From the Guidelines
Isoniazid (INH) prophylaxis is generally not routinely recommended for patients with lupus unless they have specific risk factors for tuberculosis (TB). For lupus patients who require INH prophylaxis due to positive TB screening, latent TB infection, or before starting immunosuppressive therapy, the standard regimen is isoniazid 300 mg daily for 9 months, often with vitamin B6 (pyridoxine) 25-50 mg daily to prevent peripheral neuropathy 1. Alternative shorter regimens include isoniazid 900 mg plus rifapentine weekly for 12 weeks under direct observation, or isoniazid 300 mg plus rifampin 600 mg daily for 3-4 months 1.
Key Considerations
- Lupus patients on immunosuppressive medications require careful monitoring during INH therapy due to potential hepatotoxicity, with liver function tests checked at baseline and monitored regularly, especially in the first 3 months of treatment 1.
- INH prophylaxis is particularly important for lupus patients starting medications like high-dose corticosteroids, mycophenolate mofetil, cyclophosphamide, or biologics, as these treatments increase TB reactivation risk 1.
- The decision to use INH should balance TB prevention benefits against potential drug interactions with lupus medications and the risk of drug-induced lupus, which rarely can be triggered by isoniazid itself 1.
Monitoring and Management
- Regular monitoring of liver function and adjustment of the treatment regimen as needed is crucial to minimize the risk of hepatotoxicity 1.
- Patients should be educated on the signs and symptoms of hepatotoxicity and the importance of adherence to the prescribed treatment regimen 1.
- The use of pyridoxine supplementation can help prevent peripheral neuropathy, a potential side effect of INH therapy 1.
From the Research
INH Protocol for Lupus
- The efficacy of isoniazid prophylaxis (INHP) in patients with systemic lupus erythematosus (SLE) receiving long-term glucocorticosteroid treatment was studied in a 2002 study 2.
- The study found that INHP was safe and effective in SLE, with a reduction in the incidence of tuberculosis (TB) from 11% to 2%, a reduction of 82%.
- However, liver enzyme abnormalities can occur in SLE patients, and toxic hepatitis has been associated with anti-tuberculosis medications, including isoniazid 3.
- Alternative regimens, such as weekly rifapentine plus isoniazid, have been shown to be effective and well-tolerated in treating latent tuberculosis infection (LTBI) in various populations, including solid organ transplant candidates 4, 5.
- A 2017 study found that a 12-week course of once weekly directly observed therapy (DOT) with isoniazid plus rifapentine (3HP) was safe and effective in SOT candidates, with no cases of hepatotoxicity reported 5.
Treatment Options
- INH monotherapy for 6-9 months is a common treatment for LTBI, but it can be associated with liver toxicity and low completion rates 6.
- Rifampicin-based regimens, such as rifampicin plus isoniazid or rifampicin plus pyrazinamide, have been shown to be effective alternatives to INH monotherapy, with shorter treatment durations and lower rates of hepatotoxicity 6, 4.
- Weekly rifapentine plus isoniazid has been shown to be a promising therapy for LTBI, with good protection against TB and low rates of hepatotoxicity 4, 5.