16.01.1 Antacids

Anti-acids (which are alkaline solutions) can be used to neutralise the acid in the stomach. There are lots of these available over-the-counter. Combinations of Mg²⁺ and Al³⁺ hydroxides provide a relatively fast and sustained neutralising capacity. Carbonates and bicarbonates also neutralise acid.

Mylanta is a mixture of aluminium hydroxide and magnesium hydroxide.

Gaviscon is a mixture of calcium carbonate, sodium bicarbonate and alignate, which is a viscous gum. Alignate helps protective mucus stick to the oesophagus, and this prevent acid damage.

As Mylanta and Gaviscon are available over-the-counter, it indicates that they are relatively safe agents. They are also cheap, compared to visiting a doctor and paying for a prescription. Antacids are cleared from stomach in about 30 minutes, which means that they may need to be taken frequently.

Antacids will increase the pH of the stomach, and altering gastric pH can affect dissolution, absorption and bioavailability of several drugs. In order to prevent this problem, it is best to avoid concurrent administration of antacids and other drugs. The suggestion is that there should be a two hour gap between taking antacids and other drugs.

With normal renal function, the modest accumulation of Al³⁺ from aluminium hydroxide is not a problem. However, in renal insufficiency, the increase levels of Al³⁺ can contribute to osteoporosis and proximal myopathy.

Antacids are used in the treatment of dyspepsia, heartburn, GERD, peptic ulcers and NSAIDs-induced ulcers. Antacids only relieve the symptoms; they do nothing to the underlying conditions.