HASHEM EL-SERAG, MD: The stomach is the source of acid production. In the stomach, there are specialized cells called the parietal cells that produce the gastric acid. The acid in these cells is produced in response to certain stimuli, certain things that tell the cell, "Please produce acid."
STEVE PEIKIN, MD: It turns out that there's actually three different ways to make acid. Histamine is a chemical in the body, stimulates acid secretion very potently. There's two other ways of stimulating acid -- one is gastrin, hormone in the body that stimulates acid secretion, and there is a chemical from nerves called acetylcholine and that also stimulates acid secretion. So there is three different ways.
ANNOUNCER: Block the right receptor on the parietal cells and you reduce that acid production.
STUART SPECHLER, MD: The histamine H2 receptor blockers work by blocking the receptors that are actually telling the stomach "make acid." It actually blocks the histamine receptor, and therefore it interferes with its ability to make acid.
ANNOUNCER: But it takes time for an H2 blocker to bring relief.
HASHEM EL-SERAG, MD: First it has to get absorbed into the stomach. It goes into the blood circulation and then from the blood it gets back to the stomach cells, gets absorbed into those cells and then blocks the histamine receptors or the H-2 receptors, and then the action starts. That typically takes 30 minutes to 1 hour to start working. Once it starts working, its effect lasts for a few hours; anywhere from three to six hours.
ANNOUNCER: But often delayed action will not be a problem if you can anticipate trouble.