Pyrazinamide

How it works

It is converted by mycobacterial pyrazinamidase to pyrazinoic acid, which is active against semi-dormant tubercle bacilli in the acidic environment of macrophages and inflammatory lesions, helping to shorten treatment duration.

Prescribing in practice

• It is hepatotoxic, so baseline liver function should be assessed and the drug stopped if significant hepatitis develops; it is contraindicated in established severe liver disease.
• It commonly raises serum urate and can precipitate gout or arthralgia.
• It must always be given in combination with other antituberculous agents to prevent resistance, never as monotherapy.

Monitoring

Monitor liver function before and during treatment and review patients reporting joint symptoms or features of hepatitis.

Counselling the patient

• Take all your tuberculosis tablets together exactly as prescribed and do not stop early.
• Report nausea, vomiting, abdominal pain or yellowing of the skin or eyes promptly.
• Joint aches can occur; mention them to your team rather than stopping treatment yourself.

Evidence & guidelines

Pyrazinamide is a core component of the standard four-drug initial-phase regimen recommended by NICE and WHO for active tuberculosis.