Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
A/T/S vs MAGNESIUM HYDROXIDE AND OMEPRAZOLE AND SODIUM BICARBONATE
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.
Magnesium hydroxide is an antacid that neutralizes gastric acid, increasing gastric p H. Omeprazole is a proton pump inhibitor (PPI) that irreversibly inhibits the H+/K+ ATPase enzyme system at the secretory surface of gastric parietal cells, blocking the final step of acid secretion. Sodium bicarbonate is a systemic antacid that neutralizes gastric acid and also provides alkalinization of urine.
Treatment of acne vulgaris (FDA-approved indication),Treatment of bacterial infections caused by susceptible organisms (off-label use for acne is the primary use)
Treatment of frequent heartburn (FDA-approved for over-the-counter use),Gastroesophageal reflux disease (GERD),Erosive esophagitis,Duodenal ulcer,Gastric ulcer,Zollinger-Ellison syndrome,Helicobacter pylori eradication (as part of combination therapy)
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.
One tablet (containing 400 mg magnesium hydroxide, 20 mg omeprazole, 1000 mg sodium bicarbonate) orally once daily, taken at least 1 hour before a meal.
Terminal elimination half-life: 1–2 hours (prolonged in hepatic impairment).
Magnesium hydroxide: not applicable (local action); omeprazole: 0.5-1 hour (terminal); sodium bicarbonate: not applicable (buffering agent). Omeprazole's half-life is short but pharmacodynamic effect (acid suppression) lasts ~24 hours due to covalent binding to proton pumps.
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.
Omeprazole is extensively metabolized in the liver via CYP2C19 and CYP3A4; its metabolites are inactive. Magnesium hydroxide and sodium bicarbonate are not metabolized; they act locally and are partially absorbed. Sodium bicarbonate is converted to carbon dioxide and water via carbonic anhydrase.
Renal: 10-20% (active drug and metabolites); Fecal: minimal; Biliary: not significant.
Magnesium hydroxide: primarily fecal (unabsorbed magnesium), renal (absorbed magnesium); omeprazole: renal (~77% as metabolites) and fecal (~23%); sodium bicarbonate: renal (as bicarbonate or CO2).
70-90% bound to serum albumin.
Magnesium hydroxide: negligible; omeprazole: 95% (albumin and alpha1-acid glycoprotein); sodium bicarbonate: negligible.
0.5–0.8 L/kg (low Vd, minimal tissue penetration).
Magnesium hydroxide: not applicable (local); omeprazole: 0.3-0.5 L/kg (extensive tissue distribution); sodium bicarbonate: 0.5-1 L/kg (total body water).
Topical: 1–5% (minimal systemic absorption).
Magnesium hydroxide: not absorbed orally; omeprazole: 30-40% (oral, delayed-release formulation); sodium bicarbonate: 100% (oral, completely absorbed).
No specific adjustment required; drug is not renally eliminated.
Contraindicated in severe renal impairment (e GFR <30 m L/min/1.73m²) due to risk of magnesium accumulation and sodium overload. For e GFR 30-59 m L/min/1.73m², reduce dose to one tablet every other day and monitor serum magnesium and sodium.
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: Reduce omeprazole dose to 10 mg (not available in this combination) or consider alternative; use with caution. Child-Pugh C: Contraindicated due to omeprazole accumulation.
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.
Not recommended for use in pediatric patients (safety and efficacy not established).
No specific adjustment; use standard dosing with monitoring of antithrombin activity and bleeding risk.
Use with caution due to increased risk of electrolyte imbalance (hypermagnesemia, metabolic alkalosis) and renal impairment. Consider reducing dose to one tablet every other day. Monitor renal function and serum electrolytes.
None.
None
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.
Long-term use (≥1 year) may increase risk of osteoporosis-related fractures; hypomagnesemia with prolonged PPI use; cyanocobalamin (vitamin B12) deficiency with long-term acid suppression; magnesium hydroxide may cause diarrhea; sodium bicarbonate may cause metabolic alkalosis, fluid retention, and worsen hypertension or heart failure; acute interstitial nephritis reported with PPIs; monitor renal function; interaction with clopidogrel (omeprazole reduces clopidogrel's active metabolite); increased risk of Clostridium difficile infection; avoid concurrent use of atazanavir or nelfinavir.
Hypersensitivity to erythromycin or any macrolide antibiotic.,Use with caution in patients with pre-existing QT prolongation or electrolyte abnormalities (relative contraindication).
Hypersensitivity to any component; Concurrent use of rilpivirine-containing products; Severe renal impairment (Cr Cl <30 m L/min) due to risk of magnesium toxicity; Sodium-restricted diet (due to sodium content); Patients with metabolic alkalosis; Children under 12 years for over-the-counter use (varies by product).
No specific food interactions. Avoid excessive alcohol consumption as it may increase skin dryness.
Take on empty stomach; food reduces omeprazole absorption. Avoid high-fat meals. No known specific food interactions with antacid components.
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: No evidence of teratogenicity from omeprazole or magnesium hydroxide; sodium bicarbonate may cause metabolic alkalosis. Second and third trimesters: Omeprazole is considered low risk; magnesium hydroxide can cause hypotonia and respiratory depression in neonates with prolonged use; sodium bicarbonate may lead to fluid overload or alkalosis.
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.
Omeprazole is excreted in breast milk in low amounts (M/P ratio ~0.5); magnesium hydroxide and sodium bicarbonate are poorly absorbed; considered compatible with breastfeeding, but monitor infant for diarrhea or electrolyte imbalance.
No dose adjustment required. Systemic absorption from topical application is minimal and not significantly altered by pregnancy-related pharmacokinetic changes.
No dose adjustment typically required; monitor for magnesium toxicity in renal impairment; consider reduced omeprazole dose if CYP2C19 polymorphisms present; sodium bicarbonate dose should be adjusted to avoid metabolic alkalosis.
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.
This combination uses sodium bicarbonate to rapidly raise gastric p H, enabling omeprazole absorption (enteric-coated omeprazole may be prematurely released; use non-enteric formulations). Magnesium hydroxide provides additional acid neutralization and a laxative effect. Avoid in patients with renal impairment (risk of magnesium toxicity, sodium overload). Administer on an empty stomach at least 1 hour before meals. Do not split or crush tablets.
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.
Take this medication on an empty stomach at least 1 hour before a meal.,Swallow the tablet whole; do not crush or chew it.,Do not take with other antacids or calcium supplements.,Notify your doctor if you have kidney disease or are on a low-sodium diet.,Common side effects include diarrhea or stomach pain; report severe or persistent symptoms.,Avoid alcohol and NSAIDs as they can worsen stomach irritation.
No interactions on record
"Niclosamide may inhibit the cytochrome P450 enzyme CYP2C19, which is the primary hepatic enzyme responsible for the metabolism of omeprazole. This inhibition can lead to decreased clearance and elevated plasma concentrations of omeprazole, potentially increasing its therapeutic and adverse effects. Clinically, this could result in enhanced acid suppression and an increased risk of omeprazole-related side effects such as headache, diarrhea, or vitamin B12 deficiency with prolonged use."
"Cyclosporine, a potent immunosuppressant and P-glycoprotein inhibitor, can significantly increase the systemic exposure of omeprazole by inhibiting its efflux transport and potentially its metabolism via CYP3A4 and CYP2C19. This interaction may lead to elevated omeprazole serum concentrations, increasing the risk of adverse effects such as headache, diarrhea, and vitamin B12 deficiency with long-term use. Clinicians should be vigilant for signs of omeprazole toxicity when coadministered with cyclosporine."
"Omeprazole, a proton pump inhibitor (PPI), is primarily metabolized by cytochrome P450 (CYP)2C19 and, to a lesser extent, CYP3A4. Stiripentol, an antiepileptic drug, is a potent inhibitor of CYP2C19 and CYP3A4. Coadministration may lead to a significant increase in omeprazole exposure (AUC up to 5-fold), potentially increasing the risk of adverse effects such as hypomagnesemia, Clostridioides difficile infection, or bone fracture. Conversely, stiripentol levels are not expected to be significantly affected, as omeprazole does not inhibit its metabolism."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about A/T/S vs MAGNESIUM HYDROXIDE AND OMEPRAZOLE AND SODIUM BICARBONATE, 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.. MAGNESIUM HYDROXIDE AND OMEPRAZOLE AND SODIUM BICARBONATE is a Alkalinizing Agent that works by Magnesium hydroxide is an antacid that neutralizes gastric acid, increasing gastric p H. Omeprazole is a proton pump inhibitor (PPI) that irreversibly inhibits the H+/K+ ATPase enzyme system at the secretory surface of gastric parietal cells, blocking the final step of acid secretion. Sodium bicarbonate is a systemic antacid that neutralizes gastric acid and also provides alkalinization of urine.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between A/T/S and MAGNESIUM HYDROXIDE AND OMEPRAZOLE AND SODIUM BICARBONATE 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 MAGNESIUM HYDROXIDE AND OMEPRAZOLE AND SODIUM BICARBONATE is: One tablet (containing 400 mg magnesium hydroxide, 20 mg omeprazole, 1000 mg sodium bicarbonate) orally once daily, taken at least 1 hour before a meal.. 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 MAGNESIUM HYDROXIDE AND OMEPRAZOLE AND SODIUM BICARBONATE 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 . MAGNESIUM HYDROXIDE AND OMEPRAZOLE AND SODIUM BICARBONATE is classified as Category A/B. First trimester: No evidence of teratogenicity from omeprazole or magnesium hydroxide; sodium bicarbonate may cause metabolic alkalosis. Second and third trimesters: Omeprazole is . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.