Subsequent events - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2014
Subsequent Events [Abstract]
Description of patients enrolled in study	On May 6, 2014, the Company announced the randomization of more than half of the planned number of patients required for its ongoing initial Phase 3 study of Clonidine Topical Gel, the Company’s proposed treatment for painful diabetic neuropathy (PDN). An interim analysis of the study, which will be based on the first 50% of patients entering the study, is now anticipated to occur in the third quarter of 2014.