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Antimycobacterial (Anti-tuberculosis Agent)

Aminosalicylic Acid (Para-aminosalicylic acid, PAS)

Brand names: Granupas

Aminosalicylic acid (para-aminosalicylic acid, PAS) is a second-line antituberculous agent used in combination regimens for drug-resistant tuberculosis.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It is a bacteriostatic agent that inhibits folate synthesis in Mycobacterium tuberculosis, acting as an analogue in the folate pathway.

Prescribing in practice

  • Must only be used as part of an appropriate combination regimen for drug-resistant tuberculosis to prevent further resistance.
  • Gastrointestinal intolerance is common and may limit adherence.
  • It can cause hypothyroidism and hepatotoxicity, so thyroid and liver function should be monitored.

Monitoring

Monitor liver function and thyroid function, and review gastrointestinal tolerability during treatment.

Counselling the patient

  • Take with food to reduce stomach upset.
  • Report persistent vomiting, jaundice or symptoms of an underactive thyroid such as tiredness or weight gain.
  • Complete the full course as part of your tuberculosis regimen.

Evidence & guidelines

It is included among the agents for multidrug-resistant tuberculosis in World Health Organization and NICE-aligned treatment frameworks.

Reference: NICE NG33 (Tuberculosis, 2016 updated 2023); WHO MDR-TB Guidelines (2022); BSAC/PHE TB guidelines; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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