Expiring patents on 2 popular prescription medications could save consumers, employers and health insurers billions of dollars per year.

The Blue Cross and Blue Shield Association, Chicago, and some of the association’s member companies are making those predictions in response to major developments in the world of generic drugs.

A generic version of Zocor, or simvastatin, a cholesterol-lowering drug has just come out, and the patent on Zoloft, a brand-name version sertraline, will expire next week.

Availability of generic versions of those 2 drugs alone will lead to dramatic changes in the prescription drug market, the Blues say.

“A switch to generic versions of Zocor and Zoloft represents a watershed event,” Dr. Allan Korn, the Blue Cross and Blue Shield Association chief medical officer, says in a statement.

Zocor, the second most widely prescribed statin, lowers the amount of fat, or lipids, in the blood. Zocor accounted for $4.6 billion in U.S. sales in 2004, according to IMS Health, Fairfield, Conn.

Moreover, Reuters carried an article earlier this week quoting David Fedson, a researcher who believes that statins could help reduce the severity of the bird flu in the event of a pandemic.

Zoloft, a selective serotonin reuptake inhibitor, generated $3.1 billion in U.S. sales in 2004, IMS says.

Competition from generic versions of Zocor and Zoloft could lead to 30% to 80% reductions in the cost of those drugs and the new generic alternatives, IMS says.

IMS notes that branded drugs that generate a total of $18 billion to $20 billion in U.S. sales will lose patent protection this year.