AstraZeneca has presented positive data from a late-stage trial of naloxegol in patients with non-cancer related pain and opioid-induced constipation.

In the fourth trial in a Phase III development programme designed to evaluate long-term safety and adverse event profile , 534 patients received naloxegol once-daily for up to 52 weeks, while 270 were on usual care (laxatives) for OIC. The most commonly-reported AEs occurring more frequently on naloxegol than on usual care included abdominal pain, diarrhoea, nausea and headache but the trial reported no imbalances in serious adverse events.

Briggs Morrison, head of the global medicines development at AstraZeneca, said "these high-level results are similar to the safety results seen in the Phase III studies previously reported and provide further confidence in the data we’ve seen to date for naloxegol". The programme is now complete and filings in the USA and Europe are planned for the third quarter.

Globally, some 40–50% (28-35 million) of patients taking opioids for long-term pain develop constipation and about 40–50% (11-18 million) of those OIC sufferers achieve the desired outcomes with current options, ie laxatives.

The actual timing of the submissions depend in part on a meeting with the US Food and Drug Administration as naloxegol is currently considered a Schedule II controlled substance across the Atlantic based on its "structural relatedness" to noroxymorphone. AstraZeneca says it has conducted the studies necessary to evaluate the abuse potential and dependence-producing properties of naloxegol and a petition to de-control the drug was submitted in March 2012.

Naloxegol, a peripherally-acting mu-opioid receptor antagonist  and formerly known as NKTR-118, was licensed from Nektar Therapeutics in September 2009.