PYRAZINAMIDE TABLET 500mg

Contents

Pyrazinamide

Source of information: Drugbank (External Link). Last updated on: 3rd July 18
*Trade Name used in the content below may not be the same as the HSA-registered product.

Active Ingredient / Synonyms

2-carbamylpyrazine | 2-pyrazinecarboxamide | Aldinamide | Pirazinamida | Pirazinamide | Pyrazinamid | Pyrazinamida | Pyrazinamide | Pyrazinamidum | Pyrazine carboxamide | pyrazine-2-carboxamide | Pyrazineamide | Pyrazinecarboxamide | Pyrazinoic acid amide | Pyrizinamide | Pyrazinamide |

Description

A pyrazine that is used therapeutically as an antitubercular agent.

Indication

For the initial treatment of active tuberculosis in adults and children when combined with other antituberculous agents.

Mechanism of Action

Pyrazinamide diffuses into M. tuberculosis, where the enzyme pyrazinamidase converts pyrazinamide to the active form pyrazinoic acid. Under acidic conditions, the pyrazinoic acid that slowly leaks out converts to the protonated conjugate acid, which is thought to diffuse easily back into the bacilli and accumulate. The net effect is that more pyrazinoic acid accumulates inside the bacillus at acid pH than at neutral pH. Pyrazinoic acid was thought to inhibit the enzyme fatty acid synthase (FAS) I, which is required by the bacterium to synthesise fatty acids. However, this theory was thought to have been discounted (PMID: 11914348). However, further studies reproduced the results of FAS I inhibition as the putative mechanism first in whole cell assay of replicating M. tuberculosis bacilli which have shown that pyrazinoic acid and its ester inhibit the synthesis of fatty acids (PMID: 17101678). This study was followed by in vitro assay of tuberculous FAS I enzyme that tested the activity with pyrazinamide, pyrazinoic acid and several classes of pyrazinamide analogs. Pyrazinamide and its analogs inhibited the activity of purified FAS I (PMID: 17485499). It has also been suggested that the accumulation of pyrazinoic acid disrupts membrane potential and interferes with energy production, necessary for survival of M. tuberculosis at an acidic site of infection. Pyrazinoic acid has also been shown to bind to the ribosomal protein S1 (RpsA) and inhibit trans-translation. This may explain the ability of the drug to kill dormant mycobacteria (PMID: 21835980).

Pharmacodynamics

Pyrazinamide kills or stops the growth of certain bacteria that cause tuberculosis (TB). It is used with other drugs to treat tuberculosis. It is a highly specific agent and is active only against Mycobacterium tuberculosis. In vitro and in vivo, the drug is active only at a slightly acid pH. Pyrazinamie gets activated to Pyrazinoic acid in the bacilli where it interferes with fatty acid synthase FAS I. This interferes with the bacteriums ability to synthesize new fatty acids, required for growth and replication.

Pharmacokinetics

Absorption:

Rapidly and well absorbed from the gastrointestinal tract.

Distribution:

Not Available

Metabolism:

Hepatic.

Elimination:

Approximately 70% of an oral dose is excreted in the urine, mainly by glomerular filtration within 24 hours

Half-life

9-10 hours (normal conditions)

Clearance

Not Available

Toxicity

Side effects include liver injury, arthralgias, anorexia, nausea and vomiting, dysuria,malaise and fever, sideroblastic anemia, adverse effects on the blood clotting mechanism or vascular integrity, and hypersensitivity reactions such as urticaria, pruritis and skin rashes.

References

  1. Health Science Authority of Singapore - Reclassified POM
  2. Drugbank

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Approval Information

PYRAZINAMIDE TABLET 500mg was registered with Health Science Authority of Singapore by SUNWARD PHARMACEUTICAL PTE LTD. It is marketed with the registration number of SIN00900P with effective from 1993-08-18.

This product contains 500mg of Pyrazinamide in the form of TABLET.

The medicine was manufactured by SUNWARD PHARMACEUTICAL PTE LTD in SINGAPORE

It is a Presciption Only Medicine which can only be obtained from a doctor or a dentist, or from a pharmacist with a prescription from a Singapore-registered doctor or dentist.

Anatomical Therapeutic Chemical (ATC) Classification

ATC Code: J04AK01

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