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Pyrazinamide-induced granulomatous hepatitis.

Noncaseating granulomatous hepatitis may be caused by a variety of drugs, but we have not found, by computer search of the literature, a previous describe of granulomatous hepatitis associated with pyrazinamide. We describe a 52-year-old man with hectic fever, chills, extreme fatigue, liver damage, and hyperuricemia about 4 weeks after commencing pyrazinamide therapy. A liver biopsy specimen showed noncaseating epithelioid granulomas. The patient recovered soon after the interruption of tuberculostatic treatment.

Antitubercular Agents↗

Pellagra probably due to pyrazinamide: development during combined chemotherapy of tuberculosis.

Pellagra secondary to antituberculous chemotherapy can result from isoniazide therapy, as well as from pyrazinamide treatment. Because of the similarity in structural formulas between pyrazinamide, isoniazide, and nicotinamide, the substrate competition is the mechanism most likely involved. The patient was cured by administration of nicotinamide during continued unchanged chemotherapy of her tuberculosis.

Adult↗

Radiometric method for pyrazinamide susceptibility testing of Mycobacterium tuberculosis in egg-yolk-enriched BACTEC 12A medium.

A radiometric method for testing the susceptibility of Mycobacterium tuberculosis to pyrazinamide in egg-yolk-enriched 12A medium (pH 5.5) is described. We obtained 100% agreement between the 7H10 agar method with 25 microgram of pyrazinamide per ml and the modified radiometric method with a drug concentration of 50 microgram/ml in tests of 90 clinical isolates.

Animals↗

Characterization of new mutations in pyrazinamide-resistant strains of Mycobacterium tuberculosis and identification of conserved regions important for the catalytic activity of the pyrazinamidase PncA.

A new set of mutations, including transposition of the insertion sequence IS6110, was identified in the pncA gene from 19 pyrazinamide-resistant Mycobacterium tuberculosis strains. Alignment of the PncA protein from M. tuberculosis with homologous proteins from different bacterial species revealed three highly conserved regions in PncA which may play an important role in the processing of pyrazinamide.

Amidohydrolases↗

pncA mutations in pyrazinamide-resistant Mycobacterium tuberculosis isolates from northwestern Russia.

Thirty-six pyrazinamide-resistant and eight pyrazinamide-susceptible Mycobacterium tuberculosis isolates from Russia were analyzed for their pncA mutations. Thirty-one (86.1%) of the resistant isolates had a mutation either in pncA or upstream of the gene. Twenty of the 23 different mutations found in this study had not been described earlier. pncA genotype correlated well with pyrazinamidase activity and BACTEC 460 susceptibility test results.

Amidohydrolases↗

Correlation between pyrazinamide activity and pncA mutations in Mycobacterium tuberculosis isolates in Taiwan.

A total of 76 clinical Mycobacterium tuberculosis isolates from Taiwan were tested for pyrazinamidase activity, pyrazinamide susceptibility, and pncA mutations. Frequency of resistance to PZA rose with increases in resistance to first-line drugs. Of 17 pyrazinamide-resistant strains, 7 (3 of which had not been previously described) possessed mutations in the pncA gene.

Amidohydrolases↗

Effects of pyrazinamide on fatty acid synthesis by whole mycobacterial cells and purified fatty acid synthase I.

The effects of low extracellular pH and intracellular accumulation of weak organic acids were compared with respect to fatty acid synthesis by whole cells of Mycobacterium tuberculosis and Mycobacterium smegmatis. The profile of fatty acids synthesized during exposure to benzoic, nicotinic, or pyrazinoic acids, as well as that observed during intracellular hydrolysis of the corresponding amides, was not a direct consequence of modulation of fatty acid synthesis by these compounds but reflected the response to inorganic acid stress. Analysis of fatty acid synthesis in crude mycobacterial cell extracts demonstrated that pyrazinoic acid failed to directly modulate the fatty acid synthase activity catalyzed by fatty acid synthase I (FAS-I). However, fatty acid synthesis was irreversibly inhibited by 5-chloro-pyrazinamide in a time-dependent fashion. Moreover, we demonstrate that pyrazinoic acid does not inhibit purified mycobacterial FAS-I, suggesting that this enzyme is not the immediate target of pyrazinamide.

Antitubercular Agents↗

Effects of pyrazinamide, probenecid, and benzbromarone on renal excretion of oxypurinol.

The effects of pyrazinamide, probenecid, and benzbromarone on renal excretion of oxypurinol were investigated. Pyrazinamide decreased the mean (SEM) fractional clearance of oxypurinol from 19.2 (2.1) to 8.8 (1.5). Probenecid increased the fractional clearance of oxypurinol from 14.1 (3.5) to 24.8 (4.1). Benzbromarone increased the fractional clearance of oxypurinol from 15.6 (2.3) to 33.8 (2.8). These results suggest that oxypurinol may be secreted by 'an organic acid system' and that oxypurinol is reabsorbed at a putative postsecretory site of the renal tubules.

Adult↗

Use of pyrazinamide to assess renal uric acid transport in the rat: a micropuncture study.

Free-flow micropuncture studies were performed to evaluate renal uric acid transport in control and pyrazinamide-treated rats. In all studies [2-14C]uric acid and [methoxy-3H]inulin were administered. [2-14C]uric acid was determined after column chromatographic separation from its labeled oxidation product in tubular fluid, plasma, and urine. Tubular fluid collections were obtained from the early and late proximal tubule under hydropenic conditions and from the early proximal tubule during volume expansion induced with 0.9% sodium chloride. These studies indicate that pyrazinamide, in the dose employed, provokes a uniform reduction in fractional uric acid excretion but simultaneously inhibits both net uric acid reabsorption and secretion in the early and late proximal tubule, respectively. In addition, these experiments unmasked uric acid reabsorption within the late proximal tubule and bidirectional transport beyond this nephron site. These studies also suggest at least two mechanisms for uric acid reabsorption; one sodium dependent, the other independent of sodium and water transport.

Animals↗

Familial hypouricemia due to isolated renal tubular defect. Attenuated response of uric acid clearance to probenecid and pyrazinamide.

A 37-year-old female was found to have hypouricemia (1.1-1.9 mg%) with markedly increased uric acid clearance (24.7039.5 ml/min). Uric acid excretion was only slightly affected by pyrazinamide, a drug which suppresses renal tubular uric acid secretion, and by probenecid, a drug which inhibits tubular uric acid reabsorption. The attenuated response in this subject to both drugs suggest a renal tubular defect in the proximal high capacity-high affinity uric acid reabsorption mechanism. No other renal tubular or metabolic abnormalities were detected. A survey of the family-three sisters and two brothers, revealed two similarly affected sisters. The abnormality described in this family is defined as familial renal hypouricemia due to an isolated renal tubular defect with attenuated response of uric acid clearance to probenecid and pyrazinamide.

Adult↗

Renal excretion of purine bases. Effects of probenecid, benzbromarone and pyrazinamide.

Experiments were conducted which revealed the renal transport mechanism(s) of oxypurines by employing uricosuric agents and pyrazinamide. All specimens being drawn from healthy, normal subjects, the data showed that probenecid increased fractional uric acid, fractional hypoxanthine and fractional xanthine clearance, 3.97-, 1.52- and 2.31-fold, respectively, while benzbromarone increased fractional uric acid clearance 2.11-fold, decreased fractional xanthine clearance 0.48-fold and had no effect on fractional hypoxanthine clearance. In addition, pyrazinamide decreased both fractional uric acid clearance 0.35-fold and fractional xanthine clearance 0.44-fold but increased fractional hypoxanthine clearance 1.49-fold. These results suggest the possibility of differing renal transport mechanisms among the purine bases, uric acid, hypoxanthine and xanthine.

Adult↗

Acceptability, compliance, and adverse reactions when isoniazid, rifampin, and pyrazinamide are given as a combined formulation or separately during three-times-weekly antituberculosis chemotherapy.

In Hong Kong, 627 adult Chinese patients with newly diagnosed pulmonary tuberculosis received, for the first 2 months of chemotherapy, streptomycin together with isoniazid, rifampin, and pyrazinamide allocated at random to be given either as a combined formulation or separately. Each tablet of the combined formulation, which was designed for intermittent use, contained 125 mg of isoniazid, 100 mg of rifampin, and 375 mg of pyrazinamide. Patients weighing 42 kg or less received 5 tablets per dose, 43 to 57 kg, 6 tablets per dose, and 58 kg or more, 7 tablets per dose. The dosage of each drug was very similar whether it was given combined or separately. During the 2 months, spontaneous complaints, the commonest of which were nausea and vomiting, were made by 38% of patients receiving the combined and 39% receiving the separate formulations; 1% compared with 5%, respectively, complained that the tablets or capsules were too many, too large, difficult to swallow or that they stuck in the throat (p less than 0.05), and 32% compared with 45% regularly brought their own drink (usually milk or fruit juice) to the clinic to help them swallow their medicament (p less than 0.01). Only 14% of patients in each group missed one or more doses through default. Reported adverse reactions were mainly trivial, 4% of patients receiving the combined and 7% receiving the separate formulations having the administration of one or more drugs terminated. Thus, the differences between the combined and separate formulations showed a small advantage to the combined formulation in terms of acceptability to patients.

Drug Administration Schedule↗

Assessment of a daily combined preparation of isoniazid, rifampin, and pyrazinamide in a controlled trial of three 6-month regimens for smear-positive pulmonary tuberculosis. Singapore Tuberculosis Service/British Medical Research Council.

In a study in Singapore 310 patients with sputum smear-positive pulmonary tuberculosis were allocated at random to daily chemotherapy with streptomycin, isoniazid, rifampin, and pyrazinamide (1) for 2 months (2SHRZ), (2) for 1 month (1SHRZ), or (3) for 2 months without streptomycin (2HRZ). This was followed for all patients by three times weekly isoniazid and rifampin to a total duration of 6 months. During the initial period of daily chemotherapy the patients were also allocated at random to be given their HRZ either as a combined formulation (Rifater), each tablet containing 50 mg isoniazid, 120 mg rifampin, and 300 mg pyrazinamide, or as three separate drugs. During the Rifater versus separate drugs comparison the most common spontaneous complaints were of nausea and vomiting, reported by 8% of 155 patients receiving Rifater and 7% of 155 separate drugs. Other adverse effects were also reported in similar proportions in the two series. Among 271 patients with drug-susceptible strains of tubercle bacilli pretreatment there were no bacteriologic failures during chemotherapy. During 18 months of subsequent follow-up bacteriologic relapse occurred in 3 (7%) of 46 2SHRZ, 2 (5%) of 42 1SHRZ, and 3 (8%) of 40 2HRZ patients allocated to Rifater and in 0 of 47 2SHRZ, 1 (2%) of 46 1SHRZ, and 1 (2%) of 44 2HRZ patients allocated to separate drugs. There was no evidence of therapeutic benefit from continuing SHRZ administration beyond 1 month or from adding streptomycin to HRZ. The relapse rates were slightly higher in the Rifater series (p = 0.04). Further follow-up and results from other studies are therefore needed fully to assess the combined preparation.

Adolescent↗

High hepatotoxicity of pyrazinamide and ethambutol for treatment of latent tuberculosis.

Pyrazinamide (PZA) combined with either ethambutol (EMB) or a fluoroquinolone for 6-12 months is one of the treatments recommended for latent tuberculosis infection (LTBI) in contacts exposed to multidrug-resistant tuberculosis (MDR-TB). The aim of the present study was to describe the side effects related to combined PZA and EMB treatment given for LTBI, in contacts previously exposed to MDR-TB. In total, 12 consecutive contacts, all of African origin and aged 38+/-5 yrs, were treated with daily PZA (23+/-4 mg.kg(-1)) and EMB (17+/-4 mg.kg(-1)) at Geneva University Hospital outpatient clinic (Switzerland), as a result of contact-tracing procedures for two patients with contagious MDR-TB. Clinical status and liver function tests (aspartate aminotransferase (ALAT) and alanine aminotransferase (ASAT)) were monitored monthly. In seven cases (58%) treatment was discontinued after a median of 119 days, due to hepatic toxicity in six cases (ALAT or ASAT elevation more than four times the upper normal limit), and gastrointestinal symptoms in one case. In conclusion, combined pyrazinamide and ethambutol for latent tuberculosis infection may be associated with a high risk of hepatic toxicity, and warrants close monitoring. There is clearly a need for alternative preventive treatments for contacts exposed to multidrug-resistant tuberculosis.

Adult↗

Initial experience on rifampin and pyrazinamide vs isoniazid in the treatment of latent tuberculosis infection among patients with silicosis in Hong Kong.

OBJECTIVE: To compare the adverse effects and treatment adherence between 2 months of rifampin plus pyrazinamide (2RZ) and 6 months of isoniazid (6H). BACKGROUND: Patients with silicosis in Hong Kong are at high risk of acquiring tuberculosis. A previous study showed that treatment with 6H reduced the risk of silico-tuberculosis by one half. METHOD: Patients with silicosis and a Mantoux skin test reaction > or =10 mm were randomized to receive either 2RZ or 6H daily. Liver function testing was done monthly during the initial 2 months. The adverse effects and treatment adherence were compared between the two regimens. RESULTS: Forty patients (mean age, 61.6 +/- 9.1 years) and 36 patients (mean age, 57.6 +/- 9.7 years) were randomized to the 2RZ and 6H arms, respectively (p > 0.05) [+/- SD]. Baseline characteristics were comparable. Nineteen patients in the 2RZ arm had peak alanine transaminase (ALT) levels > 1.5 times the upper limit of normal (ULN) in comparison with only five study subjects of the 6H arm (47.5% vs 13.9%, p < 0.01). Fourteen patients (35%) in the 2RZ arm and 1 patient (2.8%) in the 6H arm had peak ALT levels more than five times the ULN (p < 0.001). Only seven patients had symptoms suggestive of hepatitis; none of the patients had jaundice. All recovered after withholding treatment. In the 2RZ study arm, none of the baseline characteristics predicted hepatotoxicity. Other adverse effects were generally mild and comparable between both study arms. Treatment was stopped prematurely in 45% and 36.1% of patients in the 2RZ and 6H arms, respectively (p = 0.43). The main reasons were hepatotoxicity for the 2RZ arm and voluntary withdrawal after experiencing other minor adverse effects for the 6H arm. CONCLUSION: A higher incidence of hepatotoxicity was associated with rifampin plus pyrazinamide than isoniazid in the treatment of latent tuberculosis infection among patients with silicosis in Hong Kong.

Aged↗

A case of xanthinuria: a study on the metabolism of pyrazinamide and allopurinol.

A 74-year-old female was diagnosed as having xanthinuria by measurement of the uric acid level in plasma, purine bases in urine and activity of xanthine oxidase in the duodenal mucosa. The determination of the urinary excretion of purine bases in her family demonstrated a slightly increased urinary excretion of oxypurines in her younger brother, suggesting that he was a heterozygote. The pyrazinamide-loading test and allopurinol-loading test demonstrated that she could neither metabolize pyrazinoic acid into 5-hydroxypyrazinoic acid nor allopurinol into oxypurinol, although there was a slight metabolizing of prazinamide into 5-hydroxypyrazinamide. This suggested that she belonged to the subgroup which can neither metabolize pyrazinamide into 5-hydroxypyrazinamide, pyrazinoic acid into 5-hydroxypyrazinoic acid nor allopurinol into oxypurinol.

Aged↗

Effect of pyrazinamide and probenecid on peritoneal urate transport kinetics during continuous ambulatory peritoneal dialysis.

OBJECTIVE: We administered pyrazinamide (PZA) and probenecid (PB) --two well-known modulators of urate transport via the proximal tubules - to evaluate their impact on urate transport through the peritoneal membrane and to clarify mechanisms affecting peritoneal transport. SETTING: A continuous ambulatory peritoneal dialysis (CAPD) unit in 2nd Hospital of IKA (Social Services Institute), Greece. PATIENTS: In 20 stable CAPD patients, on the study day, a 4-hour, 2-L, 1.36% glucose exchange was performed (control exchange). Pyrazinamide 3 g was given orally and another identical exchange was performed (study exchange). The same protocol was repeated with 2 g PB. KtN, peritoneal clearances of urea, creatinine, and urate for each exchange, and mass transfer area coefficients (MTAC) for the three solutes and their dialysate-to-plasma concentration (D/P) ratios were used to estimate peritoneal transport. RESULTS: Administration of PZA resulted in decreased clearances and MTAC values for the three solutes. The D/P ratio decreased significantly only for urate, indicating a more intense influence of PZA on urate. After PB administration, clearances of urea, creatinine, and urate were increased. MTAC and DIP ratio increased significantly only for urate (p < 0.05), demonstrating an action similar to that exerted on renal tubules. CONCLUSIONS: These findings provide evidence that unrestricted diffusion is not the only transport mechanism in the case of urate, and demonstrate the existence of an active mechanism in peritoneal urate transport with a reabsorptive and, probably, a secretive component that resembles that of renal tubule urate transport. Attention should be given in the case of CAPD patients undergoing antituberculous (PZA) treatment: it might have a negative impact on urea, creatinine, and urate peritoneal transport rates.

Female↗

Pyrazinamide is not active against Mycobacterium tuberculosis residing in cultured human monocyte-derived macrophages.

SETTING: Mycobacteriology Laboratory, National Jewish Medical and Research Center, Denver, Colorado. OBJECTIVE: To evaluate the antimicrobial activity of pyrazinamide against Mycobacterium tuberculosis in cultured human monocyte-derived normal and activated macrophages. DESIGN: Monocytes separated from human blood were incubated in plastic plates for seven days to mature into macrophage monolayers. After activation with TNF-alpha or IFN-gamma or without prior treatment, the macrophages were infected with M. tuberculosis. Various concentrations of pyrazinamide (PZA), morphazinamide (MZA) or isoniazid (INH) were added the next day, and the viable counts of the intracellular bacteria were determined at days 0, 4, and 8. RESULTS: No inhibitory activity of PZA at any concentration was detected, while clear dose-dependent bacteriostatic and bactericidal activities were demonstrated by MZA and INH in the same experimental model. CONCLUSIONS: PZA has neither bacteriostatic nor bactericidal activity against M. tuberculosis persisting or multiplying in cultured monocyte-derived human macrophages, and it might be that the well-known effectiveness of this drug in tuberculosis patients is not related to its supposed activity against intracellular bacterial subpopulations.

Antitubercular Agents↗