Mesalazine
ROUTE-SPECIFIC INFORMATIONThe manufacturers of some
mesalazine gastro-resistant and modified-release medicines
(Asacol MR tablets, Ipocol, Salofalk granules) suggest that
preparations that lower stool pH (e.g. lactulose) might
prevent the release of mesalazine.Metaraminol→see sympathomimetics, vasoconstrictor
Metformin→seeTABLE 14p. 850 (antidiabetic drugs)
▶Alcohol (beverage)(excessive consumption) potentially
increases the risk of lactic acidosis when given with
metformin. Avoid excessive alcohol consumption.o
Theoretical
▶Dolutegravirslightly to moderately increases the exposure to
metformin. Use with caution and adjust dose.rStudy
▶H 2 receptor antagonists(cimetidine)slightly increase the
exposure tometformin. Monitor and adjust dose.o
Study
▶Pitolisantis predicted to increase the exposure tometformin.
qTheoretical
▶Vandetanibslightly increases the exposure tometformin.
Monitor and adjust dose.oStudy
Methadone→see opioids
Methenamine
▶Acetazolamideis predicted to decrease the efficacy of
methenamine. Avoid.oTheoretical
▶Potassium citrateis predicted to decrease the efficacy of
methenamine. Avoid.oTheoretical
▶Sodium bicarbonateis predicted to decrease the efficacy of
methenamine. Avoid.oTheoretical
▶Sodium citrateis predicted to decrease the efficacy of
methenamine. Avoid.oTheoretical
Methocarbamol→seeTABLE 11p. 849 (CNS depressant effects)
Methotrexate→seeTABLE 1p. 847 (hepatotoxicity),TABLE 15p. 850
(myelosuppression),TABLE 2p. 847 (nephrotoxicity),TABLE 5p. 847
(thromboembolism)
▶Acetazolamideincreases the urinary excretion of
methotrexate.oStudy
▶Methotrexateis predicted to decrease the clearance of
aminophylline.oTheoretical
▶Antiepileptics(levetiracetam)decrease the clearance of
methotrexate.rAnecdotal
▶Antimalarials(pyrimethamine)are predicted to increase the risk
of side-effects when given withmethotrexate.r
Theoretical→Also seeTABLE 15p. 850
▶Asparaginaseaffects the efficacy ofmethotrexate.r
Anecdotal→Also seeTABLE 1p. 847→Also seeTABLE 15p. 850
▶Aspirin(high-dose) is predicted to increase the risk of toxicity
when given withmethotrexate.rTheoretical
▶Crisantaspaseaffects the efficacy ofmethotrexate.r
Anecdotal→Also seeTABLE 1p. 847→Also seeTABLE 15p. 850
▶Live vaccinesare predicted to increase the risk of generalised
infection (possibly life-threatening) when given with
methotrexate(high-dose). Public Health England advises
avoid (refer to Green Book).rTheoretical
▶NSAIDsare predicted to increase the risk of toxicity when
given withmethotrexate. Monitor and adjust dose.r
Study→Also seeTABLE 2p. 847
▶Pegaspargaseaffects the efficacy ofmethotrexate.r
Anecdotal→Also seeTABLE 1p. 847→Also seeTABLE 15p. 850
▶Penicillinsare predicted to increase the risk of toxicity when
given withmethotrexate.rTheoretical→Also seeTABLE 1
p. 847
▶Proton pump inhibitorsdecrease the clearance ofmethotrexate
(high-dose). Use with caution or avoid.rStudy
▶Quinolones(ciprofloxacin)potentially increase the risk of
toxicity when given withmethotrexate. Avoid.rAnecdotal
▶Regorafenibis predicted to increase the exposure to
methotrexate.rTheoretical→Also seeTABLE 15p. 850
▶Retinoids(acitretin)are predicted to increase the
concentration ofmethotrexate. Avoid.oAnecdotal
▶Rolapitantis predicted to increase the exposure to
methotrexate. Avoid or monitor.oStudy
▶Methotrexateis predicted to decrease the efficacy of
sapropterin.oTheoretical▶Sulfonamidesare predicted to increase the exposure to
methotrexate. Use with caution or avoid.rTheoretical→
Also seeTABLE 15p. 850
▶Tedizolidis predicted to increase the exposure to
methotrexate. Avoid.oTheoretical
▶Methotrexateis predicted to increase the risk of toxicity when
given withtegafur.rTheoretical
▶Methotrexatedecreases the clearance oftheophylline.
oStudy
▶Trimethoprimis predicted to increase the risk of side-effects
when given withmethotrexate. Avoid.rTheoretical→Also
seeTABLE 2p. 847
Methoxyflurane→see volatile halogenated anaesthetics
Methyldopa→seeTABLE 8p. 848 (hypotension)
▶Entacaponeis predicted to increase the exposure to
methyldopa.oTheoretical
▶Iron (oral)decreases the effects ofmethyldopa.oStudy
▶Methyldopaincreases the risk of neurotoxicity when given
withlithium.rAnecdotal
▶Monoamine-oxidase A and B inhibitors, irreversibleare
predicted to alter the antihypertensive effects ofmethyldopa.
Avoid.rTheoretical→Also seeTABLE 8p. 848
Methylphenidate
▶Methylphenidateis predicted to decrease the effects of
apraclonidine. Avoid.rTheoretical
▶Methylphenidateis predicted to increase the risk of elevated
blood pressure when given withlinezolid. Avoid.r
Theoretical
▶Methylphenidateis predicted to increase the risk of a
hypertensive crisis when given withmoclobemide.r
Theoretical
▶Methylphenidateis predicted to increase the risk of a
hypertensive crisis when given withmonoamine-oxidase A and
B inhibitors, irreversible. Avoid and for 14 days after stopping
the MAOI.rTheoretical
▶Monoamine-oxidase B inhibitors(rasagiline, selegiline)are
predicted to increase the risk of a hypertensive crisis when
given withmethylphenidate. Avoid.rTheoretical
▶Risperidoneincreases the risk of dyskinesias when given with
methylphenidate.rAnecdotal
Methylprednisolone→see corticosteroids
Methylthioninium chloride→seeTABLE 13p. 850 (serotonin
syndrome)
▶Methylthioninium chlorideis predicted to increase the risk of
severe hypertension when given withbupropion. Avoid.
rTheoretical→Also seeTABLE 13p. 850
Metoclopramide
▶Metoclopramideis predicted to increase the risk of
methaemoglobinaemia when given with topicalanaesthetics,
local(prilocaine). Avoid.rTheoretical
▶Metoclopramidepotentially decreases the absorption of
antifungals, azoles(posaconazole)(oral suspension).o
Study
▶Metoclopramidedecreases the concentration ofantimalarials
(atovaquone). Avoid.oStudy
▶Metoclopramideis predicted to decrease the effects of
dopamine receptor agonists(apomorphine, bromocriptine,
cabergoline, pergolide, pramipexole, quinagolide, ropinirole,
rotigotine). Avoid.oStudy
▶Metoclopramidedecreases the effects oflevodopa. Avoid.
oStudy
▶Metoclopramideis predicted to increase the effects of
neuromuscular blocking drugs, non-depolarising.o
Theoretical
▶Metoclopramideincreases the effects ofsuxamethonium.
oStudy
Metolazone→see thiazide diuretics
Metoprolol→see beta blockers, selective
Metronidazole→seeTABLE 12p. 850 (peripheral neuropathy)
ROUTE-SPECIFIC INFORMATIONSince systemic absorption can
follow topical application, the possibility of interactions
should be borne in mind.
▶Alcohol (beverage)potentially causes a disulfiram-like
reaction when given withmetronidazole. Avoid for at least
48 hours stopping treatment.oStudy952 Mesalazine—Metronidazole BNFC 2018 – 2019
Interactions|Appendix 1A1