Rifapentine

Protease Inhibitors and Reverse Transcriptase Inhibitors. ( 5.2 , 7.1 ) Hormonal Contraceptives: Use an effective non-hormonal method of contraception or add a barrier method of contraception during treatment with PRIFTIN. ( 7.3 ) May increase metabolism and decrease the activity of drugs metabolized by cytochrome P450 3A4 and 2C8/9. Dosage adjustments may be necessary if given concomitantly. ( 7.4 )

7.1 Protease Inhibitors and Reverse Transcriptase Inhibitors Rifapentine is an inducer of CYP450 enzymes. Concomitant use of PRIFTIN with other drugs metabolized by these enzymes, such as protease inhibitors and certain reverse transcriptase inhibitors, may cause a significant decrease in plasma concentrations and loss of therapeutic effect of the protease inhibitor or reverse transcriptase inhibitor [see Warnings and Precautions (5.6) and Clinical Pharmacology (12.3) ] .

7.2 Fixed-Dose Combination of Efavirenz, Emtricitabine, and Tenofovir Once-weekly coadministration of 900 mg PRIFTIN with the antiretroviral fixed-dose combination of efavirenz 600 mg, emtricitabine 200 mg and tenofovir disoproxil fumarate 300 mg in HIV-infected patients did not result in any substantial change in steady state exposures of efavirenz, emtricitabine, and tenofovir. No clinically significant change in CD4 cell counts or viral loads were noted [see Clinical Pharmacology (12.3) ] .

7.3 Hormonal Contraceptives PRIFTIN may reduce the effectiveness of hormonal contraceptives. Patients using hormonal contraception should be advised to use an alternative non-hormonal contraceptive method or add a barrier method of contraception during treatment with PRIFTIN [see Use in Specific Populations (8.3) and Clinical Pharmacology (12.3) ] .

7.4 Cytochrome P450 3A4 and 2C8/9 Rifapentine is an inducer of cytochromes P450 3A4 and P450 2C8/9. Therefore, PRIFTIN may increase the metabolism of other coadministered drugs that are metabolized by these enzymes. Induction of enzyme activities by PRIFTIN occurred within 4 days after the first dose. Enzyme activities returned to baseline levels 14 days after discontinuing PRIFTIN. Rifampin has been reported to accelerate the metabolism and may reduce the activity of the following drugs; hence, PRIFTIN may also increase the metabolism and decrease the activity of these drugs.

Dosage adjustments of the drugs in Table 4 or of other drugs metabolized by cytochrome P450 3A4 or P450 2C8/9 may be necessary if they are given concurrently with PRIFTIN. Table 4: Drug Interactions with PRIFTIN: Dosage Adjustment May be Necessary Drug Class Examples of Drugs Within Class Antiarrhythmics Disopyramide, mexiletine, quinidine, tocainide Antibiotics Chloramphenicol, clarithromycin, dapsone, doxycycline; Fluoroquinolones (such as ciprofloxacin) Oral Anticoagulants Warfarin Anticonvulsants Phenytoin Antimalarials Quinine Azole Antifungals Fluconazole, itraconazole, ketoconazole Antipsychotics Haloperidol Barbiturates Phenobarbital Benzodiazepines Diazepam Beta-Blockers Propranolol Calcium Channel Blockers Diltiazem, nifedipine, verapamil Cardiac Glycoside Preparations Digoxin Corticosteroids Prednisone Fibrates Clofibrate Oral Hypoglycemics Sulfonylureas (e.g., glyburide, glipizide) Hormonal Contraceptives/Progestins Ethinyl estradiol, levonorgestrel Immunosuppressants Cyclosporine, tacrolimus Methylxanthines Theophylline Narcotic analgesics Methadone Phosphodiesterase-5 (PDE-5) Inhibitors Sildenafil Thyroid preparations Levothyroxine Tricyclic antidepressants Amitriptyline, nortriptyline

7.5 Other Interactions The conversion of PRIFTIN to 25-desacetyl rifapentine is mediated by an esterase enzyme. There is minimal potential for PRIFTIN metabolism to be inhibited or induced by another drug, based upon the characteristics of the esterase enzymes. Since PRIFTIN is highly bound to albumin, drug displacement interactions may also occur [see Clinical Pharmacology (12.3) ] .

7.6 Interactions with Laboratory Tests Therapeutic concentrations of rifampin have been shown to inhibit standard microbiological assays for serum folate and Vitamin B 12 . Similar drug-laboratory interactions should be considered for PRIFTIN; thus, alternative assay methods should be considered.

8.1 Pregnancy Risk Summary Based on animal data, PRIFTIN may cause fetal harm when administered to a pregnant woman. Available data from clinical trials, case reports, epidemiology studies and postmarketing experience with PRIFTIN use in pregnant women are insufficient to establish a drug-associated risk of major birth defects, adverse maternal or fetal outcomes. In two clinical trials, a total of 59 patients who were treated with rifapentine in combination with other anti-tuberculosis drugs became pregnant.

Overall, the reported rate of miscarriage following rifapentine exposure in these two clinical trials did not represent an increase over the background rate of miscarriage reported in the general population (see Data ) . There are risks associated with active tuberculosis during pregnancy. When administered during the last few weeks of pregnancy, PRIFTIN may be associated with maternal postpartum hemorrhage and bleeding in the exposed neonates (see Clinical Considerations ) .

In animal reproduction and developmental toxicity studies, adverse developmental outcomes (including cleft palate or mal-positioned aortic arches) were observed following administration of rifapentine to pregnant rats and rabbits at doses approximately 0.6 and 0.3 to 1.3 times, respectively, of the recommended human dose based on body surface area comparisons (see Data ) . Based on animal data, advise pregnant women of the risk for fetal harm.

As rifapentine is always used in combination with other antituberculosis drugs such as isoniazid, ethambutol, and pyrazinamide, refer to the prescribing information of the other drug(s) for more information on their associated risks of use during pregnancy. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2%–4% and 15%–20%, respectively.

Clinical Considerations Disease-associated maternal and/or embryo-fetal risk Active tuberculosis in pregnancy is associated with adverse maternal and neonatal outcomes including maternal anemia, cesarean delivery, preterm birth, low birth weight, birth asphyxia, and perinatal infant death. Labor or delivery When administered during the last few weeks of pregnancy, PRIFTIN may increase the risk for maternal postpartum hemorrhage and bleeding in the exposed neonate. Monitor prothrombin time of pregnant women and neonates…