To the editor: The article “Diverticular Disease: Diagnosis and Treatment”¹ in the October 1, 2005, issue of American Family Physician recommended multiple times that patients needing narcotics for pain should be treated with meperidine (Demerol) rather than morphine. The two references used to support the claim do not appear to be relevant to the recommendation. In the past, meperidine has been claimed to be superior to morphine in patients with pancreatitis because of “sphincter of Oddi spasm”² despite a complete absence of supporting outcome-based studies.³

Meperidine has a number of distinct disadvantages relative to other narcotic analgesics. Its analgesic effects are not pronounced, and its duration of action is short. It has multiple potential drug interactions, including the possibility of serotonergic crisis, and has toxic metabolites that may induce central nervous system dysfunction, including seizures.⁴ The unique disadvantages of meperidine have prompted some hospitals to ban its routine use.⁵

Proof of the alleged superiority of meperidine in the management of diverticular disease also appears to be lacking in outcome-based studies, whereas the hazards of meperidine use relative to other analgesics are well established. I would be interested in knowing if any evidence exists to support the implied claim that morphine worsens patient outcomes relative to meperidine.

in reply: I concur with Dr. Adams that there is a paucity of outcome-based research comparing meperidine (Demerol) head-to-head with morphine in the management of painful diverticular syndromes. Certainly, however, literature describes potential adverse effects of morphine on the colon. Studies performed on dogs,¹ followed by subhuman primates,² and finally in humans,³ demonstrate an increase in colonic tone and nonmigrating myoelectric spikes, with alteration of colonic motility.

It has long been generally accepted that meperidine causes less smooth muscle spasm and less constipation than morphine. As with much “conventional” clinical wisdom, there is no supporting evidence from randomized controlled trials. However, the existence of numerous case reports of morphine causing these problems, and no case reports regarding meperidine, does seem to lend this conventional wisdom some credence.

Meperidine should not be used in persons with a history of seizure disorders, nor in high doses or for prolonged periods, because accumulation of a toxic metabolite occurs and increases central nervous system excitability. As with all medications, one must be aware of drug interactions. Despite these limitations, I would continue to assert that meperidine has a place in the pain management of painful diverticular syndromes.