Proglumide as a morphine adjunct in cancer pain management

Proglumide, a cholecystokinin (CCK) antagonist, has been shown to have agonist effects at extremely low doses on both endogenous and exogenous opioid systems. To determine the effectiveness and the side effects of proglumide as an opioid agonist, a double-blind crossover study was conducted in 60 patients with cancer pain who were treated with opioid analgesics. Forty-three patients completed both treatment arms: (a) full analgesic dose plus placebo (the patient's usual analgesic dose, individualized to drug dose and route) and (b) one-half analgesic dose plus 50 mg of proglumide. An analysis of eight pain descriptors was performed to determine whether or not these treatments were associated with a difference in patients' pain perception. The level of patient anxiety differed between the two arms, but was inconsistent over time. There were no side effects detected with proglumide, as determined by clinical monitoring and patient questionnaire. No differences in pain perception were detected between the study arms. The latter finding is consistent with an augmentation of morphine analgesia, but without additional controls, the equivalency of the two arms cannot be determined with certainty. Nonetheless, this study suggests that proglumide may have use as an opioid adjunct in patients with cancer pain.