NEW YORK (AP) - Prozac, the drug that changed the way America thinks about mental illness and became a part of pop culture, is losing its title as the nation's top-selling antidepressant.

Demand for the little green capsules has ebbed because of new drugs promising greater effectiveness, fewer side effects and the ability to treat additional problems.

In January, for the first time in years, doctors wrote more new prescriptions for a competing drug, Zoloft. While Prozac remained slightly ahead in total prescriptions, the statistics illustrate its peak is past.

Introduced in 1988, Prozac quickly became a metaphor for society's obsession for quick fixes to problems. The pills not only helped the depressed, but became known for simply making people feel good.

They also helped ease the stigma surrounding mental illness, proving to many that depression is a biological problem, not one caused by a weak character or poor parenting

"It changed my whole life," said Elizabeth Wurtzel, 32, author of "Prozac Nation," which described her struggle with depression and experience with Prozac and other drugs - and exposed the collective bad mood of Generation X'ers.

"I realized it was possible to not be depressed. It was like putting glasses on and seeing the world in a different way."

Laura Miller, spokeswoman for Prozac maker Eli Lilly & Co., said: "Prozac showed people there is a safe and effective treatment for depression, allowing more people to seek help."

Prozac was the first of a new generation of anti-depression drugs called SSRI's (selective serotonin reuptake inhibitors) that were as effective as older depression drugs, but did not have many of the nasty side effects such as constipation, memory loss or high blood pressure. SSRI's work by correcting the imbalance of serotonin in the body, a natural chemical that's believed to effect one's mood.

The chance of overdosing on Prozac was significantly less than older medications, a key benefit in treating depression.

These advantages led more patients to continue their medication and more doctors to order it.

By 1990, Prozac had become the fastest selling new mental illness drug ever - a sort of Viagra of its time.

"Prozac seemed to give social confidence to the habitually timid, to make the sensitive brash, to lend the introvert the social skills of a salesman," Dr. Peter D. Kramer wrote in his 1993 book "Listening to Prozac," one of several best sellers on the drug.

In all about 17 million Americans have taken Prozac. Like a Hollywood celebrity, however, Prozac has been attacked by critics and faced intense scrutiny from the media.

Some doctors said Prozac caused patients to become more self-destructive, and other critics blamed it for the suicide of 1960s pop music star Del Shannon.

Its falling market share is seen as a natural part of the product's life cycle. Few prescription drugs stay at the top of their class for more than five or six years because of the intense competition from other brands and generics.

New drugs such as Zoloft, Paxil and Celexa have been launched with strong marketing pitches that promised less of the weariness and reduced libido that some patients felt from Prozac.

About 840,000 new Prozac prescriptions were written in January, 7,000 fewer than Zoloft, according to market data firm IMS Health. In all, nearly 2 million total prescriptions were written for each drug that month.

Prozac sales are expected to decline steadily in the next three years, as its patent expires and cheaper generics become available.

"Prozac has had its day, or more accurately, had its decade," said Christine Hollidge, an analyst with Datamonitor in London.

On the Net: http://www.prozac.com.

Copyright 2000 The Associated Press. All rights reserved.