SHIJIAZHUANG, China -- If you pop a vitamin C tablet in your mouth, it's a good bet it came from China. In less than a decade, China has captured 90 percent of the U.S. market for vitamin C, driving almost everyone else out of business. Chinese pharmaceutical companies also have taken over much of the world market in the production of antibiotics, analgesics, enzymes and primary amino acids. According to an industry group, China makes 70 percent of the world's penicillin, 50 percent of its aspirin and 35 percent of its acetaminophen (often sold under the brand name Tylenol), as...