Products
Antacids are commercially available in the form of lozenges, chewable tablets, as a powder, and as a gel (suspension) for oral use, among others. Well-known brands in many countries include Rennie, Alucol, and Riopan. The first medicines were developed as early as the 19th century.
Structure and properties
The drugs contain active ingredients that bind and neutralize stomach acid. These include, for example, carbonates such as calcium carbonate and magnesium carbonate, hydroxides such as magnesium hydroxide, and oxides such as aluminum oxide. They are bases. Magnesium hydroxide example:
- Magnesium hydroxide (Mg(OH)2) + hydrochloric acid (2HCl) magnesium chloride (MgCl2) + water (2H2O)
Example sodium hydrogen carbonate:
- Sodium hydrogen carbonate (NaHCO3) + hydrochloric acid (HCl) common salt (NaCl) + water (H2O) + carbon dioxide (CO2)
Only sodium bicarbonate produces the gas carbon dioxide, which can cause undesirable effects.
Effects
Antacids (ATC A02A) neutralize stomach acid and cause a rise in stomach pH, which relieves discomfort. Some antacids also form a protective film on the stomach lining and neutralize other components of the digestive juice, such as pepsin and bile acids.
Indications
Antacids are used for the symptomatic treatment of gastric burning, acid regurgitation, and gastroesophageal reflux disease. Indications also include indigestion and a feeling of pressure and fullness in the stomach area. In some countries, antacids are also approved for the symptomatic treatment of gastric and intestinal ulcers. Another area of application is gastric protection while taking NSAIDs. However, the proton pump inhibitors are mainly used for this purpose today.
Dosage
According to the professional information leaflet. Antacids are usually taken regularly after meals or as needed. The onset of action is rapid. Suspensions must be shaken before use. Antacids should be taken by patients in self-medication for only about two weeks. If symptoms persist for longer, medical consultation is recommended because there may be a serious underlying cause, such as a stomach or intestinal ulcer or cancer.
Active ingredients
- Aluminum hydroxide
- Aluminum magnesium silicate
- Alumina
- Calcium carbonate
- Carbaldrate
- Hydrotalcite
- Magaldrate
- Magnesium carbonate
- Magnesium hydroxide
- Magnesium oxide
- Magnesium trisilicate
- Sodium hydrogen carbonate
Contraindications
The contraindications depend on the composition. These include (selection):
- Hypersensitivity
- Renal insufficiency
- Hypercalcemia (calcium salts)
- Hypermagnesemia (magnesium salts)
- Hypophosphatemia (aluminum salts)
Full precautions can be found in the drug label.
Interactions
Anacids may form complexes with some drugs, reducing their absorption, bioavailability, and efficacy. Typical examples include quinolones, tetracyclines, NSAIDs, salicylates, bisphosphonates, and iron preparations. For this reason, there should be an interval of at least two hours between doses. Antacids are not recommended during antibiotic therapy. Raising the gastric pH may decrease the bioavailability of other drugs, such as the weak bases itraconazole and ketoconazole. Again, spacing over time is recommended.
Adverse effects
Possible adverse effects include a change in stool consistency (diarrhea or constipation), mineral balance disturbances, and carbonate regurgitation due to the formation of carbon dioxide. Disorders of mineral balance occur primarily in renal insufficiency and with prolonged and high-dose use. These include:
