Opioid agonists

Opioid agonists bind mu-opioid receptors in the brain and spinal cord to relieve moderate to severe pain. Morphine, hydromorphone, oxycodone, and fentanyl are common examples. Slowed or stopped breathing is the most dangerous effect, so breathing and alertness are monitored closely. Constipation is nearly universal and usually needs a bowel regimen, and naloxone reverses an overdose.

• HydromorphoneKnown brand names include Dilaudid.
• MorphineKnown brand names include MS Contin, Kadian, Duramorph, Infumorph, and Mitigo.