The National Academy of Sciences called Thursday for sweeping changes in the pricing, sale and promotion of prescription drugs to make lifesaving treatments more affordable without discouraging the development of new medicines. The federal government should negotiate drug prices with manufacturers, the academy said, an idea pushed by Democrats for years, embraced by President Trump during the 2016 campaign, but opposed by congressional Republicans. The government, it said, should also deny tax deductions for drug advertising aimed at consumers and set annual limits on out-of-pocket drug costs for Medicare beneficiaries.“Consumer access to effective and affordable medicines is an imperative for public health, social equity and economic development,” a panel of 17 experts said in a report issued by the academy. “However, this imperative is not being adequately served by the biopharmaceutical sector today.”