Latent TB Infection Treatment FAQs for Pharmacists

3HP is one of several regimens CDC recommends for treatment of latent TB infection.  The term 3HP comes from the regimen duration (once weekly doses for three months) and the abbreviations of each of the two drugs, isoniazid (INH) and rifapentine (RPT), in the regimen.  Some people refer to 3HP as the “12-dose regimen.” This regimen has been recommended in the United States for treating latent TB infection since 2011.

Updated recommendations for the use of 3HP appear in an article in the Morbidity and Mortality Weekly Report (MMWR) published June 28, 2018.

Pharmacists should fill prescriptions one month at a time. Clinicians are encouraged to write the prescription for one month, with monthly refills.  However, clinicians may use their discretion for individual patients. Pharmacists should contact their state and local TB programs with specific questions.

Pharmacists should make sure that patients prescribed 3HP receive isoniazid and rifapentine.  A similar rifamycin compound, rifampin, is used in a different treatment regimen for latent TB infection.

Rifapentine is a rifamycin compound; like rifampin, it induces metabolism of many medications. CDC recommends monitoring of patients when 3HP is prescribed with interacting medications (e.g., methadone or warfarin). Women who use hormonal birth control should be advised to add, or switch to, a barrier method. Women who become pregnant during 3HP treatment should consult their provider.

Information about drug-drug interactions between specific anti-mycobacterial agents including rifamycins (rifampin, rifabutin and rifapentine) and antiretroviral agents is available at Department of Health and Human Services, Guidelines for the Use of Antiretroviral Agents in HIV-1-Infected Adults and Adolescentsexternal icon.  These frequently updated guidelines include a section addressing management of latent TB infection  in persons co-infected with HIV, and tables with information on drug interactions. Tables 18 and 19a-eexternal icon provide up-to-date information concerning drug-drug interactions between specific antiretroviral agents and the several rifamycins, including rifapentine.  Use of concomitant latent TB infection treatment and antiretroviral agents should be guided by clinicians experienced in the management of both conditions.

Yes, rifamycin and rifapentine are different medications. It is important for pharmacists to know the difference between rifampin and rifapentine. Rifampin and rifapentine are not interchangeable, and clinicians and pharmacists should ensure that patients receive the correct medication for the prescribed treatment regimen.

Page last reviewed: June 26, 2018