Randolph Ross was part of the American relay team that won Olympic gold in the 4x400m in Tokyo.
Now he is suspended for not appearing at a doping control, the International Athletics Federation announces in a press release.
Kenyan marathon runner Lawrence Cherono is also suspended.
In a doping control on May 23, the banned substance trimetazidine was found in his blood.
The drug is approved in some countries to treat angina, but is banned by the anti-doping agency Wada.
Cherono came fourth in the Olympics and is the eighth fastest marathon runner of all time with his time 2.03.04 at the Valencia Marathon 2020.