BNF for Children 2011-2012

678 Appendix 1: Interactions BNFC 2011–2012Appendix 1: InteractionsBusulfan (continued). Antibacterials: plasma concentration of busulfanincreased by .metronidazole (increased risk oftoxicity)Antiepileptics: plasma concentration of busulfan possiblyreduced by phenytoinAntifungals: metabolism of busulfan inhibited by itraconazole(increased risk of toxicity). Antipsychotics: avoid concomitant use of cytotoxicswith .clozapine (increased risk of agranulocytosis)Cytotoxics: increased risk of hepatotoxicity whenbusulfan given with tioguanineButyrophenones see AntipsychoticsCabergolineAntibacterials: plasma concentration of cabergolineincreased by erythromycin (increased risk of toxicity);plasma concentration of cabergoline possiblyincreased by macrolides (increased risk of toxicity)Antipsychotics: hypoprolactinaemic and antiparkinsonianeffects of cabergoline antagonised byantipsychoticsDomperidone: hypoprolactinaemic effect of cabergolinepossibly antagonised by domperidoneMemantine: effects of dopaminergics possiblyenhanced by memantineMethyldopa: antiparkinsonian effect of dopaminergicsantagonised by methyldopaMetoclopramide: hypoprolactinaemic effect of cabergolineantagonised by metoclopramideCalcium SaltsNote see also AntacidsAntibacterials: calcium salts reduce absorption ofciprofloxacin and tetracyclineBisphosphonates: calcium salts reduce absorption ofbisphosphonatesCardiac Glycosides: large intravenous doses ofcalcium salts can precipitate arrhythmias when givenwith cardiac glycosidesCorticosteroids: absorption of calcium salts reduced bycorticosteroidsDiuretics: increased risk of hypercalcaemia whencalcium salts given with thiazides and related diureticsEltrombopag: calcium salts possibly reduce absorptionof eltrombopag (give at least 4 hours apart)Fluorides: calcium salts reduce absorption of fluoridesIron: calcium salts reduce absorption of oral ironThyroid Hormones: calcium salts reduce absorption oflevothyroxineZinc: calcium salts reduce absorption of zincCalcium-channel BlockersNote Dihydropyridine calcium-channel blockers includeamlodipine, felodipine, isradipine, lacidipine, lercanidipine,nicardipine, nifedipine, and nimodipineACE Inhibitors: enhanced hypotensive effect whencalcium-channel blockers given with ACE inhibitorsAdrenergic Neurone Blockers: enhanced hypotensiveeffect when calcium-channel blockers given withadrenergic neurone blockersAlcohol: enhanced hypotensive effect when calciumchannelblockers given with alcohol; verapamilpossibly increases plasma concentration of alcoholAldesleukin: enhanced hypotensive effect whencalcium-channel blockers given with aldesleukinAliskiren: avoidance of verapamil advised by manufacturerof aliskiren. Alpha-blockers: enhanced hypotensive effect whencalcium-channel blockers given with .alpha-blockers,also increased risk of first-dose hypotension withpost-synaptic alpha-blockers such as prazosin. Anaesthetics, General: enhanced hypotensive effectwhen calcium-channel blockers given with generalanaesthetics or isoflurane; hypotensive effect ofverapamil enhanced by .general anaesthetics (alsoAV delay)Analgesics: hypotensive effect of calcium-channelblockers antagonised by NSAIDs; diltiazem inhibitsmetabolism of alfentanil (risk of prolonged or delayedrespiratory depression)Calcium-channel Blockers (continued)Angiotensin-II Receptor Antagonists: enhancedhypotensive effect when calcium-channel blockersgiven with angiotensin-II receptor antagonists. Anti-arrhythmics: increased risk of bradycardia, AVblock and myocardial depression when diltiazem orverapamil given with .amiodarone; increased risk ofmyocardial depression and asystole when verapamilgiven with .disopyramide or .flecainide; increasedrisk of bradycardia and myocardial depression whendiltiazem and verapamil given with .dronedarone;nifedipine increases plasma concentration of.dronedarone. Antibacterials: metabolism of verapamil possiblyinhibited by .clarithromycin and .erythromycin(increased risk of toxicity); metabolism of felodipinepossibly inhibited by erythromycin (increased plasmaconcentration); manufacturer of lercanidipine advisesavoid concomitant use with erythromycin; metabolismof diltiazem, nifedipine, nimodipine andverapamil accelerated by .rifampicin (plasma concentrationsignificantly reduced); metabolism ofisradipine and nicardipine possibly accelerated by.rifampicin (possible significantly reduced plasmaconcentration). Anticoagulants: verapamil possibly increases plasmaconcentration of .dabigatran etexilate (reduce doseof dabigatran etexilate). Antidepressants: metabolism of nifedipine possiblyinhibited by fluoxetine (increased plasma concentration);diltiazem and verapamil increase plasmaconcentration of imipramine; enhanced hypotensiveeffect when calcium-channel blockers given withMAOIs; plasma concentration of verapamil significantlyreduced by .St John’s wort; plasma concentrationof nifedipine reduced by St John’s wort;plasma concentration of amlodipine possibly reducedby St John’s wort; diltiazem and verapamil possiblyincrease plasma concentration of tricyclicsAntidiabetics: glucose tolerance occasionally impairedwhen nifedipine given with insulin. Antiepileptics: effects of dihydropyridines,nicardipine and nifedipine probably reduced bycarbamazepine; effects of felodipine and isradipinereduced by carbamazepine; diltiazem and verapamilenhance effects of .carbamazepine; manufacturer ofnimodipine advises avoid concomitant use withcarbamazepine and phenytoin (plasma concentrationof nimodipine possibly reduced); manufacturer ofnimodipine advises avoid concomitant use with.phenobarbital (plasma concentration of nimodipinereduced); manufacturer of isradipine advises avoidconcomitant use with phenobarbital and phenytoin;effects of calcium-channel blockers probably reducedby .phenobarbital; effects of felodipine and verapamilreduced by phenytoin; diltiazem increasesplasma concentration of .phenytoin but also effect ofdiltiazem reduced. Antifungals: metabolism of dihydropyridines possiblyinhibited by itraconazole and ketoconazole(increased plasma concentration); metabolism offelodipine inhibited by .itraconazole and.ketoconazole (increased plasma concentration);manufacturer of lercanidipine advises avoid concomitantuse with itraconazole and ketoconazole;negative inotropic effect possibly increased whencalcium-channel blockers given with itraconazole;plasma concentration of nifedipine increased bymicafunginAntimalarials: possible increased risk of bradycardiawhen calcium-channel blockers given with mefloquineAntimuscarinics: avoidance of verapamil advised bymanufacturer of darifenacinAntipsychotics: enhanced hypotensive effect whencalcium-channel blockers given with antipsychotics. Antivirals: plasma concentration of verapamil possiblyincreased by atazanavir; plasma concentration ofdiltiazem increased by .atazanavir (reduce dose of