Effectiveness of hepatoprotective drugs for anti-tuberculosis drug-induced hepatotoxicity: a retrospective analysis
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The effectiveness of hepatoprotective drugs for DIH (drug induced hepatotoxicity) during tuberculosis treatment is not clear. We evaluated the effectiveness of hepatoprotective drugs by comparing the period until the normalization of hepatic enzymes between patients who were prescribed with the hepatoprotective drugs after DIH was occurred and patients who were not prescribed with the hepatoprotective drugs.
During 2006–2010, 389 patients with active tuberculosis were included in this study. DIH was defined as elevation of peak serum aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT) of more than twice the upper limit of normal (ULN). We divided the patients into the severe (peak serum AST and/or ALT elevation of >5 times the ULN), moderate (peak serum AST and/or ALT elevation of >3 to ≤5 times the ULN), and mild DIH groups (peak serum AST and/or ALT elevation of >2 to ≤3 times the ULN). We compared the average period until the normalization of hepatic enzymes between patient subgroups with and without hepatoprotective drugs (ursodeoxycholic acid: UDCA, stronger neo-minophagen C: SNMC, and glycyrrhizin).
In the severe group, there was no significant difference in the average period until the normalization between subgroups with and without hepatoprotective drugs (21.4 ± 10.8 vs 21.5 ± 11.1 days, P = 0.97). In the mild group, the period was longer in the subgroup with hepatoprotective drugs than that without hepatoprotective drugs (15.7 ± 6.2 vs 12.4 ± 7.9 days, P = 0.046).
Regardless of the severity, hepatoprotective drugs did not shorten the period until the normalization of hepatic enzymes.
KeywordsIsoniazid Peak Serum Hepatic Enzyme American Thoracic Society Glycyrrhizin
American Thoracic Society
British Thoracic Society
Isoniazid, rifampicin, and ethambutol
Isoniazid, rifampicin, ethambutol, and pyrazinamide
Polymerase chain reaction
Stronger neo-minophagen C
Upper limit of normal
Tuberculosis (TB) is one of the serious infectious diseases. Isoniazid, rifampicin, and pyrazinamide are the first-line standard-regimen drugs administered for TB, but these anti-TB drugs often bring some major adverse effects such as hepatotoxicity, gastrointestinal and neurological disorders, and skin reactions [1, 2, 3]. Especially, drug-induced hepatotoxicity (DIH) is one of the most serious adverse effects ascribed to anti-TB drugs. Larrey reported that hepatotoxicity accounted for more than 7.0 % of all adverse effects . Hepatotoxicity diminishes the effectiveness of anti-TB drugs because it leads to significantly poor adherence, and eventually it can lead to not only treatment failure but also recurrence of TB and drug-resistance [5, 6].
In 2006, the American Thoracic Society (ATS) reported that the frequency of DIH ranged from 5 to 33 %, and the risk factors included age over 35, female sex, alcohol use, preexisting liver damage, the presence of rifampicin in a multidrug treatment regimen, history of viral hepatitis, and use of second-line anti-TB agents . Thereafter, many studies have also shown the relationship between DIH and risk factors, but few have shown the relationship between DIH and hepatoprotective drugs. Although there is no consensus on their effectiveness against DIH, hepatoprotective drugs have often been used empirically in patients with DIH, such as herbal medicine. If hepatoprotective drugs improve hepatic enzymes in patients suffering from DIH, it may be possible to prevent interruption and failure of treatment. Therefore, we evaluated the effectiveness of hepatoprotective drugs by comparing the period until the normalization of hepatic enzymes between patients with and without hepatoprotective drugs.
The purpose of this study was to investigate the effectiveness of several hepatoprotective drugs (ursodeoxycholic acid: UDCA, stronger neo-minophagen C: SNMC, and glycyrrhizin) in patients with hepatic enzyme elevation owing to anti-TB drugs.
UDCA, SNMC, and glycyrrhizin are often used in Japan as hepatoprotective drugs.
UDCA, a hydrophilic dihydroxylated bile acid, was first identified as a major constituent of the dried bile of the Chinese black bear. Reports on a beneficial effect on serum liver tests in cholestatic disorders were first published in Western literature [8, 9, 10]. The structure of UDCA was already elucidated in 1936 by Iwasaki , and the effectiveness of UDCA against chronic hepatitis was first reported in 1961 [12, 13]. Since then, many studies have shown the effectiveness of UDCA in chronic hepatitis, and the mechanism of its action has been recognized as (1) replacement/displacement of toxic endogenous bile acids, (2) cytoprotective effects on hepatocytes and bile duct epithelial cells, (3) immunomodulatory effects, and (4) stimulation of bile secretion by hepatocytes and bile duct epithelial cells [14, 15, 16].
SNMC, an intravenous drug, contains glycyrrhizin as a principal ingredient as well as glycine and L-cysteine. It has been used to treat chronic hepatitis for over 30 years in Japan and has been shown to be effective in preventing hepatocellular carcinoma development in patients with chronic hepatitis C; however, its underlying mechanisms of action remain to be elucidated . In Japan, SNMC has been used for treating allergic diseases since 1948 and was also used for treating chronic liver disease. Suzuki et al. reported that serum levels of AST, ALT, and γ-GTP can be significantly reduced by SNMC . In Japan, the use of SNMC has been approved for managing liver function abnormalities in chronic liver disease since 1979.
Glycyrrhizin, a conjugate of one molecule of glycyrrhetinic acid with two molecules of glucuronic acid, is extracted from the roots of the Glycyrrhiza glabra plant has been used for treating chronic hepatitis for over 20 years . It has been used as an anti-allergic agent in traditional Chinese medicine and as a food additive in beverages and licorice because of its sweet taste . In 1946, Revers reported on the anti-ulcer effect of licorice . Since then, glycyrrhizin has been used in Europe as an anti-ulcer drug for several years. In 1977, Suzuki et al. reported that the plasma transaminase activity in a group of patients with chronic active liver disease treated with glycyrrhizin improved significantly compared to the placebo-treated group . However, the mechanism of action of glycyrrhizin remains unknown.
Association between hepatotoxicity and the isoniazid metabolic pathway
An association between hepatotoxicity and the isoniazid metabolic pathway has been reported in recent studies [22, 23, 24, 25, 26, 27]. According to these studies, the predominant metabolic pathway of isoniazid metabolism is acetylation by the hepatic enzyme N-acetyltransferase 2. As the acetylation rate in humans is genetically determined, humans can be categorized into slow and rapid acetylators. In rapid acetylators, isoniazid is acetylated into acetylisoniazid and then excreted as diacetylhydrazine via acetylhydrazine. In slow acetylators, however, isoniazid is directly hydrolyzed into isonicotinic acid and hydrazine. These studies have concluded that this hydrazine is the most likely cause of isoniazid-induced hepatotoxicity. The mechanism of rifampicin- and pyrazinamide-induced hepatotoxicity remains unclear, but it is known that rifampicin increases isoniazid hydrolase activity and production of the hepatotoxic metabolite of isoniazid in slow acetylators .
Study population and treatment
The study population included all patients with active TB diagnosed by smear, culture, or polymerase chain reaction (PCR) analysis of sputum specimens, gastric washing, or bronchoalveolar lavage between January 2006 and December 2010 at the Jikei University Daisan Hospital. Clinical data were obtained retrospectively from medical records. Blood tests were preformed at least once a week during the initial 2 months of TB therapy. All patients received first-line standard-regimen drugs such as daily isoniazid, rifampicin, and ethambutol (HRE regimen) or isoniazid, rifampicin, ethambutol, and pyrazinamide (HREZ regimen). According to the Japanese Society for TB, the dosages of anti-TB drugs were 5 mg/kg/day (maximum 300 mg/day) of isoniazid, 10 mg/kg/day (maximum 600 mg/day) of rifampicin, 25 mg/kg/day (maximum 750 mg/day) of ethambutol, and 25 mg/kg/day (maximum 1.5 g/day) of pyrazinamide . This study was approved by the institutional ethical committee at The Jikei University School of Medicine.
Definition of anti-TB DIH
Management of hepatotoxicity
When DIH occurred, anti-TB drugs were continued in all patients within the moderate and mild DIH groups, but these drugs were stopped immediately in all patients within the severe DIH group. Then, the decision of whether to use hepatoprotective drugs in all of the patients with hepatotoxicity was based on the judgment of the attending physicians.
Comparison factor between patients with and without hepatoprotective drugs
The purpose was to investigate retrospectively the effectiveness of hepatoprotective drugs in patients with hepatic enzyme elevation owing to anti-TB drugs. We retrospectively obtained the clinical data from medical records, and compared the average period until the normalization of the hepatic enzymes between patients with and without hepatoprotective drugs. We evaluated statistically the effectiveness of hepatoprotective drugs by comparing the differences of this period.
The Mann-Whitney U test was used to compare the differences in average values, and the chi-square test was used to compare paired proportions. A P value < 0.05 indicated statistical significance for all analyses. All statistical analyses were performed with SPSS software, version 20.0 (SPSS Inc., Chicago, IL, USA).
Results and discussion
Baseline characteristics of the patients with DIH
Baseline characteristics of the 23 patients with severe drug-induced hepatotoxicity
Patients who stopped anti-TB drugs and received hepatoprotective drugs (N = 17)
Patients who stopped anti-TB drugs but did not receive hepatoprotective drugs (N = 6)
64 ± 20
58 ± 22
Peak AST (IU/dl)
477 ± 404
278 ± 156
Peak ALT (IU/dl)
362 ± 188
262 ± 132
Baseline characteristics of the 43 patients with mild drug-induced hepatotoxicity
Patients with hepatoprotective drugs (N = 10)
Patients without hepatoprotective drug (N = 33)
57 ± 21
55 ± 23
Peak AST (IU/dl)
66 ± 19
58 ± 12
Peak ALT (IU/dl)
72 ± 21
54 ± 21
Average period until the normalization of hepatic enzymes
Comparison of the average period until normalization of hepatic enzymes in the severe DIH and its HREZ regimen group
Patients who have stopped anti-TB drugs and with hepatoprotective drugs
Patients who have stopped anti-TB drugs and without hepatoprotective drugs
severe DIH group
21 ± 10 days
(N = 17)
21 ± 11 days
(N = 6)
21 ± 8 days
(N = 11)
24 ± 10 days
(N = 5)
Comparison of the average period until normalization of hepatic enzymes in the mild DIH and its HREZ regimen group
Patients with hepatoprotective drugs
Patients without hepatoprotective drugs
Mild DIH group
15 ± 6 days
(N = 10)
12 ± 7 days
(N = 33)
16 ± 7 days
(N = 9)
13 ± 9 days
(N = 26)
Average period until the normalization of hepatic enzymes in the HREZ regimen group
All patients received first-line standard-regimen drugs such as HRE or HREZ regimen. The patients of HREZ regimen and not HRE regimen have a higher risk of hepatotoxicity than the patients of HRE regimen and not HREZ regimen because pyrazinamide have hepatotoxicity as side effect. Among the patients treated with the HREZ regimen in the severe DIH group, as shown in Table 3, there was no significant difference in the average period until the normalization of hepatic enzymes between those with and without hepatoprotective drugs (21 ± 8 vs 24 ± 10 days, P = 0.64). Of the patients treated with the HREZ regimen in the mild DIH group, as shown in Table 4, there also was no significant difference in the average period until the normalization of hepatic enzymes between those with and without hepatoprotective drugs (16 ± 7 vs 13 ± 9 days, P = 0.061).
Flow of the design and definition decisions
The present study showed that hepatoprotective drugs did not shorten the period until the normalization of hepatic enzymes regardless of the severity of the hepatotoxicity caused by anti-TB drugs. Miyazawa et al. reported in 2003 that glycyrrhizin, one of the hepatoprotective drugs, was not effective in patients with elevated hepatic enzymes owing to anti-TB drugs . To our knowledge, however, no study reported subsequently on the relationship between anti-TB DIH and hepatoprotective drugs. From this point of view, the present study has great value in terms of investigating the effectiveness of hepatoprotective drugs including UDCA and SNMC. Also, these hepaprotective drugs have never been evaluated the possibility of prophylactic effect. We believe that it is worth discussing this possibility as another potential prospective study.
Many risk factors are associated with DIH. In particular, several studies have reported a positive association between viral hepatitis and DIH [31, 32, 33]. In the present study, we excluded those patients with viral hepatitis and other liver disease to eliminate the possibility of DIH other than that of liver enzyme elevation occurring during TB treatment.
As per the hepatotoxicity definition, both the ATS and the British Thoracic Society (BTS) have recommended that potentially hepatotoxic medications should be halted if the serum ALT exceeds 5 times the ULN (with or without symptoms) or 3 times the ULN with jaundice and/or hepatitis symptoms. Furthermore, regular monitoring of liver function is recommended when the serum ALT is > 2 times the ULN. Otherwise, the Japanese Society for TB recommends that medications should be stopped if serum AST and/or ALT exceed either 5 times the ULN (with or without symptoms) or 3 times the ULN with symptoms. Referring to these recommendations, we defined DIH as an elevation of peak serum AST and/or ALT of > 2 times the ULN to detect more patients with DIH . DIH occurred in 18 % of patients who underwent anti-TB treatment in the present study. Although a wide definition of DIH was used in the present study in comparison with that of the ATS and the BTS, the percent of patients with DIH was similar to that in several previous studies [35, 36]. The ATS has also recommended that anti-TB drugs should be resumed after the serum ALT level drops to < 2 times the ULN. In present study, we resumed anti-TB drugs in all patients after both serum AST and ALT returned to normal levels.
Limitations of the present study
The present study has some limitations. First, because this is a retrospective study, the medication period and dosage of hepatoprotective drugs were not unified. Some patients were treated with two or more hepatoprotective drugs at the same time. Therefore, we could not evaluate the effectiveness of each hepatoprotective drugs individually. To our knowledge, the action of mechanism for Glycyrrhizin, SNMC, and UDCA were not clarified completely. We believe that it is necessary to examine the efficacy of each drug separately in a future prospective study. Second, we excluded the moderate DIH group because it comprised only 5 applicable patients. We also defined DIH as an elevation of peak serum AST and/or ALT > 2 times the ULN to detect more patients with DIH, but only 71 patients fit our criteria. Further investigation via a large prospective study is necessary in the future. Third, UDCA, SNMC, and glycyrrhizin are normally used for viral hepatitis and cholelithiasis, but the use of these hepatoprotective drugs for DIH has never been permitted as health care services provided by health insurance in Japan. This fact may delay investigation into the association between DIH and hepatoprotective drugs. Despite the above limitations, we believe this study has valuable implications for clinical practice.
In patients with active TB, hepatoprotective drugs did not appear to shorten the period until the normalization of hepatic enzymes, regardless of the severity of the hepatotoxicity caused by anti-TB drugs.
We are grateful to all the patients who participated in the current study.
Availability of data and materials
The datasets supporting the conclusions of the current study are available in the Jikei University Daisan Hospital.
ZS designed the study and drafted the manuscript. YK made substantial contributions to analysis and interpretation of data, and editing of the final manuscript. AK, YK, KO, TH, YY, AS, YS, HT and KK contributed to the data collection and editing of the final manuscript. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Consent for publication
Ethics approval and consent to participate
The Ethics Committee of the Jikei University Hospital approved the current study, and written informed consent was obtained from all patients.
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