A: Morphine is a medication that is used for pain management and is in the class of medications called opioid narcotics. Opioids act by attaching to specific proteins called opioid receptors, which are found in the brain, spinal cord, and gastrointestinal tract.: Morphine is a medication that is used for pain management and is in the class of medications called opioid narcotics. Opioids act by attaching to specific proteins called opioid receptors, which are found in the brain, spinal cord, and gastrointestinal tract.