The state attorney general is suing the manufacturers of a blockbuster prescription blood thinner who he says covered up evidence that the pricey alternative to aspirin would be ineffective for much of Hawaii’s population.

The lawsuit was filed in Circuit Court on Wednesday against Bristol-Myers Squibb and Sanofi-Aventis, the manufacturers of Plavix, which is supposed to reduce heart attacks, strokes and vascular death.

Attorney General David Louie said the companies engaged in a deceptive marketing strategy to increase revenues from Plavix, which had about $6.6 billion in sales in the U.S. in 2011.

"They sold it as a new drug that would be beneficial, better and safer than aspirin," he said at a news conference at the Attorney General’s Office to announce the lawsuit. "What the drug manufacturer did not tell anybody was that Plavix was not effective or had a diminished effect on people of East Asian descent or Pacific Islander descent, of which approximately 50 percent of the population in Hawaii is of that descent."

In Hawaii, more than 1 million prescriptions have been written for the drug, and sales have surpassed $100 million. Louie said the state doesn’t know of anyone dying from use of the drug.

According to the lawsuit, the drug becomes effective only after the liver processes it into its active form, but some people’s bodies cannot process the drug. When the companies started selling the drug in 1998, they did not say there is a simple test that can show whether a person’s body cannot metabolize it.

The drug is also less effective in elderly patients.

Rick Fried of Cronin Fried Sekiya Kekina & Fairbanks, a law firm hired by the state to assist, said the companies committed fraud when they marketed Plavix as safer than aspirin, despite a study 18 years ago showing the drug preformed worse than aspirin and caused more internal bleeding.

In the study, patients were given four times the daily dose of aspirin that doctors usually prescribe. They still had less bleeding in the stomach and intestines than those given the drug in Plavix.

The study also found aspirin more effective for those who recently had a heart attack. The manufacturers allegedly ignored that study and another showing Plavix caused more internal bleeding than aspirin used with other drugs.

After more reports began appearing about the drug’s ineffectiveness on some people, the manufacturers urged doctors to prescribe higher doses for their patients, which placed the patients at greater risk, the lawsuit said.

In March 2010, under orders from the U.S. Food and Drug Administration, the drugmakers added a warning to the label about the drug’s ineffectiveness.

Louie said Hawaii residents and the state, through Medicaid subsidies, may have been taken advantage of by the manufacturers of Plavix, which is 100 times more expensive than aspirin, at approximately $4 a pill.

The suit calls for civil penalties of $10,000 for each violation of the state’s deceptive practices law, $10,000 for each violation targeting elders, up to $11,000 for each act violating the state’s false claims law, and disgorgement of all profits obtained from Plavix sales in Hawaii.

Fried said the definition of a violation will be determined in court and could mean every time the drug was prescribed.

Company representatives could not immediately be reached for comment.

Hawaii joins four other states that have filed claims against the manufacturers: Louisiana, Mississippi, West Virginia and California.

Louie said patients currently using Plavix should talk to their doctors or call the Attorney General’s Office at 586-1500 with questions.