WASHINGTON — Researchers say the U.S. approved more new medicines in less time than Europe and Canada in the last decade, challenging long-standing criticisms that the Food and Drug Administration lags behind its peers in clearing important new drugs. Between 2001 and 2010, the FDA’s typical review of a new drug was about 15 percent faster than those by the European Medicines Agency and Health Canada, its foreign counterparts, according to a study published Wednesday by the New England Journal of Medicine.