BNF for Children 2011-2012

BNFC 2011–2012 Appendix 1: Interactions 733Sulfinpyrazone (continued). Ciclosporin: sulfinpyrazone reduces plasma concentrationof .ciclosporinTheophylline: sulfinpyrazone reduces plasma concentrationof theophyllineSulfonamidesAnaesthetics, General: sulfonamides enhance effectsof thiopentalAnaesthetics, Local: increased risk of methaemoglobinaemiawhen sulfonamides given with prilocaineAnti-arrhythmics: possible increased risk of ventriculararrhythmias when sulfamethoxazole (as co-trimoxazole)given with amiodarone—manufacturer ofamiodarone advises avoid concomitant use of cotrimoxazole. Antibacterials: increased risk of crystalluria whensulfonamides given with .methenamine. Anticoagulants: sulfonamides enhance anticoagulanteffect of .coumarins; sulfonamides possibly inhibitmetabolism of phenindioneAntidiabetics: sulfonamides rarely enhance the effectsof sulfonylureasAntiepileptics: sulfonamides possibly increase plasmaconcentration of phenytoin. Antimalarials: increased antifolate effect when sulfonamidesgiven with .pyrimethamine. Antipsychotics: avoid concomitant use of sulfonamideswith .clozapine (increased risk of agranulocytosis). Azathioprine: increased risk of haematological toxicitywhen sulfamethoxazole (as co-trimoxazole) givenwith .azathioprine. Ciclosporin: increased risk of nephrotoxicity whensulfonamides given with .ciclosporin; sulfadiazinepossibly reduces plasma concentration of.ciclosporin. Cytotoxics: increased risk of haematological toxicitywhen sulfamethoxazole (as co-trimoxazole) givenwith .mercaptopurine or .methotrexate; sulfonamidesincrease risk of methotrexate toxicityPotassium Aminobenzoate: effects of sulfonamidesinhibited by potassium aminobenzoateVaccines: antibacterials inactivate oral typhoidvaccine—see p. 620Sulfonylureas see AntidiabeticsSulindac see NSAIDsSulpiride see AntipsychoticsSumatriptan see 5HT 1 AgonistsSunitinibAntibacterials: metabolism of sunitinib accelerated byrifampicin (reduced plasma concentration)Antifungals: metabolism of sunitinib inhibited byketoconazole (increased plasma concentration). Antipsychotics: avoid concomitant use of cytotoxicswith .clozapine (increased risk of agranulocytosis)Suxamethonium see Muscle RelaxantsSympathomimetics. Adrenergic Neurone Blockers: ephedrine, isometheptene,metaraminol, methylphenidate, noradrenaline(norepinephrine), oxymetazoline,phenylephrine, pseudoephedrine and xylometazolineantagonise hypotensive effect of .adrenergic neuroneblockers; dexamfetamine antagonises hypotensiveeffect of .guanethidineAlcohol: effects of methylphenidate possibly enhancedby alcohol. Alpha-blockers: avoid concomitant use of adrenaline(epinephrine) or dopamine with .tolazoline. Anaesthetics, General: increased risk of arrhythmiaswhen adrenaline (epinephrine) given with .volatileliquid general anaesthetics; increased risk of hypertensionwhen methylphenidate given with .volatileliquid general anaesthetics. Anticoagulants: methylphenidate possibly enhancesanticoagulant effect of .coumarins. Antidepressants: risk of hypertensive crisis whenmethylphenidate given with .MAOIs, some manufacturersadvise avoid methylphenidate for at least 2weeks after stopping MAOIs; risk of hypertensiveSympathomimetics. Antidepressants (continued)crisis when sympathomimetics given with.MAOIs or .moclobemide; methylphenidatepossibly inhibits metabolism of SSRIs and tricyclics;increased risk of hypertension andarrhythmias when adrenaline (epinephrine) givenwith .tricyclics (but local anaesthetics with adrenalineappear to be safe); increased risk ofhypertension and arrhythmias when noradrenaline(norepinephrine) given with .tricyclicsAntiepileptics: methylphenidate possibly increasesplasma concentration of phenobarbital; methylphenidateincreases plasma concentration of phenytoinAntipsychotics: hypertensive effect of sympathomimeticsantagonised by antipsychotics; dexamfetaminepossibly antagonises antipsychotic effects ofchlorpromazine; methylphenidate possibly increasesside-effects of risperidoneAntivirals: plasma concentration of dexamfetaminepossibly increased by ritonavir. Beta-blockers: increased risk of severe hypertensionand bradycardia when adrenaline (epinephrine) givenwith non-cardioselective .beta-blockers, alsoresponse to adrenaline (epinephrine) may bereduced; increased risk of severe hypertension andbradycardia when dobutamine given with noncardioselective.beta-blockers; possible increasedrisk of severe hypertension and bradycardia whennoradrenaline (norepinephrine) given with non-cardioselective.beta-blockers. Clonidine: possible risk of hypertension when adrenaline(epinephrine) or noradrenaline (norepinephrine)given with clonidine; serious adverse events reportedwith concomitant use of methylphenidate and.clonidine (causality not established)Corticosteroids: ephedrine accelerates metabolism ofdexamethasone. Dopaminergics: risk of toxicity when isometheptenegiven with .bromocriptine; effects of adrenaline(epinephrine), dobutamine, dopamine and noradrenaline(norepinephrine) possibly enhanced by entacapone;avoid concomitant use of sympathomimeticswith .rasagiline; risk of hypertensive crisis whendopamine given with .selegilineDoxapram: increased risk of hypertension whensympathomimetics given with doxapramErgot Alkaloids: increased risk of ergotism whensympathomimetics given with ergotamine andmethysergideOxytocin: risk of hypertension when vasoconstrictorsympathomimetics given with oxytocin (due toenhanced vasopressor effect). Sympathomimetics: effects of adrenaline (epinephrine)possibly enhanced by .dopexamine; dopexaminepossibly enhances effects of .noradrenaline (norepinephrine)Theophylline: avoidance of ephedrine in childrenadvised by manufacturer of theophyllineSympathomimetics, Beta 2Antifungals: metabolism of salmeterol inhibited byketoconazole (increased plasma concentration)Atomoxetine: Increased risk of cardiovascular sideeffectswhen parenteral salbutamol given withatomoxetineCardiac Glycosides: salbutamol possibly reducesplasma concentration of digoxinCorticosteroids: increased risk of hypokalaemia whenhigh doses of beta 2 sympathomimetics given withcorticosteroids—see Hypokalaemia, p. 138Diuretics: increased risk of hypokalaemia when highdoses of beta 2 sympathomimetics given with acetazolamide,loop diuretics or thiazides and relateddiuretics—see Hypokalaemia, p. 138. Methyldopa: acute hypotension reported when infusionof salbutamol given with .methyldopaMuscle Relaxants: bambuterol enhances effects ofsuxamethoniumAppendix 1: Interactions