Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
SODIUM AMINOSALICYLATE vs PASER
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Sodium aminosalicylate inhibits folic acid synthesis in Mycobacterium tuberculosis by competing with para-aminobenzoic acid (PABA) for the enzyme dihydropteroate synthase, thereby blocking bacterial growth.
Inhibits cell wall synthesis in Mycobacterium tuberculosis by blocking mycolic acid synthesis. Also acts as a competitive inhibitor of folate synthesis.
Tuberculosis (second-line therapy, in combination with other antituberculous agents)
Treatment of tuberculosis in combination with other antituberculosis drugs,Off-label: None
4 g orally three times daily (total daily dose 12 g) for tuberculosis treatment. Also available as 10 g in 250 m L for intravenous infusion over 5-6 hours, typically once daily.
4 g (8 capsules of 500 mg) orally every 8 hours, taken with food or an acidic beverage (e.g., orange juice) to enhance absorption.
0.75-1.5 hours (parent drug); prolongs to 4-6 hours in renal impairment or with probenecid coadministration. Rapid acetylation phenotype reduces half-life by ~30%.
Terminal elimination half-life is 1.5 to 2.5 hours in patients with normal renal function. In anuria or severe renal impairment (Cr Cl <10 m L/min), half-life may extend to 8-12 hours. Clinical context: Accumulation occurs with renal failure, requiring dose adjustment.
Hepatic acetylation (N-acetyltransferase) and renal excretion of metabolites.
Hepatic via N-acetyltransferase (polymorphic acetylation); major metabolite is acetyl-PAS.
Renal: >80% as metabolites (acetylated and free), with 50-60% as N-acetyl-4-aminosalicylic acid; biliary/fecal: <1%.
Renal excretion accounts for approximately 80% of the administered dose, with about 60-70% as unchanged drug and 10-20% as metabolites (primarily acetylated). The remainder is excreted via feces (approximately 10-15%) and minor biliary elimination. Renal clearance is highly dependent on glomerular filtration rate.
50-60% bound to albumin; binding is saturable at high concentrations.
Protein binding is approximately 10-15%, primarily to albumin. Binding is low, nonlinear, and saturable at high concentrations.
0.2-0.3 L/kg (distributes into total body water; low tissue penetration except inflamed pleural fluid and caseous granulomas).
Volume of distribution is 0.5-0.7 L/kg, indicating distribution into total body water. Clinical meaning: Moderate distribution suggests penetration into well-perfused tissues but limited CNS penetration unless inflamed.
Oral: 90-100% (rapidly absorbed from GI tract); no parenteral formulation available.
Oral bioavailability is approximately 70-80% (range 60-90%). Food decreases the rate and extent of absorption, with AUC reduction of about 20-40%.
For GFR <30 m L/min: reduce dose to 4 g orally twice daily (total 8 g/day). For GFR <10 m L/min: administer 4 g orally once daily. No adjustment for GFR ≥30 m L/min.
Contraindicated in severe renal impairment (Cr Cl <30 m L/min). For Cr Cl 30-50 m L/min: reduce dose to 4 g orally every 12 hours; monitor serum concentrations. Use with caution in moderate impairment.
Child-Pugh Class A: no adjustment. Child-Pugh Class B: consider 50% dose reduction. Child-Pugh Class C: use with caution; consider further reduction or alternative therapy as pharmacokinetics are not well studied.
No specific dose adjustment guidelines for Child-Pugh classification. Use with caution in severe hepatic impairment due to potential hepatotoxicity; monitor liver function tests.
Children: 150-300 mg/kg/day orally divided into 3-4 doses, not to exceed 12 g/day. Intravenous: 150-200 mg/kg/day as a continuous infusion or in divided doses.
Not recommended for children (safety and efficacy not established).
Start at lower end of dosing range (e.g., 4 g orally twice daily) due to age-related decline in renal function. Monitor renal function and adjust per GFR-based guidelines. Caution with hepatic impairment.
Lower initial doses may be considered due to age-related decline in renal function. Monitor renal function and serum concentrations closely.
None.
None
May cause hepatotoxicity, hypersensitivity reactions (fever, rash, eosinophilia), gastrointestinal intolerance, and crystalluria. Monitor liver function tests and renal function periodically.
May cause hypothyroidism, hepatitis, and crystalluria. Use with caution in patients with renal impairment or glucose-6-phosphate dehydrogenase deficiency.
Hypersensitivity to aminosalicylic acid or any component; severe renal impairment (Cr Cl < 10 m L/min).
Hypersensitivity to para-aminosalicylic acid or any component; severe renal impairment.
Take with or after meals to minimize gastrointestinal irritation. Avoid alcohol due to increased risk of hepatotoxicity and GI upset. No specific food interactions; but a low-fat diet may help reduce GI side effects.
Take with food to reduce gastrointestinal irritation. Avoid high-fat meals as they may delay absorption. Avoid alcohol.
FDA Pregnancy Category C. First trimester: Limited data; animal studies show some teratogenicity at high doses; no adequate human studies; use only if clearly needed. Second and third trimesters: No specific known fetal risks; however, theoretical risk of kernicterus due to bilirubin displacement from albumin binding, though not confirmed with aminosalicylic acid.
PASER (aminosalicylic acid) is classified FDA pregnancy category C. First trimester: Limited human data; animal studies show no teratogenicity but some fetal toxicity at high doses. Second and third trimesters: No known major malformations; risks may include gastrointestinal intolerance in mother. Advised use only if clearly needed.
Excretion into breast milk is unknown; due to potential for serious adverse reactions in nursing infants (e.g., hypersensitivity, gastrointestinal disturbance), decision should be made to discontinue nursing or the drug, taking into account importance of drug to mother.
Excreted into breast milk in small amounts. M/P ratio unknown. Considered compatible with breastfeeding by American Academy of Pediatrics; monitor infant for diarrhea or rash.
No established dose adjustment guidelines for pregnancy; pharmacokinetic changes (increased volume of distribution, increased renal clearance) may theoretically reduce serum concentrations; therapeutic drug monitoring is not routinely recommended but may be considered if efficacy is in question.
No dosing adjustment required for pregnancy. Pharmacokinetic changes in pregnancy (increased clearance) not significant for PASER; standard adult dose of 4 g twice daily is recommended.
Sodium aminosalicylate (PAS) is a bacteriostatic agent used in combination therapy for multidrug-resistant tuberculosis. Administer with or after meals to reduce gastrointestinal upset. Monitor liver function tests and renal function periodically. Watch for hypersensitivity reactions, including fever, rash, and eosinophilia. Use with caution in patients with glucose-6-phosphate dehydrogenase deficiency due to risk of hemolytic anemia.
PASER (aminosalicylic acid) is a second-line antitubercular agent that inhibits folic acid synthesis. Administer with food to reduce GI upset; avoid concurrent use with salicylates due to additive GI irritation. Monitor for hepatotoxicity and hypersensitivity reactions. Drug levels should be monitored in patients with renal impairment.
Take this medication with or after food to reduce stomach upset.,Do not skip doses or stop taking this medication without consulting your doctor.,Report any signs of allergic reaction such as rash, fever, or swelling.,Avoid alcohol while taking this medication.,Keep all appointments for blood tests to monitor liver and kidney function.,Contact your doctor if you experience nausea, vomiting, abdominal pain, or yellowing of skin or eyes.
Take this medication with food to minimize stomach upset.,Do not crush or chew the tablets; swallow them whole.,Complete the full course of therapy even if you feel better.,Report any signs of liver problems (yellowing of skin/eyes, dark urine) or allergic reactions (rash, fever) immediately.,Avoid alcohol during treatment.,Store at room temperature away from moisture and heat.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about SODIUM AMINOSALICYLATE vs PASER, answered by our medical review team.
SODIUM AMINOSALICYLATE is a Antitubercular Agent that works by Sodium aminosalicylate inhibits folic acid synthesis in Mycobacterium tuberculosis by competing with para-aminobenzoic acid (PABA) for the enzyme dihydropteroate synthase, thereby blocking bacterial growth.. PASER is a Antitubercular Agent that works by Inhibits cell wall synthesis in Mycobacterium tuberculosis by blocking mycolic acid synthesis. Also acts as a competitive inhibitor of folate synthesis.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between SODIUM AMINOSALICYLATE and PASER depend on the specific clinical indication. These are both Antitubercular Agent agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of SODIUM AMINOSALICYLATE is: 4 g orally three times daily (total daily dose 12 g) for tuberculosis treatment. Also available as 10 g in 250 m L for intravenous infusion over 5-6 hours, typically once daily.. The standard adult dose of PASER is: 4 g (8 capsules of 500 mg) orally every 8 hours, taken with food or an acidic beverage (e.g., orange juice) to enhance absorption.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between SODIUM AMINOSALICYLATE and PASER in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. SODIUM AMINOSALICYLATE is classified as Category C. FDA Pregnancy Category C. First trimester: Limited data; animal studies show some teratogenicity at high doses; no adequate human studies; use only if clearly needed. Second and th. PASER is classified as Category C. PASER (aminosalicylic acid) is classified FDA pregnancy category C. First trimester: Limited human data; animal studies show no teratogenicity but some fetal toxicity at high doses. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.