These products have had remarkable growth. More than 7,500 compounding pharmacies operate in the U.S., up from 5,000 in 2009, Miller said. They account for a $3 billion segment of the drug market and 3 percent of all prescriptions filled.
Some say this industry needs more regulation.
"There's not a lot of oversight of compounding pharmacies" compared with drug manufacturers, said Allen Vaida, executive vice president of the Institute for Safe Medication Practices, a suburban Philadelphia advocacy group that tracks medication errors.
"They fall into this gray area and no one supervises in a rigorous fashion their manufacturing processes. The state pharmacy boards don't have the resources or the knowledge or experience," and the FDA does not get involved unless a problem occurs, he said.
The FDA has said the steroid in the current meningitis outbreak came from the New England Compounding Center, based in Framingham, Mass. The company recalled three lots of the drug last week and has said it has voluntarily suspended operations and is working with regulators to identify the source of the problem. Investigators also are looking into the antiseptic and anesthetic used during the injections.
On Thursday, investigators urged doctors nationwide to avoid all products from the New England company. At least 23 states have received vials from the three recalled lots.