BNF for Children 2011-2012

BNFC 2011–2012 Appendix 1: Interactions 707MAOIs. Sympathomimetics (continued)avoid methylphenidate for at least 2 weeks afterstopping MAOIs. Tetrabenazine: risk of CNS excitation and hypertensionwhen MAOIs given with .tetrabenazineVasodilator Antihypertensives: enhanced hypotensiveeffect when MAOIs given with hydralazine,minoxidil or sodium nitroprussideMAOIs, reversible see MoclobemideMaraviroc. Antibacterials: plasma concentration of maravirocpossibly increased by .clarithromycin and.telithromycin (consider reducing dose of maraviroc);plasma concentration of maraviroc reduced by.rifampicin—consider increasing dose of maraviroc. Antidepressants: plasma concentration of maravirocpossibly reduced by .St John’s wort—avoid concomitantuse. Antifungals: plasma concentration of maravirocincreased by .ketoconazole (consider reducing doseof maraviroc). Antivirals: plasma concentration of maravirocincreased by .atazanavir, .darunavir, .indinavir,.lopinavir and .saquinavir (consider reducing dose ofmaraviroc); plasma concentration of maraviroc possiblyreduced by .efavirenz—consider increasingdose of maraviroc; plasma concentration of maravirocpossibly reduced by etravirine; plasma concentrationof maraviroc possibly increased by.nelfinavir (consider reducing dose of maraviroc);plasma concentration of maraviroc increased byritonavirMebendazoleUlcer-healing Drugs: metabolism of mebendazolepossibly inhibited by cimetidine (increased plasmaconcentration)Medroxyprogesterone see ProgestogensMefenamic Acid see NSAIDsMefloquine. Anti-arrhythmics: increased risk of ventricular arrhythmiaswhen mefloquine given with .amiodarone—avoid concomitant use. Antibacterials: increased risk of ventricular arrhythmiaswhen mefloquine given with .moxifloxacin—avoid concomitant use; plasma concentration ofmefloquine reduced by .rifampicin—avoid concomitantuse. Antiepileptics: mefloquine antagonises anticonvulsanteffect of .antiepilepticsAntifungals: plasma concentration of mefloquineincreased by ketoconazole. Antimalarials: avoidance of antimalarials advised bymanufacturer of .artemether/lumefantrine;increased risk of convulsions when mefloquine givenwith .chloroquine and hydroxychloroquine;increased risk of convulsions when mefloquine givenwith .quinine (but should not prevent the use ofintravenous quinine in severe cases). Antipsychotics: possible increased risk of ventriculararrhythmias when mefloquine given with.haloperidol—avoid concomitant use; increased riskof ventricular arrhythmias when mefloquine givenwith .pimozide—avoid concomitant use. Atomoxetine: increased risk of ventricular arrhythmiaswhen mefloquine given with .atomoxetineBeta-blockers: increased risk of bradycardia whenmefloquine given with beta-blockersCalcium-channel Blockers: possible increased risk ofbradycardia when mefloquine given with calciumchannelblockersCardiac Glycosides: possible increased risk of bradycardiawhen mefloquine given with digoxinHistamine: avoidance of antimalarials advised bymanufacturer of histamine. Ivabradine: increased risk of ventricular arrhythmiaswhen mefloquine given with .ivabradineMefloquine (continued)Vaccines: antimalarials inactivate oral typhoidvaccine—see p. 620Megestrol see ProgestogensMelatonin see Anxiolytics and HypnoticsMeloxicam see NSAIDsMelphalanAntibacterials: increased risk of melphalan toxicitywhen given with nalidixic acid. Antipsychotics: avoid concomitant use of cytotoxicswith .clozapine (increased risk of agranulocytosis)Cardiac Glycosides: melphalan possibly reducesabsorption of digoxin tablets. Ciclosporin: increased risk of nephrotoxicity whenmelphalan given with .ciclosporinMemantine. Anaesthetics, General: increased risk of CNS toxicitywhen memantine given with .ketamine (manufacturerof memantine advises avoid concomitant use). Analgesics: increased risk of CNS toxicity whenmemantine given with .dextromethorphan (manufacturerof memantine advises avoid concomitantuse)Anticoagulants: memantine possibly enhances anticoagulanteffect of warfarinAntimuscarinics: memantine possibly enhances effectsof antimuscarinicsAntipsychotics: memantine possibly reduces effects ofantipsychotics. Dopaminergics: memantine possibly enhances effectsof dopaminergics and selegiline; increased risk ofCNS toxicity when memantine given with.amantadine (manufacturer of memantine advisesavoid concomitant use)Muscle Relaxants: memantine possibly modifieseffects of baclofen and dantroleneMepacrineAntimalarials: mepacrine increases plasma concentrationof primaquine (increased risk of toxicity)Meprobamate see Anxiolytics and HypnoticsMeptazinol see Opioid AnalgesicsMercaptopurine. Allopurinol: enhanced effects and increased toxicity ofmercaptopurine when given with .allopurinol(reduce dose of mercaptopurine to one quarter ofusual dose)Aminosalicylates: possible increased risk of leucopeniawhen mercaptopurine given with aminosalicylates. Antibacterials: increased risk of haematological toxicitywhen mercaptopurine given with.sulfamethoxazole (as co-trimoxazole); increased riskof haematological toxicity when mercaptopurinegiven with .trimethoprim (also with co-trimoxazole). Anticoagulants: mercaptopurine possibly reducesanticoagulant effect of .coumarins. Antipsychotics: avoid concomitant use of cytotoxicswith .clozapine (increased risk of agranulocytosis). Febuxostat: avoidance of mercaptopurine advised bymanufacturer of .febuxostatMeropenem. Antiepileptics: carbapenems reduce plasma concentrationof .valproate—avoid concomitant useProbenecid: excretion of meropenem reduced byprobenecidVaccines: antibacterials inactivate oral typhoidvaccine—see p. 620Mesalazine see AminosalicylatesMestranol see OestrogensMetaraminol see SympathomimeticsMetformin see AntidiabeticsMethadone see Opioid AnalgesicsMethenamineAntacids: avoid concomitant use of methenamine withantacids. Antibacterials: increased risk of crystalluria whenmethenamine given with .sulfonamidesAppendix 1: Interactions