ATC code A02

The Anatomical Therapeutic Chemical (ATC) Classification System is used for the classification of drugs and other medical products. The code A02 is designated for "Drugs for acid related disorders." These medications are primarily used to treat conditions related to excessive stomach acid production, such as gastroesophageal reflux disease (GERD), peptic ulcer disease, and dyspepsia.

Classification

ATC code A02 is divided into several subcategories, each representing a different class of drugs used to manage acid-related disorders:

A02A: Antacids

Antacids are substances that neutralize stomach acidity. They are commonly used to relieve heartburn, indigestion, or an upset stomach. Examples include:

• Aluminum hydroxide
• Magnesium hydroxide
• Calcium carbonate

A02B: Drugs for Peptic Ulcer and Gastro-Oesophageal Reflux Disease (GORD)

This category includes medications that reduce gastric acid secretion or protect the gastric mucosa. It is further divided into:

A02BA: H2-receptor antagonists

H2-receptor antagonists, also known as H2 blockers, reduce stomach acid production by blocking histamine receptors in the stomach lining. Common examples are:

• Ranitidine
• Famotidine
• Cimetidine

A02BC: Proton pump inhibitors (PPIs)

PPIs are a class of drugs that irreversibly inhibit the hydrogen/potassium ATPase enzyme system of the gastric parietal cells, leading to a significant reduction in acid secretion. Examples include:

• Omeprazole
• Lansoprazole
• Pantoprazole

A02BD: Combinations for eradication of Helicobacter pylori

These are combination therapies used to eradicate Helicobacter pylori, a bacterium associated with peptic ulcer disease. Treatment typically includes a PPI and two antibiotics, such as:

• Amoxicillin
• Clarithromycin

A02X: Other drugs for acid related disorders

This category includes other medications that do not fit into the above classifications but are used to treat acid-related disorders. An example is:

• Sucralfate

Mechanism of Action

The drugs classified under ATC code A02 work through various mechanisms to reduce gastric acidity or protect the gastric mucosa:

• Antacids neutralize existing stomach acid, providing quick relief from symptoms.
• H2-receptor antagonists block histamine from stimulating acid secretion, thus reducing acid production.
• Proton pump inhibitors inhibit the final step of acid production in the stomach, leading to a more prolonged reduction in acid secretion.
• Mucosal protectants like sucralfate form a protective barrier on the gastric lining, shielding it from acid and pepsin.

Clinical Uses

Drugs under ATC code A02 are used to treat a variety of conditions, including:

• Gastroesophageal reflux disease (GERD)
• Peptic ulcer disease
• Zollinger-Ellison syndrome
• Dyspepsia
• Helicobacter pylori eradication

Side Effects

While generally safe, these medications can have side effects:

• Antacids may cause constipation or diarrhea, depending on their composition.
• H2-receptor antagonists can cause headaches, dizziness, and gastrointestinal disturbances.
• Proton pump inhibitors are associated with an increased risk of fractures, kidney disease, and vitamin B12 deficiency with long-term use.

Conclusion

ATC code A02 encompasses a range of medications essential for managing acid-related disorders. Understanding their classification, mechanism of action, and clinical applications is crucial for effective treatment.

References

• ATC/DDD Index 2023
• Article on Proton Pump Inhibitors

See Also

• ATC code A
• Gastroenterology