BNF for Children 2011-2012

698 Appendix 1: Interactions BNFC 2011–2012Appendix 1: InteractionsHeparins (continued). Analgesics: possible increased risk of bleeding whenheparins given with NSAIDs; increased risk ofhaemorrhage when anticoagulants given with intravenous.diclofenac (avoid concomitant use, includinglow-dose heparins); increased risk of haemorrhagewhen anticoagulants given with .ketorolac (avoidconcomitant use, including low-dose heparins); anticoagulanteffect of heparins enhanced by .aspirinAngiotensin-II Receptor Antagonists: increased risk ofhyperkalaemia when heparins given with angiotensin-IIreceptor antagonistsClopidogrel: increased risk of bleeding when heparinsgiven with clopidogrelDipyridamole: anticoagulant effect of heparinsenhanced by dipyridamole. Drotrecogin Alfa: avoidance of concomitant use of highdoses of heparins with drotrecogin alfa advised bymanufacturer of .drotrecogin alfa—consult productliteratureIloprost: anticoagulant effect of heparins possiblyenhanced by iloprost. Nitrates: anticoagulant effect of heparins reduced byinfusion of .glyceryl trinitrateHistamineAntidepressants: manufacturer of histamine advisesavoid concomitant use with MAOIs; effects of histaminetheoretically antagonised by tricyclics—manufacturerof histamine advises avoid concomitant useAntihistamines: effects of histamine theoreticallyantagonised by antihistamines—manufacturer ofhistamine advises avoid concomitant useAntimalarials: manufacturer of histamine advises avoidconcomitant use with antimalarialsAntipsychotics: effects of histamine theoreticallyantagonised by antipsychotics—manufacturer ofhistamine advises avoid concomitant useAtovaquone: manufacturer of histamine advises avoidconcomitant use with atovaquoneClonidine: manufacturer of histamine advises avoidconcomitant use with clonidineCorticosteroids: manufacturer of histamine advisesavoid concomitant use with corticosteroidsUlcer-healing Drugs: effects of histamine theoreticallyantagonised by histamine H 2 -antagonists—manufacturerof histamine advises avoid concomitant useHistamine H 2 -antagonists. Alpha-blockers: cimetidine and ranitidine antagoniseeffects of .tolazolineAnalgesics: cimetidine inhibits metabolism of opioidanalgesics (increased plasma concentration). Anti-arrhythmics: cimetidine increases plasma concentrationof amiodarone and .propafenone; cimetidineinhibits metabolism of flecainide (increasedplasma concentration); cimetidine increases plasmaconcentration of .lidocaine (increased risk of toxicity)Antibacterials: histamine H 2 -antagonists reduceabsorption of cefpodoxime; cimetidine increasesplasma concentration of erythromycin (increased riskof toxicity, including deafness); cimetidine inhibitsmetabolism of metronidazole (increased plasmaconcentration); metabolism of cimetidine acceleratedby rifampicin (reduced plasma concentration). Anticoagulants: cimetidine inhibits metabolism of.coumarins (enhanced anticoagulant effect)Antidepressants: cimetidine increases plasma concentrationof citalopram, escitalopram,mirtazapine and sertraline; cimetidine inhibitsmetabolism of amitriptyline, doxepin,imipramine and nortriptyline (increased plasmaconcentration); cimetidine increases plasma concentrationof moclobemide (halve dose of moclobemide);cimetidine possibly increases plasma concentrationof tricyclicsAntidiabetics: cimetidine reduces excretion of metformin(increased plasma concentration); cimetidineenhances hypoglycaemic effect of sulfonylureasHistamine H 2 -antagonists (continued). Antiepileptics: cimetidine inhibits metabolism of.carbamazepine, .phenytoin and .valproate(increased plasma concentration). Antifungals: histamine H 2 -antagonists reduce absorptionof itraconazole and ketoconazole; avoidance ofhistamine H 2 -antagonists advised by manufacturer ofposaconazole (plasma concentration of posaconazolepossibly reduced); cimetidine reduces plasma concentrationof .posaconazole; cimetidine increasesplasma concentration of terbinafineAntihistamines: manufacturer of loratadine advisescimetidine possibly increases plasma concentrationof loratadine. Antimalarials: avoidance of cimetidine advised bymanufacturer of .artemether/lumefantrine; cimetidineinhibits metabolism of chloroquine andhydroxychloroquine and quinine (increased plasmaconcentration)Antipsychotics: cimetidine possibly enhances effects ofantipsychotics, chlorpromazine and clozapine. Antivirals: histamine H 2 -antagonists reduce plasmaconcentration of .atazanavir; histamine H 2 -antagonistspossibly increase plasma concentration ofraltegravir—manufacturer of raltegravir advises avoidconcomitant use; cimetidine possibly increasesplasma concentration of saquinavirAnxiolytics and Hypnotics: cimetidine inhibits metabolismof benzodiazepines, clomethiazole and zaleplon(increased plasma concentration); cimetidineincreases plasma concentration of melatoninBeta-blockers: cimetidine increases plasma concentrationof labetalol, metoprolol and propranololCalcium-channel Blockers: cimetidine possibly inhibitsmetabolism of calcium-channel blockers (increasedplasma concentration); cimetidine increases plasmaconcentration of isradipine (halve dose of isradipine). Ciclosporin: cimetidine possibly increases plasmaconcentration of .ciclosporin. Clopidogrel: cimetidine possibly reduces antiplateleteffect of .clopidogrel. Cytotoxics: cimetidine possibly enhances myelosuppressiveeffects of carmustine and lomustine; cimetidineincreases plasma concentration of .epirubicin;cimetidine inhibits metabolism of fluorouracil(increased plasma concentration); famotidine possiblyreduces plasma concentration of dasatinib;avoidance of cimetidine, famotidine and nizatidineadvised by manufacturer of .erlotinib; ranitidinereduces plasma concentration of .erlotinib—manufacturerof erlotinib advises give at least 2 hoursbefore or 10 hours after ranitidine; ranitidine reducesplasma concentration of .gefitinib; histamine H 2 -antagonists possibly reduce absorption of lapatinibDopaminergics: cimetidine reduces excretion of pramipexole(increased plasma concentration). Ergot Alkaloids: increased risk of ergotism whencimetidine given with .ergotamine and methysergide—avoidconcomitant useHistamine: histamine H 2 -antagonists theoreticallyantagonise effects of histamine—manufacturer ofhistamine advises avoid concomitant useHormone Antagonists: absorption of cimetidine possiblydelayed by octreotide5HT 1 Agonists: cimetidine inhibits metabolism ofzolmitriptan (reduce dose of zolmitriptan)Mebendazole: cimetidine possibly inhibits metabolismof mebendazole (increased plasma concentration)Roflumilast: cimetidine inhibits the metabolism ofroflumilastSildenafil: cimetidine increases plasma concentrationof sildenafil (consider reducing dose of sildenafil). Theophylline: cimetidine inhibits metabolism of.theophylline (increased plasma concentration)Thyroid Hormones: cimetidine reduces absorption oflevothyroxine. Ulipristal: avoidance of histamine H 2 -antagonistsadvised by manufacturer of .ulipristal (plasmaconcentration of ulipristal possibly reduced)