Final answer:
Licensed health care professionals like physicians and dentists as well as pharmacies and health institutions can purchase and possess prescription drugs following regulations to ensure safety and proper use.
Step-by-step explanation:
Health care professionals such as licensed physicians, surgeons, dentists, and veterinarians, along with pharmacies and healthcare facilities like hospitals and clinics, can purchase and possess legend drugs, provided they are authorized by relevant state laws and have the necessary credentials. These drugs are also referred to as prescription drugs and require a written order from a licensed healthcare provider to be dispensed.
The regulation of these drugs is intended to ensure patient safety by preventing misuse and ensuring proper medical supervision.