Astra Merck Inc. announced it has received clearance from the U.S. Food and Drug Administration (FDA) today to market itsantisecretory medication Prilosec(R) (omeprazole) in combination with the antibiotic Biaxin(R) (clarithromycin) for the treatment of patients with H. pylori infection and duodenal ulcer to eradicate H. pylori, the bacteria now believed to cause approximately 90 percent of peptic ulcers.