Rifapentine


Rifapentine, sold under the brand name Priftin, is an antibiotic used in the treatment of tuberculosis. In active tuberculosis it is used together with other antituberculosis medications. In latent tuberculosis it is typically used with isoniazid. It is taken by mouth.
Common side effects include low neutrophil counts in the blood, elevated liver enzymes, and white blood cells in the urine. Serious side effects may include liver problems or Clostridium difficile associated diarrhea. It is unclear if use during pregnancy is safe. Rifapentine is in the rifamycin family of medication and works by blocking DNA-dependent RNA polymerase.
Rifapentine was approved for medical use in the United States in 1998. It is on the World Health Organization's List of Essential Medicines, the safest and most effective medicines needed in a health system. In the United States it costs $100–200 per month. In many areas of the world it is not easy to get as of 2015.

Medical uses

A systematic review of regimens for prevention of active tuberculosis in HIV-negative individuals with latent TB found that a weekly, directly observed regimen of rifapentine with isoniazid for three months was as effective as a daily, self-administered regimen of isoniazid for nine months. The 3-month rifapentine-isoniazid regimen had higher rates of treatment completion and lower rates of hepatotoxicity. However, the rate of treatment-limiting adverse events was higher in the rifapentine-isoniazid regimen compared to the 9-month isoniazid regimen.

Pregnancy

Rifapentine has been assigned a pregnancy category C by the U.S. Food and Drug Administration. Rifapentine in pregnant women has not been studied, but animal reproduction studies have resulted in fetal harm and were teratogenic. If rifapentine or rifampin are used in late pregnancy, coagulation should be monitored due to a possible increased risk of maternal postpartum hemorrhage and infant bleeding.

Adverse effects

Common side effects are hyperuricemia, pyuria, hematuria, urinary tract infection, proteinuria, neutropenia, anemia, and hypoglycemia.

Contraindications

Rifapentine should be avoided in patients with an allergy to the rifamycin class of drugs. This drug class includes rifampicin and rifabutin.

Interactions

Rifapentine induces metabolism by CYP3A4, CYP2C8 and CYP2C9 enzymes. It may be necessary to adjust the dosage of drugs metabolized by these enzymes if they are taken with rifapentine. Examples of drugs that may be affected by rifapentine include warfarin, propranolol, digoxin, protease inhibitors and birth control pills.

Chemical structure

The chemical structure of rifapentine is similar to that of rifamycin, with the notable substitution of a methyl group for a cyclopentane group.

History

Rifapentine was first synthesized in 1965, by the same company that produced rifampicin. The drug was approved by the U.S. Food and Drug Administration in June 1998. It is made from rifampicin.
Rifapentine was granted orphan drug designation by the FDA in June 1995, and by the European Commission in June 2010.