Safety of Isoniazid for Latent TB Treatment in Patients Taking Hydroxychloroquine

Treatment Options for LTBI

The Centers for Disease Control and Prevention (CDC) recommends short-course rifamycin-based regimens (3-4 months) for treating latent tuberculosis infection (LTBI) due to better completion rates and similar efficacy 3, 4
The CDC and National Tuberculosis Controllers Association recommend the following regimens: 3 months of once-weekly isoniazid plus rifapentine, 4 months of daily rifampin, and 3 months of daily isoniazid plus rifampin 3
The CDC strongly recommends 6 months of daily isoniazid for HIV-negative adults and children, and conditionally recommends 9 months of daily isoniazid for adults and children 2, 3

The CDC states that there are no specific contraindications or significant drug interactions between isoniazid and hydroxychloroquine, but monitoring for hepatotoxicity is essential 1, 2
Risk factors for isoniazid hepatotoxicity include increasing age, with higher risk in older adults 2

Clinical monitoring is effective for preventing severe hepatotoxicity, and patients should be educated about symptoms of hepatotoxicity and instructed to stop treatment immediately if such symptoms occur 6
Baseline liver function tests are recommended for patients at risk for hepatotoxicity, and periodic liver function testing should be considered for patients aged 35 years or older, or those with underlying liver disease or conditions that might affect the liver 2, 6

Shorter regimens generally have higher completion rates than the 9-month isoniazid regimen, contributing to greater overall effectiveness in clinical settings 3, 4

The American Thoracic Society recommends confirming LTBI diagnosis and ruling out active TB, and checking baseline liver function tests before starting treatment 1, 6
The CDC recommends selecting a regimen based on patient factors, such as contraindications to rifamycins, and monitoring patients monthly for symptoms of hepatotoxicity during treatment 2, 3, 6