The federal government is investigating the way

Biovail

(BVF)

markets its time-release blood-pressure medication, Cardizem LA.

The Toronto-based pharmaceuticals company said it is working to respond appropriately to the preliminary administrative inquiry, which was begun by the Health and Human Services Department's office of the inspector general.

The shares were down 27 cents, or 0.7%, to $38.95 on the Instinet premarket session. Shares of

Quintiles Transnational

TST Recommends

(QTRN)

, which helps run Biovail's drug marketing program, were down 30 cents, or 2%, to $13.80.

Cardizem LA, which Biovail started selling in the U.S. last April, has been the subject of controversy after physicians raised questions about whether it works better than cheaper hypertension treatments. A

Wall Street Journal

story last month said Biovail handsomely rewarded doctors who prescribed the medicine, paying some $1,000 for getting 11 or more patients on the drug.

In its release, Biovail said it has a "warranty" from the organization that developed and implemented the program saying it "complies with all laws and regulations."

"Biovail ... and its advisers are confident that its clinical experience and marketing programs are fully compliant with all regulatory guidelines and requirements," the company said.