Federal regulators said today that they are reviewing AstraZeneca P.L.C.'s handling of alleged improper marketing and the firing of a sales director.

The U.S. Department of Health and Human Services made the comment in response to the drug company's statement today that it had concluded an internal investigation and would share findings with regulators.

"We expect to receive further information from AstraZeneca and will follow up with them as appropriate," a department spokesman, Donald White, said, giving no more details.

AstraZeneca has been operating under special federal scrutiny resulting from improper marketing practices in 2003.

On April 6, AstraZeneca fired regional sales director Michael Zubillaga, 50, of Kennett Square, after his description of cancer doctors' offices as "a bucket of money" was leaked to the Internet. He made the comments in an internal newsletter published by and for the company's Mid-Atlantic Business Center in Wayne.

His firing set off allegations from anonymous AstraZeneca employees - mostly transmitted by bloggers - that managers like Zubillaga had been pushing sales representatives to make unfounded and improper pitches for cancer drugs Arimidex and Faslodex.

Federal law prohibits drug companies from promoting drugs for uses beyond the approved label - known as off-label use - or citing unapproved or invalid statistics or comparisons with other drugs.

AstraZeneca said in today's statement: "In some cases, there was merit to the allegations, and appropriate disciplinary action has been taken. Our investigation also revealed that a number of the allegations were either unsubstantiated or a result of misunderstanding."

Responding to allegations that managers were retaliating against sales reps or quashing their complaints, the company said: "We underscore that we do not tolerate retaliation against people who raise legitimate issues and that we found no credible evidence for that here."

It declined to give specifics.

Last week, U.S. Rep. Pete Stark (D., Calif.) asked federal inspectors to investigate AstraZeneca's sales practices. They have not responded.

Contact staff writer Thomas Ginsberg at 215-854-4177 or tginsberg@phillynews.com.