What is the preferred treatment for latent tuberculosis (TB), isoniazid (INH) or rifampicin (RIF)?

From the Guidelines

For the treatment of latent tuberculosis infection (LTBI), I would generally prefer rifampin over isoniazid. This preference is based on the most recent and highest quality study, which recommends short-course (3- to 4-month) rifamycin-based treatment regimens over longer-course (6–9 month) isoniazid monotherapy for treatment of LTBI 1. Rifampin is typically given as a 4-month daily regimen (10 mg/kg/day, maximum 600 mg daily), which offers several advantages over the traditional 9-month isoniazid regimen (5 mg/kg/day, maximum 300 mg daily). The shorter duration of rifampin therapy leads to better completion rates, with studies showing approximately 80% completion for rifampin compared to 60% for isoniazid. Rifampin also has a lower risk of hepatotoxicity and serious adverse events.

Some key points to consider when choosing between rifampin and isoniazid include:

• The potential for drug interactions with rifampin, such as with warfarin, oral contraceptives, azole antifungals, and HIV antiretroviral therapy 1
• The need for baseline liver function tests and monitoring for side effects with both medications
• The option to use alternative regimens, such as a 3-month once-weekly combination of isoniazid and rifapentine, or a 3-4 month daily combination of isoniazid and rifampin, for patients who cannot tolerate either single drug
• The importance of considering the patient's specific circumstances, including comorbidities, concurrent medications, and likelihood of adherence, when making treatment decisions 1.

Overall, the choice of treatment for LTBI should be individualized based on the patient's unique needs and circumstances, with a focus on minimizing morbidity, mortality, and improving quality of life.

From the FDA Drug Label

PRIFTIN is indicated in adults and children 2 years and older for the treatment of latent tuberculosis infection caused by Mycobacterium tuberculosis in patients at high risk of progression to tuberculosis disease... PRIFTIN must always be used in combination with isoniazid as a 12-week once-weekly regimen for the treatment of latent tuberculosis infection

For the treatment of latent TB, isoniazid in combination with rifapentine is preferred, as rifapentine is only recommended to be used in combination with isoniazid for this indication 2, 2, 2.

• Rifapentine is not recommended for use alone for latent TB treatment.
• Isoniazid is used in combination with rifapentine for the treatment of latent tuberculosis infection.

From the Research

Treatment Options for Latent TB

• Isoniazid (INH) has been the mainstay of treatment for latent tuberculosis infection for almost 50 years, with a recommended regimen of 9 months daily self-administered INH 3.
• However, INH is associated with serious adverse events, including hepatotoxicity, which can be fatal 3.
• Rifampin-based regimens, such as 2 months of rifampin and pyrazinamide, have excellent efficacy but are associated with an unacceptably high rate of severe liver toxicity in non-HIV-infected adults 3.
• Three to four months of INH and rifampin has equivalent effectiveness as 6 months INH, but completion of therapy and toxicity are similar to INH 3.
• Four months of rifampin has been found to have significantly better completion and less toxicity, especially hepatotoxicity, compared to 9 months of INH 3.

Comparison of Isoniazid and Rifamycin-Based Regimens

• New rifamycin-based regimens are almost equal in effectiveness to isoniazid regimens, but have a different side effect profile 4.
• Short-duration courses, such as 3 months of rifapentine and isoniazid, tend to have a higher chance of completion 4.
• The use of rifapentine plus isoniazid for 3 months was as effective as 9 months of isoniazid alone in preventing tuberculosis, with a higher treatment-completion rate 5.
• Three-month isoniazid-rifapentine was determined to be equal to other latent tuberculosis infection regimens in effectiveness, with higher treatment completion and similar risk of adverse events 6.

Current Recommendations

• Treatment of latent tuberculosis infection regimens include once-weekly isoniazid plus rifapentine for 3 months, daily rifampin for 4 months, daily isoniazid plus rifampin for 3-4 months, and daily isoniazid for 6-9 months 7.
• Rifampin- and rifapentine-containing regimens are shorter, have similar efficacy, adequate safety, and higher treatment completion rates compared to isoniazid monotherapy 7.