Final answer:
Codeine, Hydrocodone, Morphine, and Oxycodone are the opioid analgesics, while Acetylsalicylic acid and Ibuprofen are NSAIDs and not classified as opioids.
Step-by-step explanation:
The four drugs classified as opioid analgesics from the list provided are Codeine, Hydrocodone, Morphine, and Oxycodone. Opioids are substances derived from the opium poppy, or synthetic analogues, that bind to opioid receptors in the brain to reduce pain and can produce euphoria. They are commonly prescribed for moderate to severe pain management. On the other hand, Acetylsalicylic acid (Aspirin) and Ibuprofen are classified as nonsteroidal anti-inflammatory drugs (NSAIDs), which relieve pain by blocking enzymes that contribute to inflammation. While both opioid analgesics and NSAIDs can be used to treat pain, opioids have a high potential for abuse and are associated with risks of addiction, abuse, and overdose.