BNF for Children 2011-2012

686 Appendix 1: Interactions BNFC 2011–2012Appendix 1: InteractionsCorticosteroids (continued)Aprepitant: metabolism of dexamethasone andmethylprednisolone inhibited by aprepitant (reducedose of dexamethasone and methylprednisolone)Beta-blockers: corticosteroids antagonise hypotensiveeffect of beta-blockersCalcium Salts: corticosteroids reduce absorption ofcalcium saltsCalcium-channel Blockers: corticosteroids antagonisehypotensive effect of calcium-channel blockers;plasma concentration of methylprednisoloneincreased by diltiazemCardiac Glycosides: increased risk of hypokalaemiawhen corticosteroids given with cardiac glycosides. Ciclosporin: high-dose methylprednisolone increasesplasma concentration of .ciclosporin (risk of convulsions);plasma concentration of prednisoloneincreased by ciclosporinClonidine: corticosteroids antagonise hypotensiveeffect of clonidineDiazoxide: corticosteroids antagonise hypotensiveeffect of diazoxideDiuretics: corticosteroids antagonise diuretic effect ofdiuretics; increased risk of hypokalaemia whencorticosteroids given with acetazolamide, loopdiuretics or thiazides and related diureticsHistamine: avoidance of corticosteroids advised bymanufacturer of histamineMethyldopa: corticosteroids antagonise hypotensiveeffect of methyldopaMifamurtide: avoidance of corticosteroids advised bymanufacturer of mifamurtideMifepristone: effect of corticosteroids (includinginhaled corticosteroids) may be reduced for 3–4 daysafter mifepristoneMoxonidine: corticosteroids antagonise hypotensiveeffect of moxonidineMuscle Relaxants: corticosteroids possibly antagoniseeffects of pancuronium and vecuroniumNitrates: corticosteroids antagonise hypotensive effectof nitratesOestrogens: plasma concentration of corticosteroidsincreased by oral contraceptives containing oestrogensSodium Benzoate: corticosteroids possibly reduceeffects of sodium benzoateSodium Phenylbutyrate: corticosteroids possiblyreduce effects of sodium phenylbutyrateSomatropin: corticosteroids may inhibit growth-promotingeffect of somatropinSympathomimetics: metabolism of dexamethasoneaccelerated by ephedrineSympathomimetics, Beta 2 : increased risk of hypokalaemiawhen corticosteroids given with high doses ofbeta 2 sympathomimetics—see Hypokalaemia, p. 138Theophylline: increased risk of hypokalaemia whencorticosteroids given with theophylline. Vaccines: high doses of corticosteroids impair immuneresponse to .vaccines, avoid concomitant use withlive vaccines (see p. 599)Vasodilator Antihypertensives: corticosteroids antagonisehypotensive effect of hydralazine, minoxidil andsodium nitroprussideCortisone see CorticosteroidsCo-trimoxazole see Trimethoprim and SulfamethoxazoleCoumarinsNote Change in patient’s clinical condition, particularlyassociated with liver disease, intercurrent illness, or drugadministration, necessitates more frequent testing. Majorchanges in diet (especially involving salads and vegetables)and in alcohol consumption may also affect anticoagulantcontrol. Alcohol: anticoagulant control with coumarins may beaffected by major changes in consumption of.alcoholAllopurinol: anticoagulant effect of coumarins possiblyenhanced by allopurinolCoumarins (continued). Anabolic Steroids: anticoagulant effect of coumarinsenhanced by .anabolic steroids. Analgesics: anticoagulant effect of coumarins possiblyenhanced by .NSAIDs; increased risk of haemorrhagewhen anticoagulants given with intravenous.diclofenac (avoid concomitant use, including lowdoseheparins); increased risk of haemorrhage whenanticoagulants given with .ketorolac (avoid concomitantuse, including low-dose heparins); anticoagulanteffect of coumarins enhanced by.tramadol; increased risk of bleeding when coumarinsgiven with .aspirin (due to antiplatelet effect);anticoagulant effect of coumarins possibly enhancedby prolonged regular use of paracetamol. Anti-arrhythmics: metabolism of coumarins inhibitedby .amiodarone (enhanced anticoagulant effect);anticoagulant effect of coumarins enhanced by.propafenone. Antibacterials: experience in anticoagulant clinicssuggests that INR possibly altered when coumarinsare given with .neomycin (given for local action ongut); anticoagulant effect of coumarins possiblyenhanced by .azithromycin, .aztreonam,.cephalosporins, levofloxacin, .tetracyclines,tigecycline and trimethoprim; anticoagulant effect ofcoumarins enhanced by .chloramphenicol,.ciprofloxacin, .clarithromycin, .erythromycin,.metronidazole, .nalidixic acid, .norfloxacin,.ofloxacin and .sulfonamides; studies have failed todemonstrate an interaction with coumarins, butcommon experience in anticoagulant clinics is thatINR can be altered by a course of broad-spectrumpenicillins such as ampicillin; metabolism of coumarinsaccelerated by .rifamycins (reduced anticoagulanteffect). Antidepressants: anticoagulant effect of warfarinpossibly enhanced by .venlafaxine; anticoagulanteffect of warfarin may be enhanced or reduced bytrazodone; anticoagulant effect of coumarins possiblyenhanced by .SSRIs; anticoagulant effect of coumarinsreduced by .St John’s wort (avoid concomitantuse); anticoagulant effect of warfarin enhanced bymirtazapine; anticoagulant effect of coumarins maybe enhanced or reduced by .tricyclics. Antidiabetics: anticoagulant effect of warfarin possiblyenhanced by exenatide; coumarins possibly enhancehypoglycaemic effect of .sulfonylureas, also possiblechanges to anticoagulant effect. Antiepileptics: metabolism of coumarins acceleratedby .carbamazepine and .phenobarbital (reducedanticoagulant effect); plasma concentration of warfarinreduced by eslicarbazepine; metabolism ofcoumarins accelerated by .phenytoin (possibility ofreduced anticoagulant effect, but enhancement alsoreported); anticoagulant effect of coumarins possiblyenhanced by valproate. Antifungals: anticoagulant effect of coumarinsenhanced by .fluconazole, .itraconazole,.ketoconazole and .voriconazole; anticoagulanteffect of coumarins enhanced by .miconazole(miconazole oral gel and possibly vaginal formulationsabsorbed); anticoagulant effect of coumarinsreduced by .griseofulvinAntimalarials: isolated reports that anticoagulant effectof warfarin may be enhanced by proguanil; plasmaconcentration of both drugs increased when warfaringiven with quinine. Antivirals: anticoagulant effect of warfarin may beenhanced or reduced by atazanavir, .nevirapine and.ritonavir; plasma concentration of warfarin possiblyaffected by .efavirenz; anticoagulant effect ofcoumarins may be enhanced or reduced by fosamprenavir;anticoagulant effect of coumarins possiblyenhanced by .ritonavir; anticoagulant effect of warfarinpossibly enhanced by saquinavirAnxiolytics and Hypnotics: anticoagulant effect ofcoumarins may transiently be enhanced by chloral