AstraZeneca PLC (AZN) Tuesday said it has filed a lawsuit in a U.S. court seeking a patent infringement ruling against Apotex Inc. after the Canadian drug maker won approval for a generic version of children's asthma medication Pulmicort Respules.

The U.K. pharmaceutical company is also seeking to stop sales of Apotex's generic drug until the patent infringement case has concluded.

The U.S. District Court of New Jersey will hear oral arguments on the motion April 16.

AstraZeneca said the U.S. Food and Drug Administration March 30 granted approval for a generic version of its Pulmicort Respules to Apotex.

"The lawsuit follows Apotex's indication of intent to market a generic version of AstraZeneca's Pulmicort Respules in the U.S. prior to the expiration of AstraZeneca's patents," the London-based company said.

At 0728 GMT, AstraZeneca shares, which have lost 15% of their value since the start of the year, traded up 8 pence, or 0.3%, at 2,383 pence in a slightly higher London market. Sanford Bernstein analyst Tim Anderson, who has a market-perform recommendation on the stock, has estimated that the maximum impact to AstraZeneca's earnings per share in 2009 would be around 4%, with no impact beyond 2009.

That is because Israeli drug maker Teva Pharmaceutical Industries Ltd. (TEVA) is due to launch a generic version of Pulmicort Respules at the end of 2009.

"If Apotex launches, this may allow Teva to also come in ahead of the current December, 2009, scheduled date," Anderson said.

In 2008, U.S. sales of Pulmicort totaled $982 million, about 90% of which was contributed by Pulmicort Respules.

 
   Company Web site: www.astrazeneca.com 
 
   -By Elena Berton and Jeffrey Sparshott, Dow Jones Newswires; +44 (0)207 842 9347; jeffrey.sparshott@dowjones.com