Not so long ago, the stomach was thought to be sterile. Due to the low pH associated with hydrochloric acid production, it was felt that microorganisms could never survive.
We now know this is not the case, but it was not easy to change a medical paradigm. In fact, in the mid-1980s, Australian physician Barry Marshall resorted to ingesting the bacterium Helicobacter pylori to illustrate what he had discovered in the laboratory—that H. pylori was often the cause of gastritis and peptic ulcer disease. In 2005, two decades later, Marshall and J. Robin Warren shared the Nobel Prize in Medicine for their discovery of H. pylori.
It is now recognized that nine out of 10 gastric ulcers are caused by H. pylori. The bacteria not only survive the acidic pH of the stomach but penetrate the thick protective layer of gastric mucus and attach to gastric epithelium. The release of cytotoxins and weakening of the gastric mucus layer contribute to tissue damage and inflammation. By producing urease and liberating ammonia, the organism interferes with the normal negative feedback exerted by acid on the gastrin-secreting cells, predisposing to hypergastrinemia, increased acid secretion, and gastric metaplasia. Hyperacidity and H. pylori then work synergistically to produce ulcers. Acid-suppressing drugs treated ulcers but did not cure them. Lifelong treatment was deemed necessary.
Now, however, antibiotic combinations, given over 10 to 14 days, are used to treat ulcers, leaving only a 10% chance of recurrence. But patient compliance has been a limiting factor in H. pylori eradication, due to the complicated dosing regimens. And bacterial resistance to certain antimicrobials (especially clarithromycin) has been cited, as has the potential for allergic reactions with penicillins.
Axcan Pharma has now harnessed the power of three drugs known to have antimicrobial effects, combining them into a novel formulation. Approved last year and now marketed under the trade name Pylera, the new capsule contains 140 mg bismuth subcitrate potassium, 125 mg metronidazole, and 125 mg tetracycline. It is indicated for use in combination with omeprazole for treating H. pylori infection and duodenal ulcer disease. According to Rosemary Berardi, Pharm.D., a professor of pharmacy at the University of Michigan, "The product's main advantage is that it incorporates a nonsalicylate salt as its source of bismuth, thus avoiding the side effects and cautions associated with bismuth salicylate and the need to take the bismuth salt separately."
Three capsules of Pylera should be taken four times daily after meals and at bedtime for 10 days. Additionally, 20 mg omeprazole should be taken at breakfast and dinner to reduce the amount of secreted acid, provide symptomatic relief, and aid in healing. "The addition of a twice-daily proton pump inhibitor permits a shorter duration of treatment [10 days], compared with older four-drug regimens that contained an H2-receptor antagonist," said Berardi.
Adverse effects of Pylera are often gastrointestinal in nature, with stool abnormality, diarrhea, dyspepsia, abdominal pain, and nausea reported most frequently. This regimen may be simpler than other four-drug H. pylori regimens, said Berardi, but the patient must still take three or four capsules four times a day compared with the proton-pump inhibitor-based three-drug regimens taken twice daily that provide similar eradication rates.
THE AUTHOR is a clinical writer based in the Philadelphia area.
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