BNF for Children 2011-2012

BNFC 2011–2012 Appendix 1: Interactions 671Antipsychotics. Antidepressants (continued)arrhythmias; increased risk of antimuscarinicside-effects when phenothiazines given withtricyclics; increased risk of ventricular arrhythmiaswhen pimozide given with .tricyclics—avoid concomitant use; possible increased antimuscarinicside-effects when clozapine givenwith tricyclicsAntidiabetics: phenothiazines possibly antagonisehypoglycaemic effect of sulfonylureas. Antiepileptics: antipsychotics antagonise anticonvulsanteffect of .antiepileptics (convulsivethreshold lowered); metabolism of clozapine acceleratedby .carbamazepine (reduced plasma concentration),also avoid concomitant use of drugs withsubstantial potential for causing agranulocytosis;plasma concentration of aripiprazole reduced by.carbamazepine—increase dose of aripiprazole;plasma concentration of paliperidone reduced bycarbamazepine; metabolism of haloperidol, olanzapine,quetiapine and risperidone accelerated bycarbamazepine (reduced plasma concentration);metabolism of haloperidol accelerated by phenobarbital(reduced plasma concentration); plasma concentrationof both drugs reduced whenchlorpromazine given with phenobarbital; plasmaconcentration of clozapine possibly reduced byphenobarbital; plasma concentration of aripiprazolepossibly reduced by .phenobarbital and.phenytoin—increase dose of aripiprazole; plasmaconcentration of haloperidol reduced by phenytoin;chlorpromazine possibly increases or decreasesplasma concentration of phenytoin; metabolism ofclozapine and quetiapine accelerated by phenytoin(reduced plasma concentration); increased risk ofside-effects including neutropenia when olanzapinegiven with .valproate; plasma concentration ofclozapine possibly increased or decreased by valproate;plasma concentration of quetiapine possiblyincreased by valproate. Antifungals: metabolism of aripiprazole inhibited by.ketoconazole (reduce dose of aripiprazole); metabolismof aripiprazole possibly inhibited by.itraconazole (reduce dose of aripiprazole); plasmaconcentration of haloperidol possibly increased byitraconazole; increased risk of ventricular arrhythmiaswhen pimozide given with .imidazoles or.triazoles—avoid concomitant use; plasma concentrationof quetiapine possibly increased byimidazoles and triazoles (reduce dose of quetiapine). Antimalarials: avoidance of antipsychotics advised bymanufacturer of .artemether/lumefantrine;increased risk of ventricular arrhythmias when droperidolgiven with .chloroquine andhydroxychloroquine or .quinine—avoid concomitantuse; increased risk of ventricular arrhythmias whenpimozide given with .mefloquine or .quinine—avoidconcomitant use; possible increased risk of ventriculararrhythmias when haloperidol given with.mefloquine or .quinine—avoid concomitant useAntimuscarinics: increased risk of antimuscarinic sideeffectswhen clozapine given with antimuscarinics;plasma concentration of phenothiazines reduced byantimuscarinics, but risk of antimuscarinic sideeffectsincreased; effects of haloperidol possiblyreduced by antimuscarinics. Antipsychotics: increased risk of ventricular arrhythmiaswhen amisulpride, pimozide or sulpiride givenwith .droperidol—avoid concomitant use; increasedrisk of ventricular arrhythmias when phenothiazinesthat prolong the QT interval given with .droperidol—avoid concomitant use; avoid concomitant use ofclozapine with depot formulation of .flupentixol,.fluphenazine, .haloperidol, .pipotiazine,.risperidone or .zuclopenthixol as cannot be withdrawnquickly if neutropenia occurs; increased risk ofventricular arrhythmias when sulpiride given withAntipsychotics. Antipsychotics (continued).haloperidol; chlorpromazine possibly increasesplasma concentration of haloperidol; increased risk ofventricular arrhythmias when droperidol given with.haloperidol—avoid concomitant use; increased riskof ventricular arrhythmias when pimozide given with.phenothiazines—avoid concomitant use; increasedrisk of ventricular arrhythmias when pimozide givenwith .sulpiride. Antivirals: metabolism of aripiprazole possibly inhibitedby .atazanavir, .fosamprenavir, .indinavir,.lopinavir, .nelfinavir, .ritonavir and .saquinavir(reduce dose of aripiprazole); plasma concentrationof pimozide possibly increased by .atazanavir—avoidconcomitant use; plasma concentration of aripiprazolepossibly reduced by .efavirenz and.nevirapine—increase dose of aripiprazole; plasmaconcentration of pimozide possibly increased by.efavirenz, .indinavir, .nelfinavir and .saquinavir(increased risk of ventricular arrhythmias—avoidconcomitant use); plasma concentration of pimozideincreased by .fosamprenavir and .ritonavir(increased risk of ventricular arrhythmias—avoidconcomitant use); plasma concentration of olanzapinereduced by ritonavir—consider increasing doseof olanzapine; plasma concentration of clozapineincreased by .ritonavir (increased risk of toxicity)—avoid concomitant use; plasma concentration ofantipsychotics possibly increased by .ritonavir;increased risk of ventricular arrhythmias when clozapine,haloperidol or phenothiazines given with.saquinavir—avoid concomitant use. Anxiolytics and Hypnotics: increased sedative effectwhen antipsychotics given with anxiolytics andhypnotics; serious adverse events reported withconcomitant use of clozapine and .lorazepam(causality not established); increased risk of hypotension,bradycardia and respiratory depressionwhen intramuscular olanzapine given with parenteral.benzodiazepines; plasma concentration ofhaloperidol increased by buspirone. Aprepitant: avoidance of pimozide advised by manufacturerof .aprepitant. Atomoxetine: increased risk of ventricular arrhythmiaswhen antipsychotics that prolong the QT intervalgiven with .atomoxetine. Beta-blockers: enhanced hypotensive effect whenphenothiazines given with beta-blockers; plasmaconcentration of both drugs may increase whenchlorpromazine given with .propranolol; increasedrisk of ventricular arrhythmias when amisulpride,phenothiazines, pimozide or sulpiride given with.sotalol; increased risk of ventricular arrhythmiaswhen droperidol or zuclopenthixol given with.sotalol—avoid concomitant use; possible increasedrisk of ventricular arrhythmias when haloperidolgiven with .sotalol—avoid concomitant useCalcium-channel Blockers: enhanced hypotensiveeffect when antipsychotics given with calciumchannelblockersClonidine: enhanced hypotensive effect when phenothiazinesgiven with clonidine. Cytotoxics: avoid concomitant use of clozapine with.cytotoxics (increased risk of agranulocytosis);avoidance of pimozide advised by manufacturer of.lapatinib; increased risk of ventricular arrhythmiaswhen haloperidol given with .arsenic trioxide;increased risk of ventricular arrhythmias when antipsychoticsthat prolong the QT interval given with.arsenic trioxideDesferrioxamine: manufacturer of levomepromazineadvises avoid concomitant use with desferrioxamine;avoidance of prochlorperazine advised by manufacturerof desferrioxamineDiazoxide: enhanced hypotensive effect when phenothiazinesgiven with diazoxide. Diuretics: risk of ventricular arrhythmias with amisulprideincreased by hypokalaemia caused byAppendix 1: Interactions