BNF for Children 2011-2012

716 Appendix 1: Interactions BNFC 2011–2012Appendix 1: InteractionsOpioid Analgesics. Antivirals (continued)mitant use); plasma concentration of morphinepossibly reduced by ritonavir; increased risk ofventricular arrhythmias when alfentanil,fentanyl or methadone given with .saquinavir—avoid concomitant use; buprenorphine possiblyreduces plasma concentration of tipranavir;methadone possibly increases plasma concentrationof zidovudineAnxiolytics and Hypnotics: increased sedative effectwhen opioid analgesics given with anxiolytics andhypnotics; fentanyl possibly inhibits metabolism ofmidazolam. Atomoxetine: increased risk of ventricular arrhythmiaswhen methadone given with .atomoxetine; possibleincreased risk of convulsions when tramadol givenwith atomoxetineBeta-blockers: morphine possibly increases plasmaconcentration of esmololCalcium-channel Blockers: metabolism of alfentanilinhibited by diltiazem (risk of prolonged or delayedrespiratory depression)Domperidone: opioid analgesics antagonise effects ofdomperidone on gastro-intestinal activity. Dopaminergics: avoid concomitant use of dextromethorphanwith .rasagiline; risk of CNS toxicitywhen pethidine given with .rasagiline (avoid pethidinefor 2 weeks after rasagiline); hyperpyrexia andCNS toxicity reported when pethidine given with.selegiline (avoid concomitant use); avoidance ofopioid analgesics advised by manufacturer of selegiline5HT 3 Antagonists: effects of tramadol possibly antagonisedby ondansetron. Memantine: increased risk of CNS toxicity whendextromethorphan given with .memantine (manufacturerof memantine advises avoid concomitantuse)Metoclopramide: opioid analgesics antagonise effectsof metoclopramide on gastro-intestinal activityMuscle Relaxants: increased sedative effect whenfentanyl or morphine given with baclofen. Sodium Oxybate: opioid analgesics enhance effects of.sodium oxybate (avoid concomitant use)Ulcer-healing Drugs: metabolism of opioid analgesicsinhibited by cimetidine (increased plasma concentration)OrlistatAnti-arrhythmics: orlistat possibly reduces plasmaconcentration of amiodaroneAnticoagulants: manufacturer of orlistat recommendsmonitoring anticoagulant effect of coumarinsAntidiabetics: manufacturer of orlistat advises avoidconcomitant use with acarbose. Antiepileptics: possible increased risk of convulsionswhen orlistat given with .antiepileptics. Ciclosporin: orlistat possibly reduces absorption of.ciclosporinThyroid Hormones: possible increased risk of hypothyroidismwhen orlistat given with levothyroxineOrphenadrine see AntimuscarinicsOxaliplatin see Platinum CompoundsOxandrolone see Anabolic SteroidsOxazepam see Anxiolytics and HypnoticsOxcarbazepine. 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: oxcarbazepine sometimes reducesplasma concentration of carbamazepine (but concentrationof an active metabolite of carbamazepinemay be increased), also plasma concentration of anactive metabolite of oxcarbazepine often reduced;OxcarbazepineAntiepileptics (continued)avoidance of oxcarbazepine advised by manufacturerof eslicarbazepine; oxcarbazepineincreases plasma concentration ofphenobarbital and phenytoin, also plasma concentrationof an active metabolite of oxcarbazepinereduced; plasma concentration of an activemetabolite of oxcarbazepine sometimes reducedby 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)Ciclosporin: oxcarbazepine possibly reduces plasmaconcentration of ciclosporin. Clopidogrel: oxcarbazepine possibly reduces antiplateleteffect of .clopidogrel. Cytotoxics: oxcarbazepine reduces plasma concentrationof .imatinib—avoid concomitant use. Oestrogens: oxcarbazepine accelerates metabolism of.oestrogens (reduced contraceptive effect—seep. 398). Orlistat: possible increased risk of convulsions whenantiepileptics given with .orlistat. Progestogens: oxcarbazepine accelerates metabolismof .progestogens (reduced contraceptive effect—seep. 398)Oxprenolol see Beta-blockersOxybutynin see AntimuscarinicsOxycodone see Opioid AnalgesicsOxymetazoline see SympathomimeticsOxytetracycline see TetracyclinesOxytocinAnaesthetics, General: oxytocic effect possiblyreduced, also enhanced hypotensive effect and risk ofarrhythmias when oxytocin given with volatile liquidgeneral anaestheticsProstaglandins: uterotonic effect of oxytocin potentiatedby prostaglandinsSympathomimetics: risk of hypertension when oxytocingiven with vasoconstrictor sympathomimetics(due to enhanced vasopressor effect)Paclitaxel. Antipsychotics: avoid concomitant use of cytotoxicswith .clozapine (increased risk of agranulocytosis)Antivirals: plasma concentration of paclitaxel increasedby nelfinavir and ritonavir. Cytotoxics: increased risk of neutropenia when paclitaxelgiven with .lapatinibPaliperidone see AntipsychoticsPancreatinAntidiabetics: pancreatin antagonises hypoglycaemiceffect of acarbosePancuronium see Muscle RelaxantsPantoprazole see Proton Pump InhibitorsPapaveretum see Opioid AnalgesicsParacetamolAnticoagulants: prolonged regular use of paracetamolpossibly enhances anticoagulant effect of coumarinsAntiepileptics: metabolism of paracetamol possiblyaccelerated by carbamazepineCytotoxics: paracetamol possibly inhibits metabolismof intravenous busulfan (manufacturer of intravenousbusulfan advises caution within 72 hours of paracetamol);caution with paracetamol advised bymanufacturer of imatinibLipid-regulating Drugs: absorption of paracetamolreduced by colestyramineMetoclopramide: rate of absorption of paracetamolincreased by metoclopramideParaldehyde. Alcohol: increased sedative effect when paraldehydegiven with .alcohol