OMEPRAZOLE AND SODIUM BICARBONATE
Clinical safety rating: safe
Can decrease the levels of many drugs by increasing urinary pH Can cause metabolic alkalosis and fluid overload.
Omeprazole is a proton pump inhibitor that suppresses gastric acid secretion by inhibiting the H+/K+ ATPase enzyme system at the secretory surface of gastric parietal cells. Sodium bicarbonate is an antacid that neutralizes gastric acid.
| Metabolism | Omeprazole is extensively metabolized in the liver by cytochrome P450 (CYP) enzymes, primarily CYP2C19 and CYP3A4, to inactive metabolites. Sodium bicarbonate is not metabolized; it dissociates into sodium and bicarbonate ions. |
| Excretion | Omeprazole is primarily metabolized by CYP2C19 and CYP3A4; metabolites are excreted renally (~77% as metabolites) and fecally (~20% as metabolites). Urinary excretion of unchanged omeprazole is negligible (<1%). Sodium bicarbonate is excreted renally as bicarbonate and carbon dioxide. |
| Half-life | Terminal elimination half-life of omeprazole is approximately 0.5-1 hour. However, the pharmacodynamic effect (gastric acid suppression) lasts longer due to accumulation in parietal cells. Half-life does not correlate with duration of acid suppression. |
| Protein binding | Omeprazole is 95% bound to plasma proteins, primarily albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | Apparent volume of distribution is approximately 0.3-0.5 L/kg, suggesting distribution into total body water. The active form accumulates in parietal cell canaliculi. |
| Bioavailability | Oral bioavailability is approximately 30-40% after a single dose, increasing to 60-70% with repeated administration due to decreased first-pass metabolism. Bioavailability is not affected by food but is enhanced by the sodium bicarbonate component, which protects omeprazole from acid degradation. |
| Onset of Action | Oral: Onset of acid suppression occurs within 1 hour of administration. Maximal effect on gastric pH is seen within 2-4 hours. |
| Duration of Action | Duration of acid suppression persists for up to 24 hours after a single dose, with a peak effect at 2-4 hours and sustained elevation of intragastric pH for the remainder of the day. Continuous daily dosing leads to progressive acid suppression. |
Omeprazole 20 mg plus sodium bicarbonate 1100 mg orally once daily before a meal; for gastroesophageal reflux disease, dose may be increased to 40 mg orally once daily for 4-8 weeks.
| Dosage form | FOR SUSPENSION |
| Renal impairment | No dosage adjustment required for mild to moderate renal impairment; for severe renal impairment (GFR <30 mL/min), use with caution and monitor for sodium overload. |
| Liver impairment | For mild hepatic impairment (Child-Pugh class A), no adjustment; for moderate to severe impairment (Child-Pugh class B or C), maximum dose is 20 mg omeprazole once daily due to reduced metabolism. |
| Pediatric use | Not established for omeprazole/sodium bicarbonate combination; for omeprazole alone, weight-based dosing: 10-15 mg once daily for weight 10-20 kg, 20 mg once daily for weight >20 kg. |
| Geriatric use | No specific dose adjustment; use lowest effective dose, monitor for electrolyte imbalance (sodium) and increased risk of Clostridium difficile infection. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Can decrease the levels of many drugs by increasing urinary pH Can cause metabolic alkalosis and fluid overload.
| FDA category | Animal |
| Breastfeeding | Omeprazole is excreted into breast milk with an M/P ratio of approximately 0.1-0.2. Sodium bicarbonate is also excreted. At therapeutic doses, amounts are unlikely to affect the infant. Manufacturer advises caution, but use is generally considered compatible with breastfeeding. |
| Teratogenic Risk | First trimester: No increased risk of major congenital malformations based on large cohort studies. Second and third trimesters: Limited data, but no evidence of fetal harm. Omeprazole is FDA Pregnancy Category C; sodium bicarbonate is not associated with teratogenicity. |
■ FDA Black Box Warning
No FDA black box warning.
| Common Effects | hyperkalemia |
| Serious Effects |
["Hypersensitivity to omeprazole or sodium bicarbonate","Hypersensitivity to other proton pump inhibitors","Concurrent use of rilpivirine","Severe hypokalemia or metabolic alkalosis (due to bicarbonate component)"]
| Precautions | ["Gastric malignancy: Short-term treatment does not preclude presence of gastric malignancy.","Clostridioides difficile infection: May increase risk.","Bone fracture: Long-term use may increase risk of osteoporosis-related fractures of the hip, wrist, or spine.","Hypomagnesemia: May cause low serum magnesium with prolonged use.","Cyanocobalamin (Vitamin B12) deficiency: Prolonged acid suppression may impair absorption.","Acute interstitial nephritis: Has been observed.","Cutaneous lupus erythematosus: May increase risk.","Interaction with methotrexate: May increase methotrexate toxicity.","Sodium content: Contains sodium bicarbonate; caution in patients on sodium-restricted diet.","Metabolic alkalosis: High doses of bicarbonate may cause metabolic alkalosis."] |
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| Fetal Monitoring | No specific monitoring required beyond routine prenatal care. For chronic use, monitor maternal serum electrolytes (sodium, bicarbonate) due to sodium bicarbonate component, especially with high doses or renal impairment. |
| Fertility Effects | Animal studies with omeprazole showed no adverse effects on fertility. Sodium bicarbonate does not affect fertility. Human data are lacking but no known impact on fertility. |