Updated Citrix has joined a growing group of companies who are pulling their advertising from Rush Limbaugh's radio show following his controversial remarks attacking Georgetown law student Sandra Fluke.

"Over the past day, we've heard from many great Citrix customers about our advertising on The Rush Limbaugh Show," wrote Brett Caine, GM of Citrix's online services division in a blog posting. "These customers have expressed their growing concern that some of his recent comments seem inconsistent with the core values Citrix has always stood for – humility, integrity and respect.

"While Citrix obviously does not control any show's content or endorse opinions of their hosts, we do take the concerns of our customers seriously. When they are upset about something, we listen. After careful consideration, we have decided to discontinue our advertising on The Rush Limbaugh Show."

Fluke gained national prominence when she was barred from giving testimony – on the grounds that she was unqualified – in the recent all-male Congressional hearings on the rights of employers to refuse medical coverage for procedures that are forbidden by their personal religious beliefs. Her testimony covered the case of a gay student who had lost an ovary after being denied medication that had a contraceptive effect.

On Wednesday Limbaugh described Fluke as a "slut" and a "prostitute," and said that she was asking taxpayers to pay for her to have sex. This provoked a storm of protest, but Limbaugh doubled down the next day.

"So, Ms. Fluke and the rest of you feminazis, here's the deal. If we are going to pay for your contraceptives, and thus pay for you to have sex, we want something for it, and I'll tell you what it is. We want you to post the videos online so we can all watch," he said.

The story has dominated the headlines, and President Obama personally called Fluke to show support. A #boycottrush Twitter tag was set up, and advertisers on the show are being targeted with social media protests. So far, ten advertisers have either stopped their media campaigns or are reviewing them.

It might seem odd to non-US readers that a single radio DJ can have caused such a kerfuffle, but Limbaugh is a very powerful figure in domestic politics. In 2009, the head of the Republican Party was forced to give a humbling apology after calling Limbaugh's show ugly and incendiary. His radio show, the most listened-to in the US, has earned Limbaugh a rumored $400m employment contract. ®

Update

Limbaugh has issued an apology for his comments in a statement:

"In this instance, I chose the wrong words in my analogy of the situation. I did not mean a personal attack on Ms Fluke," he said.