BNF for Children 2011-2012

BNFC 2011–2012 Appendix 1: Interactions 701Iron (continued)Methyldopa: oral iron antagonises hypotensive effectof methyldopaMycophenolate: oral iron reduces absorption ofmycophenolatePenicillamine: oral iron reduces absorption of penicillamineThyroid Hormones: oral iron reduces absorption oflevothyroxine (give at least 2 hours apart)Trientine: absorption of oral iron reduced by trientineZinc: oral iron reduces absorption of zinc, alsoabsorption of oral iron reduced by zincIsocarboxazid see MAOIsIsoflurane see Anaesthetics, GeneralIsometheptene see SympathomimeticsIsoniazidAntacids: absorption of isoniazid reduced by antacidsAntibacterials: increased risk of CNS toxicity whenisoniazid given with cycloserine. Antiepileptics: isoniazid increases plasma concentrationof .carbamazepine (also possibly increasedisoniazid hepatotoxicity); isoniazid inhibits metabolismof .ethosuximide (increased plasma concentrationand risk of toxicity); isoniazid possibly inhibitsmetabolism of phenytoin (increased risk of toxicity)Antifungals: isoniazid possibly reduces plasma concentrationof ketoconazoleAnxiolytics and Hypnotics: isoniazid inhibits themetabolism of diazepamCorticosteroids: plasma concentration of isoniazidpossibly reduced by corticosteroidsDisulfiram: isoniazid possibly increases CNS effects ofdisulfiramDopaminergics: isoniazid possibly reduces effects oflevodopaTheophylline: isoniazid possibly increases plasmaconcentration of theophyllineVaccines: antibacterials inactivate oral typhoidvaccine—see p. 620Isosorbide Dinitrate see NitratesIsosorbide Mononitrate see NitratesIsotretinoin see RetinoidsIsradipine see Calcium-channel BlockersItraconazole see Antifungals, TriazoleIvabradine. Anti-arrhythmics: increased risk of ventricular arrhythmiaswhen ivabradine given with .amiodarone or.disopyramide. Antibacterials: plasma concentration of ivabradinepossibly increased by .clarithromycin and.telithromycin—avoid concomitant use; increasedrisk of ventricular arrhythmias when ivabradine givenwith .erythromycin—avoid concomitant useAntidepressants: plasma concentration of ivabradinereduced by St John’s wort—avoid concomitant use. Antifungals: plasma concentration of ivabradineincreased by .ketoconazole—avoid concomitant use;plasma concentration of ivabradine increased byfluconazole—reduce initial dose of ivabradine;plasma concentration of ivabradine possiblyincreased by .itraconazole—avoid concomitant use. Antimalarials: increased risk of ventricular arrhythmiaswhen ivabradine given with .mefloquine. Antipsychotics: increased risk of ventricular arrhythmiaswhen ivabradine given with .pimozide. Antivirals: plasma concentration of ivabradine possiblyincreased by .nelfinavir and .ritonavir—avoid concomitantuse. Beta-blockers: increased risk of ventricular arrhythmiaswhen ivabradine given with .sotalol. Calcium-channel Blockers: plasma concentration ofivabradine increased by .diltiazem and .verapamil—avoid concomitant useGrapefruit Juice: plasma concentration of ivabradineincreased by grapefruit juice. Pentamidine Isetionate: increased risk of ventriculararrhythmias when ivabradine given with .pentamidineisetionateKaolinAnalgesics: kaolin possibly reduces absorption ofaspirinAntibacterials: kaolin possibly reduces absorption oftetracyclinesAntimalarials: kaolin reduces absorption of chloroquineand hydroxychloroquineAntipsychotics: kaolin possibly reduces absorption ofphenothiazinesKetamine see Anaesthetics, GeneralKetoconazole see Antifungals, ImidazoleKetoprofen see NSAIDsKetorolac see NSAIDsKetotifen see AntihistaminesLabetalol see Beta-blockersLacidipine see Calcium-channel BlockersLacosamide. Antidepressants: anticonvulsant effect of antiepilepticspossibly antagonised by MAOIs and .tricyclic-relatedantidepressants (convulsive threshold lowered); anticonvulsanteffect of antiepileptics antagonised by.SSRIs and .tricyclics (convulsive thresholdlowered); avoid concomitant use of antiepilepticswith .St John’s wort. Antimalarials: possible increased risk of convulsionswhen antiepileptics given with chloroquine andhydroxychloroquine; anticonvulsant effect of antiepilepticsantagonised by .mefloquine. Antipsychotics: anticonvulsant effect of antiepilepticsantagonised by .antipsychotics (convulsive thresholdlowered). Orlistat: possible increased risk of convulsions whenantiepileptics given with .orlistatLactuloseAnticoagulants: lactulose possibly enhances anticoagulanteffect of coumarinsLamivudineAntibacterials: plasma concentration of lamivudineincreased by trimethoprim (as co-trimoxazole)—avoid concomitant use of high-dose co-trimoxazoleAntivirals: avoidance of lamivudine advised by manufacturerof emtricitabine; manufacturer of lamivudineadvises avoid concomitant use with foscarnet;manufacturer of lamivudine advises avoid concomitantuse of intravenous ganciclovirLamotrigine. Antibacterials: plasma concentration of lamotriginereduced by .rifampicin. Antidepressants: anticonvulsant effect of antiepilepticspossibly antagonised by MAOIs and .tricyclic-relatedantidepressants (convulsive threshold lowered); anticonvulsanteffect of antiepileptics antagonised by.SSRIs and .tricyclics (convulsive thresholdlowered); avoid concomitant use of antiepilepticswith .St John’s wortAntiepileptics: plasma concentration of lamotrigineoften reduced by carbamazepine, also plasma concentrationof an active metabolite of carbamazepinesometimes raised (but evidence is conflicting);plasma concentration of lamotrigine reduced byphenobarbital and phenytoin; plasma concentrationof lamotrigine increased by valproate. Antimalarials: possible increased risk of convulsionswhen antiepileptics given with chloroquine andhydroxychloroquine; anticonvulsant effect of antiepilepticsantagonised by .mefloquine. Antipsychotics: anticonvulsant effect of antiepilepticsantagonised by .antipsychotics (convulsive thresholdlowered)Antivirals: plasma concentration of lamotrigine possiblyreduced by ritonavir. Oestrogens: plasma concentration of lamotriginereduced by .oestrogens—consider increasing dose oflamotrigine. Orlistat: possible increased risk of convulsions whenantiepileptics given with .orlistatProgestogens: plasma concentration of lamotriginepossibly increased by desogestrelAppendix 1: Interactions