Para-aminosalicylic acid


Concise Prescribing Info
Indications/Uses
Listed in Dosage.
Dosage/Direction for Use
Adult : PO Tuberculosis 150 mg/kg/day in 3-4 equally divided doses. Crohn's disease 1.5 g/day. Rectal Ulcerative colitis As enema: 2 g once daily.
Dosage Details
Oral
Tuberculosis
Adult: 150 mg/kg/day in 3-4 equally divided doses Take with acidic food (e.g. apple sauce, yoghurt, orange juice).
Child: 200-300 mg/kg/day in 3-4 equally divided doses.

Oral
Crohn's disease
Adult: 1.5 g/day (unlabelled use).

Rectal
Ulcerative colitis
Adult: 2 g once a day as an enema in patients who are intolerant to sulphasalazine.
Renal Impairment
Haemodialysis: Administer dose afterwards and give 50% dose. Continuous arteriovenous haemofiltration: give 50% dose.
CrCl Dosage
<10 50% dose.
10-50 50-75% dose.
Contraindications
G6PD deficiency; severe renal disease.
Special Precautions
Pregnancy, lactation; renal and hepatic impairment, sodium salt in heart failure; gastric ulcer. Monitor patient closely for 1st 3 mth of treatment and counsel to report: sore throat, fever, unusual bleeding or bruising, persistent nausea or vomiting, or abdominal pain.
Adverse Reactions
Nausea, vomiting, diarrhoea, abdominal pain; thyroid goitre, hypoglycaemia; pericarditis, vasculitis; encephalopathy, fever, skin eruptions, agranulocytosis, haemolytic anaemia, leucopenia, thrombocytopenia, hepatitis, jaundice, optic neuritis, eosinophilic pneumonia.
Overdosage
Acute symptoms: Crystalluria, renal failure, nausea and vomiting. Treatment: Sodium bicarbonate (alkalinise urine) and forced diuresis to prevent crystalluria and nephrotoxicity.
Drug Interactions
May decrease absorption of digoxin and vitamin B12; additive adverse effects of aminosalicylates and salicylates; probenecid may increase toxicity by delaying renal excretion and enhancing plasma concentrations of aminosalicylate; activity of aminosalicylic acid may be antagonised by ester-type local anaesthetics such as procaine; may enhance effect of oral anticoagulants (may need to adjust dose); ammonium chloride may increase risk of crystalluria (do not use concurrently).
Food Interaction
May be taken with food; sprinkle on apple sauce or yoghurt or suspend in tomato or orange juice; granules have an acid resistant coating that dissolves within a minute at neutral pH.
Lab Interference
Interferes with tests for glucosuria using copper reagents and for urobilinogen using Ehrlich's reagent.
Action
Description: Para-aminosalicylic acid (also known as aminosalicyclic acid) is bacteriostatic and active against M. tuberculosis. Other mycobacteria are usually resistant. It prevents plate biosynthesis in sensitive organisms. It has a relatively weak action compared with other anti-TB drugs and resistance may develop quickly if it is used alone, however it is still sometimes used in multi-drug resistant tuberculosis in combination with other anti-TB drugs.
Pharmacokinetics:
Absorption: Readily absorbed (>90%); peak plasma concentration after oral dosing: 1-4 hr. Time to peak, serum: 6 hr.
Distribution: Diffuses into most body tissues and fluids (including breast milk) except CSF (unless meninges inflamed). Plasma protein binding: sodium salt: 15%; acid: 50-70%.
Metabolism: Intestinally and hepatically (>50%) mainly by acetylation.
Excretion: Via urine: ≥80% dose within 24 hr (50% as acetylated metabolite). Half-life: approx 1 hr (reduced in renal impairment).
Storage
Granules: Before dispensing: <15°C. Once dispensed: <25°C for short periods of time. Not to be used if packet is swollen or granules are dark brown or purple.
Disclaimer: This information is independently developed by MIMS based on Para-aminosalicylic acid from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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