GlaxoSmithKline PLC (GSK) and Adolor Corporation have started an international Phase 3 clinical programme to evaluate the investigational drug alvimopan (Entereg), a peripherally acting mu-opioid receptor (PAM-OR) antagonist for the treatment of opioid-induced constipation (OIC) and associated symptoms. These distressing gastrointestinal (GI) side effects are experienced by many people taking opioids to treat chronic pain.

The Phase 3 clinical programme is comprised three studies with an expected enrolment of approximately 1,700 patients in North America, Europe and other parts of the world.

"The new studies aim to provide further clinical data on alvimopan in treating OIC in patients suffering chronic pain. Positive results from this trial could be the next step towards the introduction of a new treatment for OIC and associated symptoms with the potential to help a significant proportion of men and women suffering these often debilitating GI side effects of chronic opioid use," said Dr. Yvonne Greenstreet, senior vice president, Medicine Development Centre at GlaxoSmithKline.

Millions of people worldwide take opioid analgesics to treat moderate to severe chronic pain. Constipation, a significant side effect of these treatments, is experienced by approximately half of patients, who may also experience abdominal pain and discomfort, bloating, and loss of appetite. OIC affects men and women of all ages who are taking opioids as painkillers, but many people suffer in silence with these GI side-effects, and do not consult their physician or healthcare provider.

Opioid analgesics such as morphine are considered to be the most effective analgesics and are widely used to treat patients with moderate-to-severe pain.

Opioid-induced constipation (OIC) (sometimes referred to as opioid bowel dysfunction or OBD) is a drug-induced condition characterised by infrequent, difficult or incomplete bowel movement, straining and hard dry stools, often accompanied by other associated symptoms such as nausea, abdominal discomfort or pain, bloating and loss of appetite.

Alvimopan is an investigational peripherally-acting mu-opioid receptor antagonist (PAM-OR) designed to inhibit the negative effects of opioids, like morphine or codeine, on the gastrointestinal system without interfering with the analgesic effects on the central nervous system.