NEW YORK — The maker of Ambien said Wednesday that “racism is not a known side effect” after Roseanne Barr cited the insomnia drug in explaining the tweet that led ABC to cancel her show.

Hours after ABC pulled the plug on “Roseanne” because of her offensive tweet about former Obama adviser Valerie Jarrett — and quickly breaking a promise to stay off Twitter — the comedian was busy posting on the social media platform.

Barr tweeted that what she did was unforgivable and urged supporters not to defend her. She said of the Jarrett tweet, “It was 2 in the morning and I was ambien tweeting.”

The drug maker Sanofi took to social media to say that “while all pharmaceutical treatments have side effects, racism is not a known side effect of any Sanofi medication.”

Barr later tweeted that she has had odd experiences while taking the drug late at night. “I blame myself, not Ambien,” she tweeted.

After not mentioning Barr’s firing in a campaign-style rally in Tennessee Tuesday night, President Donald Trump broke his silence on Twitter. He noted that Robert Iger, chief executive of ABC parent Walt Disney Co., called Jarrett to tell her that ABC did not tolerate Barr’s comments.

“Gee, he never called President Donald J. Trump to apologize for the HORRIBLE statements made and said about me on ABC,” Trump wrote. “Maybe I just didn’t get the call?”

Trump reveled in the success of “Roseanne” after Barr’s character in the show came out as a supporter of his presidency.

“Roseanne” was an instant hit when it returned this spring after a two-decade hiatus. But after Barr’s tweet that likened Jarrett, who is black, to a cross between the Muslim Brotherhood and the “Planet of the Apes,” ABC canceled the show in a one-sentence statement from network entertainment president Channing Dungey. She called it “abhorrent, repugnant and inconsistent with our values.”

Barr’s agent also dropped her and several services pulled “Roseanne” reruns.

Jarrett, who said she was “fine” after the slur, urged in an MSNBC special Tuesday about racism that the incident become a teaching moment.

“Tone does start at the top, and we like to look up to our president and feel as though he reflects the values of our country,” Jarrett said. “But I also think that every individual citizen has a responsibility too, and it’s up to all of us to push back. Our government is only going to be as good as we make it be.”

Barr showed no signs of abandoning Twitter, engaging in a series of tweets that apologized to those who lost their jobs because of the “Roseanne” cancellation and expressed remorse she was being branded a racist. While asking not to be defended, she retweeted comments from supporters that attacked ABC and complained that conservatives are tweeted more harshly than liberals for their behavior.

Barr was resoundingly condemned Tuesday, including from many who helped make her show successful.

The executive producer of “Roseanne,” which came back this spring after being gone for two decades and instantly became television’s second most popular comedy, said he supported ABC’s decision.

“Our goal was to promote constructive discussion about the issues that divide us,” said Tom Werner. “It represented the work of hundreds of talented people. I hope the good work done is not totally eclipsed by those abhorrent and offensive comments, and that Roseanne seeks the help she so clearly needs.”

ABC and Disney had taken notable steps to be more inclusive in its entertainment, and Dungey is the first black to be entertainment president of a major broadcast network. But much of its progress would have been threatened if it looked the other way at Barr’s tweet.

She has a history of diving into political conspiracy theories on Twitter, and that’s how she ended her Memorial Day weekend. She criticized Democratic financier George Soros and tweeted that Chelsea Clinton was “Chelsea Soros Clinton,” implying she was married to a nephew of Soros. Clinton herself corrected Barr online. Donald Trump Jr. retweeted two of Barr’s statements about Soros, although not the remark about Jarrett.

Jarrett’s name came up in response to Twitter commentary that raised her name in relation to an Obama conspiracy theory. Barr tweeted: “muslim brotherhood & planet of the apes had a baby=vj.”

Three weeks earlier, “Roseanne” was the toast of ABC’s annual presentation of its programming plans to advertisers. Dungey’s boss, network chief Ben Sherwood, even joked then: “If anyone came to play a drinking game based on how many times we mention ‘Roseanne,’ you’re welcome.”

“Roseanne” earned an estimated $45 million in advertising revenue for ABC through its nine episodes that started airing in March, according to Kantar Media. The firm estimates that the 13 episodes that had been ordered for next season would have brought in as much as $60 million, with more through repeat episodes.

The cancellation has no clear precedent in television history, said David Bianculli, professor at Rowan University in New Jersey. The closest analogy is CBS pulling the plug on the Smothers Brothers variety show due to their anti-war views in the late 1960s and the same network not renewing “Lou Grant” at its peak, which star Ed Asner always contended was due to his outspoken political beliefs.

But canceling “Roseanne” is “like taking off ‘All in the Family’ or ‘I Love Lucy’ or Andy Griffith at their zenith,” he said.

There was also CBS’ firing of Charlie Sheen from “Two and a Half Men” during his bizarre spate of behavior. Sheen, for one, saw an opportunity in Tuesday’s events.

“Good riddance,” he tweeted about the “Roseanne” cancellation. “Hashtag NOT Winning. The runway is now clear for OUR reboot.”

Barr retweeted that, too.