Federal Register regulation 42 §482.25(b)(2)(i)
"All drugs and biologicals must be kept in a secure area, and locked when appropriate. (ii) Drugs listed in Schedules II, III, IV, and V of the Comprehensive Drug Abuse Prevention and Control Act of 1970 must be kept locked within a secure area. (iii) Only authorized personnel may have access to locked areas." - 11/27/06