Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
IBU vs A/T/S
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Non-selective inhibitor of cyclooxygenase (COX-1 and COX-2), decreasing prostaglandin synthesis, thereby reducing inflammation, pain, and fever.
A/T/S (erythromycin) is a macrolide antibiotic that acts by binding to the 50S ribosomal subunit of susceptible bacteria, inhibiting protein synthesis and bacterial growth.
Rheumatoid arthritis,Osteoarthritis,Mild to moderate pain,Dysmenorrhea,Fever,Patent ductus arteriosus closure in neonates (off-label)
Treatment of acne vulgaris (FDA-approved indication),Treatment of bacterial infections caused by susceptible organisms (off-label use for acne is the primary use)
200-800 mg orally every 6-8 hours as needed; maximum 3200 mg/day. For OTC use: 200-400 mg every 4-6 hours; max 1200 mg/day.
Dosing is individualized based on antithrombin activity level. For acute thrombotic events: initial bolus of 30-50 IU/kg followed by maintenance dosing to achieve target activity levels (80-120% of normal). Prophylaxis: 40-60 IU/kg every 24 hours.
Terminal elimination half-life: 2-4 hours in adults; prolonged in neonates (30 hours) and elderly (up to 6 hours). No accumulation with recommended dosing due to short t½.
Terminal elimination half-life: 1–2 hours (prolonged in hepatic impairment).
Hepatic metabolism primarily via CYP2C9 to inactive metabolites; minor pathways include CYP2C8.
Antithrombin is a glycoprotein; its metabolism involves cellular uptake and catabolism, but specific CYP450 enzymes are not involved. Degradation occurs via proteolysis and reticuloendothelial system clearance.
Renal (90% as conjugated metabolites, 10% unchanged), biliary/fecal (minor, <5%)
Renal: 10-20% (active drug and metabolites); Fecal: minimal; Biliary: not significant.
99% bound primarily to albumin
70-90% bound to serum albumin.
0.1-0.2 L/kg, indicating low tissue distribution; predominantly confined to plasma and extracellular fluid.
0.5–0.8 L/kg (low Vd, minimal tissue penetration).
Oral: 80-100% (immediate-release), 70-90% (extended-release); Topical: approximately 5-10% systemic absorption; Intravenous: 100%.
Topical: 1–5% (minimal systemic absorption).
Cr Cl >30 m L/min: no adjustment. Cr Cl 10-30 m L/min: 200 mg every 12 hours; avoid if Cr Cl <10 m L/min.
No specific adjustment required; drug is not renally eliminated.
Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 50% or avoid. Child-Pugh C: contraindicated due to risk of hepatotoxicity.
No specific adjustment; antithrombin is produced in the liver, but exogenous replacement does not require dose adjustment in hepatic impairment.
6 months to 12 years: 5-10 mg/kg/dose every 6-8 hours; max 40 mg/kg/day. For juvenile idiopathic arthritis: 30-40 mg/kg/day divided every 6-8 hours; max 50 mg/kg/day.
Dosing based on weight and antithrombin levels; typical initial dose 30-50 IU/kg, followed by maintenance to achieve target levels. Clinical trial data limited in neonates.
Initiate at lowest effective dose; consider 200 mg every 8-12 hours; monitor renal function and GI bleeding risk.
No specific adjustment; use standard dosing with monitoring of antithrombin activity and bleeding risk.
NSAIDs cause an increased risk of serious cardiovascular thrombotic events, myocardial infarction, and stroke, which can be fatal. Risk may increase with duration of use. Contraindicated for treatment of peri-operative pain in coronary artery bypass graft (CABG) surgery.
None.
Cardiovascular thrombotic events,Gastrointestinal bleeding, ulceration, and perforation,Hypertension,Heart failure exacerbation,Renal toxicity,Anaphylactic reactions,Serious skin reactions (e.g., Stevens-Johnson syndrome),Hematologic effects (anemia, bleeding)
Hypersensitivity reactions including anaphylaxis have occurred.,Prolonged use may result in overgrowth of nonsusceptible organisms including fungi.,Use with caution in patients with hepatic impairment.,Potential for QT prolongation and ventricular arrhythmias, especially with intravenous administration or concomitant drugs that prolong QT interval.
History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs,Peri-operative pain in CABG surgery,Active gastrointestinal bleeding,Advanced renal disease,Third trimester of pregnancy
Hypersensitivity to erythromycin or any macrolide antibiotic.,Use with caution in patients with pre-existing QT prolongation or electrolyte abnormalities (relative contraindication).
Ibuprofen can increase the risk of stomach bleeding when taken with alcohol. No specific food restrictions, but taking with food or milk can reduce GI irritation.
No specific food interactions. Avoid excessive alcohol consumption as it may increase skin dryness.
First and second trimester: Increased risk of miscarriage and congenital malformations (particularly cardiac defects) associated with NSAID use. Third trimester: Known risk of premature closure of ductus arteriosus, oligohydramnios, and neonatal renal impairment; contraindicated after 30 weeks gestation.
FDA Pregnancy Category B. No evidence of teratogenicity in animal studies; no adequate human studies in first trimester. Topical erythromycin has minimal systemic absorption; risk to fetus is low across all trimesters.
Ibuprofen is excreted into breast milk in low concentrations (M/P ratio approximately 0.01-0.03). Considered compatible with breastfeeding by the American Academy of Pediatrics; use lowest effective dose for shortest duration.
Compatible with breastfeeding. Erythromycin is excreted into breast milk in small amounts (M/P ratio approximately 0.5). Topical use results in negligible systemic exposure; unlikely to cause adverse effects in nursing infants.
Increased plasma volume and renal clearance in pregnancy may reduce drug levels; however, no standard dose adjustment recommended. Use lowest effective dose, avoid in third trimester.
No dose adjustment required. Systemic absorption from topical application is minimal and not significantly altered by pregnancy-related pharmacokinetic changes.
Ibuprofen is a nonselective COX inhibitor with anti-inflammatory, analgesic, and antipyretic effects. Avoid in patients with aspirin allergy, active peptic ulcer, or severe renal impairment. Use lowest effective dose for shortest duration to minimize GI and cardiovascular risks. Not recommended in patients with advanced chronic kidney disease (e GFR <30 m L/min/1.73 m²). For acute pain, ibuprofen 200-400 mg every 6 hours PRN. Monitor for signs of GI bleeding, hypertension, and fluid retention.
A/T/S (erythromycin 2% topical solution) is indicated for acne vulgaris. Avoid contact with eyes, mouth, and mucous membranes. May cause skin dryness or irritation; use moisturizer. Effectiveness may decrease with prolonged use due to bacterial resistance. Not recommended for use with other topical erythromycin products or clindamycin to avoid antagonism.
Take with food or milk to reduce stomach upset.,Do not exceed 1200 mg per day unless directed by your doctor.,Avoid alcohol while taking this medication.,Stop use and seek medical help if you experience chest pain, weakness, slurred speech, or signs of stomach bleeding (black/tarry stools, vomit that looks like coffee grounds).,Do not take with other NSAIDs or aspirin without consulting your healthcare provider.
Apply a thin layer to affected areas twice daily after washing.,Avoid contact with eyes, lips, and mouth; if contact occurs, rinse thoroughly with water.,May cause stinging, burning, or peeling; if irritation persists, consult your doctor.,Use sunscreen daily as this medication may increase sensitivity to sunlight.,Do not use more than prescribed; overuse may increase side effects without improving results.,Inform your doctor if you are pregnant, planning to become pregnant, or breastfeeding.,Keep away from open flames or heat sources; product is flammable.
"Concomitant use of Ibuprofen (a nonsteroidal anti-inflammatory drug, NSAID) and Methylprednisolone (a systemic corticosteroid) synergistically increases the risk of gastrointestinal (GI) ulceration, bleeding, and perforation due to additive inhibition of prostaglandin synthesis and mucosal protection. Additionally, Ibuprofen may potentiate the immunosuppressive effects of Methylprednisolone, elevating infection risk. This interaction can lead to serious clinical outcomes, including acute GI hemorrhage, perforation, and impaired wound healing."
"The combination of olopatadine, an antihistamine with sedative properties, and ibuprofen, a nonsteroidal anti-inflammatory drug (NSAID), may result in additive central nervous system (CNS) depression, leading to increased sedation, dizziness, and impaired psychomotor function. Ibuprofen can inhibit the metabolism of olopatadine via competition for hepatic CYP450 enzymes, potentially elevating olopatadine plasma concentrations and prolonging its systemic effects. Clinically, patients may experience exacerbated drowsiness, reduced alertness, and increased risk of falls or accidents, especially in the elderly or those with compromised hepatic function."
"Ibuprofen, a nonsteroidal anti-inflammatory drug (NSAID), can decrease the metabolism of pioglitazone, a thiazolidinedione antidiabetic agent, by inhibiting cytochrome P450 2C8 (CYP2C8) enzyme activity. This inhibition elevates plasma concentrations of pioglitazone, potentially enhancing its hypoglycemic effects and increasing the risk of adverse reactions such as edema, weight gain, and heart failure exacerbation. Clinically, concomitant use may lead to improved glycemic control but also raises concerns for dose-dependent toxicities, necessitating careful monitoring and possible dose adjustment of pioglitazone."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about IBU vs A/T/S, answered by our medical review team.
IBU is a Nonsteroidal Anti-inflammatory Drug (NSAID) that works by Non-selective inhibitor of cyclooxygenase (COX-1 and COX-2), decreasing prostaglandin synthesis, thereby reducing inflammation, pain, and fever.. A/T/S is a Macrolide antibiotic that works by A/T/S (erythromycin) is a macrolide antibiotic that acts by binding to the 50S ribosomal subunit of susceptible bacteria, inhibiting protein synthesis and bacterial growth.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between IBU and A/T/S 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 IBU is: 200-800 mg orally every 6-8 hours as needed; maximum 3200 mg/day. For OTC use: 200-400 mg every 4-6 hours; max 1200 mg/day.. The standard adult dose of A/T/S is: Dosing is individualized based on antithrombin activity level. For acute thrombotic events: initial bolus of 30-50 IU/kg followed by maintenance dosing to achieve target activity levels (80-120% of normal). Prophylaxis: 40-60 IU/kg every 24 hours.. 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 IBU and A/T/S 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. IBU is classified as Category C. First and second trimester: Increased risk of miscarriage and congenital malformations (particularly cardiac defects) associated with NSAID use. Third trimester: Known risk of prem. A/T/S is classified as Category C. FDA Pregnancy Category B. No evidence of teratogenicity in animal studies; no adequate human studies in first trimester. Topical erythromycin has minimal systemic absorption; risk . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.