Anti-secretory drugs reduce the production of gastric acid in the stomach. They are used to treat conditions such as gastroesophageal reflux disease (GERD), peptic ulcer disease, and Zollinger-Ellison syndrome. Here’s an overview of these drugs, their mechanisms of action, uses, considerations, and side effects according to UK standards.
Proton Pump Inhibitors (PPIs)
Mechanism of Action: Proton Pump Inhibitors (PPIs) irreversibly block the hydrogen/potassium ATPase enzyme system (also known as the proton pump) of the gastric parietal cells. The proton pump is the final pathway for acid secretion in the stomach. By inhibiting this enzyme, PPIs prevent the secretion of hydrogen ions (protons) into the gastric lumen, thereby reducing gastric acid production significantly.
Medications:
- Omeprazole (Losec)
- Lansoprazole (Zoton)
- Esomeprazole (Nexium)
- Pantoprazole (Protium)
- Rabeprazole (Pariet)
Uses:
- GERD
- Peptic ulcer disease
- Zollinger-Ellison syndrome
- Helicobacter pylori eradication (in combination with antibiotics)
Considerations:
- Long-term use should be regularly reviewed due to potential risks.
- PPIs can interact with certain medications, such as clopidogrel.
- Use the lowest effective dose for the shortest possible duration.
Side Effects:
- Headache
- Diarrhoea
- Nausea
- Vitamin B12 deficiency with long-term use
- Increased risk of fractures with prolonged use
H2 Receptor Antagonists (H2RAs)
Mechanism of Action: H2 receptor antagonists (H2RAs) block histamine H2 receptors on the gastric parietal cells. Histamine is a potent stimulator of acid secretion. By blocking these receptors, H2RAs reduce both the volume of gastric acid and its hydrogen ion concentration.
Medications:
- Ranitidine (Zantac)
- Famotidine (Pepcid)
- Nizatidine (Axid)
- Cimetidine (Tagamet)
Uses:
- GERD
- Peptic ulcer disease
- Dyspepsia
- Short-term relief of acid indigestion and heartburn
Considerations:
- Ranitidine has been withdrawn in many markets due to contamination with NDMA, a probable human carcinogen.
- Cimetidine can interact with a wide range of medications due to its inhibition of cytochrome P450 enzymes.
Side Effects:
- Headache
- Dizziness
- Constipation or diarrhoea
- Gynecomastia with long-term use of cimetidine