Proglumide, sold under the brand name Milid, is a drug that inhibits gastrointestinal motility and reduces gastric secretions.

[6][7] This can make it a useful adjuvant treatment to use alongside opioid drugs in the treatment of chronic pain conditions such as cancer, where opioid analgesics may be required for long periods and development of tolerance reduces clinical efficacy of these drugs.

[8][9] Proglumide has also been shown to act as a δ-opioid receptor (DOR) agonist, which may contribute to its analgesic effects.

[12] The supposed mechanism is an enhancement of the neural pathways of expectation as a result of dopamine and endogenous opioids being suddenly released throughout numerous structures of the brain and spinal cord.

The ventral tegmental area is the structure believed to mediate proglumide's analgesic and euphoric effects, however dozens of areas with a wide range of physical and psychological functions are implicated in the mediation of the placebo effect (this accounts for proglumide's ability to produce physically measurable effects on vital signs such as heart rate, blood pressure, respiration rate, and tidal volume which cannot be accounted for by its clinically insignificant δ-opioid affinity.