indication

For the treatment of Tuberculosis and Tuberculosis-related mycobacterial infections.

pharmacology

Rifampin is an antibiotic that inhibits DNA-dependent RNA polymerase activity in susceptible cells. Specifically, it interacts with bacterial RNA polymerase but does not inhibit the mammalian enzyme. It is bactericidal and has a very broad spectrum of activity against most gram-positive and gram-negative organisms (including Pseudomonas aeruginosa) and specifically Mycobacterium tuberculosis. Because of rapid emergence of resistant bacteria, use is restricted to treatment of mycobacterial infections and a few other indications. Rifampin is well absorbed when taken orally and is distributed widely in body tissues and fluids, including the CSF. It is metabolized in the liver and eliminated in bile and, to a much lesser extent, in urine, but dose adjustments are unnecessary with renal insufficiency.

mechanism of action

Rifampin acts via the inhibition of DNA-dependent RNA polymerase, leading to a suppression of RNA synthesis and cell death.

toxicity

LD₅₀=1570 mg/kg (rat), chronic exposure may cause nausea and vomiting and unconsciousness

biotransformation

Primarily hepatic, rapidly deacetylated.

absorption

Well absorbed from gastrointestinal tract.

half life

3.35 (+/- 0.66) hours

route of elimination

Less than 30% of the dose is excreted in the urine as rifampin or metabolites.

drug interactions

Acenocoumarol: Rifampin may decrease the anticoagulant effect of acenocoumarol by increasing its metabolism.

Acetohexamide: Rifampin may decrease the effect of sulfonylurea, acetohexamide.

Alfentanil: Rifampin reduces levels and efficacy of alfentanil

Aminophylline: Rifampin decreases the effect of theophylline

Amiodarone: Rifampin decreases the effect of amiodarone

Amitriptyline: The rifamycin, rifampin, may decrease the effect of the tricyclic antidepressant, amitriptyline, by increasing its metabolism. Monitor for changes in the therapeutic and adverse effects of amitriptyline if rifampin is initiated, discontinued or dose changed.

Amoxapine: The rifamycin, rifampin, may decrease the effect of the tricyclic antidepressant, amoxapine, by increasing its metabolism. Monitor for changes in the therapeutic and adverse effects of amoxapine if rifampin is initiated, discontinued or dose changed.

Amprenavir: In presence of rifampin anticipate decrease of amprenavir efficiency

Anisindione: Rifampin may decrease the anticoagulant effect of anisindione.

Aprepitant: The CYP3A4 inducer, rifampin, may decrease the effect of aprepitant.

Atazanavir: Rifampin reduces levels and efficacy of atazanavir

Atorvastatin: Rifampin may decrease the effect of atorvastatin by increasing its metabolism. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of atorvastatin if rifampin is initiated, discontinued or dose changed.

Atovaquone: Rifampin may decrease the effect of atovaquone.

Betamethasone: The enzyme inducer, rifampin, may decrease the effect of the corticosteroid, betamethasone.

Bisoprolol: Rifampin may decrease the serum concentration of bisprolol by increasing its metabolism.

Bromazepam: Rifampin may decrease the serum concentration of bromazepam by increasing its metabolism. Monitor for changes in the therapeutic and adverse effects of bromazepam if rifampin is initiated, discontinued or dose changed.

Bupropion: Rifampin reduces bupropion levels

Buspirone: Rifampin decreases the effect of buspirone

Caspofungin: Decreased levels/effects of caspofungin

Celecoxib: Rifampin, a strong CYP2C9 inducer, may decrease the serum levels of celecoxib by increasing its metabolism. Monitor for changes in the therapeutic and adverse effects if rifampin is initiated, discontinued or dose changed.

Cerivastatin: Rifampin may decrease the effect of cerivastatin by increasing its metabolism. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of cerivastatin if rifampin is initiated, discontinued or dose changed.

Chloramphenicol: Rifampin decreases the effect of chloramphenicol

Chlorpropamide: Rifampin may decrease the effect of sulfonylurea, chlorpropamide.

Clarithromycin: The rifamycin, rifampin, may decrease the effect of the macrolide, clarithromycin.

Clomipramine: The rifamycin, rifampin, may decrease the effect of the tricyclic antidepressant, clomipramine, by increasing its metabolism. Monitor for changes in the therapeutic and adverse effects of clomipramine if rifampin is initiated, discontinued or dose changed.

Clozapine: Rifampin decreases the effect of clozapine

Cortisone acetate: The enzyme inducer, rifampin, may decrease the effect of the corticosteroid, cortisone acetate.

Cyclosporine: The rifamycin decreases the effect of cyclosporine

Dabigatran etexilate: P-Glycoprotein inducers such as rifampin may decrease the serum concentration of dabigatran etexilate. This combination should be avoided.

Dapsone: Decreased levels of dapsone

Dasatinib: Rifampin may decrease the serum level and efficacy of dasatinib.

Delavirdine: Rifampin decreases the effect of delavirdine

Desipramine: The rifamycin, rifampin, may decrease the effect of the tricyclic antidepressant, desipramine, by increasing its metabolism. Monitor for changes in the therapeutic and adverse effects of desipramine if rifampin is initiated, discontinued or dose changed.

Dexamethasone: The enzyme inducer, rifampin, may decrease the effect of the corticosteroid, dexamethasone.

Diazepam: Rifampin may decrease the effect of the benzodiazepine, diazepam.

Diclofenac: Rifampin, a CYP2C9 inducer, may increase the metabolism of diclofenac.

Dicumarol: Rifampin may decrease the anticoagulant effect of dicumarol.

Diltiazem: Rifampin decreases levels of diltiazem

Disopyramide: Rifampin decreases the effect of disopyramide

Doxepin: The rifamycin, rifampin, may decrease the effect of the tricyclic antidepressant, doxepin, by increasing its metabolism. Monitor for changes in the therapeutic and adverse effects of doxepin if rifampin is initiated, discontinued or dose changed.

Doxycycline: The rifamycin decreases the effect of doxycycline

Dyphylline: Rifampin decreases the effect of theophylline

Enalapril: Rifampin, a strong CYP3A4 inducer, may increase the metabolism of enalapril. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of enalapril if rifampin is initiated, discontinued or dose changed.

Erlotinib: Decreased levels/effect of erlotinib

Erythromycin: The rifamycin, rifampin, may decrease the effect of the macrolide, erythromycin.

Ethinyl Estradiol: This product may cause a slight decrease of contraceptive effect

Ethotoin: Rifampin decreases the effect of the hydantoin

Etoricoxib: Rifampin reduces levels and efficacy of etoricoxib

Fentanyl: Rifampin may decrease the serum level and therapeutic effect of fentanyl.

Fluconazole: Rifampin may decrease the effect of fluconazole.

Fludrocortisone: The enzyme inducer, rifampin, may decrease the effect of the corticosteroid, fludrocortisone.

Fluvastatin: Rifampin may decrease the effect of fluvastatin by increasing its metabolism. Monitor for changes in the therapeutic and adverse effects of fluvastatin if rifampin is initiated, discontinued or dose changed.

Fosamprenavir: Rifampin may decrease the effectiveness of fosamprenavir.

Fosphenytoin: Rifampin may decrease the effect of fosphenytoin.

Gefitinib: Rifampin reduces levels and efficacy of gefitinib

Gliclazide: Rifampin may decrease the effect of sulfonylurea, gliclazide.

Glimepiride: Rifampin may decrease the effect of sulfonylurea, glimepiride.

Glipizide: Rifampin may decrease the effect of sulfonylurea, glipizide.

Glisoxepide: Rifampin may decrease the effect of sulfonylurea, glisoxepide.

Glyburide: Rifampin may decrease the effect of sulfonylurea, glibenclamide.

Glycodiazine: Rifampin may decrease the effect of sulfonylurea, glycodiazine.

Haloperidol: The rifamycin decreases the effect of haloperidol

Hydrocortisone: The enzyme inducer, rifampin, may decrease the effect of the corticosteroid, hydrocortisone.

Imatinib: Rifampin decreases levels of imatinib

Imipramine: The rifamycin, rifampin, may decrease the effect of the tricyclic antidepressant, imipramine, by increasing its metabolism. Monitor for changes in the therapeutic and adverse effects of imipramine if rifampin is initiated, discontinued or dose changed.

Indinavir: Rifampin decreases the effect of indinavir

Itraconazole: Rifampin may decrease the effect of itraconazole.

Josamycin: The rifamycin, rifampin, may decrease the effect of the macrolide, josamycin.

Ketoconazole: Rifampin may decrease the effect of ketoconazole.

Lamotrigine: Rifampin decreases levels of lamotrigine

Leflunomide: Rifampin increases the effect of leflunomide

Losartan: Rifampin decreases the effect of losartan

Lovastatin: Rifampin may decrease the effect of lovastatin by increasing its metabolism. Consider alternate therapy or monitor for changes in the therapeutic and adverse effects of lovastatin if rifampin is initiated, discontinued or dose changed.

Mefloquine: Rifampin lowers mefloquine levels

Mephenytoin: Rifampin decreases the effect of the hydantoin

Mestranol: This product may cause a slight decrease of contraceptive effect

Methadone: The rifamycin decreases the effect of methadone

Methylprednisolone: The enzyme inducer, rifampin, may decrease the effect of the corticosteroid, methylprednisolone.

Metoprolol: Rifampin may decrease the serum concentration of metoprolol by increasing its metabolism.

Mexiletine: Rifampin decreases the effect of mexiletine

Midazolam: Rifampin may increase the metabolism of midazolam. Monitor for changes in the therapeutic and adverse effects of midazolam if rifampin is initiated, discontinued or dose changed.

Morphine: Rifampin decreases the effect of morphine/codeine

Mycophenolate mofetil: Rifampin may decrease the serum concentration of mycophenolate. Concomitant therapy should be avoided.

Nelfinavir: Rifampin decreases the effect of nelfinavir

Nifedipine: Rifampin decreases the effect of the calcium channel blocker, nifedipine.

Norethindrone: This product may cause a slight decrease of contraceptive effect

Nortriptyline: The rifamycin, rifampin, may decrease the effect of the tricyclic antidepressant, nortriptyline, by increasing its metabolism. Monitor for changes in the therapeutic and adverse effects of nortriptyline if rifampin is initiated, discontinued or dose changed.

Oxtriphylline: Rifampin may decrease the effect and toxicity of oxtriphylline.

Paramethasone: The enzyme inducer, rifampin, may decrease the effect of the corticosteroid, paramethasone.

Phenytoin: Rifampin may decrease the therapeutic and adverse effects of phenytoin.

Praziquantel: Significant decrease in praziquantel level

Prednisolone: The enzyme inducer, rifampin, may decrease the effect of the corticosteroid, prednisolone.

Prednisone: The enzyme inducer, rifampin, may decrease the effect of the corticosteroid, prednisone.

Propafenone: Rifampin decreases the effect of propafenone

Propranolol: Rifampin may decrease the serum concentration of propranolol by increasing its metabolism.

Protriptyline: The rifamycin, rifampin, may decrease the effect of the tricyclic antidepressant, protriptyline, by increasing its metabolism. Monitor for changes in the therapeutic and adverse effects of protriptyline if rifampin is initiated, discontinued or dose changed.

Quinidine: Rifampin decreases the effect of quinidine

Quinidine barbiturate: Rifampin decreases the effect of quinidine

Ramelteon: Rifampin reduces the levels/effect of ramelteon

Repaglinide: Rifampin decreases the effect of repaglinide

Ritonavir: Rifampin decreases the effect of ritonavir

Rosiglitazone: Rifampin reduces levels and efficacy of rosiglitazone

Saquinavir: Rifampin decreases the effect of saquinavir

Simvastatin: Rifampin may decrease the effect of simvastatin by increasing its metabolism. Monitor for changes in the therapeutic and adverse effects of simvastatin if rifampin is initiated, discontinued or dose changed.

Sirolimus: The rifamycin decreases the effect of sirolimus

Sunitinib: Possible decrease in sunitinib levels

Tacrolimus: Rifampin may decrease the blood concentration of Tacrolimus. Monitor for changes in the therapeutic/toxic effects of Tacrolimus if Rifampin therapy is initiated, discontinued or altered.

Tadalafil: Rifampin may reduce Tadalafil plasma concentrations and efficacy.

Tamoxifen: The rifamycin decreases the effect of anti-estrogen

Telithromycin: Rifampin may decrease the plasma concentration of Telithromycin. Concomitant therapy should be avoided.

Temsirolimus: Rifampin may increase the metabolism of Temsirolimus decreasing its efficacy. Concomitant therapy should be avoided.

Terbinafine: Rifampin may increase the metabolism and clearance of Terbinafine. Co-administration may result in Terbinafine treatment failure.

Theophylline: Rifampin decreases the effect of theophylline

Tipranavir: Rifampin may decrease the plasma concentration of Tipranavir. Concomitant use is not recommended.

Tocainide: Rifampin lowers tocainide levels/effects

Tolazamide: Rifampin may decrease the effect of sulfonylurea, tolazamide.

Tolbutamide: Rifampin may decrease the effect of sulfonylurea, tolbutamide.

Toremifene: The rifamycin decreases the effect of anti-estrogen

Tramadol: Rifampin may decrease the effect of Tramadol by increasing Tramadol metabolism and clearance.

Trazodone: The CYP3A4 inducer, Rifampin, may decrease Trazodone efficacy by increasing Trazodone metabolism and clearance. Monitor for changes in Trazodone efficacy/toxicity if Rifampin is initiated, discontinued or dose changed.

Tretinoin: The strong CYP2C8 inducer, Rifampin, may increase the metabolism and clearance of oral Tretinoin. Consider alternate therapy to avoid failure of Tretinoin therapy or monitor for changes in Tretinoin effectiveness and adverse/toxic effects if Rifampin is initiated, discontinued or dose changed.

Triamcinolone: The enzyme inducer, rifampin, may decrease the effect of the corticosteroid, triamcinolone.

Triazolam: Rifampin may decrease the effect of the benzodiazepine, triazolam.

Trimethoprim: Rifampin decreases the effect of trimethoprim

Trimipramine: The rifamycin, rifampin, may decrease the effect of the tricyclic antidepressant, trimipramine, by increasing its metabolism. Monitor for changes in the therapeutic and adverse effects of trimipramine if rifampin is initiated, discontinued or dose changed.

Valproic Acid: Rifampin may reduce the serum concentration of Valproic acid by increasing Valproic acid metabolism. Valproic acid dose adjustments may be required during concomitant therapy. Monitor Valproic acid serum concentrations, efficacy and toxicity if Rifampin is initiated, discontinued or dose changed.

Verapamil: Rifampin, a CYP3A4 inducer, may decrease the serum concentration of Verapamil by increasing its metabolism (particularly in the intestinal mucosa) and decreasing its absorption. Monitor for changes in the therapeutic/adverse effects of Verapamil if Rifampin is initiated, discontinued or dose changed.

Voriconazole: Rifampin may decrease the serum concentration of voriconazole likely by increasing its metabolism via CYP3A enzymes. Voriconazole may increase the serum concentration of rifampin likely by inhibiting its metabolism via CYP3A. Concomitant therapy is contraindicated.

Warfarin: Rifampin may decrease the anticoagulant effect of warfarin by increasing its metabolism.

Zaleplon: Rifampin decreases the effect of zaleplon

Zidovudine: Rifampin may decrease the serum concentration of zidovudine by increasing its metabolism. Monitor for changes in the serum concentration and therapeutic and adverse effects of zidovudine if rifampin is initiated, discontinued or dose changed.