Final answer:
Controlled substances may be placed in an EDK in regulated healthcare facilities like hospitals or clinics, and include medications necessary for emergencies, subject to strict legal guidelines.
Step-by-step explanation:
Controlled substances may be placed in an emergency drug kit (EDK) in a setting that is typically regulated such as a hospital or clinic, especially in areas where quick access to such medications is crucial during an emergency situation. In some jurisdictions, other healthcare settings like nursing homes or ambulances may also include EDKs with controlled substances following strict guidelines to ensure security, proper usage, and compliance with legal requirements. The substances in the EDK are usually selected based on the types of emergencies that are expected to occur in the particular setting and may include drugs for cardiac arrest, allergic reactions, pain management, and sedation, among others.