CHICAGO--Methylnaltrexone, an agent that blocks the side effects
of morphine without interfering with pain relief, has been granted
orphan drug status for use in patients with cancer pain.
"Orphan drug status is a big step toward bringing this important
drug to a population of patients in need," said Michael Roizen,
MD. He and his colleague Joseph Foss, MD, both of the University
of Chicago, have done the preliminary animal and clinical testing
of the drug, which is being developed in collaboration with UR
Methylnaltrexone was invented by the late University of Chicago
pharmacologist Leon Goldberg, MD, PhD, to help a friend suffering
from cancer. By attaching a methyl group to the naltrexone molecule,
an anti-addiction agent, he altered the drug to prevent it from
crossing the blood-brain barrier. As a result, it did not interfere
with morphine's effects on pain, centered in the brain, but did
prevent its others effects, such as nausea and constipation. Phase
II/III trials of the orphan drug are planned this year.