▶Amfetaminesare predicted to decrease the effects of
chlorpromazine.oStudy
▶Phenothiazinesare predicted to decrease the effects of
amfetamines.oStudy
▶Antacidsdecrease the absorption ofphenothiazines.o
Anecdotal
▶Chlorpromazinedecreases the concentration ofantiepileptics
(phenobarbital, primidone)andantiepileptics(phenobarbital,
primidone)decrease the concentration ofchlorpromazine.
oStudy→Also seeTABLE 11p. 849
▶Chlorpromazineis predicted to increase the risk of
hyponatraemia when given withdesmopressin.r
Theoretical
▶Phenothiazinesare predicted to decrease the effects of
dopamine receptor agonists. Avoid.oTheoretical→Also
seeTABLE 8p. 848→Also seeTABLE 9p. 849→Also seeTABLE 10
p. 849
▶Eliglustatis predicted to increase the exposure to
perphenazine. Adjust dose.oTheoretical
▶Phenothiazinesare predicted to decrease the antihypertensive
effects ofguanethidine.oTheoretical→Also seeTABLE 8
p. 848
▶Phenothiazinesdecrease the effects oflevodopa. Avoid or
monitor worsening parkinsonian symptoms.rStudy→
Also seeTABLE 8p. 848
▶Phenothiazinespotentially increase the risk of neurotoxicity
when given withlithium.rAnecdotal→Also seeTABLE 9
p. 849
▶Chlorpromazinedecreases the effects ofmetyrapone. Avoid.
oTheoretical
▶Moclobemideincreases the risk of side-effects when given
withlevomepromazine.oStudy
▶Monoamine-oxidase A and B inhibitors, irreversibleare
predicted to increase the risk of neuroleptic malignant
syndrome when given withphenothiazines.rTheoretical→
Also seeTABLE 8p. 848
▶Panobinostatis predicted to increase the exposure to
perphenazine. Monitor and adjust dose.rTheoretical
▶SSRIs(paroxetine)markedly increase the exposure to
perphenazine.rStudy
Phenoxymethylpenicillin→see penicillins
Phenylephrine→see sympathomimetics, vasoconstrictor
Phenytoin→see antiepileptics
Pholcodine
▶Pholcodineis predicted to increase the risk of CNS excitation
or depression when given withmonoamine-oxidase A and B
inhibitors, irreversible. Avoid and for 14 days after stopping
the MAOI.rTheoretical
Phosphodiesterase type-5 inhibitors→seeTABLE 8p. 848
(hypotension),TABLE 9p. 849 (QT-interval prolongation)
avanafil.sildenafil.tadalafil.vardenafil..
▶Alpha blockerscause significant hypotensive effects when
given withphosphodiesterase type-5 inhibitors. Patient should
be stabilised onfirst drug then second drug should be added
at the lowest recommended dose.rStudy→Also see
TABLE 8p. 848
▶Antiarrhythmics(dronedarone)are predicted to increase the
exposure toavanafil. Adjustavanafildose.oTheoretical
▶Antiarrhythmics(dronedarone)are predicted to increase the
exposure tosildenafil. Monitor or adjustsildenafildose with
moderate inhibitors of CYP3A4,p. 120.oStudy→Also
seeTABLE 9p. 849
▶Antiarrhythmics(dronedarone)are predicted to increase the
exposure totadalafil.rTheoretical
▶Antiarrhythmics(dronedarone)are predicted to increase the
exposure tovardenafil. Adjust dose.rTheoretical→Also
seeTABLE 9p. 849
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the exposure
tophosphodiesterase type-5 inhibitors(avanafil, tadalafil). Avoid.
rStudy
▶Antiepileptics(carbamazepine, fosphenytoin, phenobarbital,
phenytoin, primidone)are predicted to decrease the exposure
tophosphodiesterase type-5 inhibitors(sildenafil, vardenafil).
oTheoretical
▶Antifungals, azoles(fluconazole, isavuconazole, posaconazole)
are predicted to increase the exposure toavanafil. Adjust
avanafildose.oTheoretical
▶Antifungals, azoles(fluconazole, isavuconazole, posaconazole)
are predicted to increase the exposure tosildenafil. Monitor or
adjustsildenafildose with moderate inhibitors of CYP3A4,
p. 120.oStudy→Also seeTABLE 9p. 849
▶Antifungals, azoles(fluconazole, isavuconazole, posaconazole)
are predicted to increase the exposure totadalafil.r
Theoretical
▶Antifungals, azoles(fluconazole, isavuconazole, posaconazole)
are predicted to increase the exposure tovardenafil. Adjust
dose.rTheoretical→Also seeTABLE 9p. 849
▶Antifungals, azoles(itraconazole, ketoconazole, voriconazole)are
predicted to increase the exposure tosildenafil. Avoid potent
inhibitors of CYP3A4 or adjustsildenafildose,p. 120.r
Study→Also seeTABLE 9p. 849
▶Antifungals, azoles(itraconazole, ketoconazole, voriconazole)are
predicted to increase the exposure totadalafil. Use with
caution or avoid.rStudy
▶Antifungals, azoles(miconazole)are predicted to increase the
exposure tosildenafil. Use with caution and adjust dose.
rTheoretical
▶Antifungals, azoles(itraconazole, ketoconazole, voriconazole)are
predicted to increase the exposure tophosphodiesterase type-5
inhibitors(avanafil, vardenafil). Avoid.rStudy→Also see
TABLE 9p. 849
▶Aprepitantis predicted to increase the exposure toavanafil.
Adjustavanafildose.oTheoretical
▶Aprepitantis predicted to increase the exposure tosildenafil.
Monitor or adjustsildenafildose with moderate inhibitors of
CYP3A4,p. 120.oStudy
▶Aprepitantis predicted to increase the exposure totadalafil.
rTheoretical
▶Aprepitantis predicted to increase the exposure tovardenafil.
Adjust dose.rTheoretical
▶Bosentandecreases the exposure tophosphodiesterase type-5
inhibitors.oStudy
▶Calcium channel blockers(diltiazem, verapamil)are predicted to
increase the exposure toavanafil. Adjustavanafildose.
oTheoretical→Also seeTABLE 8p. 848
▶Calcium channel blockers(diltiazem, verapamil)are predicted to
increase the exposure tosildenafil. Monitor or adjustsildenafil
dose with moderate inhibitors of CYP3A4,p. 120.o
Study→Also seeTABLE 8p. 848
▶Calcium channel blockers(diltiazem, verapamil)are predicted to
increase the exposure totadalafil.rTheoretical→Also see
TABLE 8p. 848
▶Calcium channel blockers(diltiazem, verapamil)are predicted to
increase the exposure tovardenafil. Adjust dose.r
Theoretical→Also seeTABLE 8p. 848
▶Cobicistatis predicted to increase the exposure to
phosphodiesterase type-5 inhibitors(avanafil, vardenafil). Avoid.
rStudy
▶Cobicistatis predicted to increase the exposure tosildenafil.
Avoid potent inhibitors of CYP3A4 or adjustsildenafildose,
p. 120.rStudy
▶Cobicistatis predicted to increase the exposure totadalafil.
Use with caution or avoid.rStudy
▶Crizotinibis predicted to increase the exposure toavanafil.
Adjustavanafildose.oTheoretical
▶Crizotinibis predicted to increase the exposure tosildenafil.
Monitor or adjustsildenafildose with moderate inhibitors of
CYP3A4,p. 120.oStudy→Also seeTABLE 9p. 849
▶Crizotinibis predicted to increase the exposure totadalafil.
rTheoretical
▶Crizotinibis predicted to increase the exposure tovardenafil.
Adjust dose.rTheoretical→Also seeTABLE 9p. 849
▶Efavirenzis predicted to decrease the exposure to
phosphodiesterase type-5 inhibitors.oTheoretical→Also
seeTABLE 9p. 849
▶Enzalutamideis predicted to decrease the exposure to
phosphodiesterase type-5 inhibitors(avanafil, tadalafil). Avoid.
rStudyBNFC 2018 – 2019 Phenothiazines—Phosphodiesterase type-5 inhibitors 973
Interactions|Appendix 1A1