ABSTRACT
Tuberculosis (TB) is an important infectious disease caused by Mycobacterium tuberculosis (Mtb) and responsible for thousands of deaths every year. Although there are antimycobacterial drugs available in therapeutics, just few new chemical entities have reached clinical trials, and in fact, since introduction of rifampin only two important drugs had reached the market. Pyrazinoic acid (POA), the active agent of pyrazinamide, has been explored through prodrug approach to achieve novel molecules with anti-Mtb activity, however, there is no activity evaluation of these molecules against non-replicating Mtb until the present. Additionally, pharmacokinetic must be preliminary evaluated to avoid future problems during clinical trials. In this paper, we have presented six POA esters as prodrugs in order to evaluate their anti-Mtb activity in replicating and non-replicating Mtb, and these showed activity highly influenced by medium composition (especially by albumin). Lipophilicity seems to play the main role in the activity, possibly due to controlling membrane passage. Novel duplicated prodrugs of POA were also described, presenting interesting activity. Cytotoxicity of these prodrugs set was also evaluated, and these showed no important cytotoxic profile.
Subject(s)
Antitubercular Agents/pharmacology , Esters/pharmacology , Mycobacterium tuberculosis/drug effects , Prodrugs/pharmacology , Pyrazinamide/analogs & derivatives , Animals , Antitubercular Agents/chemical synthesis , Antitubercular Agents/toxicity , Cell Proliferation/drug effects , Chlorocebus aethiops , Dose-Response Relationship, Drug , Esters/chemical synthesis , Esters/toxicity , Inhibitory Concentration 50 , Microbial Sensitivity Tests , Microbial Viability/drug effects , Molecular Structure , Mycobacterium tuberculosis/growth & development , Prodrugs/chemical synthesis , Prodrugs/toxicity , Pyrazinamide/chemical synthesis , Pyrazinamide/pharmacology , Pyrazinamide/toxicity , Structure-Activity Relationship , Vero CellsABSTRACT
La toxicidad hepática en pacientes tratados con drogas antituberculosas es relativamente infrecuente, probablemente debido a este hecho no contamos con una buena definición de toxicidad hepática. Existen algunas condiciones de los enfermos en que la hepatotoxicidad es más frecuente, tales como pacientes envejecidos, bebedores de alcohol, desnutrición, uso de ciertas drogas e hipoalbuminemia. Las drogas antituberculosas más frecuentemente involucradas en hepatotoxicidad son la pirazinamida, la isoniacida y la rifampicina. En este artículo analizamos el problema clínico de la hepatotoxicidad de la terapia antituberculosa y proponemos el manejo de diferentes situaciones. Discutimos cuando se debe suspender la administración de una droga, cómo se debe evaluar el daño hepático y qué drogas alternativas pueden usarse durante el tratamiento de la tuberculosis.
Liver toxicity in patients being treated with antituberculosis drugs is relatively uncommon, although transient elevation of liver enzymes is very common. Probably because of this there is not a good definition for liver toxicity. There are conditions in which hepatotoxicity is more frequent, such as elderly patients, alcohol consumption, malnutrition, use of certain drugs, and hypoalbuminemia. Pirazinamide, isoniazid and rifampicin are the antituberculosis drugs more commonly involved in liver toxicity. In this article we analyze the clinical problem of hepatotoxicity of antituberculosis therapy and propose the management of different situations. We discuss when a drug administration should be discontinued, how liver damage should be assesed and which alternative drugs should be used during the antituberculosis treatment.
Subject(s)
Humans , Antitubercular Agents/toxicity , Isoniazid/toxicity , Liver Diseases , Pyrazinamide/toxicity , Rifampin/toxicity , Tuberculosis/drug therapy , Antitubercular Agents/adverse effects , Isoniazid/adverse effects , Pyrazinamide/adverse effects , Risk Factors , Rifampin/adverse effectsABSTRACT
The phototoxic antitubercular drug pyrazinamide (1) is photolabile under irradiation with UV-A light as well as with a N2 laser (at 337 nm) in aerobic conditions. Irradiation in methanolic and in aqueous solutions of 1 produces four and three photoproducts, respectively. Their formation involves primary alpha-cleavage between the excited carbonyl of the amido group and the aromatic ring followed by hydrogen abstraction and dimerization. Pyrazinamide was able to cause photohemolysis in human erythrocytes and peroxidation of linoleic acid. Inhibition of both processes on addition of reduced glutathione (GSH) or ascorbic acid suggests the involvement of radicals. The absence of inhibition of the photohemolysis and lipid peroxidation processes in the presence of sodium azide (NaN3), or irradiation under argon, and the absence of singlet oxygen during the photolysis confirmed with 2,5-dimethylfuran rules out the possibility of participation of 1O2 in this process. Glutathione depletion was also observed. A radical intermediate was evidenced by thiobarbituric acid that was used as a radical probe, as well as by the dimerization of cysteine. No photohemolysis was detected in presence of the isolated photoproduct. We have also determined the relative efficiencies for the formation of single strand breaks after the irradiation of pBR322 DNA and pyrazinamide, which was also reduced in the presence of GSH.
Subject(s)
Antitubercular Agents/radiation effects , Photolysis/radiation effects , Pyrazinamide/radiation effects , Antitubercular Agents/toxicity , Dermatitis, Phototoxic/metabolism , Erythrocytes/drug effects , Erythrocytes/radiation effects , Humans , Photolysis/drug effects , Pyrazinamide/toxicity , Ultraviolet Rays/adverse effectsABSTRACT
To evaluate the risk factors involved in antituberculosis treatment-induced hepatotoxicity. In a retrospective study we analyzed the rate of drug-induced hepatotoxicity in a sample of 456 patients. Patients received a combination of drugs including isoniazid, rifampin, pirazinamide and streptomycinor or ethambutol. The association among hepatotoxicity and several risk factors (age, sex, alcoholism and HIV infection) was studied by univariate methods, stratified analysis and the multiple logistic regression model. Signs of liver injury were found in 9.86 percent of the treated patients. In the logistic model, the adjusted odds ratios (OR) and significance were found as follows: a) for alcoholism, OR=17.31 (95 percent CI:6.35-47.16), p<0.001; b) for HIV infection, OR=3.23 (95 percent CI:1.47-7.11), p=0.003 and c) for female Sex, OR=2.44 (95 percent CI:1.22-4.86), p=0.011. Age was not significantly associated with hepatotoxicity. Alcoholism, HIV infection and female sex were associated with an increased risk of hepatotoxicity in this study.
Subject(s)
Humans , Male , Female , Child , Adolescent , Adult , Middle Aged , Antitubercular Agents/toxicity , Liver Diseases/chemically induced , Liver/drug effects , Alcoholism , Ethambutol/toxicity , HIV Infections , Isoniazid/toxicity , Liver/metabolism , Logistic Models , Pyrazinamide/toxicity , Retrospective Studies , Rifampin/toxicity , Risk Factors , Sex Factors , Streptomycin/toxicityABSTRACT
To evaluate the risk factors involved in antituberculosis treatment-induced hepatotoxicity. In a retrospective study we analyzed the rate of drug-induced hepatotoxicity in a sample of 456 patients. Patients received a combination of drugs including isoniazid, rifampin, pirazinamide and streptomycinor or ethambutol. The association among hepatotoxicity and several risk factors (age, sex, alcoholism and HIV infection) was studied by univariate methods, stratified analysis and the multiple logistic regression model. Signs of liver injury were found in 9.86 percent of the treated patients. In the logistic model, the adjusted odds ratios (OR) and significance were found as follows: a) for alcoholism, OR=17.31 (95 percent CI:6.35-47.16), p<0.001; b) for HIV infection, OR=3.23 (95 percent CI:1.47-7.11), p=0.003 and c) for female Sex, OR=2.44 (95 percent CI:1.22-4.86), p=0.011. Age was not significantly associated with hepatotoxicity. Alcoholism, HIV infection and female sex were associated with an increased risk of hepatotoxicity in this study. (AU)