The US Food and Drug Administration has approved AstraZeneca’s Movantik for opioid-induced constipation in adults with chronic non-cancer pain.

Movantik (naloxegol), an oral once-a-day treatment licensed from Nektar Therapeutics, belongs to a class of drugs called peripherally-acting mu-opioid receptor antagonists, which are used to decrease the constipating effects of opioids. The drug’s safety and effectiveness were established in two trials of 1,352 participants who had taken opioids for at least four weeks for non-cancer related pain and had opioid-induced constipation.

Participants were randomly assigned to receive 12.5mg or 25mg of Movantik or placebo once daily for 12 weeks. Results of the first trial showed that 44% on the second dose and 41% on 12.5mg experienced an increase in bowel movements per week, compared to 29% for the placebo arm. The second trial showed similar results.

The FDA is asking for a postmarketing study to evaluate the potential risk of cardiovascular adverse events in patients taking Movantik. In June, the agency held a public meeting and decided that large cardio safety trials were not needed before approval of this new class of drugs.

One issue is that Movantik is currently classified as a schedule II controlled substance because it is structurally related to noroxymorphone. However, the approved label indicates that it has no risk of abuse or dependency and the company submitted a petition for the descheduling of Movantik to the US Drug Enforcement Administration in March 2012.

While it waits to hear back from the DEA, AstraZeneca said that it expects to launch Movantik in the first half of 2015.