A simple microassay for the determination of hydrazine in biological samples. Effect of hydrazine and isoniazid on liver and brain glutathione

A simple microassay for the determination of hydrazine in laboratory samples is presented. The colored product of the reaction of p-dimethylaminobenzaldehyde with hydrazine was tested at 470 nm using double-beam mode in different samples. Internal standards and data on blood serum, liver, and brain of rats treated with hydrazine or isoniazid are presented. The tissue glutathione content of these rats was determined, and the possible implication of glutathione in the brain toxicity of hydrazine is discussed.     

Rifampicin exacerbates isoniazid-induced toxicity in human but not in rat hepatocytes in tissue-like cultures

BACKGROUND AND PURPOSE: Rifampicin has been extensively reported to exacerbate the hepatotoxicity of isoniazid in patients with tuberculosis. However, this was controversially claimed by previous reports using rat models. This study evaluated the effect of rifampicin on isoniazid-induced hepatocyte toxicity by using human and rat hepatocytes in tissue-like culture.EXPERIMENTAL APPROACH: Hepatocytes in tissue-like gel entrapment were used to examine isoniazid toxicity, as shown by cell viability, intracellular glutathione content and albumin secretion. For demonstration of the differential effects of rifampicin on human and rat hepatocytes, induction by rifampicin of cytochrome P450 (CYP) 2E1, a major enzyme associated with isoniazid hepatotoxicity, was detected by 4-nitrocatechol formation and RT-PCR analysis.KEY RESULTS: Rifampicin (12 microM) enhanced isoniazid-induced toxicity in human hepatocytes but not in rat hepatocytes. Enhanced CYP 2E1 enzymic activity and mRNA expression were similarly detected in human hepatocytes but not in rat hepatocytes. Both rat and human hepatocytes in gel entrapment were more sensitive to isoniazid treatment compared with the corresponding hepatocytes in a monolayer culture.CONCLUSIONS AND IMPLICATIONS: The difference in induction of CYP 2E1 by rifampicin between rat and human hepatocytes accounted for the difference in exacerbation of isoniazid hepatocyte toxicity by rifampicin, with more significant toxicity in gel entrapment than in monolayer cultures. Thus, human hepatocytes in tissue-like cultures (gel entrapment) could be an effective model for hepatotoxicity research in vitro, closer to the in vivo situation.     

Subchronic Toxicity of Human Immunodeficiency Virus and Tuberculosis Combination Therapies in B6C3F1 Mice

Combination therapy with anti-HIV drugs and opportunistic infectiondrugs is a common practice in treatment of AIDS patients. Althoughtoxic effects of most individual therapies are known, the toxicpotential of most combination therapies has not been established.To understand the toxic consequences of combination therapies,the commonly used anti-HIV drug 3'-azido-3'-deoxythymidine (AZT)and tuberculosis infection therapies pyra-zinamide, isoniazid,and rifampicin were evaluated by 13-week gavage studies in B6C3F1mice, either alone or AZT in combination with one of the antituberculosisdrugs. The doses include AZT 100, 200, and 400; pyrazinamide1000 and 1500; isoniazid 50,100, and 150; and rifampicin 100,200, and 400 mg/kg/day. AZT alone caused hematopoietic toxicitywith dose-related bone marrow suppression, macrocytic anemia,and thrombocytosis. Pyrazinamide or isoniazid alone at the dosestested did not cause significant toxicity. Rifampicin alonecaused hematopoietic toxicity and possibly mild hepatic toxicity.Pyrazinamide below 10 times the therapeutic dose when givenwith AZT did not increase the hemato-logical toxicity of AZT.Isoniazid markedly increased the hematological toxicity of AZTand contributed to mortality at 3 to 4 times the therapeuticdose combinations. Administration of rifampicin with AZT atthe calculated therapeutic doses resulted in toxicity of fargreater magnitude than that caused by AZT or rifampicin alone.Combination treatment with AZT and rifampicin caused severeanemia with mortality at 2 to 4 times the therapeutic dose combinations.However, AZT did not enhance the hepatotoxicity of rifampicin.Increased hematopoietic toxicity of AZT when given in combinationwith the above antituberculosis drugs may be due to changesin the metabolism of AZT. Results of these studies indicatethat toxicological effects of combination therapies could beconsiderably more severe than and different from the toxicityof individual therapies.     

Isoniazid overdose : a case series, literature review and survey of antidote availability

Tuberculosis has re-emerged as a significant public health threat over the last decade both globally and within Australia. This is thought to be largely due to the HIV epidemic, a growing itinerant population, and immigration. The antibiotic isoniazid remains an integral part of drug therapy. With the numbers of patients receiving isoniazid remaining high, the number of cases of acute poisoning is expected to be significant. This paper presents a series of two cases of isoniazid poisoning presenting to a tertiary referral centre in North Queensland. Isoniazid toxicity produces a triad of coma, metabolic acidosis and seizures. The seizures are often refractory to traditional antiepileptics. A specific antidote is available (pyridoxine [vitamin B6]) and both patients were administered this as part of their treatment. We also surveyed all hospitals in Australia with an accredited adult Emergency Department to assess the availability of pyridoxine.     

Metabolomic analysis reveals novel isoniazid metabolites and hydrazones in human urine

Isoniazid (INH) is a first-line drug for tuberculosis control; the side effects of INH are thought to be associated with its metabolism, and this study was designed to globally characterize isoniazid metabolism. Metabolomic strategies were used to profile isoniazid metabolism in humans. Eight known and seven novel INH metabolites and hydrazones were identified in human urine. The novel products included two hydroxylated INH metabolites and five hydrazones. The two novel metabolites were determined as 2-oxo-1,2-dihydro-pyridine-4-carbohydrazide and isoniazid N-oxide. Five novel hydrazones were produced by condensation of isoniazid with keto acids that are intermediates in the metabolism of essential amino acids, namely, leucine and/or isoleucine, lysine, tyrosine, tryptophan, and phenylalanine. This study enhances our knowledge of isoniazid metabolism and disposition and may offer new avenues for investigating INH-induced toxicity.     

Uniform procedure of (1)H NMR analysis of rat urine and toxicometabonomics Part II: comparison of NMR profiles for classification of hepatotoxicity.

A procedure of nuclear magnetic resonance (NMR) urinalysis using pattern recognition is proposed for early detection of toxicity of investigational compounds in rats. The method is applied to detect toxicity upon administration of 13 toxic reference compounds and one nontoxic control compound (mianserine) in rats. The toxic compounds are expected to induce necrosis (bromobenzene, paracetamol, carbon tetrachloride, iproniazid, isoniazid, thioacetamide), cholestasis (alpha-naphthylisothiocyanate (ANIT), chlorpromazine, ethinylestradiol, methyltestosterone, ibuprofen), or steatosis (phenobarbital, tetracycline). Animals were treated daily for 2 or 4 days except for paracetamol and bromobenzene (1 and 2 days) and carbon tetrachloride (1 day only). Urine was collected 24 h after the first and second treatment. The animals were sacrificed 24 h after the last treatment, and NMR data were compared with liver histopathology as well as blood and urine biochemistry. Pathology and biochemistry showed marked toxicity in the liver at high doses of bromobenzene, paracetamol, carbon tetrachloride, ANIT, and ibuprofen. Thioacetamide and chlorpromazine showed less extensive changes, while the influences of iproniazid, isoniazid, phenobarbital, ethinylestradiol, and tetracycline on the toxic parameters were marginal or for methyltestosterone and mianserine negligible. NMR spectroscopy revealed significant changes upon dosing in 88 NMR biomarker signals preselected with the Procrustus Rotation method on principal component discriminant analysis (PCDA) plots. Further evaluation of the specific changes led to the identification of biomarker patterns for the specific types of liver toxicity. Comparison of our rat NMR PCDA data with histopathological changes reported in humans and/or rats suggests that rat NMR urinalysis can be used to predict hepatotoxicity.     

异烟肼常见含量测定方法综述

异烟肼对结核杆菌有高度选择性，有较强的抑制和杀灭作用，因其具有疗效高、毒性小、口服方便、价格低廉等优点，是目前临床治疗结核病的首选药物。药物中异烟肼的含量测定方法很多，进行系统的报道尚未见到。在此，笔者将国内常见的方法作一综述。     

Short-course drug therapy for tuberculosis

The cost, patient compliance considerations, and toxicity of short-course chemotherapy (SCC) and conventional 18- to 24-month treatment regimens for pulmonary tuberculosis are compared; studies of the efficacy of SCC regimens are evaluated; and the future of SCC in the United States is examined. SCC is defined as treatment for nine months or less. A definite advantage of SCC over conventional therapy in terms of cost, patient compliance, or adverse effects has not been established. A series of studies conducted by the East African-British Medical Research Council documented the efficacy of various six-month, multiple-drug regimens that contain rifampin and verified the sterilizing activity of pyrazinamide during the first two months of therapy. The studies of the Hong Kong Chest Service and British Medical Research Council documented the efficacy of several intermittent drug regimens. Acceptable relapse rates were achieved with streptomycin, isoniazid, and pyrazinamide given two or three times a week for four or six months, preceded by a two-month, multiple-drug, daily regimen, and various four-drug, pyrazinamide-containing intermittent regimens. The benefit of pyrazinamide in reducing the relapse rate with SCC was confirmed by studies of the British Thoracic and Tuberculosis Association. Few studies of SCC have been conducted in the United States. Treatment practices in the United States are becoming more uniform, and SCC is being used more frequently for uncomplicated pulmonary tuberculosis. SCC will probably be used more widely in the future. Current guidelines of the Centers for Disease Control recommend treatment for nine months with isoniazid and rifampin, plus ethambutol in areas where resistance to isoniazid is common. In vitro data suggest that the addition of pyrazinamide may be more effective, but clinical experience with this drug in the United States is limited.     

Acute isoniazid toxicity and the need for adequate pyridoxine supplies

A 25-year-old, 54-kg Hispanic man who had recently started multidrug therapy for pulmonary tuberculosis presented in status epilepticus after ingesting 9 g of isoniazid in a suicide attempt. Successful management of this patient required collaboration between several institutions to provide the large amount of necessary intravenous pyridoxine. Ultimately, this single overdose depleted the supply of intravenous pyridoxine for a significant region of the state of Nebraska. Isoniazid is commonly used to treat tuberculosis, but it is encountered relatively infrequently as the cause of an acute overdose. Severe isoniazid overdoses may present as seizure activity that is refractory to conventional antiepileptic therapy. Although intravenous pyridoxine is an effective antidote for isoniazid overdoses in patients presenting with status epilepticus, this agent has few indications and is typically stocked in limited quantities. In regions with large populations of patients who receive antituberculosis therapy, collaborative networks must be created to ensure that adequate supplies of intravenous pyridoxine (> or = 20 g) are available for effective treatment of isoniazid poisonings.     

Genetically determined variability in acetylation and oxidation. Therapeutic implications

The clinical significance of two separate genetic polymorphisms which alter drug metabolism, acetylation and oxidation is discussed, and methods of phenotyping for both acetylator and polymorphic oxidation status are reviewed. Particular reference is made to the dapsone method, which provides a simple means of distinguishing fast and slow - and possibly intermediate - acetylators, and to the sparteine method which allows a clear separation of oxidation phenotypes. Although acetylation polymorphism has been known for some time, definite indications for phenotyping are few. It is doubtful whether acetylator phenotype makes a significant difference to the outcome in most isoniazid treatment regimens, and peripheral neuropathy from isoniazid in slow acetylators is easily overcome by pyridoxine administration. However, in comparison with rapid acetylators, slow acetylators receiving isoniazid have an increased susceptibility to phenytoin toxicity, and perhaps also to carbamazepine toxicity. It is also possible that rapid acetylators receiving isoniazid attain higher serum fluoride concentrations from enflurane and similar anaesthetics than do similarly treated slow acetylators. Thus, when drug interactions of these types are suspected, phenotyping for acetylator status may be advisable. If routine monitoring of serum procainamide and N-acetylprocainamide concentrations is practised, phenotyping of subjects prior to therapy with these agents should not be necessary. Although acetylator phenotype influences serum concentrations of hydralazine, when this drug is given in combination with other drugs acetylator phenotype has not been shown to influence the therapeutic response. Slow acetylator phenotype along with female gender and the presence of HLA-DR antigens appear to be risk factors in the development of hydralazine-induced systemic lupus erythematosus (SLE). Determination of acetylator phenotype may therefore help determine susceptibility to this adverse reaction. In the case of sulphasalazine, adult slow acetylators require a lower daily dose of the drug than fast acetylators in order to maintain ulcerative colitis in remission without significant side effects. It is therefore advisable to determine acetylator phenotype prior to sulphasalazine therapy. Work on the association of acetylation polymorphism with various disease states is also reviewed. It is possible that a higher incidence of bladder cancer is associated with slow acetylation phenotype - especially in individuals exposed to high levels of arylamines. The question as to whether idiopathic SLE is more common in slow acetylators remains unresolved. There appears to be no difference between fa     

Role of hydrazine in isoniazid-induced hepatotoxicity in a hepatocyte inflammation model

Isoniazid is an anti-tuberculosis drug that can cause hepatotoxicity in 20% of patients that is usually associated with an inflammatory response. Hepatocytes when exposed to non-toxic levels of H2O2, to simulate H2O2 formation by inflammatory cells, became twice as sensitive to isoniazid toxicity. Isoniazid cytotoxicity was prevented by 1-aminobenzotriazole, a non-selective P450 inhibitor or by bis-p-nitrophenyl phosphate (BNPP), an esterase inhibitor. Moreover, the cytotoxicity of hydrazine, the metabolite formed by amidase-catalyzed hydrolysis of isoniazid, was increased 16-fold by a non-toxic H2O2-generating system. The acetylhydrazine metabolite was found to be much less cytotoxic than hydrazine in this hepatocyte inflammation model. Hydrazine, therefore, seems to be the isoniazid reactive metabolite in this inflammation model. The molecular mechanism of hydrazine-induced cytotoxicity was attributed to oxidative stress as reactive oxygen species (ROS) and protein carbonyl formation occurred before the onset of hepatocyte toxicity. Hydrazine toxicity also involved significant production of endogenous H2O2 which resulted in lysosomal membrane damage and leads to a collapse in mitochondrial membrane potential. These results implicated H2O2, a cellular mediator of inflammation, as a potential risk factor for the manifestation of adverse drug reactions, particularly those caused by hydrazine containing drugs.     

Extracorporeal treatments for isoniazid poisoning: Systematic review and recommendations from the EXTRIP workgroup

Isoniazid toxicity from self-poisoning or dosing errors remains common in regions of the world where tuberculosis is prevalent. Although the treatment of isoniazid poisoning is centered on supportive care and pyridoxine administration, extracorporeal treatments (ECTRs), such as hemodialysis, have been advocated to enhance elimination of isoniazid. No systematic reviews or evidence-based recommendations currently exist on the benefit of ECTRs for isoniazid poisoning. The Extracorporeal Treatments in Poisoning (EXTRIP) workgroup systematically collected and rated the available evidence on the effect of and indications for ECTRs in cases of isoniazid poisoning. We conducted a systematic review of the literature, screened studies, extracted data on study characteristics, outcomes, and measurement characteristics, summarized findings, and formulated recommendations following published EXTRIP methods. Forty-three studies (two animal studies, 34 patient reports or patient series, and seven pharmacokinetic studies) met inclusion criteria. Toxicokinetic or pharmacokinetic analysis was available for 60 patients, most treated with hemodialysis (n = 38). The workgroup assessed isoniazid as “Moderately Dialyzable” by hemodialysis for patients with normal kidney function (quality of evidence = C) and “Dialyzable” by hemodialysis for patients with impaired kidney function (quality of evidence = A). Clinical data for ECTR in isoniazid poisoning were available for 40 patients. Mortality of the cohort was 12.5%. Historical controls who received modern standard care including appropriately dosed pyridoxine generally had excellent outcomes. No benefit could be extrapolated from ECTR, although there was evidence of added costs and harms related to the double lumen catheter insertion, the extracorporeal procedure itself, and the extracorporeal removal of pyridoxine. The EXTRIP workgroup suggests against performing ECTR in addition to standard care (weak recommendation, very low quality of evidence) in patients with isoniazid poisoning. If standard dose pyridoxine cannot be administered, we suggest performing ECTR only in patients with seizures refractory to GABA_A receptor agonists (weak recommendation, very low quality of evidence).     

Simultaneous determination of rifampicin, isoniazid and pyrazinamide in tablet preparations by multivariate spectrophotometric calibration

The use of multivariate spectrophotometric calibration is presented for the simultaneous determination of the active components of tablets used in the treatment of pulmonary tuberculosis. The resolution of ternary mixtures of rifampicin, isoniazid and pyrazinamide has been accomplished by using partial least squares (PLS-1) regression analysis. Although the components show an important degree of spectral overlap, they have been simultaneously determined with high accuracy and precision, rapidly and with no need of nonaqueous solvents for dissolving the samples. No interference has been observed from the tablet excipients. A comparison is presented with the related multivariate method of classical least squares (CLS) analysis, which is shown to yield less reliable results due to the severe spectral overlap among the studied compounds. This is highlighted in the case of isoniazid, due to the small absorbances measured for this component.     

Treatment of tuberculous infection and disease in children: the North American perspective

The standard preventive therapy for paediatric patients with tuberculous infection centres on isoniazid therapy. The chosen regimen of isoniazid therapy is based on individual patient factors. In the case of known or suspected resistance, combination therapy [e.g. isoniazid and rifampicin (rifampin)] or alternative therapies (e.g. pyrazinamide, a fluoroquinolone and/or ethambutol) should be employed. The goal of treatment of tuberculous disease is to achieve sterilisation in the shortest possible time. More intensive multiple drug combination regimens (e.g. isoniazid, rifampicin and pyrazinamide) have resulted in successful 6- and 9-month treatment regimens in children. If drug resistance is suspected then a fourth drug is added to the initial treatment regimen and the length of therapy may be extended to 18 months. The paediatric information available on the commonly used antituberculous agents (e.g. isoniazid, rifampicin, pyrazinamide and ethambutol) is reviewed in this article. Agents are described with an emphasis on their formulation availability, mechanism of action, pharmacokinetic properties (e.g. absorption, distribution, metabolism and elimination), adverse effects, and interactions (e.g. drug-drug, drug-food and drug-disease).     

异烟肼致肝脏毒性的蛋白质组学分析

 目的：应用蛋白质组学技术研究异烟肼致大鼠肝脏损伤时肝脏蛋白质表达谱的变化,为从分子水平上寻找毒性损伤标志物以及阐明异烟肼毒性机制奠定基础。方法：将Wistar大鼠随机分为生理盐水正常对照组和异烟肼组（400 mg?kg-1）,分别连续灌胃14 d后处死大鼠,提取肝脏总蛋白,双向凝胶电泳分离蛋白质组成分,采用考马斯亮蓝R-250染色,经ImageMaster 2D Platinum 5.0软件分析比较两组图谱,并对差异蛋白斑点进行基质辅助激光解吸/电离飞行时间质谱(MALD-TOF-MS)分析鉴定。结果：发现11个差异有统计学意义的蛋白质点,鉴定出8个蛋白,其中,异烟肼处理组比对照组表达升高的蛋白质有鸟氨酸转氨酶、葡萄糖调节蛋白、乙醛脱氢酶和3α-羟甾类脱氢酶,比对照组表达降低的蛋白质有抗氧化酶B166、谷胱苷肽转硫酶、醛铜还原酶和碳酸酐酶。结论：异烟肼可能造成肝脏抗氧化系统和氧化应激异常,这对阐明异烟肼的肝损伤机制具有十分重要的作用。     

Drug treatment of tuberculosis--1992.

The impact of the acquired immunodeficiency syndrome (AIDS) pandemic has made tuberculosis an increasing worldwide problem, and the effectiveness of modern chemotherapy has been blunted by the high incidence of primary drug resistance, especially in developing countries. The prospect of finding new and highly effective drugs similar to isoniazid or rifampicin is dim, yet the maximum benefits from the existing drugs which are highly effective have not been received. A 6-month regimen of isoniazid plus rifampicin, supplemented by pyrazinamide during the first 2 months, for treatment of uncomplicated tuberculosis is highly effective and the regimen of choice. Ethambutol should be added if the risk of isoniazid resistance is increased. A regimen of isoniazid, rifampicin, pyrazinamide and streptomycin for 4 months provides effective defence against smear-negative pulmonary tuberculosis. Re-treatment of multiple drug-resistant tuberculosis remains a difficult therapeutic problem. At least 3 drugs that the patient has never previously received, and that are effective according to laboratory susceptibility testing, must be used. Preventive therapy against tuberculosis is accomplished with isoniazid for 6 to 12 months, although rifampicin plus isoniazid for 3 months has been used in the United Kingdom with success. In a mouse model, rifampicin plus pyrazinamide for 2 months is more effective than isoniazid for 6 months as preventive treatment. Patient noncompliance with medication remains the biggest problem in tuberculosis control, and is a complex issue. It can only be resolved by multiple approaches. Intermittent directly observed short course chemotherapy is a major, but not the only, possible solution.     

Transdermal delivery of isoniazid and rifampin in guinea pigs by electro-phonophoresis

Electro-phonophoresis (EP) has been used as a drug delivery approach in clinical fields. The objective of the present study is to evaluate the skin permeability of isoniazid and rifampin in guinea pigs by EP to provide reference basis for clinical applications of such transdermal delivery system in the treatment of patients with superficial tuberculosis. Isoniazid and rifampin solutions were delivered transdermally with or without EP in health guinea pigs for 0.5?h. Local skin and blood samples were collected serially at 0, 1/2, 1, 2, 4, 6 and 24?h after dosing. Drug concentrations in local skin and blood were evaluated by high-performance liquid chromatography. Isoniazid concentrations in local skin of guinea pigs receiving isoniazid through EP transdermal delivery were significantly higher than in animals receiving only isoniazid with transdermal patch. However, for rifampin, patches alone group presented almost uniform concentration versus time curve with that of EP group, and both groups had concentrations much higher than the therapeutic concentration of the drug over sustainable time. After EP transdermal delivery, the mean peak concentrations of isoniazid and rifampin in skin were 771.0?±?163.4?μg/mL and 81.2?±?17.3?μg/mL respectively. Neither isoniazid nor rifampin concentration in blood could be detected (below the lower detection limit of 1?μg/mL) at any time point. The present study showed that application of EP significantly enhanced INH penetration through skin in guinea pigs, while RIF patch alone obtained therapeutic concentration in local skin. Our work suggests several possible medication approaches for efficient treatment of superficial tuberculosis.     

A rare case of isoniazid-induced erythroderma

Tuberculosis is a common infectious disease in developing countries. Isoniazid is established the first-line antitubercular drug and an essential component of all antitubercular regimens. Erythroderma caused by isoniazid is an uncommon but serious adverse drug reaction. We report here a case of a 63-year-old female patient who presented with generalized redness and scaling with itching after 8 weeks of antitubercular treatment (ATT). ATT was stopped immediately, and antihistaminics were started. The patient improved over a period of 2 weeks. On sequential rechallenge, she developed similar lesions all over the body with isoniazid, hence confirming the diagnosis of isoniazid-induced erythroderma.KEY WORDS: Adverse cutaneous drug reaction, erythroderma, isoniazid     

Drug treatment for tuberculosis during pregnancy: safety considerations.

Untreated tuberculosis in pregnancy poses a significant threat to the mother, fetus and family. Adherence to treatment is especially difficult in pregnancy because of the general fear of any medication and pregnancy-related nausea. Supervised treatment is especially helpful in encouraging adherence. All 4 first line drugs [isoniazid, rifampicin (rifampin), ethambutol and pyrazinamide] have an excellent safety record in pregnancy and are not associated with human fetal malformations. Drug-induced hepatitis, especially with isoniazid, is a significant problem in treating tuberculosis, not peculiar to pregnancy; close monitoring of liver function is recommended. Liver enzyme induction by rifampicin alters the metabolism of other drugs, e.g. methadone doses will need to be increased. Streptomycin should not be used in pregnancy, as perhaps 1 in 6 babies will have problems with hearing and/or balance. Ciprofloxacin has the best safety profile of second line drugs in the treatment of drug-resistant tuberculosis. Preventive treatment with isoniazid can be undertaken safely during pregnancy. Pyridoxine (vitamin B6) should be added to the drug treatment of tuberculosis in all pregnant women taking isoniazid. Neither tuberculin nor the bacille Calmette Guérin (BCG) vaccine are treatments for tuberculosis, but they play an important role in the management of the disease. Tuberculin testing is safe, but BCG vaccination should be avoided in pregnancy and instead given earlier in life.