BNF for Children 2011-2012

BNFC 2011–2012 Appendix 1: Interactions 727Rifamycins (continued). Progestogens: rifamycins accelerate metabolism of.progestogens (reduced contraceptive effect—seep. 398). Ranolazine: rifampicin reduces plasma concentrationof .ranolazine—manufacturer of ranolazine advisesavoid concomitant useRoflumilast: rifampicin reduces plasma concentrationof roflumilast—consider increasing dose of roflumilast. Sirolimus: rifabutin and rifampicin reduce plasmaconcentration of .sirolimus—avoid concomitant use. Tacrolimus: rifabutin possibly reduces plasma concentrationof tacrolimus; rifampicin reduces plasmaconcentration of .tacrolimus. Tadalafil: rifampicin reduces plasma concentration of.tadalafil—manufacturer of tadalafil advises avoidconcomitant useTheophylline: rifampicin accelerates metabolism oftheophylline (reduced plasma concentration)Thyroid Hormones: rifampicin accelerates metabolismof levothyroxine (may increase requirements forlevothyroxine in hypothyroidism)Tibolone: rifampicin accelerates metabolism of tibolone(reduced plasma concentration)Tolvaptan: rifampicin reduces plasma concentration oftolvaptanUlcer-healing Drugs: rifampicin accelerates metabolismof cimetidine (reduced plasma concentration). Ulipristal: avoidance of rifampicin advised by manufacturerof .ulipristal (contraceptive effect of ulipristalpossibly reduced)Vaccines: antibacterials inactivate oral typhoidvaccine—see p. 620Risedronate Sodium see BisphosphonatesRisperidone see AntipsychoticsRitodrine see Sympathomimetics, Beta 2Ritonavir. Alpha-blockers: ritonavir possibly increases plasmaconcentration of .alfuzosin—avoid concomitant use. Analgesics: ritonavir possibly increases plasma concentrationof NSAIDs and buprenorphine; ritonavirincreases plasma concentration of.dextropropoxyphene and .piroxicam (risk of toxicity)—avoidconcomitant use; ritonavir increasesplasma concentration of .alfentanil and .fentanyl;ritonavir reduces plasma concentration of methadone;ritonavir possibly reduces plasma concentrationof morphine; ritonavir reduces plasmaconcentration of .pethidine, but increases plasmaconcentration of toxic metabolite of pethidine (avoidconcomitant use). Anti-arrhythmics: ritonavir increases plasma concentrationof .amiodarone and .propafenone (increasedrisk of ventricular arrhythmias—avoid concomitantuse); ritonavir possibly increases plasma concentrationof .disopyramide (increased risk of toxicity);avoidance of ritonavir advised by manufacturer of.dronedarone; ritonavir possibly increases plasmaconcentration of .flecainide (increased risk ofventricular arrhythmias—avoid concomitant use). Antibacterials: ritonavir possibly increases plasmaconcentration of azithromycin and erythromycin;ritonavir increases plasma concentration of.clarithromycin (reduce dose of clarithromycin inrenal impairment); ritonavir increases plasma concentrationof .rifabutin (increased risk of toxicity);plasma concentration of ritonavir possibly reducedby rifampicin; plasma concentration of both drugsincreased when ritonavir given with .fusidic acid—avoid concomitant use; avoidance of concomitantritonavir in severe renal and hepatic impairmentadvised by manufacturer of .telithromycin. Anticoagulants: ritonavir may enhance or reduceanticoagulant effect of .warfarin; ritonavir possiblyenhances anticoagulant effect of .coumarins and.phenindione; ritonavir increases plasma concentrationof .rivaroxaban—manufacturer of rivaroxabanadvises avoid concomitant useRitonavir (continued). Antidepressants: ritonavir possibly reduces plasmaconcentration of paroxetine; ritonavir increasesplasma concentration of .trazodone (increased risk oftoxicity); ritonavir possibly increases plasma concentrationof .SSRIs and .tricyclics; plasma concentrationof ritonavir reduced by .St John’s wort—avoidconcomitant useAntidiabetics: ritonavir possibly increases plasmaconcentration of tolbutamide. Antiepileptics: ritonavir possibly increases plasmaconcentration of .carbamazepine; ritonavir possiblyreduces plasma concentration of lamotrigine; plasmaconcentration of ritonavir possibly reduced byphenytoin, also plasma concentration of phenytoinpossibly affected. Antifungals: combination of ritonavir with.itraconazole or .ketoconazole may increase plasmaconcentration of either drug (or both); plasmaconcentration of ritonavir increased by fluconazole;ritonavir reduces plasma concentration of.voriconazole—avoid concomitant useAntihistamines: ritonavir possibly increases plasmaconcentration of non-sedating antihistamines. Antimalarials: caution with ritonavir advised bymanufacturer of artemether/lumefantrine; ritonavirincreases plasma concentration of .quinine(increased risk of toxicity)Antimuscarinics: avoidance of ritonavir advised bymanufacturer of darifenacin and tolterodine; manufacturerof fesoterodine advises dose reduction whenritonavir given with fesoterodine—consult fesoterodineproduct literature; ritonavir increases plasmaconcentration of solifenacin. Antipsychotics: ritonavir possibly increases plasmaconcentration of .antipsychotics; ritonavir possiblyinhibits metabolism of .aripiprazole (reduce dose ofaripiprazole); ritonavir increases plasma concentrationof .clozapine (increased risk of toxicity)—avoidconcomitant use; ritonavir reduces plasma concentrationof olanzapine—consider increasing dose ofolanzapine; ritonavir increases plasma concentrationof .pimozide (increased risk of ventricular arrhythmias—avoidconcomitant use). Antivirals: ritonavir increases toxicity of efavirenz,monitor liver function tests; ritonavir increasesplasma concentration of indinavir, maraviroc and.saquinavir; combination of ritonavir with nelfinavirmay increase plasma concentration of either drug (orboth). Anxiolytics and Hypnotics: ritonavir possibly increasesplasma concentration of .anxiolytics and hypnotics;ritonavir possibly increases plasma concentration of.alprazolam, .diazepam, .flurazepam and .zolpidem(risk of extreme sedation and respiratory depression—avoidconcomitant use); ritonavir possiblyincreases plasma concentration of .midazolam (riskof prolonged sedation—avoid concomitant use oforal midazolam); ritonavir increases plasma concentrationof buspirone (increased risk of toxicity)Aprepitant: ritonavir possibly increases plasma concentrationof aprepitantBosentan: ritonavir possibly increases plasma concentrationof bosentanBupropion: ritonavir reduces plasma concentration ofbupropion. Calcium-channel Blockers: ritonavir possibly increasesplasma concentration of .calcium-channel blockers;avoidance of ritonavir advised by manufacturer oflercanidipineCardiac Glycosides: ritonavir possibly increasesplasma concentration of digoxin. Ciclosporin: ritonavir possibly increases plasma concentrationof .ciclosporin. Colchicine: ritonavir possibly increases risk of.colchicine toxicity—suspend or reduce dose ofcolchicine (avoid concomitant use in hepatic or renalimpairment)Appendix 1: Interactions