BNF for Children 2011-2012

696 Appendix 1: Interactions BNFC 2011–2012Appendix 1: InteractionsFluoridesCalcium Salts: absorption of fluorides reduced bycalcium saltsFluorouracilNote Capecitabine is a prodrug of fluorouracilNote Tegafur is a prodrug of fluorouracil. Allopurinol: manufacturer of capecitabine advisesavoid concomitant use with .allopurinolAntibacterials: metabolism of fluorouracil inhibited bymetronidazole (increased toxicity). Anticoagulants: fluorouracil enhances anticoagulanteffect of .coumarinsAntiepileptics: fluorouracil possibly inhibits metabolismof phenytoin (increased risk of toxicity). Antipsychotics: avoid concomitant use of cytotoxicswith .clozapine (increased risk of agranulocytosis)Cytotoxics: capecitabine possibly increases plasmaconcentration of erlotinibFilgrastim: neutropenia possibly exacerbated whenfluorouracil given with filgrastim. Temoporfin: increased skin photosensitivity whentopical fluorouracil used with .temoporfinUlcer-healing Drugs: metabolism of fluorouracilinhibited by cimetidine (increased plasma concentration)Fluoxetine see Antidepressants, SSRIFlupentixol see AntipsychoticsFluphenazine see AntipsychoticsFlurazepam see Anxiolytics and HypnoticsFlurbiprofen see NSAIDsFlutamide. Anticoagulants: flutamide enhances anticoagulanteffect of .coumarinsFluticasone see CorticosteroidsFluvastatin see StatinsFluvoxamine see Antidepressants, SSRIFolatesAminosalicylates: absorption of folic acid possiblyreduced by sulfasalazineAntiepileptics: folates possibly reduce plasma concentrationof phenobarbital and phenytoin. Cytotoxics: avoidance of folates advised by manufacturerof .raltitrexedFolic Acid see FolatesFolinic Acid see FolatesFormoterol see Sympathomimetics, Beta 2FosamprenavirNote Fosamprenavir is a prodrug of amprenavirAnalgesics: fosamprenavir reduces plasma concentrationof methadone. Anti-arrhythmics: fosamprenavir possibly increasesplasma concentration of .amiodarone,.flecainide and .propafenone (increased risk ofventricular arrhythmias—avoid concomitant use);fosamprenavir possibly increases plasma concentrationof .lidocaine—avoid concomitant use. Antibacterials: fosamprenavir increases plasma concentrationof .rifabutin (reduce dose of rifabutin);plasma concentration of fosamprenavir significantlyreduced by .rifampicin—avoid concomitant use;avoidance of concomitant fosamprenavir in severerenal and hepatic impairment advised by manufacturerof .telithromycinAnticoagulants: fosamprenavir may enhance or reduceanticoagulant effect of coumarins; avoidance offosamprenavir advised by manufacturer of rivaroxaban. Antidepressants: plasma concentration of fosamprenavirreduced by .St John’s wort—avoid concomitantuseAntiepileptics: plasma concentration of fosamprenavirpossibly reduced by carbamazepine and phenobarbitalAntifungals: fosamprenavir increases plasma concentrationof ketoconazole (also plasma concentration offosamprenavir possibly increased); plasma concentrationof both drugs may increase when fosamprenavirgiven with itraconazoleFosamprenavir (continued). Antimalarials: caution with fosamprenavir advised bymanufacturer of artemether/lumefantrine; fosamprenavirpossibly increases plasma concentration of.quinine (increased risk of toxicity)Antimuscarinics: avoidance of fosamprenavir advisedby manufacturer of darifenacin and tolterodine. Antipsychotics: fosamprenavir possibly inhibitsmetabolism of .aripiprazole (reduce dose of aripiprazole);fosamprenavir increases plasma concentrationof .pimozide (increased risk of ventriculararrhythmias—avoid concomitant use). Antivirals: plasma concentration of fosamprenavirreduced by efavirenz and .tipranavir; plasma concentrationof fosamprenavir increased by .etravirine(consider reducing dose of fosamprenavir); plasmaconcentration of fosamprenavir reduced by lopinavir,effect on lopinavir plasma concentration not predictable—avoidconcomitant use; plasma concentrationof fosamprenavir possibly reduced by nevirapine. Anxiolytics and Hypnotics: fosamprenavir possiblyincreases plasma concentration of .midazolam (riskof prolonged sedation—avoid concomitant use oforal midazolam). Ciclosporin: fosamprenavir increases plasma concentrationof .ciclosporin. Ergot Alkaloids: increased risk of ergotism whenfosamprenavir given with .ergotamine and methysergide—avoidconcomitant use. Lipid-regulating Drugs: possible increased risk ofmyopathy when fosamprenavir given with atorvastatin;possible increased risk of myopathy whenfosamprenavir given with .rosuvastatin—manufacturerof rosuvastatin advises avoid concomitant use;possible increased risk of myopathy when fosamprenavirgiven with .simvastatin—avoid concomitantuse. Ranolazine: fosamprenavir possibly increases plasmaconcentration of .ranolazine—manufacturer ofranolazine advises avoid concomitant useSildenafil: fosamprenavir possibly increases plasmaconcentration of sildenafil. Tacrolimus: fosamprenavir increases plasma concentrationof .tacrolimusTadalafil: fosamprenavir possibly increases plasmaconcentration of tadalafilVardenafil: fosamprenavir possibly increases plasmaconcentration of vardenafilFosaprepitant see AprepitantFoscarnetAntivirals: avoidance of foscarnet advised by manufacturerof lamivudine. Pentamidine Isetionate: increased risk of hypocalcaemiawhen foscarnet given with parenteral .pentamidineisetionateFosinopril see ACE InhibitorsFosphenytoin see PhenytoinFramycetin see AminoglycosidesFrovatriptan see 5HT 1AgonistsFurosemide see DiureticsFusidic Acid. Antivirals: plasma concentration of both drugsincreased when fusidic acid given with .ritonavir—avoid concomitant use. Lipid-regulating Drugs: possible increased risk ofmyopathy when fusidic acid given with atorvastatin;increased risk of myopathy when fusidic acid givenwith .simvastatinSugammadex: fusidic acid possibly reduces responseto sugammadexVaccines: antibacterials inactivate oral typhoidvaccine—see p. 620GabapentinAnalgesics: bioavailability of gabapentin increased bymorphineAntacids: absorption of gabapentin reduced byantacids