Wyeth and partner Progenics Pharmaceuticals have got the backing of European regulators to sell Relistor, a treatment for opiod-induced constipation.

The companies have received marketing approval for Relistor (methylnaltrexone) subcutaneous injection in the 27 member states of the European Union as well as Iceland, Norway, and Liechtenstein for OIC in advanced illness patients who are receiving palliative care when response to usual laxative therapy has not been sufficient. The drug is the first approved treatment for OIC in the EU and will be rolled out on a country-by-country basis beginning later this month.

The green light from the European Commission comes a little over a month since Relistor was launched in the USA following Food and Drug Administration approval in April. In March, the drug was approved by Health Canada and a decision is expected soon from an application that was submitted to the Australian Therapeutic Goods Administration in August 2007.

Relistor is a peripherally acting mu-opioid receptor antagonist that decreases the constipating effects of opioid painkillers in the gastrointestinal tract without affecting their ability to relieve pain. Each year, more than 1.5 million Americans receive palliative care due to an advanced illness, such as incurable cancer and other end-stage diseases, Wyeth said.

It noted that similar figures are not available for Europe as a whole, which Wyeth claims “may be considered indicative of the fact that this is an overlooked condition and an area of unmet medical need”. Still the company has in the past predicted that global peak sales of Relistor should pass the $1 billion mark.

Wyeth and Progenics recently presented data from a 122-patient Phase II study of an oral formulation of the drug which showed positive activity for OIC, though the intravenous formulation of Relistor failed to make the grade in a late-stage trial in post-operative ileus.