Pyrazinamide In Patients Research Articles

Effect of Metformin on Plasma Exposure of Rifampicin, Isoniazid, and Pyrazinamide in Patients on Treatment for Pulmonary Tuberculosis.

To evaluate the effect of metformin on the plasma levels of rifampicin, isoniazid, and pyrazinamide in patients with drug-sensitive pulmonary tuberculosis being treated with first-line antituberculosis treatment (ATT) and to assess the influence of gene polymorphisms on the metabolic pathway of metformin and plasma levels of antitubercular drugs. Nondiabetic adults aged 18-60 years with pulmonary tuberculosis were randomized to either the standard ATT (ATT group) or ATT plus metformin (METRIF group) groups in a phase IIB clinical trial. An intensive pharmacokinetic study with blood collection at 0 hour (predosing), followed by 1, 2, 4, 6, 8, and 12 hours after dosing was conducted during the first month of treatment in a subset of 60 study participants after a minimum of 14 doses. Plasma concentrations of rifampicin, isoniazid, pyrazinamide, and metformin were measured by high-performance liquid chromatography using validated methods, and pharmacokinetic parameters and OCT1 and MATE1 gene polymorphisms were compared between the groups. Significant increases in the clearance of rifampicin, isoniazid, and pyrazinamide were observed in patients in the METRIF group (n = 29) compared with those in the ATT group (n = 31). The AA genotypes of the single-nucleotide polymorphism of rs2289669 ( MATE1 ) in the METRIF group showed a significantly decreased area under the concentration-time curve to the last observation point and increased clearance of rifampicin. Metformin altered rifampicin and isoniazid plasma concentrations in patients receiving antituberculosis treatment for pulmonary tuberculosis with little effect on sputum conversion at the end of treatment. Studies with larger sample sizes are needed to understand host drug-drug interactions.

Population Pharmacokinetic Modelling and Limited Sampling Strategies for Therapeutic Drug Monitoring of Pyrazinamide in Patients with Tuberculosis.

Pyrazinamide is one of the first-line antituberculosis drugs. The efficacy of pyrazinamide is associated with the ratio of 24-h area under the concentration-time curve (AUC24) to MIC. The objective of this study was to develop and validate a limited sampling strategy (LSS) based on a population pharmacokinetic (popPK) model to predict AUC24. A popPK model was developed using an iterative two-stage Bayesian procedure and was externally validated. Using data from 20 treatment-naive adult tuberculosis (TB) patients, a one compartment model with transit absorption and first-order elimination best described pyrazinamide pharmacokinetics and fed state was the only significant covariate for absorption rate constant (ka). External validation, using data from 26 TB patients, showed that the popPK model predicted AUC24 with a slight underestimation of 2.1%. LSS were calculated using Monte Carlo simulation (n = 10,000). External validation showed LSS with time points 0 h, 2 h, and 6 h performed best with RMSE of 9.90% and bias of 0.06%. Food slowed absorption of pyrazinamide, but did not affect bioavailability, which may be advantageous in case of nausea or vomiting in which food can be used to diminish these effects. In this study, we successfully developed and validated a popPK model and LSS, using 0 h, 2 h, and 6 h postdose samples, that could be used to perform therapeutic drug monitoring (TDM) of pyrazinamide in TB patients.

Establishing Population Pharmacokinetic Model for Pyrazinamide in Pulmonary Tuberculosis Patients

In this study, a reasonable population pharmacokinetic model with influencing covariates for pyrazinamide was established based on the data of 129 pulmonary tuberculosis patients in 3 hospitals: Hanoi Lung Hospital, K74 Hospital, and Central Lung Hospital. Blood samples were obtained on the 10-14th day after initiation of treatment. Time-concentration data were incorporated into the software MONOLIX 2019R2 for model building by non-linear mixed effect modeling method. The final population pharmacokinetic model is a one-compartment model, first-order absorption with lag time (Ka = 3.99 h-1, Tlag = 0.445 h), linear elimination, volume of distribution V = 27.5 L, and clearance rate Cl = 2.65 L/h. Janmahasatian’s Fat-free mass was found to be influential to the inter-individual variability of volume of distribution and rate of clearance.
 Keywords
 Population pharmacokinetic, pyrazinamide, pulmonary tuberculosis, fat-free mass.
 References
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Evaluating the Frequency of Resistance to Pyrazinamide Among Drug-resistant Strains of Mycobacterium tuberculosis in Isfahan, Iran

Background: Pyrazinamide is one of the most important first-line medications for the treatment of tuberculosis and an alternative intake for MDR-TB and XDR-TB patients. Objectives: The purpose of this study was to evaluate resistance to pyrazinamide in the isolates resistant to the Mycobacterium tuberculosis drug in patients in the city of Isfahan. Methods: In this study, the drug susceptibility test was performed with pyrazinamide using the proportion method and PZA assay on 47 isolates resistant to Mycobacterium tuberculosis. Then, the mutations of the pncA and rpsA genes of the isolates resistant to pyrazinamide were evaluated by the sequencing method. Results: According to the proportion method, 19 cases were resistant to pyrazinamide, 16 of which had mutations in their pncA and rpsA genes. Besides, five new mutations were recorded, and three isolates lacked mutations in the mentioned genes. Conclusions: Pyrazinamide resistance is high in MDR-TB and INH mono-resistant isolates. Therefore, evaluating the susceptibility to pyrazinamide in patients with MDR-TB before the initiation of treatment with pyrazinamide is considered essential.

Simultaneous determination of first-line anti-tuberculosis drugs and one metabolite of isoniazid by liquid chromatography/tandem mass spectrometry in patients with human immunodeficiency virus-tuberculosis coinfection

The incidence rate of tuberculosis (TB) in patients with human immunodeficiency virus (HIV) infection is 26 times higher than that in other patients. Patients with both infections require long-term combination therapy, which increases therapy complexity and might lead to serious adverse reactions and drug-drug interactions. To optimize therapy for patients with HIV and TB coinfection, we developed an ultra-high-performance liquid chromatography/tandem mass spectrometry (UHPLC-MS/MS) method to simultaneously quantify four anti-tuberculosis drugs and one isoniazid (INH) metabolite. Blood samples (n = 32) from 16 patients with HIV and TB coinfection were collected. Plasma protein precipitation with acetonitrile was followed by a hydrazine reaction between INH and cinnamaldehyde (CA) to produce phenylhydrazone (CA-INH) and dilution with heptafluorobutyric acid. The separation was performed on an Acquity UHPLC HSS T3 1.8 μm column (2.1 × 100 mm, Waters) with a mobile phase consisting of 10 mmol/L ammonium formate (pH = 4) in water (solvent A) and 0.1 % formic acid in methanol (solvent B) in a gradient elution. The compounds were detected using a positive multiple reaction monitoring model. INH, acetyl-INH (AC-INH), rifampicin (RIF), ethambutol (EMB), and pyrazinamide (PZA) showed good linear relationships in their quantitative ranges, with lower limits of quantification of 48, 192, 200, 96, and 480 ng/mL, respectively. The inter- and intraday precision was within 15 %, and the accuracy was between 85 % and 115 %. The mean plasma concentrations of INH, AC-INH, RIF, EMB, and PZA in patients were 1990.23 (24–16 600), 863.06 (96–2880), 3507.05 (229–9800), 808.10 (149–2130), and 18 838.33 (240–34 800) ng/mL, respectively. The plasma concentrations detected in the 16 patients were lower than the targeted concentrations in HIV-negative TB patients. In summary, we developed a simple UHPLC-MS/MS method for simultaneous quantification of first-line TB drugs, and successfully applied it for therapeutic drug monitoring in patients with HIV and TB coinfection. This method will facilitate monitoring of TB drugs in the future.

Population Pharmacokinetic Modelling of Pyrazinamide and Pyrazinoic Acid in Patients with Multi-Drug Resistant Tuberculosis.

Pyrazinamide, a drug used in the regimen for the treatment of drug-sensitive tuberculosis, is also used for the treatment of multidrug-resistant tuberculosis (MDR-TB). We aimed to describe the population pharmacokinetics of pyrazinamide and its major metabolite, pyrazinoic acid, in patients with MDR-TB and characterise the effects of demographic variables. This was a non-randomised clinical study involving 51 adult patients admitted for the intensive phase of MDR-TB treatment. Blood samples were collected at pre-dose and at 0.5, 1, 1.5, 2, 3, 4, 8, 16 and 24h after drug administration. Plasma concentrations of pyrazinamide and pyrazinoic acid were analysed using a validated LC-MS/MS method. Nonlinear mixed-effects modelling using Monolix 2018R1 software was employed to estimate population pharmacokinetic parameters. A one-compartment pharmacokinetic model with transit compartment absorption process and first-order elimination best described the pyrazinamide and pyrazinoic acid concentration-time data. The estimated population pharmacokinetic parameters were 0.7h, 3.38h-1, 57.1l, 4.37L/h and 10.5L/h for mean transit time, absorption rate constant, apparent distribution volume for pyrazinamide, and apparent clearance for pyrazinamide and pyrazinoic acid (CLm/F), respectively. These parameters were not affected by patient age, HIV status or sex. The parameter variability in CLm/F was the highest (83.5%), while the rest of the parameters ranged from 16.2 to 58%. The developed population pharmacokinetic model adequately described the disposition of pyrazinamide and pyrazinoic acid and can be useful for dose determination of pyrazinamide in patients with MDR-TB.

Risk of Cardiovascular Event and Influence of Pyrazinamide in Patients With Active TB in South Korea: A Population-Based Cohort Study

Risk of Cardiovascular Event and Influence of Pyrazinamide in Patients With Active TB in South Korea: A Population-Based Cohort Study

Population Pharmacokinetics of Pyrazinamide in Patients with Tuberculosis.

The current treatment used for tuberculosis (TB) is lengthy and needs to be shortened and improved. Pyrazinamide (PZA) has potent sterilizing activity and has the potential to shorten the TB treatment duration, if treatment is optimized. The goals of this study were (i) to develop a population pharmacokinetic (PK) model for PZA among patients enrolled in PK substudies of Tuberculosis Trial Consortium (TBTC) trials 27 and 28 and (ii) to determine covariates that affect PZA PK. (iii) We also performed simulations and target attainment analysis using the proposed targets of a maximum plasma concentration (Cmax) of >35 μg/ml or an area under the concentration-versus-time curve (AUC) of >363 μg · h/ml to see if higher weight-based dosing could improve PZA efficacy. Seventy-two patients participated in the substudies. The mean (standard deviation [SD]) Cmax was 30.8 (7.4) μg/ml, and the mean (SD) AUC from time zero to 24 h (AUC0-24) was 307 (83) μg · h/ml. A one-compartment open model best described PZA PK. Only body weight was a significant covariate for PZA clearance. Women had a lower volume of distribution (V/F) than men, and both clearance (CL/F) and V/F increased with body weight. Our simulations show that higher doses of PZA (>50 mg/kg of body weight) are needed to achieve the therapeutic target of an AUC/MIC of >11.3 in >80% of patients, while doses of >80 mg/kg are needed for target attainment in 90% of patients, given specific assumptions about MIC determinations. For the therapeutic targets of a Cmax of >35 μg/ml and/or an AUC of >363 μg · h/ml, doses in the range of 30 to 40 mg/kg are needed to achieve the therapeutic target in >90% of the patients. Further clinical trials are needed to evaluate the safety and efficacy of higher doses of PZA.

Hepatotoxicity due to rifampicin, isoniazid and pyrazinamide in patients with tuberculosis: Is anti-HCV a risk factor?

Background and Rationale. Among the adverse events related to tuberculosis treatment, hepatotoxicity is the most serious, and recognition of risk factors for it is essential to achieve successful therapy. The aim of the study is to evaluate the role of anti-HCV as a risk factor for hepatotoxicity in hospitalized patients under tuberculosis treatment with rifampicin, isoniazid and pyrazinamide (RHZ).Methods. Historical cohort study carried out at Hospital Sanatório Partenon, from 1998 to 2006. Patients aged 18 years or older, tested for anti-HCV, who presented normal pre-treatment aminotransferases (AST, ALT) and bilirrubin and who used RHZ during hospitalization were included in the study. Individuals who used anti-tuberculosis drugs six months prior to hospitalization, had clinical evidence of chronic liver disease or showed previous history of hepatotoxicity to RHZ were excluded.Results. A sample of 534 patients was studied. The incidence of hepatotoxicity was 8.8% (n = 47). After univariate analysis, the following variables were associated to hepatotoxicity: anti-HIV positive, anti-HCV positive, use of antiretroviral therapy and high doses of rifampicin and isoniazid per kg of body weight (p < 0.05). When Cox regression was performed, anti-HIV positive [RR = 2.3 (IC95% 1.2-4.1); p = 0.008] and high doses of isoniazid per kg of body weight [RR = 1.3 (IC95% 1.1-1.7); p = 0.016] remained independently associated to development of hepatotoxicity.Conclusions. In conclusion, the anti-HIV positive and high doses of isoniazid were considered independent risk factors for hepatotoxicity due to RHZ esqueme in the present study. Though univariate analysis showed that anti-HCV was associated to the outcome, it was not identified as an independent risk factor for hepatotoxicity related to the use of RHZ when the analysis was controlled to HIV.

Intestinal barrier function and serum concentrations of rifampin, isoniazid and pyrazinamide in patients with pulmonary tuberculosis

Intestinal barrier function and serum concentrations of rifampin, isoniazid and pyrazinamide were studied in healthy controls and patients with active pulmonary tuberculosis. A case-control study of 29 controls and 30 cases attending at the Health Center, July, 2004 to December, 2005 was conducted. The body mass index was significantly reduced in cases compared to controls (p < 0.001). The intestinal paracellular transport of lactulose was significantly (p = 0.019) reduced in cases compared to controls. The transcellular transport of mannitol and the lactulose:mannitol ratio were not significantly (p = 0.0698) reduced in cases compared to controls. Low serum concentrations of rifampin, isoniazid and pyrazinamide were observed in 81% (48/59), 92% (54/59) and 28% (12/59), respectively, in all individuals. The results demonstrated a marked decrease on intestinal paracellular transport in patients with active pulmonary tuberculosis and reduced serum concentrations of rifampin and isoniazid in both groups.

Risk factors for side-effects of isoniazid, rifampin and pyrazinamide in patients hospitalized for pulmonary tuberculosis.

The aim of this study was to determine the current incidence of side-effects severe enough to cause intolerance of standard antituberculosis therapy with isoniazid, rifampin and pyrazinamide in patients hospitalized as a result of pulmonary tuberculosis. Five hundred and nineteen patients with proven pulmonary tuberculosis, who initially received standard antituberculosis therapy, were retrospectively studied in the department of infectious diseases in a teaching chest hospital. The incidence of severe side-effects related to the therapy, which led to the definitive termination of one of the three standard drugs, was measured and the risk factors for intolerance were analysed. Final termination of either isoniazid, rifampin or pyrazinamide because of severe side-effects was necessary in 121 of the 519 patients (23%). The most severe side-effects leading to final termination of one drug were hepatotoxicity (11%), exanthema (6%), and arthralgia (2%). Pyrazinamide showed more severe side-effects (15%) than isoniazid (7%) and rifampin (1.5%). Significant risk factors for intolerance of the standard therapy following a multivariate analysis were a history of hepatitis (odds ratio (OR) 3.4; 95% confidence interval (95% CI) 1.6-7.6; p = 0.0026) and an age > or = 60 yrs (OR 1.9; 95% CI 1.2-3.2; p = 0.017). Both of these risk factors were also significantly associated with the intolerance of pyrazinamide (history of hepatitis: OR 2.5; 95% CI 1.4-4.3; p = 0.0045; age > or = 60 yrs: OR 2.1, 95% CI 1.3-3.5; p = 0.0029) but not of isoniazid and rifampin. The side-effects of standard antituberculosis therapy are frequent in hospitalized patients aged > or = 60 yrs or with a history of previous hepatitis, and are probably due to pyrazinamide rather than to isoniazid or rifampin.

Effect of pyrazinamide on rifampicin kinetics in patients with tuberculosis

Rifampicin and pyrazinamide constitute an important part of drug regimens advocated for tuberculosis therapy, along with INH and streptomycin/ethambutol. The International Union against Tuberculosis and Lung Disease has also suggested the inclusion of these two drugs as part of short course chemotherapy for tuberculosis. Hence this study was undertaken to evaluate the influence of pyrazinamide on rifampicin kinetics when the two are given together. In a randomized, cross-over, single dose study, 16 patients with untreated pulmonary tuberculosis, after an overnight fast, were administered either rifampicin 450 mg + INH 300 mg (study A) or rifampicin 450 mg + INH 300 mg + pyrazinamide 1500 mg (study B). Blood samples were collected for serum rifampicin estimation at 0,0.5, 2,4,6 and 8 h. Various pharamcokinetic parameters (Cmax, Tmax, t 1 2 , Kel, area under plasma concentration time curve (AUC), Vd & Cpl of rifampicin) were calculated. It was observed that rifampicin concentration in study A in contrast to study B was significantly higher at 6 h ( P < 0.01) and 8 h ( P < 0.05), while there were no significant differences in serum rifampicin concentration at 0.5,2 and 4 h. A significant difference was also observed in AUC and Cpl. In study A, AUC was higher ( P < 0.05), while Cpl was lower ( P < 0.02), than in study B. From the above data it appears that on concomitant administration of pyrazinamide in patients on rifampicin therapy, AUC of rifampicin is decreased while its clearance is increased.

Absorption, metabolism and excretion of pyrazinamide in man

Countercurrent distribution studies demonstrated that after oral dosage with pyrazinamide only two nitroprusside-reacting compounds are excreted in the urine: unchanged pyrazinamide and its metabolite pyrazinoic acid.Sensitive and specific chemical methods are described for the determination of pyrazinamide and pyrazinoic acid in serum and urine, based on differential solvent extraction followed by reaction with alkaline nitroprusside.These methods were used to study the pharmacology of pyrazinamide in patients participating in a clinical trial in East Africa in which pyrazinamide (with streptomycin) was given in doses of 0·5 g. thrice daily, l·5 g. daily and 3 g. on alternate days. Peak serum concentrations of pyrazinamide occurred at about two hours and were proportional to the dose of pyrazinamide. On each of these regimens, patients excreted about 4% of the dose unchanged and about 30% as pyrazinoic acid. After three hours, serum pyrazinamide concentrations fell exponentially with half-lives having a mean of about six hours. The serum concentrations of pyrazinamide expected with each of the regimens were calculated and the clinical implication of these findings are discussed.Two detailed pharmacokinetic studies were also undertaken at an interval of three years on a healthy British subject, which demonstrated the constancy of the absorption, metabolism and excretion of pyrazinamide. The fall with time in the urinary excretion of pyrazinamide and pyrazinoic acid paralleled the decreasing serum concentrations of these compounds. In the serum, the maximum concentration of pyrazinoic acid was much less than that of the unchanged drug.