BNF for Children 2011-2012

738 Appendix 1: Interactions BNFC 2011–2012Appendix 1: InteractionsTopiramate. Antidepressants (continued)lowered); avoid concomitant use of antiepilepticswith .St John’s wortAntidiabetics: topiramate possibly increases plasmaconcentration of metformin; topiramate possiblyreduces plasma concentration of glibenclamide. Antiepileptics: plasma concentration of topiramateoften reduced by carbamazepine; plasma concentrationof topiramate possibly reduced by phenobarbital;topiramate increases plasma concentration of.phenytoin (also plasma concentration of topiramatereduced); hyperammonaemia and CNS toxicityreported when topiramate given with 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)Diuretics: plasma concentration of topiramate possiblyincreased by hydrochlorothiazideLithium: topiramate possibly affects plasma concentrationof lithium. Oestrogens: topiramate accelerates metabolism of.oestrogens (reduced contraceptive effect—seep. 398). Orlistat: possible increased risk of convulsions whenantiepileptics given with .orlistat. Progestogens: topiramate accelerates metabolism of.progestogens (reduced contraceptive effect—seep. 398)Torasemide see DiureticsToremifene. Anticoagulants: toremifene possibly enhances anticoagulanteffect of .coumarinsAntiepileptics: metabolism of toremifene possiblyaccelerated by carbamazepine (reduced plasmaconcentration); metabolism of toremifene acceleratedby phenobarbital (reduced plasma concentration);metabolism of toremifene possibly acceleratedby phenytoinDiuretics: increased risk of hypercalcaemia whentoremifene given with thiazides and related diureticsTrabectedin. Antipsychotics: avoid concomitant use of cytotoxicswith .clozapine (increased risk of agranulocytosis)Tramadol see Opioid AnalgesicsTrandolapril see ACE InhibitorsTranylcypromine see MAOIsTrazodone see Antidepressants, Tricyclic (related)Tretinoin see RetinoidsTriamcinolone see CorticosteroidsTriamterene see DiureticsTrientineIron: trientine reduces absorption of oral ironZinc: trientine reduces absorption of zinc, alsoabsorption of trientine reduced by zincTrifluoperazine see AntipsychoticsTrihexyphenidyl see AntimuscarinicsTrilostaneDiuretics: increased risk of hyperkalaemia when trilostanegiven with potassium-sparing diuretics andaldosterone antagonistsTrimethoprimACE Inhibitors: possible increased risk of hyperkalaemiawhen trimethoprim given with ACE inhibitorsAngiotensin-II Receptor Antagonists: possibleincreased risk of hyperkalaemia when trimethoprimgiven with angiotensin-II receptor antagonistsAnti-arrhythmics: possible increased risk of ventriculararrhythmias when trimethoprim (as co-trimoxazole)given with amiodarone—manufacturer of amiodaroneadvises avoid concomitant use of co-trimoxazoleAntibacterials: plasma concentration of trimethoprimpossibly reduced by rifampicin; plasma concentrationTrimethoprimAntibacterials (continued)of both drugs may increase when trimethoprimgiven with dapsoneAnticoagulants: trimethoprim possibly enhances anticoagulanteffect of coumarinsAntidiabetics: trimethoprim possibly enhances hypoglycaemiceffect of repaglinide—manufactureradvises avoid concomitant use; trimethoprim rarelyenhances the effects of sulfonylureas. Antiepileptics: trimethoprim increases plasma concentrationof .phenytoin (also increased antifolateeffect). Antimalarials: increased antifolate effect when trimethoprimgiven with .pyrimethamineAntivirals: trimethoprim (as co-trimoxazole) increasesplasma concentration of lamivudine—avoid concomitantuse of high-dose co-trimoxazole. Azathioprine: increased risk of haematological toxicitywhen trimethoprim (also with co-trimoxazole) givenwith .azathioprineCardiac Glycosides: trimethoprim possibly increasesplasma concentration of digoxin. Ciclosporin: increased risk of nephrotoxicity whentrimethoprim given with .ciclosporin, also plasmaconcentration of ciclosporin reduced by intravenoustrimethoprim. Cytotoxics: increased risk of haematological toxicitywhen trimethoprim (also with co-trimoxazole) givenwith .mercaptopurine or .methotrexateDiuretics: increased risk of hyperkalaemia when trimethoprimgiven with eplerenoneVaccines: antibacterials inactivate oral typhoidvaccine—see p. 620Trimipramine see Antidepressants, TricyclicTripotassium DicitratobismuthateAntibacterials: tripotassium dicitratobismuthatereduces absorption of tetracyclinesTropicamide see AntimuscarinicsTrospium see AntimuscarinicsTryptophan. Antidepressants: CNS toxicity reported when tryptophangiven with fluoxetine; possible increasedserotonergic effects when tryptophan given withduloxetine; CNS excitation and confusion whentryptophan given with .MAOIs (reduce dose oftryptophan); agitation and nausea may occur whentryptophan given with .SSRIs. Antimalarials: avoidance of antidepressants advised bymanufacturer of .artemether/lumefantrineAtomoxetine: possible increased risk of convulsionswhen antidepressants given with atomoxetineTyphoid Vaccine (oral) see VaccinesTyphoid Vaccine (parenteral) see VaccinesUbidecarenoneAnticoagulants: ubidecarenone may enhance orreduce anticoagulant effect of warfarinUlcer-healing Drugs see Histamine H 2-antagonists,Proton Pump Inhibitors, Sucralfate, and TripotassiumDicitratobismuthateUlipristal. Antacids: manufacturer of ulipristal advises avoidconcomitant use with .antacids (plasma concentrationof ulipristal possibly reduced). Antibacterials: manufacturer of ulipristal advises avoidconcomitant use with .rifampicin (contraceptiveeffect of ulipristal possibly reduced). Antidepressants: manufacturer of ulipristal advisesavoid concomitant use with .St John’s wort (contraceptiveeffect of ulipristal possibly reduced). Antiepileptics: manufacturer of ulipristal advises avoidconcomitant use with .carbamazepine,.phenobarbital and .phenytoin (contraceptive effectof ulipristal possibly reduced). Antivirals: manufacturer of ulipristal advises avoidconcomitant use with .ritonavir (contraceptive effectof ulipristal possibly reduced)