The AIDS Healthcare foundation has filed a lawsuit against Pfizer Inc. on Monday over ads the group says encourage use of Viagra as a party drug. The group said recreational use of the drug furthers the spread of HIV and other sexually transmitted diseases.

The AIDS Healthcare Foundation charges the marketing of Viagra fosters an increase in the spread of sexually transmitted diseases. Studies have found the drug is used — illegally — in conjunction with crystal methamphetamine to form a recreational drug "cocktail."

The lawsuit, calls Pfizer's ads for the impotence drug false and misleading. The suit follows allegations made in an ad campaign announced by the group last month.

While crystal methamphetamine can heighten sexual desire, it also can impair the ability to have an erection, said Michael Weinstein, president of the AIDS Healthcare Foundation. "In order to satisfy that heightened desire, you have to take Viagra," Weinstein told reporters.

Pfizer denied it promotes the recreational use of its blockbuster drug. In 2005, Pfizer had $860 million in U.S. Viagra sales, according to IMS Health Inc.

The suit, filed in Los Angeles Superior Court, seeks to stop the New York company from running ads like those promoting the drug's use on New Year's Eve and Super Bowl Sunday, said Tom Myers, the AIDS group's legal counsel. In the lawsuit, AIDS Healthcare Foundation claims the ads, which included the tagline "Be this Sunday's MVP" encourage recreational use.

The lawsuit seeks to require Pfizer to undertake a public information campaign on the dangers of misusing and abusing the prescription drug. Furthermore, it also seeks an unspecified amount to cover an increase in treatment costs borne by the nonprofit group, which runs free treatment clinics.

Pfizer said it and a company foundation already support AIDS prevention efforts, including a three-year, $6 million project undertaken in 2003 in nine southern states.

The advertisements in question featured younger-looking men than earlier Viagra ads using retired Sen. Bob Dole, then in his 70s, as a pitchman. Myers said the newer ads imply the drug is meant to enhance the sexual experience and not to treat a medical condition.

A Pfizer official warned against confusing age with the degree of impotence.

"The age of the personality that's always seen in promotional materials doesn't necessarily depict severity," said Dr. Ivan Levinson, senior medical director for Pfizer Urology and Sexual Health.

The AIDS Healthcare Foundation is also asking the Federal Drug Administration to step up its oversight of Viagra ads.

Pfizer was warned by the FDA in 2004 that some television ads for Viagra made it clear the drug was for sex, but failed to note it was to treat impotence. According to the letter, the ads at issue failed to provide information on its major side effects.

Filing of the suit came as Pfizer announced it would cut 10,000 jobs in seeking to trim its annual costs by $2 billion.