Medical Health Encyclopedia

Interactions with Other Drugs. Antacids can interact with a number of drugs in the intestines and reduce their absorption. Conversely, some antacids increase the potency of certain drugs. The interactions can be avoided by taking these other drugs one hour before or three hours after the antacid.

Drug Interactions with Antacids (e.g., Maalox, Mylanta)
Drugs that are less absorbed with antacids	Drugs that are made more potent with antacids
Text Continues Below tetracycline ciprofloxacin (Cipro) propranolol (Inderal) captopril (Capoten) ranitidine (Zantac) famotidine (Pepcid AC)	valproic acid sulfonylureas quinidine levodopa

Antibiotics

H. pylori is usually highly sensitive to certain antibiotics, particularly amoxicillin or antibiotics such as clarithromycin that belong to the drug class known macrolides. Either type of agent serves effectively as a second antibiotic in a three-drug regimen. Others being used are tetracycline, metronidazole, and ciprofloxacin.

• Amoxicillin is the most common form of penicillin. It is inexpensive, but many people are allergic to it.
• Clarithromycin (Biaxin) is a macrolide and is the most expensive of the antibiotics used against H. pylori. It is also very effective, but there is growing bacterial resistance to this drug. Resistance rates tend to be higher in women and increase with age. Researchers fear that resistance will increase as the drug is used more and more against H. pylori.
• Tetracycline is effective, but tetracyclines have unique side effects among antibiotics, including skin reactions to sunlight, possible burning in the throat, and tooth discoloration. Pregnant women cannot take it.
• Ciprofloxacin (Cipro), known as a fluoroquinolone, is also sometimes used in ulcer regimens.
• Metronidazole (Flagyl) was the mainstay in initial combination regimens for H. pylori. As with clarithromycin, however, there continues to be growing bacterial resistance to the drug (about 25% to 35% of H. pylori bacteria).