Treating Opioid side-effects with a new/old drug

The story of a new drug FDA approved to treat constipation resulting from use of opioid pain relievers such as codeine, oxycontin, and morphine, begins with a compassionate University of Chicago pharmacologist who wanted to help a terminally ill friend. Leon Goldberg, MD, PhD was struck by the suffering of his dying friend's struggle with this common and severe side-effect, and in 1979 began his quest to find relief for seriously ill patients who depend on opioids for serious and end of life care. Unfortunately, he didn't live to see his efforts to their final result in the drug Relistor, but millions of people will be glad that he began that journey and that other dedicated colleagues, Joseph Foss, Jonathan Moss, Michael Roizen, Chun-Su Yuan and others in the University's department of anesthesiology and critical care continued his work.

It's long been acknowledged that opioids slow the bowel, and in fact for centuries was used as a treatment for diarrhea. Some patients with chronic diarrhea and IBS-like conditions (refractory to other treatments) use small dose opioids today to ease the pain and desperate need for a bathroom, though they are no longer the drug of choice.

Dr. Goldberg knew that the drug Naltrexone, long used in high doses for drug addiction, might hold the key to his friend's suffering, and he was right. He began by testing derivatives of naltrexone, blocking the body's opioid receptors which gives no place for the opioid drugs to attach and effect the body. In a person using naltrexone, codeine and even morphine have no effect. Addicts take the opioids and no 'high' is achieved.

Naltrexone is also being used off-label in very low doses to treat autoimmune and other disorders. Patients (who are not taking opioid pain relief) take tiny doses of naltexone at bedtime which block the opioid receptors in the brain and gut. Because it blocks the action of the normally present natural chemicals made by the body, but only at night, this action encourages the body to make more of its own endorphins and other chemicals with beneficial effects to the patient.

The drug Relistor is a derivitive of naltrexone called Methylnaltrexone bromide. Taken as an injection up to once daily, this type of naltrexone doesn't cross the blood brain barrier. This means that the opioids remain effective in the brain as pain relievers, but do not effect the rest of the body. In the case of the digestive system, it remains functioning as it normally would without the presence of opioid pain relievers. This means no constipation and no nausea. Other studies suggest Relistor may also be useful in relieving other side-effects including urinary retention, pruritus (itching) and to facilitate feeding in critically ill patients.

Because I have autoimmune disease, I have long been interested and watching low dose naltrexone as it begins its long journey to gain approval for treatment of these types of diseases. Because of Migraine, Cluster, Trigeminal Neuralgia, Dystonia and Lupus pain I have been in situations when only these powerful opioids can give me relief from my struggle, yet suffer terribly from side-effects for which I am unable to take other medications. When a close relative recently began the painful stages of his battle with cancer, that nagging voice inside my head wanted to be sure that nothing was missed in his treatment. He deserves as good and noble an experience in the end to his life as modern knowledge allows, and that includes freedom from side-effects of his treatment. That led to my discovery of the story of Relistor and as usual, I can't keep a good thing to myself. :)

Sources:

University of Chicago Medical Center
Rxlist.com