Omeprazole

# Omeprazole ## Overview - **Classification**: Proton Pump Inhibitor (PPI) - **Mechanism**: Irreversibly inhibits the H+/K+-ATPase (proton pump) in gastric parietal cells, blocking the final step in acid secretion. ## Primary Indications 1. **Gastroesophageal Reflux Disease (GERD)** - Including erosive esophagitis. 2. **Peptic Ulcer Disease (PUD)** - Duodenal and gastric ulcers, including *H. pylori* eradication. 3. **Zollinger-Ellison Syndrome (ZES)** - Pathological hypersecretory conditions. ## Adult Dosing ### Standard Dosing **Gastroesophageal Reflux Disease (GERD) / Erosive Esophagitis** - **Treatment**: **20 mg** once daily for 4-8 weeks. - **Maintenance**: **20 mg** once daily. - **Route**: Oral **Duodenal Ulcer** - **Dose**: **20 mg** once daily - **Frequency**: Once daily - **Route**: Oral - **Duration**: 4 weeks (up to 8 weeks if needed). **Gastric Ulcer** - **Dose**: **40 mg** once daily - **Frequency**: Once daily - **Route**: Oral - **Duration**: 4-8 weeks. ***H. pylori* Eradication (Triple Therapy)** - **Dose**: **20 mg** - **Frequency**: Twice daily - **Route**: Oral - **Duration**: 10-14 days (with clarithromycin + amoxicillin or metronidazole). **Zollinger-Ellison Syndrome (ZES)** - **Initial Dose**: **60 mg** once daily - **Frequency**: Once daily (or divided if >80 mg/day) - **Route**: Oral - **Special Considerations**: Titrate dose to control acid output. Doses up to **360 mg/day** have been used. ### Dose Adjustments - **Renal Impairment**: No dose adjustment needed. - **Hepatic Impairment**: Max dose **20 mg** daily for severe impairment (Child-Pugh Class C). - **Elderly Patients**: No specific adjustment; consider lower end of dosing range. ## Pediatric Dosing ### Neonates (0-28 days) - **Dose**: Limited data. Not routinely recommended due to lack of safety/efficacy. - **Special Notes**: Use alternative therapies if possible. Consult GI specialist. ### Infants (1-12 months) - GERD/Erosive Esophagitis - **Dose**: **0.7 mg/kg** - **Frequency**: Once daily - **Maximum**: **20 mg** per day. Max **10 mg** for infants <10 kg. - **Special Notes**: Oral suspension or capsule contents mixed with apple juice/applesauce. ### Children (1-12 years) - GERD/Erosive Esophagitis - **Weight < 20 kg**: **10 mg** - **Weight ≥ 20 kg**: **20 mg** - **Frequency**: Once daily - **Maximum**: **20 mg** per day for GERD. Up to **40 mg** once daily for severe erosive esophagitis under specialist guidance. - ***H. pylori***: **0.7-1 mg/kg/day** divided twice daily (max **20 mg BID**), as part of combination therapy. ### Adolescents (13-18 years) - GERD/Erosive Esophagitis - **Dose**: Follow adult dosing recommendations. - **Maximum**: **20 mg** once daily for GERD, **40 mg** for erosive esophagitis. ## Safety Information ### Contraindications - **Absolute**: Hypersensitivity to omeprazole or substituted benzimidazoles. - **Absolute**: Concomitant use with **nelfinavir** (significantly reduces nelfinavir levels). - **Relative**: Concomitant use with **rilpivirine** (reduced antiretroviral efficacy). ### Common Adverse Effects - **Common (1-10%)**: Headache, abdominal pain, nausea, diarrhea, vomiting, flatulence, constipation. - **Serious but Rare**: *Clostridium difficile* infection, bone fracture (long-term use), hypomagnesemia (long-term use), acute interstitial nephritis, fundic gland polyps (long-term use), cutaneous lupus erythematosus. ### Key Drug Interactions - **Clopidogrel**: May reduce antiplatelet effect of clopidogrel. Avoid concomitant use if possible. - **Methotrexate**: May increase methotrexate levels. Monitor for toxicity, consider dose adjustment. - **Warfarin**: May prolong INR. Monitor INR closely, adjust warfarin dose as needed. - **Diazepam/Phenytoin**: May increase levels of these drugs. Monitor for toxicity. - **Iron salts/Calcium carbonate**: Reduced absorption due to increased gastric pH. ## Monitoring & Follow-up - **Before Treatment**: Assess for malignancy symptoms if esophageal/gastric symptoms are present. - **During Treatment**: Monitor for symptom resolution. Long-term use: consider magnesium levels, bone density. - **Clinical Signs**: Watch for persistent symptoms, signs of GI bleeding, new fractures, muscle weakness (hypomagnesemia). ## Clinical Pearls - 💡 **Tip 1**: Take **30-60 minutes BEFORE the first meal** of the day for optimal efficacy. - 💡 **Tip 2**: Do not crush or chew delayed-release capsules/tablets. For patients unable to swallow, capsule contents can be mixed with applesauce/juice. - 💡 **Tip 3**: Long-term use (typically >1 year) is associated with increased risk of bone fracture, *C. difficile* infection, and hypomagnesemia. Periodically reassess the need for continued PPI therapy. - 💡 **Tip 4**: For patients on clopidogrel, assess the risk/benefit or consider an alternative PPI with less interaction (e.g., pantoprazole) or an H2RA. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.