Relistor methylnaltrexone regulatory update

Salix disclosed in its 3Q12 earnings that FDA indicated it will require "a very large, well-controlled, chronic administration trial" to assess the safety of subcutaneous Relistor methylnaltrexone prior to approval for the treatment of opioid-induced constipation (OIC) in patients with non-cancer pain. FDA communicated the request during an October end-of-review meeting with the agency to discuss the contents of a July complete response letter for an sNDA for the subcutaneous formulation of the peripheral mu opioid receptor ( OPRM1; MOR) antagonist in the indication (see BioCentury, Aug. 6). At the meeting, Salix said the agency expressed a concern of a risk associated with the chronic use of mu opioid antagonists. However, the company said that available postmarketing, clinical and preclinical data for Relistor "adequately demonstrate an appropriate and expected safety profile sufficient to permit" approval of the sNDA and that it anticipates "a path forward could be reached" with FDA during 2013. ...