An antacid (plural: antacids) is a drug that can be used in medicine to neutralize the acidic gastrointestinal environment. The active ingredients used as antacids are mainly salts of weak acids or weak bases. The common feature of all antacids is that they act as a buffer on the gastric juice and can thus neutralise it.
In this way, the use of antacids can help to relieve heartburn, inflammation of the stomach lining and pain in the upper digestive tract. The main number of antacids includes: In addition, recently, especially combination preparations of aluminium and magnesium hydroxide have been widely used in the treatment of chronic heartburn. The combination of two different active substances offers the advantage that the rapid onset of action of one substance can be combined with the long duration of action of the other.
The overall effect of the antacid can be increased many times over in this way. In addition, the combination of aluminium hydroxide and magnesium hydroxide proved to be useful, as the occurrence of side effects could be significantly reduced by taking both active ingredients at the same time. In this context, extensive studies have shown, for example, that patients who were treated with combination antacids over a longer period of time suffered less frequently from constipation on average. – magnesium,
- Aluminium or
- Calcium-containing compounds.
Although antacids have a proven protective effect on the stomach and the lower part of the oesophagus and prevent the occurrence of acid damage by neutralizing stomach acid, this group of drugs is a purely symptomatic drug. A curative (i.e. healing) effect of the antacids has not been proven to date. While taking antacids, various undesirable drug effects (side effects) can occur.
In connection with the intake of antacids described above, changes in stool consistency, diarrhoea and constipation can occur. Antacids also have an influence on kidney function. For this reason, a shift in electrolyte ratios has been observed in some patients. When taking antacids, it must also be taken into account that the absorption and effect of other drugs can be reduced, sometimes drastically.
Mode of action
The effect of the antacids is particularly evident in a neutralization of the acidic stomach environment. Excess gastric acid is buffered by using the weak bases (or salts) contained in the various antacids. This means that the smallest components of the antacid agent form a chemical bond with the stomach acid and thus permanently “inactivate” it.
The stomach acid thus loses its acidic character and can no longer cause any damage to the irritated mucous membranes of the oesophagus or stomach. Some active ingredients are also able to leave a protective film on the mucous membrane of the oesophagus and stomach. In general, the effect of antacids begins a few minutes after they are taken and lasts up to four hours.
In addition to the duration and speed of action of the antacids, the so-called buffer capacity (or neutralisation capacity) of the respective active ingredient plays a considerable role. The term buffer capacity describes nothing more than the amount of active strength that an antacid can apply. Active substances with a high neutralisation capacity have a strong effect; they can bind and neutralise a large number of acidic valencies.