A study to evaluate the hepatoprotective effect of N- acetylcysteine on anti tuberculosis drug induced hepatotoxicity and quality of life.

BACKGROUND

Drug induced liver injury (DILI) is a serious adverse effect caused by first-line anti-TB (ATT) drugs, limiting the TB-treatment. The tissue inflammation induced by free radical burst and poor dietary intake in TB induces oxidative stress, which was proposed as one of the mechanisms responsible for ATT induced DILI. N-acetylcysteine (NAC) exerts a hepato-protective effect by enhancing the cellular antioxidant defense mechanism. There are few studies evaluating the effect of NAC on ATT induced DILI in Indian-population.

METHODS

This is a prospective, randomized, double-blind, placebo-controlled, parallel-group study. Thirty-eight newly diagnosed TB patients on first-line ATT with normal liver function test (LFT) were recruited and randomized to receive either NAC 600 mg tablet or placebo twice daily for 4 weeks and followed-up for next 4 weeks. LFT [AST, ALT, ALP and Total bilirubin] was assessed at baseline, 2, 4 and 8 weeks. Oxidative-stress biomarkers [Malondialdehyde (MDA), Nitric Oxide (NO), Glutathione (GSH)] and quality of life (QOL) by SF-36 questionnaire were assessed at baseline, 4 and 8 weeks. Adverse Drug Reactions (ADRs) were monitored at every visit. Compliance was assessed by pill-count method.

RESULTS

Baseline characteristics were homogenous among both the groups. In the NAC group, there was significant reduction in ALT (p < 0.01), ALP (p < 0.01), total bilirubin (p < 0.001) at 4 weeks compared to baseline. AST, MDA and NO showed a reduction of 19%, 21.6% and 5.5% respectively from baseline and GSH at showed an increase of 2.6% from baseline at 4 weeks in the NAC group, however these were not statistically significant. These effects in LFT and oxidative biomarkers persisted even at the end of 8 weeks. Significant improvement from baseline in QOL was observed in both the groups (p < 0.05). Between group analysis showed, significant reduction in ALT (p < 0.05) and AST (p < 0.05) in NAC group at 4 weeks, whereas bilirubin, MDA, NO and GSH showed improvement at 4 weeks compared to placebo in NAC group, however it was not statistically significant. This improvement in the LFT and oxidative biomarkers continued even at the end of 8 weeks. Itching and rashes were the most common ADRs, with similar incidence in both the groups. Compliance to treatment was good in both the groups.

CONCLUSION

Significant improvement in liver function parameters is suggestive of hepatoprotective effect of NAC. This observed effect at 4 weeks was found to be persistent at 8 weeks, which signifies prolonged hepato-protective effect of NAC. Long duration studies with large sample size are required for further confirmation of hepato-protective action of NAC.