The European Commission Wednesday said it has opened an antitrust case against Les Laboratoires Servier and several other drug makers, suspecting they colluded to keep the generic form of a blood pressure medication off the market.

The commission, the European Union's regulatory arm, said Teva Pharmaceutical Industries Ltd. (TEVA), Krka d.d. (KRKG.LJ), Lupin Ltd. (500257.BY), Matrix Laboratories Ltd. (524794.BY), a subsidiary of Mylan Inc. (MYL), and Niche Generics Ltd., a unit of Unichem Laboratories Ltd. (506690.BY) also are involved in its antitrust probe.

The case, which could lead to fines against the companies, follows a broader commission investigation into the pharmaceutical sector. That study identified problems in the way companies that develop drugs compete with generic producers.

Les Laboratoires Servier developed the blood pressure medication perindopril, a so-called ACE inhibitor. The drug is sold under several brand names, including Coversyl and Aceon.

The commission said it suspects Les Laboratoires Servier might have violated antitrust laws, both through its own actions, and in concert with the other drug companies. It didn't disclose details of these possible offenses.

-By Adam Cohen, Dow Jones Newswires; +322 741 1486; adam.cohen@dowjones.com