Opiate-receptor blockade as therapy for Crohn’s disease?

The search for new treatments in Crohn’s disease never stops. Endogenous opiates are known to influence both growth and immunity, and Met⁵-enkephalin has effects on a number of immune effector cells. Low-dose naltrexone can produce intermittent blockade of opioid receptors, resulting in a rise in tissue levels of Met⁵-enkaphalin and endorphins. Naltrexone has been used to aid healing of corneal abrasions and is known to block tumour necrosis factor (TNF)-α synthesis. Stimulators of μ-opioid receptors reduce inflammation in the trinitrobenzenesulphonic acid (TNB) colitis model in mice.

The authors designed a prospective, pilot study of low-dose naltrexone (4.5 mg at night, compared with the usual 50 mg dose used in alcohol or opioid abuse) given for 12 weeks to a group of 17 patients with moderate to severe active Crohn’s disease (Crohn’s Disease Activity Index (CDAI) score >220). Most patients had previously received infliximab, but not for at least 8 weeks prior to the study. Other medications for Crohn’s disease were kept stable during the study (47% were taking immunomodulators and 24% were taking corticosteroids).

Within 4 weeks, there was a …