Britain’s GW Pharmaceuticals said Monday it was accelerating plans to introduce its cannabis-based medicines into the United States as U.S. founder investors increased their stake in the business.GW said it had engaged U.S.-based Apjohn Group LLC, a 10-member group of former major U.S. pharmaceutical company executives with extensive experience in U.S. clinical development, regulatory affairs and public policy.It also said U.S. founder investors had put a further $4.8 million into the business, taking their stake to 9.62 percent from 7.79 percent.GW has had a roller-coaster ride with Sativex, an under-the-tongue cannabis spray to treat the symptoms of multiple sclerosis and neuropathic pain.The drug has won qualified approval in Canada, but is still awaiting a green light in Britain, where approval has been repeatedly delayed.