Flex Pharma Inc., of Boston, initiated a human proof-of-concept efficacy study in nocturnal leg cramps with its chemically synthesized, single molecule, transient receptor potential ion channel activator, formulated as an orally disintegrating tablet. The randomized, blind, controlled, cross-over study is designed to evaluate the safety and efficacy of its single agent in more than 50 subjects who suffer from nocturnal leg cramps on a frequent basis. Nocturnal leg cramps can cause severe pain, interrupted sleep, reduced quality of life and interference with activities of daily living. The company estimates that NLC affects more than 4 million Americans nightly.