"I think Joe Rogan is right about ambien," Barr said in a now deleted tweet that she sent about 2am on Wednesday. "Not giving excuses for what I did (tweeted) but I've done weird stuff while on ambien-cracked eggs on the wall at 2am etc."
Pharmaceutical giant Sanofi, the maker of Ambien, hit back.
"People of all races, religions and nationalities work at Sanofi every day to improve the lives of people around the world," the company tweeted. "While all pharmaceutical treatments have side effects, racism is not a known side effect of any Sanofi medication."
ABC cancelled the hit sitcom "Roseanne" following the comedian's tweets on Tuesday. "Roseanne" averaged 23.2 million viewers, according to Nielsen, making it the most popular show of the year so far.
Ambien, which is used to treat insomnia, does have side effects, as do most pharmaceutical drugs. But none of them could directly lead to racist tweeting. Some users of Ambien report headaches, dizziness, drowsiness, and nausea. A small percentage of users have reported side effects such as disorientation and hallucinations.