Which of the following is NOT classified as an opioid?

Cyclobenzaprine is not classified as an opioid; it is actually a muscle relaxant. Opioids are a class of drugs that are used primarily for pain relief and are derived from the opium poppy or are synthetic analogs. The other substances listed – oxycodone, hydrocodone, and fentanyl – are all opioids. Oxycodone and hydrocodone are commonly prescribed medications for pain, while fentanyl is a powerful synthetic opioid used medically to treat severe pain. Understanding the distinctions between these classifications is critical, especially in a law enforcement context, as it relates to drug recognition and responses to substance abuse issues.