Amgen Inc. on Friday was sued by 14 states and the District of Columbia, which accuse the Thousand Oaks biotech of offering kickbacks to medical providers to boost sales of its troubled anemia drug Aranesp.

The New York Attorney General’s Office was the lead agency on the suit, which targets Amgen and two other companies that are subsidiaries of AmerisourceBergen Corp. of Chesterbrook, Penn. The two companies, International Nephrology Network, a specialty group-purchasing organization, and ASD Healthcare, a wholesaler of pharmaceuticals, are both in Frisco, Texas.

The lawsuit accuses the companies of encouraging medical providers to bill third party payers such as Medicaid for amounts of Aranesp that essentially were provided at no cost. The free product consisted of overfill amounts in the vials of Aranesp they received, the suit contends.

Amgen was accused of paying INN to market Aranesp to its customers and convert them from a competing Johnson & Johnson anemia drug, Procrit. INN is accused of conspiring with Amgen and its preferred distributor, ASD Healthcare, to offer illegal inducements to its member-customers to increase Aranesp sales. The defendants allegedly conspired to offer sham consultancy agreements and weekend retreats, among other kickbacks, to medical providers for buying and prescribing the drug.

"Drugs should be prescribed to patients on the basis of need, effectiveness, and safety, not on a corporate giant's promise of an all-expense paid vacation," New York Attorney General Andrew Cuomo said in a statement.

Aranesp, approved in 2001, is a longer-lasting version of the company’s first drug Epogen. It is used by cancer and kidney disease patients to help alleviate anemia. Sales, totaling more than $11 billion over the years, have lagged since 2006 when clinical studies pointed to increased risks for heart attacks and death if the drug was over-used or taken at high doses. The FDA eventually required the company to print stricter warnings on the label and criteria for reimbursement were tightened.

Amgen said it was studying the complaint and believes the allegations “are without merit.”

“Amgen has a solid compliance program and code of conduct called ‘Do The Right Thing,’ and we expect that all of our employees follow it at all times,” the company said in a statement.

Besides New York, the states involved in the case are California, Delaware, Florida, Hawaii, Illinois, Indiana, Louisiana, Massachusetts, Michigan, Nevada, New Hampshire, Tennessee and Virginia.

Amgen shares closed down 67 cents, or 1 percent, to $53.62 on the Nasdaq.