Omeprazole Flashcards
What is omeprazole?
pro-drug activated in acidic condition of stomach.
substituted benzimidazoles
What class of compounds does omeprazole belong to?
hyperacidicity, reflux and ulcers
What are other compounds in the same class as omeprazole?
antacids cimetidine ranitidine misoprostol simethicone bismuth trioxide pantoprazole famotidine
What is omeprazole indicated for?
- GORD
- benign duodenal ulcer and gastric ulcer
- NSAID-associated peptic ulcer and gastro-duodenal erosions
- Acid related dyspepsia
- Adjunct in eradication of H. pylori
- Severe reflux oesophagitis
- Injectable form primarily for Zollinger-Ellison syndrome
What is the mechanism of action of omeprazole?
omeprazole is a PPI which suppresses gastric acid secretion by inhibiting the H+/K+ ATPase in the gastric parietal cell specifically. It blocks the final step in acid production and reduces gastric acidity.
What is the role of omeprazole in GORD?
- as part of the step up/step down therapy. Generally used if antacids/alginates do not work.
What is the role of omeprazole in H pylori eradication?
20mg bd Adjunct to amoxicillin (1g bd) and clarithromycin (500mg bd)
What are the preacautions associated with omeprazole use?
- may mask symptoms of gastric cancer
- should be prescribed for appropriate conditions at the lowest effective dose for the shortest period
- need for long term treatment should be reviewed periodically
- if hepatic impairment: no more than 20mg OD
- may increase risk of infections due to reduced acid secretions
- Pregnancy B3 but comaptible with breastfeeding
What are the contraindications with omeprazole use?
hypersensitivity to substituted benzimidazoles
What are the relevant PD/PK parameters with omeprazole?
PD: onset of anti-secretory effect occurs within 1 hour, increasing to max at 2 hours.
Effect lasts for a long time despite short half life due to prolonged binding
Discontinuation of the drug will cause secretory activity to return to baseline over 3-5 days.
PK: 95% bound to plasma protein Metabolised hepatically by 2C19 and 3A4 Eliminated by kidneys half life: 0.5-1 hour
What are the drug interactions associated with omeprazole use?
May reduce effects of clopidogrel, itraconazole, atanavir
What are the alarm bells associated with omeprazole use?
Symptoms of overdose include: confusion drowsiness blurred vision tachycardia nausea diaphoresis flushing headache dry mouth
