esomeprazole

Esomeprazole is a proton pump inhibitor (PPI) in the benzimidazole class and the S-enantiomer of omeprazole. It suppresses gastric acid secretion by irreversibly inhibiting the H+/K+-ATPase enzyme system of gastric parietal cells, leading to decreased acid production.

Clinically, esomeprazole is used for gastroesophageal reflux disease (GERD) and for healing and maintenance therapy of erosive esophagitis. It is also used for duodenal ulcers, gastric ulcers, and in combination regimens to eradicate Helicobacter pylori. Higher-dose regimens may be used for pathological hypersecretory conditions such as Zollinger-Ellison syndrome.

Esomeprazole is administered orally as enteric-coated granules to protect the drug from degradation by stomach acid. It is a prodrug that requires an acidic environment for activation; once activated, it forms an active sulfenamide that inhibits the proton pumps. It is mainly metabolized in the liver by CYP2C19 and, to a lesser extent, by CYP3A4. Peak plasma concentrations occur within 1–2 hours; the plasma half-life is short, but the acid-suppressing effect lasts because the drug irreversibly inhibits the proton pumps.

Typical adult dosing is 20–40 mg once daily, with treatment durations of 4–8 weeks for erosive esophagitis and longer-term maintenance doses as needed. Pediatric dosing varies by age and weight. The medication is available as oral capsules or tablets and also as an intravenous formulation for patients who cannot take oral medication.

Common adverse effects include headache, diarrhea, nausea, and abdominal pain. Long-term use has been associated with hypomagnesemia, vitamin B12 deficiency, osteoporosis-related fractures, and an increased risk of certain infections; rare cases of kidney injury and liver injury have been reported. Esomeprazole can interact with clopidogrel by reducing its activation, potentially diminishing antiplatelet effect, and with certain antifungals and HIV protease inhibitors. Brand-name Nexium; generic esomeprazole is widely available, including OTC in many markets.