The four most recent Food and Drug Administration commissioners are warning Congress that legalizing the importation of drugs from other countries — an idea that has drawn support from both Senator Bernie Sanders and President Trump — is a risky approach that would endanger consumers by exposing them to fake, substandard, and contaminated drugs.

The open letter to Congress, posted Friday by the Margolis Center for Health Policy at Duke University, was signed by two former FDA heads who served during the Obama administration — Robert Califf and Margaret Hamburg — and two who served under former president George W. Bush — Andrew von Eschenbach and Mark McClellan.

While acknowledging that drug importation is designed to give Americans access to less expensive medicines, it also would likely ‘‘harm patients and consumers and compromise the carefully constructed system that guards the safety of our nation’s medical products,’’ they write.

Medications in many countries are cheaper than in the United States due to government price controls.

Scott Gottlieb, a physician who the White House recently announced would be nominated to lead the FDA, agrees with his predecessors. He said in a March 2016 article in Forbes that importation wouldn’t achieve its aim of providing cheaper drugs but would pose significant cost and safety problems.

Washington Post