Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
MAGNESIUM HYDROXIDE AND OMEPRAZOLE AND SODIUM BICARBONATE vs BENEMID
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
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.
Competitive inhibitor of renal tubular secretion of organic acids (urate, penicillin, other drugs), enhancing urate excretion and reducing serum uric acid levels. Also inhibits renal transport of weak organic acids.
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)
Treatment of hyperuricemia associated with gout and gouty arthritis,Adjunctive therapy for penicillin and cephalosporin antibiotics to prolong their serum half-life
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.
250 mg orally twice daily for 1 week, then 500 mg orally twice daily; maximum 2 g/day.
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.
Terminal elimination half-life 6-12 hours in adults; prolonged to 12-24 hours in renal impairment or elderly; clinically significant for twice-daily dosing
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.
Hepatic metabolism via oxidation and glucuronidation; minimal CYP450 involvement.
Magnesium hydroxide: primarily fecal (unabsorbed magnesium), renal (absorbed magnesium); omeprazole: renal (~77% as metabolites) and fecal (~23%); sodium bicarbonate: renal (as bicarbonate or CO2).
Renal (70-80% as unchanged drug and metabolites), biliary/fecal (20-30%)
Magnesium hydroxide: negligible; omeprazole: 95% (albumin and alpha1-acid glycoprotein); sodium bicarbonate: negligible.
Approximately 85-95% bound primarily to albumin
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).
0.15-0.30 L/kg; indicates limited extravascular distribution, consistent with high protein binding and renal elimination
Magnesium hydroxide: not absorbed orally; omeprazole: 30-40% (oral, delayed-release formulation); sodium bicarbonate: 100% (oral, completely absorbed).
Oral: >90%
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.
Cr Cl <50 m L/min: avoid use; Cr Cl 50-90 m L/min: reduce dose by 50%.
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.
No specific guidelines; use with caution in severe hepatic impairment.
Not recommended for use in pediatric patients (safety and efficacy not established).
Not recommended for children under 2 years. For older children: 25 mg/kg/day divided every 6 hours, up to 40 mg/kg/day maximum 2 g/day.
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.
Start at low end of dosing range (250 mg twice daily); monitor renal function and urate levels.
None
No FDA black box warning.
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.
Risk of acute gouty arthritis upon initiation; use NSAIDs or colchicine prophylactically. Use with caution in patients with peptic ulcer disease, renal impairment (Cr Cl <50 m L/min), or history of uric acid calculi. May cause aplastic anemia and other blood dyscrasias. Avoid use during acute gout attack.
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).
Known hypersensitivity to probenecid; use with methotrexate or other nephrotoxic agents; severe renal impairment (Cr Cl <50 m L/min); blood dyscrasias; uric acid kidney stones; children under 2 years of age.
Take on empty stomach; food reduces omeprazole absorption. Avoid high-fat meals. No known specific food interactions with antacid components.
Avoid high doses of aspirin or salicylate-containing foods. Maintain adequate fluid intake. No specific food restrictions but alcohol may increase serum uric acid and reduce efficacy. Avoid large doses of vitamin C (may acidify urine and increase urate stone risk).
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.
FDA Pregnancy Category D for second and third trimesters due to risk of neonatal hemolysis and jaundice from sulfonamide component; first trimester use associated with possible neural tube defects based on animal data and limited human reports.
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.
Small amounts of probenecid and sulfonamide excreted into breast milk; M/P ratio not established. Potential for hemolysis in G6PD-deficient infants, jaundice, and kernicterus in premature infants. Contraindicated in nursing mothers due to sulfonamide component.
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.
Increased renal clearance and volume of distribution in pregnancy may reduce probenecid half-life; dose adjustment based on therapeutic response and serum uric acid levels is recommended. No specific dosing guidelines; clinical judgment advised.
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.
BENEMID (probenecid) inhibits renal tubular secretion of penicillins and cephalosporins, increasing their serum levels. Use with caution in patients with G6PD deficiency due to risk of hemolytic anemia. Avoid in patients with blood dyscrasias or peptic ulcer disease. Ensure adequate hydration to prevent urate nephropathy during gout therapy.
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.
Take with food or milk to reduce gastrointestinal upset.,Drink plenty of fluids (at least 2 liters daily) to prevent kidney stones.,Do not take with aspirin or other salicylates as they may reduce effectiveness.,This medication may increase the effects of other drugs like penicillins and methotrexate.,Report any signs of allergic reaction, severe skin rash, or joint pain immediately.
"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."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about MAGNESIUM HYDROXIDE AND OMEPRAZOLE AND SODIUM BICARBONATE vs BENEMID, answered by our medical review team.
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.. BENEMID is a Uricosuric Agent that works by Competitive inhibitor of renal tubular secretion of organic acids (urate, penicillin, other drugs), enhancing urate excretion and reducing serum uric acid levels. Also inhibits renal transport of weak organic acids.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between MAGNESIUM HYDROXIDE AND OMEPRAZOLE AND SODIUM BICARBONATE and BENEMID 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 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.. The standard adult dose of BENEMID is: 250 mg orally twice daily for 1 week, then 500 mg orally twice daily; maximum 2 g/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 MAGNESIUM HYDROXIDE AND OMEPRAZOLE AND SODIUM BICARBONATE and BENEMID 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. 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 . BENEMID is classified as Category C. FDA Pregnancy Category D for second and third trimesters due to risk of neonatal hemolysis and jaundice from sulfonamide component; first trimester use associated with possible neu. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.