Pyrazinamide
A first-line tuberculosis drug given for the opening 2 months, active against slowly dividing bacilli at acidic pH.
Also called PZA (abbreviation) or Z (letter in TB regimen codes).
Drug card
- How it works
- Turning into pyrazinoic acid, which kills slowly dividing bacilli at acid pH
- Used for
- Active tuberculosis, in the first 2 months
- Drug-resistant tuberculosis, in tailored regimens
- Known for
- Hepatitis
- High uric acid
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does pyrazinamide work?
A prodrug: mycobacterial pyrazinamidase removes its amide group to give the active pyrazinoic acid. It works only at slightly acidic pH and is most active against slowly multiplying bacilli inside cells, which other drugs leave unharmed. Its exact target is unknown.
Like other first-line tuberculosis drugs: The four first-line drugs hit Mycobacterium tuberculosis in different ways: isoniazid and ethambutol stop it building its cell wall (mycolic acids and arabinogalactan), rifampicin blocks its RNA polymerase, and pyrazinamide acts on slowly dividing bacilli at acidic pH. Resistance arises fast to any one drug alone, so they are given together: all four for 2 months, then isoniazid and rifampicin for 4.
Uses
What is pyrazinamide used for?
- Active tuberculosis, in the first 2 months
- Drug-resistant tuberculosis, in tailored regimens
Side effects
Side effects of pyrazinamide
- HepatitisKnown forSerious
- High uric acidKnown for
- Gout attacks
- Joint and muscle aches
- Nausea and vomiting
- Loss of appetite
- Rash and itching
- Sensitivity to sunlight
- Sideroblastic anemia, rarelySerious
- Interstitial nephritis, rarelySerious
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Contraindicated in severe liver damage and in acute gout.
- Check uric acid and liver tests before starting, and stop it for hepatitis or gouty arthritis.
- Diabetes may become harder to control.
Good to know: Its activity in acid conditions reaches bacilli that survive the other drugs; primary resistance to it is uncommon.
Remember it
A way to remember it
RIPE
- R
- Rifampicin: orange-red urine, sweat and tears
- I
- Isoniazid: peripheral neuropathy and hepatitis
- P
- Pyrazinamide: high uric acid and gout
- E
- Ethambutol: eye damage (optic neuritis)
RIPE names the four first-line drugs, and each letter carries the side effect that drug is best known for.
A mnemonic widely used in teaching
Its class
First-line tuberculosis drugs
Other first-line tuberculosis drugs with a card:
Easily mixed up with fluoroquinolones.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Pyrazinamide tablets: label (DailyMed)
- Pyrazinamide (NCI Thesaurus)
- WHO consolidated guidelines on tuberculosis: module 4: treatment and care, 2nd edition (WHO)
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Antibiotics: DNA, folate and tuberculosis
Pyrazinamide is one of 11 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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