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

Overview

Tuberculosis (TB) remains a significant public health concern in Thailand and globally, especially in tropical regions, with pulmonary TB being predominant. Besides affecting the lungs, TB can also impact extrapulmonary organs. Standard TB treatment involves a combination of drugs administered for at least 6 months, but it can cause adverse effects such as hepatitis. Hepatotoxicity, occurring in 20-60% of patients, is commonly linked to isoniazid, rifampicin, and pyrazinamide. Slow acetylators of the NAT2 gene are particularly susceptible. Previous research suggests N-acetylcysteine (NAC) may mitigate hepatotoxicity, especially among slow acetylators. A recent study by Kittichai Samaithongcharoen and team showed that NAC reduced hepatotoxicity incidence significantly among slow acetylators. This underscores the potential of NAC in preventing drug-induced hepatotoxicity in TB treatment, warranting further investigation against standard treatment protocols.

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.