Antacids
Acid Neutralizers
Antacids have been around forever with roots that extend back to the chewing of herbs, plants, and roots. An archaic term, dyspepsia, provides a clue to the original use for mints. Over time, as our understanding of gastric pain has changed, we have begun to use more direct acid neutralizers.
Bicarbonate of soda, appearing as bubbly liquids, was popular decades ago, as it was felt that a simple acid-base reaction would be the solution for the painful symptoms. Additionally, people were told to drink plenty of milk and eat a bland diet. This was boring, mildly unpleasant, and usually worthless. More recently,
bicarbonate salts have become popular for a variety of reasons. Aluminum bicarbonate and Magnesium bicarbonate mixtures, like Maalox and Mylanta, are relatively easy to use. These chemicals are combined because the former is constipating and the latter is cathartic (produces diarrhea).
Calcium bicarbonate, Tums and Rolaids, is even more popular now because of the beneficial properties of Calcium on the bone. However, one major drawback for this category of medicines is that they have to be used when there is actually acid present in the stomach - after recently ingested food has passed on. Therefore, one must take these products four times a day, one hour after meals and at bedtime.
Topical coatings that form a protective film have also been tried. Initially, it was felt that milk had such an effect but this turns out not to be the case. Carafate (sucralfate) is a tablet that dissolves and forms such a barrier. A significant problem is that it can block the absorption of any other medications that one might be taking.
Acid Production Inhibitors
As our understanding of the cellular mechanisms of the gastrointestinal tract improves, so do our weapons. Research has been able to identify actual molecular pumps that cause the secretion of acid from the cells lining the stomach. Obviously, attacking these would be the most logical step. Over the last two decades we have had a class of drugs known as type-2 histamine blockers (H2-blockers, H2 receptor antagonists). These drugs interact with type 2 histamine receptors and prevent acid-secreting cells from receiving a molecular signal to pump acid out in to the stomach chamber, thereby reducing the acid load by 65%. These drugs should not be confused with the morefamiliar antihistamines (those used for respiratory allergies), which are type-1 histamine blockers. After many years of use, H2-blockers are now available as both prescription and over-the-counter versions (Tagamet, Zantac, Pepcid, Axid - listed in order of introduction). Some are combined with an acid neutralizing coating as well (Pepcid Complete). While quite effective, these drugs still have an indirect effect on acid secretion.
The latest technology involves the actual block of the proton-pump mechanism in the cell walls to reduce by over 95% the secreted acid. These drugs include
Prilosec and Prevacid. As their patents run out, long acting versions are appearing, notably Nexxium - which is essentially Prilosec.
The last category is also used for duodenal ulcers and esophagitis, gastroesophageal reflux disease (GERD), as well as for gastritis.
