

aliskiren. Avoid.rStudy

▶ Grapefruit juice increases the exposure to antiarrhythmics

(amiodarone). Avoid.oStudy

▶ Grapefruit juice moderately increases the exposure to

antiarrhythmics (dronedarone). Avoid.rStudy

▶ Grapefruit juice increases the exposure to antiarrhythmics

(propafenone). Monitor and adjust dose.oStudy

▶ Grapefruit juice slightly increases the exposure to antiepileptics

(carbamazepine). Monitor and adjust dose.oStudy

▶ Grapefruit juice slightly decreases the exposure to

antihistamines, non-sedating (bilastine). Bilastine should be

taken 1 hour before or 2 hours after

Study

grapefruit juice.o ▶ Grapefruit juice increases the exposure to antihistamines, nonsedating (rupatadine). Avoid.oStudy

▶ Grapefruit juice increases the exposure to antimalarials

(artemether).qStudy

▶ Grapefruit juice is predicted to increase the concentration of

antimalarials (piperaquine). Avoid.rTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

axitinib.oTheoretical

▶ Grapefruit juice greatly decreases the exposure to beta blockers,

selective (celiprolol).oStudy

▶ Grapefruit juice is predicted to increase the exposure to

bosutinib. Avoid.oTheoretical

▶ Grapefruit juice is predicted to increase the concentration of

brigatinib. Avoid.rStudy

▶ Grapefruit juice increases the exposure to buspirone. Avoid.

nStudy

▶ Grapefruit juice is predicted to increase the exposure to

cabozantinib.oTheoretical

▶ Grapefruit juice very slightly increases the exposure to calcium

channel blockers (amlodipine). Avoid.nStudy

▶ Grapefruit juice increases the exposure to calcium channel

blockers (felodipine). Avoid.oStudy

▶ Grapefruit juice is predicted to increase the exposure to calcium

channel blockers (lercanidipine). Avoid.oTheoretical

▶ Grapefruit juice increases the exposure to calcium channel

blockers (nicardipine).nStudy

▶ Grapefruit juice increases the exposure to calcium channel

blockers (nifedipine, verapamil). Avoid.nStudy

▶ Grapefruit juice is predicted to increase the exposure to

cariprazine. Avoid.oStudy

▶ Grapefruit juice is predicted to increase the exposure to

ceritinib. Avoid.rTheoretical

▶ Grapefruit juice increases the concentration of ciclosporin.

Avoid.rStudy

▶ Grapefruit juice markedly decreases the exposure to

clopidogrel.rStudy

▶ Grapefruit juice is predicted to increase the exposure to

cobimetinib. Avoid.rTheoretical

▶ Grapefruit juice moderately increases the exposure to oral

corticosteroids (budesonide). Avoid.oStudy

▶ Grapefruit juice is predicted to increase the exposure to

crizotinib. Avoid.oTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

darifenacin.oStudy

▶ Grapefruit juice is predicted to increase the exposure to

dasatinib. Avoid.oTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

eliglustat. Avoid.rTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

encorafenib. Avoid.oStudy

▶ Grapefruit juice is predicted to increase the exposure to

ergometrine.rTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

ergotamine.rTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

erlotinib.oTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

everolimus. Avoid.rTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

guanfacine. Avoid.oTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

ibrutinib. Avoid.oTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

imatinib.oTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

ivabradine. Avoid.oStudy

▶ Grapefruit juice is predicted to increase the exposure to

ivacaftor. Avoid.oTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

lapatinib. Avoid.oTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

lomitapide

Theoretical

. Separate administration by 12 hours.o ▶ Grapefruit juice is predicted to increase the exposure to

lurasidone. Avoid.rTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

naloxegol. Avoid.oTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

nilotinib. Avoid.rTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

olaparib. Avoid.oTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

palbociclib. Avoid.rTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

pazopanib. Avoid.rTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

phosphodiesterase type-5 inhibitors

o

. Use with caution or avoid.

Study

▶ Grapefruit juice

r

increases the exposure to pimozide. Avoid.

Theoretical

▶ Grapefruit juice is predicted to increase the exposure to

ponatinib.oTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

praziquantel.oStudy

▶ Grapefruit juice is predicted to increase the exposure to

quetiapine. Avoid.rTheoretical

▶ Grapefruit juice is predicted to increase the concentration of

ranolazine. Avoid.rTheoretical

1460 Glecaprevir — Grapefruit juice BNF 78

Interactions | Appendix 1

A1

▶ Grapefruit juice is predicted to increase the exposure to

regorafenib. Avoid.oTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

ribociclib. Avoid.oTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

ruxolitinib.rTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

saxagliptin.nTheoretical

▶ Grapefruit juice increases the concentration of sirolimus.

Avoid.oStudy

▶ Grapefruit juice moderately increases the exposure to SSRIs

(sertraline). Avoid.oStudy

▶ Grapefruit juice increases the exposure to statins (atorvastatin).

nStudy

▶ Grapefruit juice increases the exposure to statins (simvastatin).

Avoid.rStudy

▶ Grapefruit juice is predicted to increase the exposure to

sunitinib. Avoid.oTheoretical

▶ Grapefruit juice greatly increases the concentration of

tacrolimus. Avoid.rStudy

▶ Grapefruit juice is predicted to increase the concentration of

temsirolimus. Use with caution or avoid.oTheoretical

▶ Grapefruit juice is predicted to increase the exposure to

tezacaftor. Avoid.rStudy

▶ Grapefruit juice moderately increases the exposure to

ticagrelor.oStudy

▶ Grapefruit juice

o

 

Study

. Avoid or adjust enzalutamide dose, p. 947.r

▶ Fibrates are predicted to increase the risk of gallstones when

given with ezetimibe.rTheoretical

▶ Fibrates are predicted to increase the risk of hypoglycaemia

when given with insulins.oTheoretical

▶ Gemfibrozil is predicted to increase the exposure to irinotecan.

Avoid.oTheoretical

▶ Gemfibrozil is predicted to increase the concentration of

letermovir.oStudy

▶ Gemfibrozil is predicted to moderately increase the exposure

to montelukast.oStudy

▶ Fibrates are predicted to increase the anticoagulant effect of

phenindione. Monitor INR and adjust dose.rStudy

▶ Gemfibrozil increases the exposure to pioglitazone. Monitor

blood glucose and adjust dose.rStudy

▶ Gemfibrozil

r

increases the exposure to repaglinide. Avoid.

Study

▶ Gemfibrozil is predicted to increase the exposure to retinoids

(alitretinoin)

Theoretical

. Adjust alitretinoin dose, p. 1262.o ▶ Gemfibrozil increases the concentration of retinoids

(bexarotene). Avoid.rStudy

▶ Gemfibrozil

Study

increases the exposure to selexipag. Avoid.r

▶ Ciprofibrate increases the risk of rhabdomyolysis when given

with statins (atorvastatin). Avoid or adjust dose.rStudy

▶ Bezafibrate increases the risk of rhabdomyolysis when given

with statins (atorvastatin, fluvastatin).rStudy

▶ Fenofibrate increases the risk of rhabdomyolysis when given

with statins (atorvastatin, simvastatin). Adjust fenofibrate dose,

p. 199.rAnecdotal

▶ Ciprofibrate increases the risk of rhabdomyolysis when given

with statins (fluvastatin).rStudy

▶ Fenofibrate is predicted to increase the risk of rhabdomyolysis

when given with statins (fluvastatin). Adjust fenofibrate dose,

p. 199.rTheoretical

▶ Fenofibrate is predicted to increase the risk of rhabdomyolysis

when given with statins (pravastatin). Avoid.rTheoretical

▶ Fibrates (bezafibrate, ciprofibrate) increase the risk of

rhabdomyolysis when given with

r

statins (pravastatin). Avoid.

Study

▶ Fenofibrate increases the risk of rhabdomyolysis when given

with statins (rosuvastatin). Adjust fenofibrate and rosuvastatin

doses, p. 199, p. 204.rAnecdotal

▶ Fibrates (bezafibrate, ciprofibrate) increase the risk of

rhabdomyolysis when given with statins (rosuvastatin). Adjust

rosuvastatin dose, p. 204.rStudy

▶ Fibrates (bezafibrate, ciprofibrate) increase the risk of

rhabdomyolysis when given with statins (simvastatin). Adjust

simvastatin dose, p. 205.rStudy

▶ Gemfibrozil increases the risk of rhabdomyolysis when given

with statins. Avoid.rAnecdotal

▶ Fibrates are predicted to increase the risk of hypoglycaemia

when given with sulfonylureas.oTheoretical

▶ Gemfibrozil is predicted to increase the concentration of

taxanes (paclitaxel).rAnecdotal

▶ Fibrates are predicted to decrease the efficacy of

ursodeoxycholic acid. Avoid.rTheoretical

Fidaxomicin

▶ Antiarrhythmics (amiodarone, dronedarone) are predicted to

increase the exposure to fidaxomicin. Avoid.oStudy

▶ Antifungals, azoles (itraconazole, ketoconazole) are predicted to

increase the exposure to fidaxomicin. Avoid.oStudy

▶ Calcium channel blockers (verapamil) are predicted to increase

the exposure to fidaxomicin. Avoid.oStudy

▶ Ciclosporin is predicted to increase the exposure to

fidaxomicin. Avoid.oStudy

▶ HIV-protease inhibitors (lopinavir, ritonavir, saquinavir) are

predicted to increase the exposure to

o

fidaxomicin. Avoid.

Study

▶ Lapatinib is predicted to increase the exposure to fidaxomicin.

Avoid.oStudy

▶ Macrolides are predicted to increase the exposure to

fidaxomicin. Avoid.oStudy

▶ Ranolazine is predicted to increase the exposure to

fidaxomicin. Avoid.oStudy

▶ Vemurafenib is predicted to increase the exposure to

fidaxomicin. Avoid.oStudy

Fingolimod → see TABLE 6 p. 1376 (bradycardia), TABLE 9 p. 1377 (QTinterval prolongation)

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to fingolimod.oStudy

▶ Calcium channel blockers (diltiazem, verapamil) are predicted to

increase the exposure to

Theoretical → Also see TABLE 6

fingolimod

p. 1376

. Avoid.o ▶ Enzalutamide is predicted to decrease the exposure to

fingolimod.oStudy

▶ Live vaccines are predicted to increase the risk of generalised

infection (possibly life-threatening) when given with

fingolimod. Public Health England advises avoid (refer to

Green Book).rTheoretical

▶ Mitotane

o

is predicted to decrease the exposure to fingolimod.

Study

▶ Rifampicin

o

is predicted to decrease the exposure to fingolimod.

Study

▶ St John’s Wort is predicted to decrease the exposure to

fingolimod. Avoid.oTheoretical

Flavoxate → see TABLE 10 p. 1377 (antimuscarinics)

Flecainide → see antiarrhythmics

Flucloxacillin → see penicillins

Fluconazole → see antifungals, azoles

Flucytosine

▶ Amphotericin increases the risk of toxicity when given with

flucytosine.rStudy

▶ Cytarabine

r

decreases the concentration of flucytosine. Avoid.

Study

▶ Zidovudine increases the risk of haematological toxicity when

given with

Theoretical

flucytosine. Monitor and adjust dose.r

Fludarabine → see TABLE 15 p. 1378 (myelosuppression)

▶ Live vaccines are predicted to increase the risk of generalised

infection (possibly life-threatening) when given with

fludarabine. Public Health England advises avoid (refer to

Green Book).rTheoretical

▶ Fludarabine increases the risk of pulmonary toxicity when

given with pentostatin. Avoid.rStudy → Also see TABLE 15

p. 1378

Fludrocortisone → see corticosteroids

Fluocinolone

ROUTE-SPECIFIC INFORMATION With intravitreal use in adults:

caution with concurrent administration of anticoagulant or

antiplatelet drugs (higher incidence of conjunctival

haemorrhage).

Interactions do not generally apply to corticosteroids used for

topical action unless specified.

BNF 78 Fexofenadine — Fluocinolone 1457

Interactions | Appendix 1

A1

Fluorouracil → see TABLE 15 p. 1378 (myelosuppression), TABLE 5

p. 1375 (thromboembolism)

ROUTE-SPECIFIC INFORMATION Since systemic absorption can

follow topical application, the possibility of interactions

should be borne in mind.

▶ Fluorouracil increases the concentration of antiepileptics

(fosphenytoin, phenytoin). Monitor concentration and adjust

dose.rAnecdotal

▶ Fluorouracil

r

increases the anticoagulant effect of coumarins.

Anecdotal

▶ Folates (folic acid) are predicted to increase the risk of toxicity

when given with fluorouracil. Avoid.rTheoretical

▶ Folates (folinic acid) are predicted to increase the risk of

toxicity when given with fluorouracil. Monitor and adjust

dose.rTheoretical

▶ H2 receptor antagonists (cimetidine) slightly increase the

exposure to fluorouracil.rStudy

▶ Live vaccines are predicted to increase the risk of generalised

infection (possibly life-threatening) when given with

fluorouracil. Public Health England advises avoid (refer to

Green Book).rTheoretical

▶ Methotrexate potentially increases the risk of severe skin

reaction when given with topical

Anecdotal → Also see TABLE 15 p. 1378

fluorouracil

→ Also see TABLE 5

.r

p. 1375

▶ Metronidazole increases the risk of toxicity when given with

fluorouracil.rStudy

Fluoxetine → see SSRIs

Flupentixol → see TABLE 8 p. 1376 (hypotension), TABLE 11 p. 1377 (CNS

depressant effects)

▶ Flupentixol is predicted to decrease the effects of dopamine

receptor agonists. Avoid.oTheoretical → Also see TABLE 8

p. 1376

▶ Flupentixol decreases the effects of levodopa. Avoid or monitor

worsening parkinsonian symptoms.rTheoretical → Also

see TABLE 8 p. 1376

Fluphenazine → see phenothiazines

Flurazepam → see TABLE 11 p. 1377 (CNS depressant effects)

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

exposure to flurazepam. Avoid.oTheoretical

Flurbiprofen → see NSAIDs

Fluticasone → see corticosteroids

Fluvastatin → see statins

Fluvoxamine → see SSRIs

Folates

folic acid . folinic acid . levofolinic acid. ▶ Folates are predicted to decrease the concentration of

antiepileptics (fosphenytoin, phenobarbital, phenytoin,

primidone)

Study

. Monitor concentration and adjust dose.r

▶ Folates are predicted to increase the risk of toxicity when

given with capecitabine.rAnecdotal

▶ Folic acid is predicted to increase the risk of toxicity when

given with fluorouracil. Avoid.rTheoretical

▶ Folinic acid is predicted to increase the risk of toxicity when

given with

Theoretical

fluorouracil. Monitor and adjust dose.r

▶ Folates

o

are predicted to alter the effects of raltitrexed. Avoid.

Study

▶ Sulfasalazine

o

is predicted to decrease the absorption of folates.

Study

▶ Folates are predicted to increase the risk of toxicity when

given with tegafur.rTheoretical

Folic acid → see folates

Folinic acid → see folates

Fondaparinux → see TABLE 3 p. 1375 (anticoagulant effects)

Formoterol → see beta2 agonists

Fosamprenavir → see HIV-protease inhibitors

Fosaprepitant

▶ Fosaprepitant is predicted to increase the exposure to

alkylating agents (ifosfamide).rTheoretical

▶ Fosaprepitant is predicted to increase the exposure to

alprazolam.oStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to fosaprepitant. Avoid.oTheoretical

▶ Antifungals, azoles (itraconazole, ketoconazole, voriconazole) are

predicted to increase the exposure to

Theoretical

fosaprepitant.o ▶ Antifungals, azoles (posaconazole) are predicted to increase the

exposure to fosaprepitant.oStudy

▶ Bosentan is predicted to decrease the exposure to

fosaprepitant.oTheoretical

▶ Fosaprepitant is predicted to increase the exposure to

bosutinib.rTheoretical

▶ Cobicistat is predicted to increase the exposure to

fosaprepitant.oTheoretical

▶ Fosaprepitant is predicted to decrease the efficacy of combined

hormonal contraceptives. For FSRH guidance, see

Contraceptives, interactions p. 794.rStudy

▶ Fosaprepitant is predicted to decrease the anticoagulant effect

of coumarins.oTheoretical

▶ Fosaprepitant is predicted to decrease the efficacy of

desogestrel. For FSRH guidance, see Contraceptives,

interactions p. 794.rTheoretical

▶ Efavirenz is predicted to decrease the exposure to

fosaprepitant.oTheoretical

▶ Enzalutamide is predicted to decrease the exposure to

fosaprepitant. Avoid.oTheoretical

▶ Fosaprepitant is predicted to decrease the efficacy of

etonogestrel. For FSRH guidance, see Contraceptives,

interactions p. 794.rTheoretical

▶ Fosaprepitant is predicted to increase the concentration of

guanfacine.oTheoretical

▶ HIV-protease inhibitors are predicted to increase the exposure

to fosaprepitant.oTheoretical

▶ Fosaprepitant is predicted to decrease the effects of hormone

replacement therapy.oAnecdotal

▶ Fosaprepitant is predicted to slightly increase the exposure to

ibrutinib.oTheoretical

▶ Idelalisib is predicted to increase the exposure to

fosaprepitant.oTheoretical

▶ Fosaprepitant is predicted to increase the exposure to

intravenous irinotecan.rTheoretical

▶ Fosaprepitant is predicted to decrease the efficacy of

levonorgestrel. For FSRH guidance, see Contraceptives,

interactions p. 794.rTheoretical

▶ Fosaprepitant is predicted to increase the exposure to

lomitapide

Theoretical

. Separate administration by 12 hours.o ▶ Macrolides (clarithromycin) are predicted to increase the

exposure to fosaprepitant.oTheoretical

▶ Fosaprepitant

o

slightly increases the exposure to midazolam.

Study

▶ Mitotane is predicted to decrease the exposure to

fosaprepitant. Avoid.oTheoretical

▶ Nevirapine is predicted to decrease the exposure to

fosaprepitant.oTheoretical

▶ Fosaprepitant is predicted to decrease the efficacy of

norethisterone. For FSRH guidance, see Contraceptives,

interactions p. 794.rAnecdotal

▶ Fosaprepitant is predicted to increase the exposure to

pimozide. Avoid.rTheoretical

▶ Rifampicin is predicted to decrease the exposure to

fosaprepitant. Avoid.oTheoretical

▶ St John’s Wort is predicted to decrease the exposure to

fosaprepitant. Avoid.oTheoretical

▶ Fosaprepitant decreases the efficacy of ulipristal. For FSRH

guidance, see

Anecdotal

Contraceptives, interactions p. 794.r

▶ Fosaprepitant is predicted to increase the exposure to vinca

alkaloids.rTheoretical

Foscarnet → see TABLE 2 p. 1375 (nephrotoxicity)

▶ Foscarnet increases the risk of hypocalcaemia when given with

pentamidine.rAnecdotal → Also see TABLE 2 p. 1375

Fosinopril → see ACE inhibitors

Fosphenytoin → see antiepileptics

Frovatriptan → see TABLE 13 p. 1378 (serotonin syndrome)

1458 Fluorouracil — Frovatriptan BNF 78

Interactions | Appendix 1

A1

▶ SSRI

rs (fluvoxamine) increase the concentration of frovatriptan.

Study → Also see TABLE 13 p. 1378

Fulvestrant → see TABLE 5 p. 1375 (thromboembolism)

Furosemide → see loop diuretics

Fusidic acid

ROUTE-SPECIFIC INFORMATION Interactions do not generally

apply to topical use unless specified.

▶ Fusidic acid increases the risk of rhabdomyolysis when given

with statins. Avoid.rAnecdotal

Gabapentin → see antiepileptics

Galantamine → see anticholinesterases, centrally acting

Ganciclovir → see TABLE 15 p. 1378 (myelosuppression), TABLE 2 p. 1375

(nephrotoxicity)

ROUTE-SPECIFIC INFORMATION Since systemic absorption can

follow topical application, the possibility of interactions

should be borne in mind.

▶ Ganciclovir is predicted to increase the risk of seizures when

given with carbapenems (imipenem). Avoid.rAnecdotal

▶ Ganciclovir

o

decreases the exposure to antimalarials (artemether).

Study

▶ Etravirine is predicted to decrease the exposure to bedaquiline.

Avoid.rTheoretical

▶ Bosentan is predicted to decrease the exposure to etravirine.

Avoid.rStudy

▶ Etravirine is predicted to decrease the exposure to bosutinib.

Avoid.rTheoretical

▶ Etravirine is predicted to decrease the exposure to brigatinib.

Avoid.oTheoretical

▶ Etravirine

o

increases the anticoagulant effect of coumarins.

Theoretical

▶ Etravirine is predicted to decrease the exposure to dasabuvir.

Avoid.rTheoretical

▶ Etravirine moderately decreases the exposure to dolutegravir.

Avoid unless given with atazanavir, darunavir, or lopinavir (all

boosted with ritonavir).rStudy

▶ Efavirenz is predicted to decrease the exposure to etravirine.

Avoid.rStudy

▶ Etravirine is predicted to decrease the exposure to elbasvir.

Avoid.qTheoretical

▶ Enzalutamide is predicted to decrease the exposure to

etravirine. Avoid.rTheoretical

▶ Etravirine is predicted to decrease the exposure to grazoprevir.

Avoid.nTheoretical

▶ HIV-protease inhibitors (tipranavir) decrease the exposure to

etravirine. Avoid.rStudy

▶ Etravirine increases the exposure to HIV-protease inhibitors

(fosamprenavir boosted with ritonavir). Refer to specialist

literature.oStudy

▶ Etravirine

o

is predicted to decrease the exposure to letermovir.

Theoretical

▶ Etravirine decreases the exposure to macrolides

(clarithromycin) and macrolides (clarithromycin) slightly

increase the exposure to etravirine.rStudy

▶ Etravirine (with a boosted protease inhibitor) increases the

exposure to maraviroc. Avoid or adjust dose.oStudy

▶ Mitotane is predicted to decrease the exposure to etravirine.

Avoid.rTheoretical

▶ Nevirapine is predicted to decrease the exposure to etravirine.

Avoid.rStudy

▶ Etravirine is predicted to decrease the exposure to ombitasvir.

Avoid.rTheoretical

▶ Etravirine is predicted to decrease the exposure to

paritaprevir. Avoid.rTheoretical

▶ Etravirine moderately decreases the exposure to

phosphodiesterase type-5 inhibitors

Study

. Adjust dose.o ▶ Rifabutin decreases the exposure to etravirine.oStudy

▶ Rifampicin is predicted to decrease the exposure to etravirine.

Avoid.rTheoretical

▶ Etravirine is predicted to decrease the exposure to rilpivirine.

Avoid.rTheoretical

▶ St John’s Wort is predicted to decrease the exposure to

etravirine. Avoid.rStudy

Everolimus → see TABLE 15 p. 1378 (myelosuppression)

▶ Everolimus potentially increases the risk of angioedema when

given with ACE inhibitors.rAnecdotal

▶ Antiarrhythmics (dronedarone) are predicted to increase the

concentration of

Study

everolimus. Avoid or adjust dose.o ▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the

concentration of everolimus. Avoid or adjust dose.rStudy

▶ Antifungals, azoles (fluconazole, isavuconazole, posaconazole)

are predicted to increase the concentration of everolimus.

Avoid or adjust dose.oStudy

▶ Antifungals, azoles (itraconazole, ketoconazole, voriconazole) are

predicted to increase the concentration of

r

everolimus. Avoid.

Study

▶ Apalutamide is predicted to decrease the exposure to

everolimus. Avoid or monitor.oStudy

▶ Aprepitant is predicted to increase the concentration of

everolimus. Avoid or adjust dose.oStudy

▶ Bosentan is predicted to decrease the concentration of

everolimus. Avoid or adjust dose.rStudy

▶ Calcium channel blockers (diltiazem, verapamil) are predicted to

increase the concentration of everolimus. Avoid or adjust

dose.oStudy

▶ Ceritinib

o

is predicted to increase the exposure to everolimus.

Theoretical → Also see TABLE 15 p. 1378

▶ Ciclosporin moderately increases the exposure to everolimus.

Avoid or adjust dose.rStudy

▶ Cobicistat is predicted to increase the concentration of

everolimus. Avoid.rStudy

▶ Crizotinib is predicted to increase the concentration of

everolimus. Avoid or adjust dose.oStudy → Also see

TABLE 15 p. 1378

▶ Efavirenz is predicted to decrease the concentration of

everolimus. Avoid or adjust dose.rStudy

▶ Eliglustat is predicted to increase the exposure to everolimus.

Adjust dose.oStudy

▶ Enzalutamide is predicted to decrease the concentration of

everolimus. Avoid or adjust dose.rStudy

▶ Grapefruit juice is predicted to increase the exposure to

everolimus. Avoid.rTheoretical

▶ HIV-protease inhibitors are predicted to increase the

concentration of everolimus. Avoid.rStudy

▶ Idelalisib is predicted to increase the concentration of

everolimus. Avoid.rStudy → Also see TABLE 15 p. 1378

▶ Imatinib is predicted to increase the concentration of

everolimus. Avoid or adjust dose.oStudy → Also see

TABLE 15 p. 1378

▶ Lapatinib

o

is predicted to increase the exposure to everolimus.

Theoretical

▶ Letermovir is predicted to increase the concentration of

everolimus. Monitor and adjust dose.rStudy

▶ Live vaccines are predicted to increase the risk of generalised

infection (possibly life-threatening) when given with

BNF 78 Etonogestrel — Everolimus 1455

Interactions | Appendix 1

A1

Everolimus (continued)

everolimus. Public Health England advises avoid (refer to

Green Book).rTheoretical

▶ Everolimus is predicted to increase the exposure to lomitapide.

Separate administration by 12 hours.oTheoretical

▶ Lumacaftor is predicted to decrease the exposure to

everolimus. Avoid.rTheoretical

▶ Macrolides (clarithromycin) are predicted to increase the

concentration of everolimus. Avoid.rStudy

▶ Macrolides (erythromycin) are predicted to increase the

Study

concentration of everolimus. Avoid or adjust dose.o ▶ Mirabegron is predicted to increase the exposure to

everolimus.nTheoretical

▶ Mitotane is predicted to decrease the concentration of

everolimus. Avoid or adjust dose.rStudy → Also see

TABLE 15 p. 1378

▶ Netupitant is predicted to increase the concentration of

everolimus. Avoid or adjust dose.oStudy

▶ Nevirapine is predicted to decrease the concentration of

everolimus. Avoid or adjust dose.rStudy

▶ Nilotinib is predicted to increase the concentration of

everolimus. Avoid or adjust dose.oStudy → Also see

TABLE 15 p. 1378

▶ Palbociclib is predicted to increase the exposure to everolimus.

Adjust dose.oTheoretical

▶ Pibrentasvir (with glecaprevir) is predicted to increase the

exposure to everolimus.oStudy

▶ Pitolisant is predicted to decrease the exposure to everolimus.

Avoid.rTheoretical

▶ Ribociclib is predicted to increase the exposure to everolimus.

Use with caution and adjust dose.oTheoretical

▶ Rifampicin is predicted to decrease the concentration of

everolimus. Avoid or adjust dose.rStudy

▶ St John’s Wort is predicted to decrease the concentration of

everolimus. Avoid or adjust dose.rStudy

▶ Velpatasvir is predicted to increase the exposure to

everolimus.rTheoretical

▶ Venetoclax is predicted to increase the exposure to everolimus.

Avoid or adjust dose.rStudy

Exemestane

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) moderately decrease the exposure to

exemestane.oStudy

▶ Enzalutamide moderately decreases the exposure to

exemestane.oStudy

▶ Mitotane

o

moderately decreases the exposure to exemestane.

Study

▶ Rifampicin

o

moderately decreases the exposure to exemestane.

Study

▶ St John’s Wort is predicted to decrease the exposure to

exemestane.oTheoretical

Exenatide → see TABLE 14 p. 1378 (antidiabetic drugs)

SEPARATION OF ADMINISTRATION With standard-release

exenatide: some orally administered drugs should be taken at

least 1 hour before, or 4 hours after, exenatide injection.

Ezetimibe

▶ Ciclosporin moderately increases the exposure to ezetimibe

and

o

ezetimibe slightly increases the exposure to ciclosporin.

Study

▶ Fibrates are predicted to increase the risk of gallstones when

given with ezetimibe.rTheoretical

▶ Ezetimibe potentially increases the risk of rhabdomyolysis

when given with statins.rAnecdotal

Famotidine → see H2 receptor antagonists

Fampridine

▶ H2 receptor antagonists (cimetidine) increase the concentration

of fampridine. Avoid.rTheoretical

Febuxostat

▶ Febuxostat is predicted to increase the exposure to

azathioprine. Avoid.rTheoretical

▶ Febuxostat

r

is predicted to increase the exposure to didanosine.

Theoretical

▶ Febuxostat is predicted to increase the exposure to

mercaptopurine. Avoid.rTheoretical

Felbinac → see NSAIDs

Felodipine → see calcium channel blockers

Fenofibrate → see fibrates

Fentanyl → see opioids

Ferric carboxymaltose → see iron (injectable)

Ferric maltol → see iron (oral)

Ferrous fumarate → see iron (oral)

Ferrous gluconate → see iron (oral)

Ferrous sulfate → see iron (oral)

Fesoterodine → see TABLE 10 p. 1377 (antimuscarinics)

▶ Antiarrhythmics (dronedarone) are predicted to increase the

exposure to fesoterodine. Adjust fesoterodine dose with

moderate inhibitors of CYP3A4 in hepatic and renal

impairment, p. 777.nStudy

▶ Antiepileptics (carbamazepine, fosphenytoin, phenobarbital,

phenytoin, primidone) are predicted to decrease the exposure

to fesoterodine. Avoid.oStudy

▶ Antifungals, azoles (fluconazole, isavuconazole, posaconazole)

are predicted to increase the exposure to fesoterodine. Adjust

fesoterodine dose with moderate inhibitors of CYP3A4 in

hepatic and renal impairment, p. 777.nStudy

▶ Antifungals, azoles (itraconazole, ketoconazole, voriconazole) are

predicted to moderately increase the exposure to fesoterodine.

Adjust fesoterodine dose with potent inhibitors of CYP3A4;

avoid in hepatic and renal impairment, p. 777.rStudy

▶ Aprepitant is predicted to increase the exposure to

fesoterodine. Adjust fesoterodine dose with moderate

inhibitors of CYP3A4 in hepatic and renal impairment, p. 777.

nStudy

▶ Calcium channel blockers (diltiazem, verapamil) are predicted to

increase the exposure to fesoterodine. Adjust fesoterodine

dose with moderate inhibitors of CYP3A4 in hepatic and renal

impairment, p. 777.nStudy

▶ Cobicistat is predicted to moderately increase the exposure to

fesoterodine. Adjust fesoterodine dose with potent inhibitors

of CYP3A4; avoid in hepatic and renal impairment,

r

p. 777.

Study

▶ Crizotinib is predicted to increase the exposure to

fesoterodine. Adjust fesoterodine dose with moderate

inhibitors of CYP3A4 in hepatic and renal impairment, p. 777.

nStudy

▶ Enzalutamide is predicted to decrease the exposure to

fesoterodine. Avoid.oStudy

▶ HIV-protease inhibitors are predicted to moderately increase

the exposure to fesoterodine. Adjust fesoterodine dose with

potent inhibitors of CYP3A4; avoid in hepatic and renal

impairment, p. 777.rStudy

▶ Idelalisib is predicted to moderately increase the exposure to

fesoterodine. Adjust fesoterodine dose with potent inhibitors

of CYP3A4; avoid in hepatic and renal impairment,

r

p. 777.

Study

▶ Imatinib is predicted to increase the exposure to fesoterodine.

Adjust fesoterodine dose with moderate inhibitors of CYP3A4

in hepatic and renal impairment, p. 777.nStudy

▶ Macrolides (clarithromycin) are predicted to moderately

increase the exposure to fesoterodine. Adjust fesoterodine

dose with potent inhibitors of CYP3A4; avoid in hepatic and

renal impairment, p. 777.rStudy

▶ Macrolides (erythromycin) are predicted to increase the

exposure to fesoterodine. Adjust fesoterodine dose with

moderate inhibitors of CYP3A4 in hepatic and renal

impairment, p. 777.nStudy

▶ Mitotane is predicted to decrease the exposure to fesoterodine.

Avoid.oStudy

▶ Netupitant is predicted to increase the exposure to

fesoterodine. Adjust fesoterodine dose with moderate

inhibitors of CYP3A4 in hepatic and renal impairment, p. 777.

nStudy

▶ Nilotinib is predicted to increase the exposure to fesoterodine.

Adjust fesoterodine dose with moderate inhibitors of CYP3A4

in hepatic and renal impairment, p. 777.nStudy

▶ Rifampicin is predicted to decrease the exposure to

fesoterodine. Avoid.oStudy

▶ St John’s Wort is predicted to decrease the exposure to

fesoterodine. Avoid.rTheoretical

1456 Everolimus — Fesoterodine BNF 78

Interactions | Appendix 1

A1

Fexofenadine → see antihistamines, non-sedating

Fibrates

bezafibrate . ciprofibrate . fenofibrate . gemfibrozil. ▶ Antacids slightly to moderately decrease the exposure to

gemfibrozil.oStudy

▶ Gemfibrozil is predicted to increase the exposure to

apalutamide.nStudy

▶ Bezafibrate is predicted to increase the risk of nephrotoxicity

when given with ciclosporin.rTheoretical

▶ Fenofibrate increases the risk of nephrotoxicity when given

with ciclosporin.rStudy

▶ Colchicine increases the risk of rhabdomyolysis when given

with fibrates.rAnecdotal

▶ Fibrates are predicted to increase the anticoagulant effect of

coumarins. Monitor INR and adjust dose.rStudy

▶ Gemfibrozil is predicted to increase the exposure to

dabrafenib.oTheoretical

▶ Fibrates are predicted to increase the risk of rhabdomyolysis

when given with daptomycin.rTheoretical

▶ Gemfibrozil is predicted to very markedly increase the

exposure to dasabuvir. Avoid.rStudy

▶ Gemfibrozil moderately increases the exposure to

enzalutamide