Final answer:
The Schedule IV controlled substance that is a commonly used narcotic analgesic is butorphanol.
Step-by-step explanation:
The commonly used narcotic analgesic that is a Schedule IV controlled substance is butorphanol. Schedule IV controlled substances are drugs that have a low potential for abuse and a low risk of dependence. These drugs have recognized medical uses but can still lead to physical or psychological dependence.
Learn more about Schedule IV controlled substance