Excipient (pharmacologically inactive substance)
What is it?
FDA regulates color additives used in foods, drugs, cosmetics, and medical devices. Ferric (iron) oxides are inorganic pigments used in the pharmaceutical industry as coating pigments. Iron oxides are also commonly used in the cosmetics industry. Iron oxides for use in pharmaceutical manufacturing may also be synthetic. 
 Dave RH. Overview of pharmaceutical excipients used in tablets and capsules. Drug Topics (online). Advanstar. 10/24/2008 http://drugtopics.modernmedicine.com/drugtopics/Top+News/Overview-of-pharmaceutical-excipients-used-in-tabl/ArticleStandard/Article/detail/561047. Accessed 08/19/2011
 U.S. Food and Drug Administration. Color Additives: FDA's Regulatory Process and Historical Perspectives. Accessed 10/20/2011. http://www.fda.gov/ForIndustry/ColorAdditives/RegulatoryProcessHistoricalPerspectives/default.htm