For people with Obsessive-Compulsive Disorder (OCD) who have not been helped by standard drug treatments, a weekly dose of oral morphine may ease their symptoms, according to a small pilot study.

The newer class of antidepressants known as SRIs is approved for treating OCD, but up to 40 percent of patients fail to respond to two or more of these drugs, Dr. Lorrin M. Koran and his associates explain in the Journal of Clinical Psychiatry.

Quite why morphine can be effective is not known, but other small studies have suggested a role for drugs that interact with opioid receptors because there is a high concentration of opioid receptors in an area of the brain thought to be involved in OCD.

For their trial, Koran’s group enrolled 23 subjects with OCD who had tried anywhere from two to six different SRIs. The participants were assigned to once-weekly oral morphine, the anti-anxiety drug lorazepam, or an inactive placebo, in random order for two weeks each.

Average scores on a standard OCD scale declined from 29 to 25 while the subjects were taking morphine, and to 27 in the lorazepam phase.

Seven of the 23 subjects were deemed to be responders to morphine based on score decreases of 25 percent or more. There were four subjects who responded to lorazepam.

Among those responding to morphine, the most noticeable effect began the day after taking the drug and lasted for two to five days. These individuals reported decreased frequency and persistence of obsessions and anxiety, as well as an increased ability to resist their compulsions.

The researchers saw no euphoric effects from taking the drugs - although one subject later admitted to having abused hydrocodone for several years, which he said reduced his OCD symptoms.

“The response seen, its rapidity, and the relative tolerability of the treatment are encouraging and warrant larger and longer term studies” of morphine or other opiate drugs for treatment-resistant OCD, the team concludes.

SOURCE: Journal of Clinical Psychiatry, March 2005.