If someone cannot take rifapentine, which LTBI treatment option is commonly used?

• A. Isoniazid for 6–9 months.
• B. Rifapentine-based regimen.
• C. Pyrazinamide alone for 4 months.
• D. No treatment.

Answer: (A)

When rifapentine cannot be used, the commonly chosen LTBI treatment is isoniazid taken regularly for 6 to 9 months. This long-standing regimen effectively reduces the risk of progressing to active TB and is widely recommended when rifamycins aren’t an option. Isoniazid requires monitoring for liver safety, especially in older individuals or those with liver disease, and supplementation with vitamin B6 can help prevent neuropathy in at-risk people. In contrast, a regimen that uses rifapentine-based therapy isn’t possible here, and using pyrazinamide alone isn’t recommended for LTBI due to limited evidence and a higher risk of liver injury. Not treating LTBI leaves a real chance of developing active TB, so the isoniazid option is the practical alternative in this scenario.