Antituberculous Agents Pregnancy: No sufficient clinical data in pregnant women; animal studies do not suggest detrimental effects. Use only when potential benefit clearly outweighs risk to the foetus. Contra-indicated in breast-feeding mothers.

Pyrazinamide

Brand names: Zinamide

Pyrazinamide is a first-line antituberculous agent used in the initial intensive phase of treatment for active tuberculosis, given orally as part of combination therapy. It is typically used alongside rifampicin, isoniazid and ethambutol.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Under 50 kg: max 1.5 g/day (3 x 500 mg tablets); over 50 kg: max 2.0 g/day (4 x 500 mg tablets)

Route: Oral

Frequency: Once daily (standard unsupervised 2-month treatment)

Max: 2.0 g/day (over 50 kg); 1.5 g/day (under 50 kg)

Adults and adolescents; component of the initial-phase pulmonary tuberculosis regimen. Used in combination with other anti-tubercular agents over a total of 8 weeks (may be continued up to 3 months to prevent recurrent infection). Intermittent supervised 2-month therapy (only if daily administration not feasible): under 50 kg 2.0 g (4 tablets) three times a week; over 50 kg 2.5 g (5 tablets) three times a week. Must be administered under supervision of a physician trained in the management of tuberculosis. In meningeal or pericardial TB, a corticosteroid should be started at the same time.

Paediatric dose

Dose: 35 mg/kg

Route: Oral

Frequency: Once daily (standard unsupervised 2-month treatment)

Max: 1.5 g/day

Equivalent in children aged 4-10: 0.5-1 g (1-2 x 500 mg tablets); aged 11-14: 1-1.5 g (2-3 x 500 mg tablets). Intermittent supervised 2-month regimen (only if daily not feasible): 50 mg/kg three times weekly. Used in combination with other anti-tubercular agents. Verify against a children's formulary.

Dose adjustments

Renal

In renal impairment prescribe in emergencies only and administer intermittently; reduction in size and/or frequency of dose is recommended. Test liver and kidney function before and during treatment (every 3-4 weeks).

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Paediatric weight-based calculator

Patient weight (kg)

Verify in a children's formulary

Contraindications

Hypersensitivity to the active substance or to any of the excipients
Severe hepatic impairment, acute liver disease (e.g. hepatitis) and up to 6 months after occurrence of hepatitis
Acute porphyria
Hyperuricaemia and/or acute gouty arthritis
Breast-feeding mothers

Side effects

Hepatic reaction (most common): raised serum transaminases, liver function disorders, hepatomegaly, jaundice, hepatic failure (which may be fatal)
Hyperuricaemia; gout, arthralgias
Gastrointestinal: loss of appetite, nausea, vomiting, heartburn, abdominal spasms, weight loss
Sideroblastic anaemia, thrombocytopenia (with or without purpura), porphyria, splenomegaly
Photosensitivity, flushing, rash, urticaria, pruritus, erythema multiforme

Clinical monograph

How it works

It is a prodrug converted by mycobacterial pyrazinamidase to pyrazinoic acid, which is bactericidal against semi-dormant tubercle bacilli in the acidic intracellular environment.

Prescribing in practice

Pyrazinamide is hepatotoxic, so check baseline liver function and warn patients to stop and seek urgent review if they develop jaundice, dark urine, nausea or abdominal pain.
It commonly raises serum urate and can precipitate gout or arthralgia, and should be avoided in acute gout.
Always use within a supervised multidrug regimen to prevent resistance, never as monotherapy.

Monitoring

Monitor liver function and clinical hepatotoxicity, and assess for arthralgia or gout related to raised urate during treatment.

Counselling the patient

Stop and seek urgent advice if you become jaundiced, very nauseated or develop dark urine.
Take all your TB tablets together exactly as prescribed without missing doses.
Report painful or swollen joints.

Evidence & guidelines

Established UK tuberculosis guidance includes pyrazinamide in the standard intensive-phase combination regimen for active disease.

Reference: NICE NG33; WHO TB Guidelines 2022; BTS TB Guidelines; BMJ Best Practice TB; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

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