Proton pump inhibitor
Pantoprazole (Protonix)
Also called Protonix
Indications
- Peptic ulcer bleeding: high-dose IV for 72 h after endoscopic hemostasis of a high-risk ulcer, and often before endoscopy (off-label)
- Stress ulcer prophylaxis in ventilated or other high-risk ICU patients (off-label)
- GERD with erosive esophagitis when oral therapy is not possible, for 7–10 days
- Zollinger-Ellison syndrome and other hypersecretory states
- Aspiration prophylaxis before anesthesia (off-label)
Dosing
Infusion start: 80 mg bolus, then 8 mg/h for 72 hours after endoscopy for a high-risk ulcer. Titration: Fixed rate; intermittent high-dose dosing is an accepted alternative.
| Where | Dose |
|---|---|
| Daily ICU prophylaxis | Pantoprazole: Prophylaxis: 40 mg IV or enteral once daily; famotidine 20 mg twice daily is an equal choice (halve it at CrCl under 50) |
On the quick cards
Mechanism of action
Pantoprazole is a prodrug: a weak base (pyridine pKa about 3.9) that crosses membranes uncharged and is trapped and concentrated in the acid canaliculus of active parietal cells. There acid converts it to a cyclic sulfenamide, which binds cysteines 813 and 822 of the H⁺/K⁺-ATPase covalently through disulfide bonds and blocks the final step of acid secretion whatever the stimulus (histamine, gastrin or acetylcholine). Cysteine 822 lies deep in the membrane where glutathione cannot reach it, so acid secretion returns only as new pumps are made, long after the 1 h plasma half-life.
Pharmacology
- GI: suppresses basal and stimulated acid; high-dose infusion aims for a gastric pH near 6, which protects an ulcer-bed clot (pepsin is inactive above pH 4, and platelets aggregate poorly in acid)
- GI: blocks only actively secreting pumps, so steady inhibition needs repeated doses or an infusion
- Infectious: less acid allows bacterial overgrowth, linked to C. difficile; REVISE found no rise in ventilator pneumonia
- Endocrine: raises gastrin and chromogranin A, which can give false-positive tumor tests
Pharmacokinetics
| Onset | IV: within 15–30 min (label) |
|---|---|
| Peak | 80 mg IV fully suppresses stimulated acid in about 2 h (label) |
| Duration | Over 24 h; acid secretion recovers with a half-time of about 46 h as new pumps are made (Shin 2002) |
| Half-life | About 1 h; 3.5–10 h in CYP2C19 poor metabolizers |
| Distribution | Vd 11–23.6 L, mainly extracellular |
| Protein binding | About 98%, mainly albumin |
| Metabolism | CYP2C19 demethylation then sulfation; minor CYP3A4; metabolites inactive |
| Elimination | 71% in urine and 18% in feces as metabolites |
| Organ failure | No change in renal failure; not dialyzed; liver impairment raises AUC 5–7-fold (half-life 7–9 h) without a dose change |
Chemistry
- A benzimidazole sulfoxide with a difluoromethoxy group, racemic at the sulfur; both enantiomers form the same achiral sulfenamide
- Its very low benzimidazole pKa (about 0.1) makes it activate slowly at pH 3–5, more stable than other PPIs, yet quickly at the canalicular pH near 1
- 40 mg freeze-dried vial with edetate disodium; reconstituted with 10 mL NS (4 mg/mL, pH 9.0–10.5); use within 6 h, or 24 h once diluted in NS or D5W; protect from light
- Dedicated line or a Y-site flushed with NS or D5W; midazolam is incompatible (label)
Adverse effects and cautions
Sources
- FDA label: Protonix I.V. (2024)
- REVISE trial (Cook 2024)
- ACG guideline: ulcer bleeding (Laine 2021)
- Shin and Sachs 2002 (pump recovery)
For education and exam preparation only. Follow your institution’s protocols. Typical adult values for study. Follow the order, the label and your institution's protocols.