The FDA publication "Orange Book: Approved Drug Products with Therapeutic Equivalence," which lists all branded drugs and their generic equivalents that are approved for sale in the United States, shows each drug's manufacturer. The book is available from the U.S. Government Printing Office at bookstore.gpo.gov as a downloadable PDF.
The FDA also has an online catalog of approved drugs, Drugs@FDA, which lists drugs by brand name and shows their manufacturers. The catalog is updated daily and includes all human drugs available by prescription or over-the-counter. The home page provides an alphabetical list to help visitors locate the drug brand name.