BNF for Children 2011-2012

726 Appendix 1: Interactions BNFC 2011–2012Appendix 1: InteractionsRifamycins. Antidiabetics (continued)possibly antagonises hypoglycaemic effect ofrepaglinide; rifamycins possibly acceleratemetabolism of .sulfonylureas (reduced effect). Antiepileptics: rifabutin reduces plasma concentrationof .carbamazepine; rifampicin reduces plasma concentrationof .lamotrigine; plasma concentration ofrifampicin possibly reduced by phenobarbital; rifamycinsaccelerate metabolism of .phenytoin(reduced plasma concentration). Antifungals: rifampicin accelerates metabolism of.ketoconazole (reduced plasma concentration), alsoplasma concentration of rifampicin may be reducedby ketoconazole; plasma concentration of rifabutinincreased by .fluconazole (increased risk of uveitis—reduce rifabutin dose); rifampicin acceleratesmetabolism of .fluconazole (reduced plasma concentration);rifabutin and rifampicin reduce plasmaconcentration of .itraconazole—manufacturer ofitraconazole advises avoid concomitant use; plasmaconcentration of rifabutin increased by.posaconazole (also plasma concentration of posaconazolereduced); rifampicin reduces plasma concentrationof .posaconazole and .terbinafine; plasmaconcentration of rifabutin increased by.voriconazole, also rifabutin reduces plasma concentrationof voriconazole (increase dose of voriconazoleand also monitor for rifabutin toxicity);rifampicin reduces plasma concentration of.voriconazole—avoid concomitant use; rifampicininitially increases and then reduces plasma concentrationof caspofungin (consider increasing dose ofcaspofungin); plasma concentration of rifabutinpossibly increased by .triazoles (increased risk ofuveitis—reduce rifabutin dose)Antihistamines: rifampicin possibly reduces effects offexofenadine. Antimalarials: rifampicin reduces plasma concentrationof .mefloquine—avoid concomitant use; rifampicinreduces plasma concentration of .quinineAntimuscarinics: rifampicin reduces plasma concentrationof active metabolite of fesoterodine. Antipsychotics: rifampicin accelerates metabolism of.haloperidol (reduced plasma concentration);rifabutin and rifampicin possibly reduce plasmaconcentration of .aripiprazole—increase dose ofaripiprazole; rifampicin possibly reduces plasmaconcentration of clozapine. Antivirals: rifampicin possibly reduces plasma concentrationof abacavir and ritonavir; rifampicinreduces plasma concentration of .atazanavir,.lopinavir and .nevirapine—avoid concomitant use;plasma concentration of rifabutin increased by.atazanavir, .darunavir, .fosamprenavir and.tipranavir (reduce dose of rifabutin); rifampicinsignificantly reduces plasma concentration of.darunavir, .fosamprenavir and .nelfinavir—avoidconcomitant use; plasma concentration of rifabutinreduced by efavirenz—increase dose of rifabutin;rifampicin reduces plasma concentration of efavirenz—increasedose of efavirenz; plasma concentrationof both drugs reduced when rifabutin given with.etravirine; avoidance of rifampicin advised bymanufacturer of etravirine and zidovudine; rifampicinaccelerates metabolism of .indinavir (reducedplasma concentration—avoid concomitant use);plasma concentration of rifabutin increased by.indinavir—avoid concomitant use; rifampicinreduces plasma concentration of .maraviroc and.raltegravir—consider increasing dose ofmaraviroc and raltegravir; plasma concentration ofrifabutin increased by .nelfinavir (halve dose ofrifabutin); plasma concentration of rifabutin possiblyincreased by nevirapine; plasma concentration ofrifabutin increased by .ritonavir (increased risk oftoxicity); rifampicin significantly reduces plasmaconcentration of .saquinavir, also risk of hepatotoxi-Rifamycins. Antivirals (continued)city—avoid concomitant use; plasma concentrationof rifabutin increased by .saquinavir (alsoplasma concentration of saquinavir reduced);rifampicin possibly reduces plasma concentrationof .tipranavir—avoid concomitant useAnxiolytics and Hypnotics: rifampicin acceleratesmetabolism of diazepam (reduced plasma concentration);rifampicin possibly accelerates metabolismof benzodiazepines (reduced plasma concentration);rifampicin possibly accelerates metabolism ofbuspirone and zaleplon; rifampicin acceleratesmetabolism of zolpidem (reduced plasma concentrationand reduced effect); rifampicin significantlyreduces plasma concentration of zopicloneAprepitant: rifampicin reduces plasma concentration ofaprepitant. Atovaquone: rifabutin and rifampicin reduce plasmaconcentration of .atovaquone (possible therapeuticfailure of atovaquone)Beta-blockers: rifampicin accelerates metabolism ofbisoprolol and propranolol (plasma concentrationsignificantly reduced); rifampicin reduces plasmaconcentration of carvedilol, celiprolol and metoprolol. Bosentan: rifampicin reduces plasma concentration of.bosentan—avoid concomitant use. Calcium-channel Blockers: rifampicin possibly acceleratesmetabolism of .isradipine and .nicardipine(possible significantly reduced plasma concentration);rifampicin accelerates metabolism of.diltiazem, .nifedipine, .nimodipine and .verapamil(plasma concentration significantly reduced)Cardiac Glycosides: rifampicin possibly reducesplasma concentration of digoxin. Ciclosporin: rifampicin accelerates metabolism of.ciclosporin (reduced plasma concentration). Corticosteroids: rifamycins accelerate metabolism of.corticosteroids (reduced effect). Cytotoxics: rifampicin accelerates metabolism of.dasatinib (reduced plasma concentration—avoidconcomitant use); rifampicin accelerates metabolismof erlotinib and sunitinib (reduced plasma concentration);rifampicin reduces plasma concentration of.everolimus and sorafenib; rifampicin reducesplasma concentration of .gefitinib, .imatinib and.nilotinib—avoid concomitant use; avoidance ofrifabutin and rifampicin advised by manufacturer of.lapatinib; avoidance of rifampicin advised by manufacturerof .pazopanib; rifampicin reduces plasmaconcentration of active metabolite of.temsirolimus—avoid concomitant use; rifampicinpossibly reduces plasma concentration of.vinflunine—manufacturer of vinflunine advisesavoid concomitant useDeferasirox: rifampicin reduces plasma concentrationof deferasirox. Diuretics: rifampicin reduces plasma concentration of.eplerenone—avoid concomitant useHormone Antagonists: rifampicin possibly reducesplasma concentration of exemestane; rifampicinaccelerates metabolism of tamoxifen (reducedplasma concentration)5HT 3 Antagonists: rifampicin accelerates metabolismof ondansetron (reduced effect)Leflunomide: rifampicin possibly increases plasmaconcentration of active metabolite of leflunomideLipid-regulating Drugs: rifampicin possibly reducesplasma concentration of atorvastatin and simvastatin;rifampicin accelerates metabolism of fluvastatin(reduced effect). Mycophenolate: rifampicin reduces plasma concentrationof active metabolite of .mycophenolate. Oestrogens: rifamycins accelerate metabolism of.oestrogens (reduced contraceptive effect—seep. 398)