The list of survivors is Bcom3 Group's Starcom Worldwide, WPP Group's Media Edge and Empower MediaMarketing.
The pharmaceutical company sent out requests for information only last week, and made the cuts without hearing pitches.
An Eli Lilly executive declined to comment on the matter.
The company, which is based in Indianapolis, markets Prozac and is expected to introduce a competitive brand to Pfizer's Viagra next year.
According to executives involved in the review, agencies without prior pharmaceutical experience as well as shops with conflicting brands were eliminated from the competition.