Drug Detail

Para-aminosalicylic acid

Last Updated June 10, 2016

Trade Names

Paser Equity.

Drug Classification

Bacteriostatic antimycobacterial agent


Delayed-release granules: 4 g packet

Indications and Pharmacology

Indication: used in treatment of extensively drug-resistant tuberculosis and pre-extensively drug-resistant tuberculosis in combination with other second-line drugs.

Mechanism of action: postulated inhibition of folic acid synthesis and/or inhibition of cell wall component mycobactin synthesis, reducing iron uptake; also inhibits onset of resistance to isoniazid and streptomycin.

Pharmacokinetics: readily absorbed and widely distributed with only limited cerebrospinal fluid distribution; rapid production of toxic inactive metabolite under acidic conditions; mean Cmax 20 μg/mL, median Tmax 6 hours; half-life ~ 8.8 hours. Poor central nervous system penetration.


Adult Dose: 150 mg/kg/day* orally or 8-12 g/day in 2 divided doses

Take with food without chewing by sprinkling on an acidic food (eg, apple sauce or yogurt) or swirl with juice (eg, apple, orange, tomato, grape).*

Use in Renal or Hepatic Insufficiency: 

  • Creatinine clearance < 30 mL/min: 4 g/dose twice daily.*
  • Patients receiving haemodialysis: 4 g/dose twice daily.*
  • No adjustments needed for hepatic insufficiency but use with caution in hepatic disease.*

Use in Pregnancy and Breastfeeding: Pregnancy category C. Teratogenicity in animals has been reported; give only if clearly needed. Excreted in breast milk.

Use in Children: 150-200 mg/kg/day in single or divided dose; maximum 10 g/day.


Contraindicated for patients with hypersensitivity to this product or severe renal disease.

Drug-induced hepatitis has been reported; may not be well tolerated by patients with hepatic disease.

Monitor monthly for signs of hypothyroidism, measure thyroid stimulating hormone 6 monthly in adults and 2 monthly in children.*

If on treatment for more than 1 month consider vitamin B supplementation.*

Malabsorption syndrome can develop.*

Use alone or failure to complete full treatment regimen may result in rapid development of resistance.

Do not use if packets are swollen or granules have lost their tan colour and are purple or dark brown.*

Drug–Drug Interactions

May reduce acetylation of isoniazid.

Reduced absorption of vitamin B12.

May interfere with tests for serum albumin, urine ketones, bilirubin, urobilinogen, and porphobilinogen.

Considerations for Special Populations

See above for pregnancy and lactation.

Adverse Effects

Anorexia, nausea, vomiting, diarrhoea, abdominal pain, hypothyroidism, hepatitis, hypersensitivity reactions, goiter, malabsorption syndrome, prolonged prothrombin time, crystalluria.*

Hypersensitivity reaction: includes rashes, fever, leucopenia, agranulocytosis, thrombocytopenia, Coomb-positive haemolytic anaemia, jaundice, hepatitis, pericarditis, hypoglycaemia, optic neuritis, encephalopathy, hypereosinophilia syndrome, vasculitis, reduced prothrombin time.*

*Information from Aurum Institute Drugs on the Go.
Information from US Prescribing Information.