Representatives Rosa DeLauro and Edward Markey said in separate statements Tuesday that they will draft legislation to give the Food and Drug Administration more authority to police the safety of custom-mixed medicines, known as compounded drugs.

Compounding pharmacies traditionally supply products that are not available commercially, based on an individual doctor's prescription. But some pharmacies have grown into larger businesses, operating across state lines and supplying drugs to thousands of hospitals, clinics and physicians.

The Centers for Disease Control and Prevention says as many as 13,000 people received steroid shots from the New England Compounding Center of Framingham, Mass.