Alkermes has started the Phase 2b study of ALKS 37, an orally active, peripherally restricted opioid antagonist for the treatment of opioid-induced constipation (OIC).

The multicentre randomised double-blind placebo-controlled fixed-dose study will evaluate the safety and efficacy of daily administration of a 100mg dose of ALKS 37 versus placebo for 12 weeks in approximately 80 patients with OIC.

In the study, the primary efficacy endpoint is the change from baseline in the frequency of weekly complete spontaneous bowel movements (CSBMs) during the initial four weeks of the treatment period.

Additional endpoints of the study include the change from baseline in the frequency of weekly spontaneous bowel movements (SBMs), a responder analysis and the median time to first SBM and CSBM following the first dose of ALKS 37.

An earlier Phase 2 study showed ALKS 37 improved gastrointestinal motility and the frequency of bowel movements in patients with OIC, while simultaneously preserving the analgesic effects of opioid treatment.

Alkermes chief medical officer Elliot Ehrich said ALKS 37 has the potential to normalise bowel function in patients being treated with opioids for chronic pain, without affecting their analgesic effects.

”We look forward to seeing the results of both phase 2b studies of ALKS 37 in mid-2012," Ehrich added.