Methylnaltrexone is a peripherally acting mu-opioid receptor antagonist that is designed to treat opioid-induced constipation (OIC) without interfering with pain relief. A new drug application for the subcutaneous formulation of methylnaltrexone was submitted by Progenics to the FDA in March 2007, and a marketing authorization application was submitted by Wyeth to the European Medicines Agency in May 2007.
All of the primary efficacy end points were positive and statistically significant, and the therapy generally was well tolerated in these studies. After being accepted for evaluation, the TGA has 255 working days to review the application.
Opioid analgesics are commonly prescribed to manage pain in patients receiving palliative care but can frequently cause constipation. There currently is no approved medication that specifically targets the underlying cause of OIC to relieve constipation in this patient population.
In December 2005, Wyeth and Progenics entered into an exclusive, worldwide agreement for the joint development and commercialization of methylnaltrexone for the treatment of opioid-induced side effects. Under the terms of the collaboration, Wyeth received worldwide rights to methylnaltrexone, and Progenics retained an option to co-promote the product in the US.