Only 5 to 10 percent of all GERD sufferers are in fact secreting too much stomach acid. Once that LES sphincter delivers the food into the stomach and squeezes shut like it's supposed to, acid-laced food will no longer come back up into your esophagus. No more half-digested food, no more reflux or heartburn, and therefore, no more need to use antacids or H2 receptor antagonists.
In cases in which you have severe reflux that has caused esophagitis or an ulcer, an H2 receptor drug, such as cimetidine, famotidein, nizatidine, or ranitidine, can help to alleviate your acid symptoms until the prokineteic drug starts to work its magic. Many doctors in this case will instead prescribe one of the proton pump inhibitors, such as omeprezole, which inhibits an enzyme necessary for acid secretion.
If you have only mild reflux, even regular over-the-counter antacids, combined with prokinetic drugs, may help. In most cases of GERD, however, the acid is simply in the wrong spot - something an acid-lowering drug cannot do much about.