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Relistor
RELISTOR (methylnaltrexone bromide) subcutaneous injection was approved in Canada in April 2008 for the treatment of opioid-induced constipation in patients with advanced illness, receiving palliative care. For the package insert and to learn more about RELISTOR, please visit www.relistor.com (COMING SOON).
RELISTOR
RELISTOR is a selective, peripherally acting, mu-opioid-receptor antagonist that reverses certain side effects induced by opioid use. RELISTOR competes with opioid analgesics for binding sites on opioid receptors, and its chemical composition restricts its ability to cross the blood-brain barrier. As a result, RELISTOR "turns off" the effects of opioid analgesics outside the central nervous system, including the gastrointestinal tract, but does not interfere with opioid activity within the central nervous system, namely analgesia. RELISTOR is designed to treat OIC without interfering with the pain relief that the opioids provide, an important need not currently met by any approved drugs. To date, individuals treated with RELISTOR, in addition to opioid pain medications, have experienced a reversal of many of the side effects induced by opioids and have reported no diminution in pain relief. Methylnaltrexone has been studied in numerous clinical trials. To date, RELISTOR has been generally well tolerated and certain formulations have been active in inducing laxation in individuals suffering from OIC without interfering with pain relief.
Subcutaneous RELISTOR
RELISTOR subcutaneous injection is approved for marketing in Canada in patients with advanced illness, receiving palliative care a treatment for opioid-induced constipation and is under regulatory review in the United States, Europe and Australia. RELISTOR subcutaneous injection is also being investigated by Progenics and Wyeth as a treatment for chronic pain and orthopedic rehabilitation patients with opioid-induced constipation. Constipation is a serious medical problem for patients who are being treated with opioid medications. We estimate that each year in the U.S., approximately 1.5 million patients receiving palliative care experience opioid-induced constipation.
Intravenous RELISTOR
We are also developing, in collaboration with Wyeth, an intravenous formulation of RELISTOR for the management of post-operative ileus ("POI"), a temporary impairment of the gastrointestinal tract function. Of the patients who undergo surgery in the U.S. each year, approximately 2.4 million patients are at high risk for developing POI. Post-operative ileus is believed to be caused in part by the release by the body of endogenous opioids in response to the trauma of surgery and may be exacerbated by the use of opioids, such as morphine, in surgery and in the post-operative period. Post-operative ileus is a major factor in increasing hospital stay, as patients are typically not discharged until bowel function is restored. Development of the intravenous formulation of RELISTOR for POI has been granted "Fast Track" status from the FDA, which facilitates development and expedites regulatory review of drugs intended to address an unmet medical need for serious or life-threatening conditions.
Oral RELISTOR
We and Wyeth are also developing an oral formulation of RELISTOR for the treatment of opioid-induced constipation in patients with chronic pain. More than 215 million prescriptions are written annually for opioids and approximately 12 million patients in the U.S. use opioids chronically (i.e., six months or more), many of whom experience opioid-induced constipation.
About Opioids
Opioid-based medications such as morphine and codeine, which are often referred to as narcotics, are the mainstay used by healthcare practitioners to control moderate-to-severe pain. We estimate that approximately 240 million prescriptions for opioids are written annually in the U.S. Physicians prescribe opioids for patients receiving palliative care, undergoing surgery or experiencing chronic pain, as well as for other medical conditions.
Opioids relieve pain by interacting with receptors that are located in the brain and spinal cord, which comprise the central nervous system. At the same time, opioids also activate receptors outside the central nervous system, resulting, in many cases, in undesirable side effects, including constipation, delayed gastric emptying, nausea and vomiting, itching and urinary retention. Current treatment options for opioid-induced constipation include laxatives and stool softeners, which are often therapeutically insufficient, are not recommended for chronic use and do not address the other associated side effects. As a result, many patients may have to stop or reduce their opioid therapy and many opt to endure pain in order to obtain relief from opioid-induced constipation and its associated side effects.