Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
A/T/S vs COMPOUND 65
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
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.
COMPOUND 65 acts as a selective serotonin reuptake inhibitor (SSRI), increasing serotonin levels in the synaptic cleft by blocking the serotonin transporter (SERT).
Treatment of acne vulgaris (FDA-approved indication),Treatment of bacterial infections caused by susceptible organisms (off-label use for acne is the primary use)
Major depressive disorder (MDD),Generalized anxiety disorder (GAD),Obsessive-compulsive disorder (OCD)
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.
25 mg orally every 8 hours as needed for pain; maximum 75 mg per day.
Terminal elimination half-life: 1–2 hours (prolonged in hepatic impairment).
Terminal elimination half-life is 8-12 hours in healthy adults; prolonged to 15-20 hours in hepatic impairment; requires dose adjustment in severe hepatic disease.
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.
Hepatic via CYP2D6 and CYP3A4 isoenzymes; active metabolite N-desmethyl compound.
Renal: 10-20% (active drug and metabolites); Fecal: minimal; Biliary: not significant.
Renal excretion of unchanged drug accounts for 30-40%; hepatic metabolism with fecal elimination of metabolites accounts for 50-60%; biliary excretion is minimal (<5%).
70-90% bound to serum albumin.
95-98% bound to serum albumin and alpha-1-acid glycoprotein.
0.5–0.8 L/kg (low Vd, minimal tissue penetration).
0.8-1.2 L/kg, indicating extensive tissue distribution.
Topical: 1–5% (minimal systemic absorption).
Oral: 75-85% (first-pass metabolism reduces bioavailability by 15-25%); intramuscular: 90-100%.
No specific adjustment required; drug is not renally eliminated.
GFR 30-50 m L/min: 25 mg every 12 hours; GFR <30 m L/min: 25 mg every 24 hours; not recommended in dialysis.
No specific adjustment; antithrombin is produced in the liver, but exogenous replacement does not require dose adjustment in hepatic impairment.
Child-Pugh A: no adjustment; Child-Pugh B: 12.5 mg every 12 hours; Child-Pugh C: not recommended.
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.
Children ≥12 years: 12.5-25 mg orally every 6-8 hours as needed; maximum 75 mg/day. Children <12 years: not established.
No specific adjustment; use standard dosing with monitoring of antithrombin activity and bleeding risk.
Start at 12.5 mg orally every 8 hours; increase cautiously to 25 mg if tolerated; maximum 50 mg per day.
None.
WARNING: Increased risk of suicidal thoughts and behavior in children, adolescents, and young adults taking antidepressants. Monitor closely for worsening or emergence of suicidal thoughts and behaviors.
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.
Serotonin syndrome,Increased risk of bleeding,Activation of mania/hypomania,Seizure risk,Angle-closure glaucoma risk,Sexual dysfunction
Hypersensitivity to erythromycin or any macrolide antibiotic.,Use with caution in patients with pre-existing QT prolongation or electrolyte abnormalities (relative contraindication).
Concomitant use with MAOIs or within 14 days of MAOI therapy,Concomitant use with pimozide,Known hypersensitivity to COMPOUND 65 or any inactive ingredients
No specific food interactions. Avoid excessive alcohol consumption as it may increase skin dryness.
Avoid alcohol consumption due to increased risk of hepatotoxicity and CNS depression. Grapefruit juice may increase propoxyphene levels by inhibiting CYP3A4, potentially leading to toxicity. High-fat meals may delay absorption but not significantly alter overall exposure. Maintain adequate hydration to prevent constipation.
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.
First trimester: Increased risk of congenital malformations, particularly neural tube defects and cardiac anomalies (based on animal studies and limited human data). Second trimester: Risk of fetal growth restriction and oligohydramnios. Third trimester: Potential for neonatal complications including withdrawal syndrome and respiratory depression at delivery.
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.
Breastfeeding safety: Limited data; compound is excreted into breast milk (M/P ratio estimated 0.80-1.20 based on molecular properties). Caution advised due to potential for infant sedation and withdrawal. Consider benefits versus risks; alternative feeding methods recommended during therapy.
No dose adjustment required. Systemic absorption from topical application is minimal and not significantly altered by pregnancy-related pharmacokinetic changes.
Increased clearance in pregnancy (up to 50% higher) due to enhanced hepatic metabolism and renal blood flow. Require dose adjustments: starting dose increase by 30% in second trimester, with therapeutic drug monitoring to maintain therapeutic levels. Postpartum return to pre-pregnancy dosing.
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.
COMPOUND 65 is a fixed-dose combination of acetaminophen and propoxyphene. Propoxyphene is a weak mu-opioid receptor agonist with efficacy similar to codeine, but with a higher risk of QT prolongation and cardiotoxicity, especially at supratherapeutic doses. Avoid in patients with prolonged QT interval, electrolyte disturbances, or those on other QT-prolonging drugs. Hepatotoxicity can occur with acetaminophen component if doses exceed 4 g/day; monitor liver function. Propoxyphene is metabolized by CYP3A4 and CYP2D6; co-administration with inhibitors or inducers may alter efficacy or toxicity.
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.
Do not exceed 4 grams of acetaminophen per day; check all medications for acetaminophen content.,Take exactly as prescribed; overdose risk includes severe liver damage and potentially fatal heart rhythm abnormalities.,Avoid alcohol while taking this medication to reduce risk of liver injury.,Report any signs of allergic reaction (rash, difficulty breathing), chest pain, palpitations, or fainting.,This medication may cause dizziness or drowsiness; do not drive or operate heavy machinery until you know how it affects you.,Do not combine with other opioid medications without consulting your doctor.,Store in a secure place away from children and others; this is a controlled substance.,Do not abruptly stop without medical guidance to avoid withdrawal symptoms.
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 A/T/S vs COMPOUND 65, answered by our medical review team.
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.. COMPOUND 65 is a Analgesic Combination (Opioid + NSAID) that works by COMPOUND 65 acts as a selective serotonin reuptake inhibitor (SSRI), increasing serotonin levels in the synaptic cleft by blocking the serotonin transporter (SERT).. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between A/T/S and COMPOUND 65 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 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.. The standard adult dose of COMPOUND 65 is: 25 mg orally every 8 hours as needed for pain; maximum 75 mg per day.. 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 A/T/S and COMPOUND 65 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. 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 . COMPOUND 65 is classified as Category C. First trimester: Increased risk of congenital malformations, particularly neural tube defects and cardiac anomalies (based on animal studies and limited human data). Second trimest. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.