Prilosec Drug Classification
Prilosec (omeprazole) is a proton pump inhibitor (PPI). 1
Mechanism of Action
PPIs work by irreversibly binding to the hydrogen/potassium-exchanging adenosine triphosphatase (H+/K+-ATPase) enzyme in gastric parietal cells, blocking the final step of gastric acid secretion. 2, 3 This covalent binding renders the proton pump nonfunctional, providing potent and prolonged acid suppression regardless of the stimulus. 4
Drug Class Members
The PPI class includes several agents available by prescription, with omeprazole also available over-the-counter for frequent heartburn 1:
- Omeprazole (Prilosec)
- Lansoprazole
- Pantoprazole
- Rabeprazole
- Esomeprazole
- Dexlansoprazole 1
Key Pharmacologic Characteristics
Omeprazole is a prodrug that requires conversion to its active sulfonamide form in the acidic environment of gastric parietal cells. 1 The drug has a plasma half-life of less than 2 hours, but its duration of action exceeds 24 hours due to irreversible enzyme binding. 3
Metabolism occurs primarily through the CYP2C19 pathway, making omeprazole susceptible to genetic polymorphisms and drug-drug interactions. 5 This distinguishes it from newer potassium-competitive acid blockers (P-CABs), which are not metabolized by CYP2C19 and demonstrate less pharmacokinetic variability. 1
Clinical Implications
The CYP2C19-mediated metabolism creates important drug interactions, particularly with clopidogrel, where omeprazole can significantly decrease antiplatelet effects. 1 This interaction has led to FDA warnings about concomitant use in patients requiring dual antiplatelet therapy. 1
Unlike P-CABs, PPIs are acid-labile and require enteric coating, with optimal dosing 30-60 minutes before meals to coincide with peak proton pump activity. 1 PPIs typically require 3-5 days to achieve maximal acid suppression, compared to 1 day for P-CABs. 1