Presidential candidates Donald Trump and Hillary Clinton have said that giving Medicare the ability to negotiate prices directly with drugmakers could yield important savings that firm up Medicare's financial future. However, industry experts are increasingly questioning that thinking. Can Medicare's negotiating might rein in high drug costs, or are there better options?

Medicare provides a healthcare safety net to American seniors, but the payment of medicine used to treat Medicare patients falls on private insurers, not government.

That's because Medicare relies on part D to provide drug coverage, and Part D plans are private plans offered by insurers, including UnitedHealth Group (NYSE: UNH), the nation's largest health insurer. UnitedHealth Group's part D plans insure 4.9 million Americans, and overall, UnitedHealth's various individual, employer, Medicare, and Medicaid plans cover 50 million Americans.