fentanyl + methadone + morphine

This is a combination of three opioid analgesics—fentanyl, methadone, and morphine. All three are potent opioids used primarily for the management of severe pain that cannot be controlled by other means. Fentanyl is a synthetic opioid approximately 100 times more potent than morphine and is used for pain relief and anesthesia[3][9]. Methadone is a synthetic opioid with unique properties as both a full µ-opioid receptor agonist and an N-methyl-D-aspartate (NMDA) receptor antagonist; it is used for severe pain as well as in the treatment of opioid dependence[5]. Morphine, derived from opium poppy, acts mainly as a µ-opioid receptor agonist to provide analgesia[2][6]. The combination would have additive or potentially synergistic effects on pain relief but also significantly increases the risk of adverse effects such as respiratory depression, sedation, overdose, and death due to their overlapping mechanisms.