November 03, 2005

Dr. Susan Froshauer, President and Chief Executive Officer
of Rib-X Pharmaceuticals, will present at the
CIBC World Markets 16th Annual Healthcare Conference

November 7, 2005
New York City

An audio webcast of Dr. Froshauer’s remarks will be available live. You can access the webcast at:, source code: november

About Rib-X Pharmaceuticals, Inc.
Rib-X Pharmaceuticals is a product driven small molecule drug discovery and development company focused on the structure-based design of new classes of antibiotics. The Company’s drug discovery strategy exploits its proprietary high-resolution crystal structure of the 50S subunit of the ribosome, which performs an essential role in the fundamental process of protein synthesis. The 50S is the target for many clinically valuable classes of antibiotics, including those used to treat infections caused by serious, drug-resistant, community-acquired and hospital pathogens. The Company’s integrated research approach combines state of the art, computational analysis, x-ray crystallography, medicinal chemistry, microbiology and biochemistry, allowing for the rapid synthesis of new classes of antibiotics, which avoid typical antibiotic resistance mechanisms. During 2005, Rib-X expects to initiate Phase I studies for at least one clinical candidate from its most advanced program. This program (the Rc-01 program) has yielded attractive, orally active compounds with attributes appropriate for therapeutic applications in either the hospital Gram-positive or community respiratory tract infection marketplace. Rib-X’s iterative approach has yielded several distinctive chemical classes in addition to those defined by the Rc-01 program. The Company is currently well-positioned to develop a pipeline of differentiable products that are expected to address distinct markets for the treatment of bacterial infections.

For more information on the ribosome and the Rib-X mission, please visit the Company website at

Rx Communications Group
Rhonda Chiger (investors)