Gene-guided N-acetyl Cysteine for Prophylaxis of Anti-tuberculous Drug- Induced Hepatitis

Tuberculosis (TB) is a significant public health problem in Thailand and globally, especially in hot climates. TB infection is commonly found in the lungs, but it can also affect other important organs such as lymph nodes, pleura, abdomen, musculoskeletal system, urinary tract, and nervous system. The current standard treatment regimen for TB consists of a combination of drugs (isoniazid, rifampicin, pyrazinamide, and ethambutol), used for new TB patients who have not been treated before or have received less than 1 month of treatment. A major challenge in TB treatment is that patients must take multiple drugs continuously for at least 6 months, with common side effects including skin rash, dizziness, hepatitis, nausea, vomiting, and abdominal pain, often occurring within the first 2 months of treatment. Hepatotoxicity from anti-TB drugs is a common side effect, occurring in 20-60% of patients, mostly within the first 2 weeks to 2 months of starting treatment. Isoniazid, rifampicin, and pyrazinamide are the drugs most commonly associated with hepatotoxicity, typically causing hepatocellular injury of varying severity. NAT2 slow acetylator phenotype individuals are at higher risk. Studies in Thailand have found a high prevalence (25-30%) of NAT2 slow acetylators among Thai people. Preventing hepatotoxicity from anti-TB drugs is crucial, especially for high-risk patients, although clear guidelines are lacking. Previous studies have shown that administering N-acetylcysteine (NAC), an antioxidant, can reduce hepatotoxicity, particularly in slow acetylators. A recent controlled study by Kittichai Samaithongcharoen and colleagues demonstrated the significant efficacy of NAC in preventing hepatotoxicity in slow acetylators receiving standard TB treatment, with no cases of hepatotoxicity compared to a 50% incidence in the control group. Further research is needed to explore the effectiveness of NAC administration for preventing hepatotoxicity from anti-TB drugs, based on NAT2 genotype testing, compared to current standard TB treatment protocols.

Inclusion criteria

• Patients aged 18 - 80 years old.
• Newly diagnosed tuberculosis patients (both pulmonary and extrapulmonary).
• Received standard anti-tuberculosis medication according to standard regimens (2HRZE/4HR, 2HRE/7HR).
• Willing to participate in the research

Exclusion criteria

• Infected with HIV.
• Severe liver dysfunction classified as Child-Pugh B or C.
• Chronic untreated liver diseases such as hepatitis B or C, alcoholic liver disease.
• Abnormal liver function tests including AST > 1.5 times the upper limit of normal (48 U/L), ALT > 1.5 times the upper limit of normal (55 U/L), ALP > upper limit of normal (110 U/L), Total bilirubin > upper limit of normal (1.2 mg/dL).
• Diagnosed with cancer.
• History of allergy to N-acetylcysteine (NAC).
• Pregnant or breastfeeding.
• Severe comorbidities such as CKD stage 4-5, chronic heart failure, severe pulmonary diseases (COPD, bronchiectasis).