Clinical perspectives of isoniazid-induced liver injury

Latent TB treatment regimens in 2023: Wetmore TB clinic in New Orleans

The USPSTF has updated Latent TB Infection (LTBI) screening and treatment recommendations in 2023; describing treatment courses, side effects and benefits associated with each regimen. Overall, rifampin-containing shortened regimens are the preferred modality for LTBI treatment. A recent study in 2023 evaluated adherence and tolerance of the isoniazid(INH) + rifapentine(RPT), or "3HP" regimen and identified patient groups that may be at higher risk for non-completion of this regimen. It emphasized the need for targeted education at the beginning of treatment, to avoid early discontinuation. Our experience in New Orleans demonstrated that the 3HP is well-tolerated, with higher completion rates than other LTBI regimens. Utilizing a retrospective chart review model, we reviewed 756 patients who were treated for LTBI over a two-year period from 1/2021--12/2022. The three possible treatment regimens included isoniazid (INH) alone, rifampin (RIF) alone, or INH + RPT (3HP). Of these regimens, the highest completion rate was in the 3HP group, despite literature suggesting this regimen is difficult to tolerate. Our experience suggests that this may still be an efficacious regimen that is well-tolerated if there is good access to clinicians to discuss mitigating side effects. More data is needed to determine factors that led to the success or failure for each regimen. Our clinic does have increased availability of nursing and medical staff to discuss side effects and answer questions, which may have contributed to our relatively higher success rate. In addition, we applied the review recommendations to our patient population, and would recommend the consideration of diabetes, heavy alcohol use, and tobacco use as risk factors for patients that would benefit from LTBI screening and treatment.

In silico drug design strategies for discovering novel tuberculosis therapeutics

INTRODUCTION

Tuberculosis remains a significant concern in global public health due to its intricate biology and propensity for developing antibiotic resistance. Discovering new drugs is a protracted and expensive endeavor, often spanning over a decade and incurring costs in the billions. However, computer-aided drug design (CADD) has surfaced as a nimbler and more cost-effective alternative. CADD tools enable us to decipher the interactions between therapeutic targets and novel drugs, making them invaluable in the quest for new tuberculosis treatments.

AREAS COVERED

In this review, the authors explore recent advancements in tuberculosis drug discovery enabled by in silico tools. The main objectives of this review article are to highlight emerging drug candidates identified through in silico methods and to provide an update on the therapeutic targets associated with Mycobacterium tuberculosis.

EXPERT OPINION

These in silico methods have not only streamlined the drug discovery process but also opened up new horizons for finding novel drug candidates and repositioning existing ones. The continued advancements in these fields hold great promise for more efficient, ethical, and successful drug development in the future.

Effect of NAT2, GSTM1 and CYP2E1 genetic polymorphisms on plasma concentration of isoniazid and its metabolites in patients with tuberculosis, and the assessment of exposure-response relationships

Objectives: Isoniazid is a key drug in the chemotherapy of tuberculosis (TB), however, interindividual variability in pharmacokinetic parameters and drug plasma levels may affect drug responses including drug induced hepatotoxicity. The current study investigated the relationships between isoniazid exposure and isoniazid metabolism-related genetic factors in the context of occurrence of drug induced hepatotoxicity and TB treatment outcomes. Methods: Demographic characteristics and clinical information were collected in a prospective TB cohort study in Latvia (N = 34). Time to sputum culture conversion (tSCC) was used as a treatment response marker. Blood plasma concentrations of isoniazid (INH) and its metabolites acetylisoniazid (AcINH) and isonicotinic acid (INA) were determined at three time points (pre-dose (0 h), 2 h and 6 h after drug intake) using liquid chromatography-tandem mass spectrometry. Genetic variations of three key INH-metabolizing enzymes (NAT2, CYP2E1, and GSTM1) were investigated by application PCR- and Next-generation sequencing-based methods. Depending on variables, group comparisons were performed by Student's t-test, one-way ANOVA, Mann-Whitney-Wilcoxon, and Kruskal-Wallis tests. Pearson correlation coefficient was calculated for the pairs of normally distributed variables; model with rank transformations were used for non-normally distributed variables. Time-to-event analysis was performed to analyze the tSCC data. The cumulative probability of tSCC was obtained using Kaplan-Meier estimators. Cox proportional hazards models were fitted to estimate hazard rate ratios of successful tSCC. Results: High TB treatment success rate (94.1%) was achieved despite the variability in INH exposure. Clinical and demographic factors were not associated with either tSCC, hepatotoxicity, or INH pharmacokinetics parameters. Correlations between plasma concentrations of INH and its metabolites were NAT2 phenotype-dependent, while GSTM1 genetic variants did not showed any effects. CYP2E1*6 (T > A) allelic variant was associated with INH pharmacokinetic parameters. Decreased level of AcINH was associated with hepatotoxicity, while decreased values of INA/INH and AcINH/INH were associated with month two sputum culture positivity. Conclusion: Our findings suggest that CYP2E1, but not GSTM1, significantly affects the INH pharmacokinetics along with NAT2. AcINH plasma level could serve as a biomarker for INH-related hepatotoxicity, and the inclusion of INH metabolite screening in TB therapeutic drug monitoring could be beneficial in clinical studies for determination of optimal dosing strategies.

Drug-induced liver injury and anti-hepatotoxic effect of herbal compounds: a metabolic mechanism perspective

BACKGROUND

Drug-induced liver injury (DILI) is the most challenging and thought-provoking liver problem for hepatologists owing to unregulated medication usage in medical practices, nutritional supplements, and botanicals. Due to underreporting, analysis, and identification issues, clinically evaluated medication hepatotoxicity is prevalent yet hard to quantify.

PURPOSE

This review's primary objective is to thoroughly compare pharmaceutical drugs and herbal compounds that have undergone clinical trials, focusing on their metabolic mechanisms contributing to the onset of liver illnesses and their hepatoprotective effects.

METHODS

The data was gathered from several online sources, such as PubMed, Scopus, Google Scholar, and Web of Science, using appropriate keywords.

RESULTS

The prevalence of conventional and herbal medicine is rising. A comprehensive understanding of the metabolic mechanism is necessary to mitigate the hepatotoxicity induced by drugs and facilitate the incorporation or substitution of herbal medicine instead of pharmaceuticals. Moreover, pre-clinical pharmacological research has the potential to facilitate the development of natural products as therapeutic agents, displaying promising possibilities for their eventual clinical implementation.

CONCLUSIONS

Acetaminophen, isoniazid, rifampicin, diclofenac, and pyrogallol have been identified as the most often reported synthetic drugs that produce hepatotoxicity by oxidative stress, inflammation, apoptosis, and fibrosis during the last several decades. Due to their ability to downregulate many factors (such as cytokines) and activate several enzyme/enzyme systems, herbal substances (such as Gingko biloba extract, curcumin, resveratrol, and silymarin) provide superior protection against harmful mechanisms which induce hepatotoxicity with fewer adverse effects than their synthetic counterparts.

Hepatoprotective effects of natural drugs: Current trends, scope, relevance and future perspectives

BACKGROUND

The liver is a well-known player in the metabolism and removal of drugs. Drug metabolizing enzymes in the liver detoxify drugs and xenobiotics, ultimately leading to the acquisition of homeostasis. However, liver toxicity and cell damage are not only related to the nature and dosage of a particular drug but are also influenced by other factors such as aging, immune status, environmental contaminants, microbial metabolites, gender, obesity, and expression of individual genes Furthermore, factors such as drugs, alcohol, and environmental contaminants could induce oxidative stress, thereby impairing the regenerative potential of the liver and causing several diseases. Persons suffering from other ailments and those with comorbidities are found to be more prone to drug-induced toxicities. Moreover, drug composition and drug-drug interactions could further aggravate the risk of drug-induced hepatotoxicity. A plethora of mechanisms are responsible for initiating liver cell damage and further aggravating liver cell injury, followed by impairment of homeostasis, ultimately leading to the generation of reactive oxygen species, immune-suppression, and oxidative stress.

OBJECTIVE

To summarize the potential of phytochemicals and natural bioactive compounds to treat hepatotoxicity and other liver diseases.

STUDY DESIGN

A deductive qualitative content analysis approach was employed to assess the overall outcomes of the research and review articles pertaining to hepatoprotection induced by natural drugs, along with analysis of the interventions.

METHODS

An extensive literature search of bibliographic databases, including Web of Science, PUBMED, SCOPUS, GOOGLE SCHOLAR, etc., was carried out to understand the role of hepatoprotective effects of natural drugs.

RESULTS

Bioactive natural products, including curcumin, resveratrol, etc., have been seen as neutralizing agents against the side effects induced by the drugs. Moreover, these natural products are dietary and are readily available; thus, could be supplemented along with drugs to reduce toxicity to cells. Probiotics, prebiotics, and synbiotics have shown promise of improving overall liver functioning, and these should be evaluated more extensively for their hepatoprotective potential. Therefore, selecting an appropriate natural product or a bioactive compound that is free of toxicity and offers a reliable solution for drug-induced liver toxicity is quintessential.

CONCLUSIONS

The current review highlights the role of natural bioactive products in neutralizing drug-induced hepatotoxicity. Efforts have been made to delineate the possible underlying mechanism associated with the neutralization process.

Association of Cytochrome P450 2E1 and N-Acetyltransferase 2 Genotypes with Serum Isoniazid Level and Anti-Tuberculosis Drug-Induced Hepatotoxicity: A Cross-Sectional Study

Background

Anti-tuberculosis drug-induced hepatotoxicity can result from genetic polymorphism of the isoniazid (INH) metabolizing enzyme. This study aimed to determine the effect of genetic polymorphism of N-acetyltransferase 2 (NAT2) and cytochrome P450 2E1 (CYP2E1) genes on serum isoniazid level and drug-induced hepatotoxicity.

Methods

A cross-sectional study was conducted on 120 patients (with and without hepatotoxicity) with pulmonary tuberculosis from June 2019 to April 2022 in Tehran (Iran). High-performance liquid chromatography was used to measure the serum concentration of INH and acetylisoniazid (AcINH). NAT2 and CYP2E1 genotypes were determined using polymerase chain reaction and restriction fragment length polymorphism methods. Data were analyzed using SPSS software (version 22.0) with independent two-sample t test, Chi square test, or Fisher's exact test. P<0.05 was considered statistically significant.

Results

A total of 40 patients showed hepatotoxicity. The risk of anti-tuberculosis drug-induced hepatotoxicity was significantly higher in patients who are slow acetylator (SA) phenotype than in rapid or intermediate acetylator (P<0.001). NAT2*4/*4 genotypes were not found in patients with hepatotoxicity. The frequency of NAT2*5 and NAT2*6 haplotypes and serum INH concentration was significantly higher in patients with hepatotoxicity than in those without (P=0.003, P<0.001, and P<0.001, respectively). NAT2*4 haplotype was correlated with protection against hepatotoxicity. A combination of SA and CYP2E1 C1/C1 genotype was significantly associated with hepatotoxicity (P<0.001).

Conclusion

Hepatotoxicity in Iranian patients with tuberculosis was confirmed due to the presence of NAT2 SA polymorphism. Determining NAT2 and CYP2E1 genotypes and/or INH concentration can be a valuable tool to identify patients susceptible to hepatotoxicity.

Isoniazid-Induced Acute Liver Failure Requiring Liver Transplantation

Tuberculosis (TB) is a contagious disease caused by the bacilli Mycobacterium tuberculosis complex. Currently, about a quarter of the world's population is infected with Mycobacterium tuberculosis. According to the World Health Organization, in 2018, Portugal had a TB incidence rate of about 24 cases per 100,000 inhabitants. It is estimated that 5-15% of individuals with latent TB infection progress to active TB. Isoniazid is one of the most widely used drugs for the treatment of active and latent TB. However, care must be taken with the possible development of toxicity, particularly hepatic. The authors report a case of a 60-year-old woman diagnosed with latent TB who started therapy with isoniazid. Five months later, she developed acute liver failure secondary to the drug, requiring liver transplantation, with a favorable clinical outcome. Thus, we intend to alert to the potential toxicities of isoniazid, establishing follow-up strategies in patients on this therapy.

Mechanisms of isoniazid and rifampicin-induced liver injury and the effects of natural medicinal ingredients: A review

Isoniazid (INH) and rifampicin (RFP) are the first-line medications for tuberculosis treatment, and liver injury is the major adverse effect. Natural medicinal ingredients provide distinct benefits in alleviating patients’ symptoms, lowering the liver injury risk, delaying disease progression, and strengthening the body’s ability to heal. This paper summarises the recent research on the mechanisms of INH and RFP-induced liver injury and the effects of natural medicinal ingredients. It is believed that INH-induced liver injury may be attributed to oxidative stress, mitochondrial dysfunction, drug metabolic enzymes, protoporphyrin IX accumulation, endoplasmic reticulum stress, bile transport imbalance, and immune response. RFP-induced liver injury is mainly related to cholestasis, endoplasmic reticulum stress, and liver lipid accumulation. However, the combined effect of INH and RFP on liver injury risk is still uncertain. RFP can increase INH-induced hepatotoxicity by regulating the expression of drug-metabolizing enzymes and transporters. In contrast, INH can antagonize RFP-induced liver injury by reducing the total bilirubin level in the blood. Sagittaria sagittifolia polysaccharide, quercetin, gallic acid, and other natural medicinal ingredients play protective roles on INH and RFP-induced liver injury by enhancing the body’s antioxidant capacity, regulating metabolism, inhibiting cell apoptosis, and reducing the inflammatory response. There are still many gaps in the literature on INH and RFP-induced liver injury mechanisms and the effects of natural medicinal ingredients. Thus, further research should be carried out from the perspectives of liver injury phenotype, injury markers, in vitro and in vivo liver injury model construction, and liver-gut axis. This paper comprehensively reviewed the literature on mechanisms involved in INH and RFP-induced liver injury and the status of developing new drugs against INH and RFP-induced liver injury. In addition, this review also highlighted the uses and advantages of natural medicinal ingredients in treating drug-induced liver injury.

Protection Against Drug-Induced Liver Injuries Through Nutraceuticals via Amelioration of Nrf-2 Signaling

Hepatotoxicity caused by the overdose of various medications is a leading cause of drug-induced liver injury. Overdose of drugs causes hepatocellular necrosis. Nutraceuticals are reported to prevent drug-induced liver failure. The present article aims to review the protection provided by various medicinal plants against hepatotoxic drugs. Ayurveda is considered a conventional restorative arrangement in India. It is consistently used for ages and is still used today to cure drug-induced hepatotoxicity by focusing on antioxidant stress response pathways such as the nuclear factor erythroid-2 (Nrf-2) antioxidant response element signaling pathway. Nrf-2 is a key transcription factor that entangles Kelch-like ECH-associating protein 1, a protein found in the cell cytoplasm. Some antioxidant enzymes, such as gamma glycine cysteine ligase (γ-GCL) and heme oxygenase-1 (HO-1), are expressed in Nrf-2 targeted genes. Their expression, in turn, decreases the stimulation of hepatic macrophages and induces the messenger RNA (mRNA) articulation of proinflammatory factors including tumor necrosis factor α. This review will cover various medicinal plants from a mechanistic view and how they stimulate and interact with Nrf-2, the master regulator of the antioxidant response to counterbalance oxidative stress. Interestingly, therapeutic plants have become popular in the medical sector due to safer yet effective supplementation for the prevention and treatment of new human diseases. The contemporary study is expected to collect information on a variety of therapeutic traditional herbs that have been studied in the context of drug-induced liver toxicity, as nutraceuticals are the most effective treatments for oxidative stress-induced hepatotoxicity. They are less genotoxic, have a lower cost, and are readily available. Together, nutraceuticals exert protective effects against drug-induced hepatotoxicity through the inhibition of oxidative stress, inflammation, and apoptosis. Its mechanism(s) are considered to be associated with the γ-GCL/HO-1 and Nrf-2 signaling pathways. KEY TEACHING POINTSThe liver is the most significant vital organ that carries out metabolic activities of the body such as the synthesis of glycogen, the formation of triglycerides and cholesterol, as well as the formation of bile.Acute liver failure is caused by the consumption of certain drugs; drug-induced liver injury is the major condition.The chemopreventive activity of nutraceuticals may be related to oxidative stress reduction and attenuation of biosynthetic processes involved in hepatic injury via amelioration of the nuclear factor erythroid-2 (Nrf-2) signaling pathway.Nrf-2 is a key transcription factor that is found in the cell cytoplasm resulting in the expression of various genes such as gamma glycine cysteine ligase and heme oxygenase-1.Nutraceutical-rich phytochemicals possess high antioxidant activity, which helps in the prevention of hepatic injury.

Design and Synthesis of Highly Active Antimycobacterial Mutual Esters of 2-(2-Isonicotinoylhydrazineylidene)propanoic Acid

The combination of two active scaffolds into one molecule represents a proven approach in drug design to overcome microbial drug resistance. We designed and synthesized more lipophilic esters of 2-(2-isonicotinoylhydrazineylidene)propanoic acid, obtained from antitubercular drug isoniazid, with various alcohols, phenols and thiols, including several drugs, using carbodiimide-mediated coupling. Nineteen new esters were evaluated as potential antimycobacterial agents against drug-sensitive Mycobacterium tuberculosis (Mtb.) H₃₇Rv, Mycobacterium avium and Mycobacterium kansasii. Selected derivatives were also tested for inhibition of multidrug-resistant (MDR) Mtb., and their mechanism of action was investigated. The esters exhibited high activity against Mtb. (minimum inhibitory concentrations, MIC, from ≤0.125 μM), M. kansasii, M. avium as well as MDR strains (MIC from 0.25, 32 and 8 µM, respectively). The most active mutual derivatives were derived from 4-chloro/phenoxy-phenols, triclosan, quinolin-8-ol, naphthols and terpene alcohols. The experiments identified enoyl-acyl carrier protein reductase (InhA), and thus mycobacterial cell wall biosynthesis, as the main target of the molecules that are activated by KatG, but for some compounds can also be expected adjunctive mechanism(s). Generally, the mutual esters have also avoided cytotoxicity and are promising hits for the discovery of antimycobacterial drugs with improved properties compared to parent isoniazid.