Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
P.A.S. SODIUM vs ACULAR LS
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
P. A. S. (p-aminosalicylic acid) sodium is a bacteriostatic agent that competitively inhibits the synthesis of folic acid in Mycobacterium tuberculosis by antagonizing the incorporation of p-aminobenzoic acid (PABA) into dihydrofolate. It is selective for mycobacterial folate synthase.
Selective COX-2 inhibitor; inhibits prostaglandin synthesis, reducing ocular inflammation and pain.
Treatment of tuberculosis (TB) in combination with other antituberculosis agents, particularly in multidrug-resistant TB (FDA-approved).,Off-label: Used as a second-line agent in atypical mycobacterial infections and in Crohn's disease (though not FDA-approved for these indications).
FDA: Treatment of postoperative inflammation in patients who have undergone cataract surgery,Off-label: Relief of ocular pain, photophobia, and inflammation associated with corneal abrasion or refractive surgery
Oral: 4 g three times daily (total daily dose 12 g); IV: 12 g daily in 2-4 divided doses.
1 drop in the affected eye(s) four times daily
1 hour (normal renal function); prolonged to 5-7 hours in anuria or severe renal impairment; clinical context: requires frequent dosing or renal dose adjustment
The terminal elimination half-life is approximately 1.8 hours (range 1.2–2.5 hours) following topical ocular administration. This short half-life is consistent with rapid clearance from the systemic circulation.
Primarily metabolized by hepatic acetylation via N-acetyltransferase (NAT); minor pathways include glycine conjugation and renal excretion of unchanged drug.
Primarily hepatic via CYP2C9; undergoes glucuronidation and oxidation to inactive metabolites.
Renal (80% as active drug and metabolites, primarily acetylated form); fecal (minor; <10%)
Renal excretion of metabolites and unchanged drug accounts for approximately 26% of the dose. Fecal excretion accounts for approximately 74% of the dose, primarily as metabolites.
50-60% (primarily to albumin)
Ketorolac is highly protein bound, approximately 99% bound to plasma proteins, primarily albumin.
0.5-0.6 L/kg (indicates distribution into total body water, with some tissue binding)
The volume of distribution is approximately 0.12 L/kg, indicating distribution primarily into extracellular fluid with limited tissue penetration.
Oral: approximately 90% (well absorbed from GI tract)
Ophthalmic bioavailability is approximately 2% of the administered dose due to extensive nasolacrimal drainage and systemic absorption. Oral bioavailability of ketorolac is approximately 80-100%, but this route is not used for ophthalmic formulations.
Cr Cl <50 m L/min: reduce dose by 50%; Cr Cl <10 m L/min: avoid use or reduce to 25% of normal dose.
No dosage adjustment required for renal impairment
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use.
No dosage adjustment required for hepatic impairment but use with caution in severe hepatic disease due to potential for increased systemic exposure
Oral: 200-300 mg/kg/day in 3-4 divided doses, maximum 12 g/day.
Safety and efficacy in pediatric patients below 2 years of age have not been established; for children 2 years and older, same as adult dosing
Start at lower end of dosing range; monitor renal function and adjust based on Cr Cl; typical initial dose 4 g twice daily.
No specific dose adjustment recommended; use with caution due to increased incidence of age-related ocular conditions
None explicitly stated in current FDA labeling; however, caution is advised in hepatic impairment due to risk of hepatitis.
None
May cause severe hypersensitivity reactions (e.g., fever, rash, lymphadenopathy).,Hepatic toxicity: risk of hepatitis, especially with prolonged use; monitor liver function.,Renal impairment: dose adjustment required in severe renal disease.,Gastrointestinal intolerance: nausea, vomiting, diarrhea common.,Development of resistance if used as monotherapy.,May induce hemolytic anemia in G6PD deficiency.
Increased risk of bleeding and bleeding-related adverse events due to platelet inhibition,May prolong bleeding time,Cross-sensitivity with aspirin and other NSAIDs,Caution in patients with prior history of corneal epithelial defects or ocular surgery,Not for intraocular injection
Hypersensitivity to p-aminosalicylic acid or any component.,Severe hepatic impairment.,Severe renal failure (unless dose-adjusted).,Contraindicated in patients with active peptic ulcer disease.
Hypersensitivity to ketorolac tromethamine or any component of the formulation,Patients with active peptic ulcer disease, recent GI bleeding, or perforation,Patients with advanced renal disease or at risk for renal failure,Patients with known history of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs
Take with food, especially acidic foods (e.g., applesauce, yogurt) to improve taste and reduce gastrointestinal irritation. Avoid alkaline foods (e.g., milk, antacids) as they may decrease absorption. Avoid alcohol due to increased risk of hepatotoxicity.
No known food interactions for ophthalmic ketorolac. However, maintain good hydration and nutrition to support corneal healing.
First trimester: No evidence of teratogenicity in human studies; limited animal data show no adverse effects. Second trimester: No specific risks identified. Third trimester: No known adverse fetal effects; use only if clearly needed.
Ketorolac tromethamine, the active ingredient in ACULAR LS, is a nonsteroidal anti-inflammatory drug (NSAID). In animal reproduction studies, administration of ketorolac during organogenesis resulted in increased embryofetal mortality, delayed ossification, and increased incidence of skeletal abnormalities at doses less than the maximum recommended human ophthalmic dose. However, systemic exposure following ocular administration is very low. NSAIDs are generally avoided during pregnancy, especially in the third trimester, due to the risk of premature closure of the ductus arteriosus and oligohydramnios. The risk is considered low for ophthalmic use but should be used only if clearly needed.
Excreted into breast milk in low amounts; M/P ratio not determined. Considered compatible with breastfeeding; monitor infant for diarrhea or rash.
It is not known whether ketorolac is excreted in human milk after ophthalmic administration. Systemic levels are low, and following oral administration, ketorolac is excreted in breast milk at low concentrations (M/P ratio approximately 0.37). Due to the potential for adverse effects on the nursing infant, caution should be exercised. The low systemic absorption likely poses minimal risk.
No pharmacokinetic changes requiring dose adjustment in pregnancy; use standard dosing but monitor for hepatotoxicity, which may be increased.
No dosing adjustments are necessary for ophthalmic use during pregnancy due to negligible systemic absorption. Standard dosing (1 drop in the affected eye(s) four times daily) is recommended. Systemic NSAIDs may require dose adjustment due to increased volume of distribution and renal changes, but this does not apply to topical ocular ketorolac.
Sodium aminosalicylate (PAS sodium) is a second-line antituberculosis agent used in multidrug-resistant TB (MDR-TB). It is bacteriostatic against Mycobacterium tuberculosis by inhibiting folate synthesis. Must be administered with other antitubercular drugs to prevent resistance. Monitor for hepatotoxicity, hypersensitivity reactions (fever, rash, eosinophilia), and gastrointestinal intolerance. Can cause hypothyroidism; monitor thyroid function. Drug interactions: may increase phenytoin levels; avoid concurrent probenecid (increases PAS levels). PAS granules should be sprinkled on soft acidic food to reduce GI upset.
ACULAR LS (ketorolac tromethamine ophthalmic solution 0.4%) is a nonsteroidal anti-inflammatory drug (NSAID) indicated for the reduction of ocular pain and photophobia following corneal refractive surgery. Use with caution in patients with known bleeding tendencies or those on anticoagulants due to increased risk of ocular bleeding. Avoid concurrent use with other NSAIDs or steroids to minimize corneal adverse effects. Monitor for corneal epithelial breakdown or delayed healing.
Take this medication exactly as prescribed, usually twice daily with food to reduce stomach upset.,Do not skip doses; complete the full course to prevent drug resistance.,Report any signs of liver problems: yellowing of skin/eyes, dark urine, severe abdominal pain.,Notify your doctor if you develop fever, rash, or unusual tiredness.,You may need regular blood tests to monitor thyroid and liver function.,Avoid alcohol while taking this medication.,Keep all appointments for TB treatment monitoring.
Do not touch the dropper tip to any surface to avoid contamination.,Remove contact lenses before instillation and wait at least 10 minutes before reinserting.,Use only in the affected eye(s) as prescribed; do not use for longer than directed.,Temporary stinging or burning may occur upon instillation.,Report any persistent pain, redness, or visual changes to your doctor immediately.,Avoid driving or operating machinery if vision is blurred after use.
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 P.A.S. SODIUM vs ACULAR LS, answered by our medical review team.
P.A.S. SODIUM is a Antitubercular Agent that works by P. A. S. (p-aminosalicylic acid) sodium is a bacteriostatic agent that competitively inhibits the synthesis of folic acid in Mycobacterium tuberculosis by antagonizing the incorporation of p-aminobenzoic acid (PABA) into dihydrofolate. It is selective for mycobacterial folate synthase.. ACULAR LS is a NSAID Ophthalmic that works by Selective COX-2 inhibitor; inhibits prostaglandin synthesis, reducing ocular inflammation and pain.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between P.A.S. SODIUM and ACULAR LS depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of P.A.S. SODIUM is: Oral: 4 g three times daily (total daily dose 12 g); IV: 12 g daily in 2-4 divided doses.. The standard adult dose of ACULAR LS is: 1 drop in the affected eye(s) four times daily. 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 P.A.S. SODIUM and ACULAR LS 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. P.A.S. SODIUM is classified as Category C. First trimester: No evidence of teratogenicity in human studies; limited animal data show no adverse effects. Second trimester: No specific risks identified. Third trimester: No kn. ACULAR LS is classified as Category C. Ketorolac tromethamine, the active ingredient in ACULAR LS, is a nonsteroidal anti-inflammatory drug (NSAID). In animal reproduction studies, administration of ketorolac during org. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.