 In January 2018 darunavir was still the most recent HIV protease inhibitor to reach the market.In 2006, GlaxoSmithKline discontinued the phase II clinical development of brecanavir, an investigational protease inhibitor for the treatment of HIV, due to insurmountable issues regarding formulation.In the summer of 2009, GlaxoSmithKline and Concert Pharmaceuticals announced their collaboration to develop and commercialise deuterium-containing medicines.