Merck and Paratek Pharmaceuticals Sign Collaboration Agreement for Novel Antibiotic PTK 0796 Currently in Phase 1 Testing

Business Wire, March 9, 2006

WHITEHOUSE STATION, N.J. & BOSTON -- Merck & Co., Inc. and Paratek Pharmaceuticals, Inc. announced today that Paratek has entered into an exclusive, worldwide collaborative development and license agreement with Merck --through an affiliate -- for PTK 0796, a novel, broad-spectrum aminomethylcycline (AMC) antibiotic with oral and intravenous (IV) formulations currently in Phase I clinical testing.

PTK 0796 represents a significant advance over the well-known tetracycline family, and has been shown to be highly effective in animal models at treating increasingly problematic, clinically prevalent infections caused by gram-positive bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), and by gram-negative, atypical and anaerobic bacteria, including those resistant to currently available classes of antibiotics and known to cause diseases such as pneumonias, urinary tract infections, skin diseases and blood-borne infections in both the hospital and community settings.

"Merck has long been a world leader in the fight against infections, and this agreement is a further demonstration of our commitment to this field of medicine," said Peter S. Kim, Ph.D., President, Merck Research Laboratories. "We are excited about our collaboration with Paratek to develop new antibiotics that have the potential to improve the care of patients and provide physicians with new treatment options at a time of increased antibiotic resistance."

"We are pleased to announce our collaboration with Merck, a global leader in the development and commercialization of anti-infectives and other innovative drugs that address serious medical problems, such as the growing problem of antibiotic resistance," said Thomas J. Bigger, President and CEO of Paratek Pharmaceuticals. "We have been very impressed by Merck's commitment to antibiotic research and development and are pleased by the collaborative process of establishing this important partnership. Their enthusiasm for our PTK 0796 project and embrace of the collaborative process demonstrate a new side of Merck that we found very compelling, in addition to their strong current presence in the hospital anti-infectives market with CANCIDAS(R), INVANZ(R), and PRIMAXIN(R) and their legacy of innovating and delivering important new therapeutics to the marketplace."

Under the terms of the agreement, Merck provided undisclosed upfront funding, will assume primary responsibility for clinical development of the IV and oral formulations of PTK 0796 and has the right to market such products worldwide. Paratek will participate in clinical development and be eligible to receive payments upon achievement of certain milestones; these payments could total as much as $127 million once PTK 0796 is approved for marketing. Paratek will also receive royalties on net sales and have the opportunity to co-promote the IV formulation of PTK 0796 in the United States.

Background on AMCs

Using Paratek's novel medicinal chemistry techniques, AMCs were evolved from tetracycline antibiotics as potential agents to combat multiple antibiotic-resistant bacteria, including MRSA, penicillin-resistant Streptococcus pneumoniae (PRSP), vancomycin-resistant Enterococcus (VRE), multidrug resistant Escherichia coli and other difficult-to-treat pathogens. Introduced more than 50 years ago, tetracyclines remain among the most commonly used anti-infective agents to combat bacterial infections. However, the emergence of resistance has curtailed their effectiveness in certain infections. Paratek has utilized its expertise to create AMC compounds, such as PTK 0796, that retain the appealing safety and spectrum of activity of the tetracyclines while overcoming tetracycline and multi-drug resistance. Evidence to date indicates that PTK 0796 is also not affected by resistance to other classes of antibiotics. PTK 0796 is being evaluated in Phase I both as an IV and oral formulation and may have potential utility against the broad spectrum of pathogens prevalent in the community, including activity against resistant pathogens such as community-associated MRSA.

About Merck

Merck & Co., Inc. is a global research-driven pharmaceutical company dedicated to putting patients first. Established in 1891, Merck discovers, develops, manufactures and markets vaccines and medicines to address unmet medical needs. The Company devotes extensive efforts to increase access to medicines through far-reaching programs that not only donate Merck medicines but help deliver them to the people who need them. Merck also publishes unbiased health information as a not-for-profit service. For more information, visit www.merck.com.

About Paratek Pharmaceuticals

Paratek Pharmaceuticals, Inc. is engaged in the discovery and commercialization of new therapeutics that treat serious and life-threatening diseases, with a particular focus on the growing worldwide problem of antibiotic resistance. Paratek is advancing novel compounds that can circumvent or block bacterial resistance involving technology initially developed by Paratek co-founder Dr. Stuart Levy's laboratory at Tufts University School of Medicine, and licensed by Paratek. In addition to its tetracycline-derived antibacterials, Paratek is developing small molecule drugs that can prevent infection by interfering with Multiple Adaptational Response (MAR) mechanisms in bacteria.