Peninsula Pharmaceuticals, Inc. Announces Doripenem is Active Against Common Lung Pathogens Found in Cystic Fibrosis Patients

ALAMEDA, Calif. -- Peninsula Pharmaceuticals, Inc., a privately-held biopharmaceutical company, announced today non-clinical in vitro data that demonstrates doripenem (also known as S-4661), a broad-spectrum carbapenem antibiotic, is highly active against two of the most common lung pathogens infecting patients with cystic fibrosis (CF).

The non-clinical study investigated the in vitro bactericidal activity of doripenem, tobramycin, aztreonam, ceftazidime, and imipenem against Pseudomonas aeruginosa, a ubiquitous aerobic gram-negative bacterium, and Burkholderia cepacia, a gram-negative bacterial pathogen. Both bacteria are established pathogens in the lungs of patients with CF and are of evolving importance in other patient populations, including individuals with compromised immunity.

Doripenem demonstrated between a two-fold and 64-fold increase in activity relative to the other antibiotics tested against P. aeruginosa isolates obtained from both CF and non-CF patients. Although the minimal inhibition concentrations (MIC) of doripenem versus isolates obtained from CF patients increased slightly, it remains the most potent compound among the agents tested. Unlike other antibiotics with poor or limited anti-B. cepacia activity, doripenem displayed respectable in vitro potency against B. cepacia, a pathogen associated with high mortality in CF patients.

"The degree of activity we observed in this study of doripenem helps to validate our commitment to develop this compound to treat serious bacterial infections," said Yigong Ge, MD, PhD, senior director of preclinical development at Peninsula. "The non-clinical data provide a clear picture for investigating the advantages of doripenem in difficult to treat infections caused by these and other pathogens."

CF is a genetic disease affecting approximately 30,000 children and adults in the United States. Patients with CF develop thick, mucus which clogs passages in many of the body's organs, primarily the lungs and the pancreas. In the lungs, bacteria become trapped in the mucus creating a constant infection that interferes with breathing and progressively destroys lung tissue. More than 90 percent of patients with CF eventually die of their lung disease.

Doripenem is the newest member of the carbapenem class of antibacterials and displays broad in vitro potency against aerobic, anaerobic, gram-positive and gram-negative bacteria. Discovered by Shionogi & Co., Ltd. of Osaka, Japan, doripenem has demonstrated potent in vitro efficacy against Pseudomonas aeruginosa, methicillin-susceptible strains of Staphylococcus aureus, and penicillin-resistant strains of Streptococcus pneumoniae (PRSP). Current in vitro and in vivo data support its clinical development as a therapeutic agent for a number of serious bacterial infections.

The worldwide hospital antibacterial market exceeds $8 billion annually and the worldwide market for carbapenems (a member of the well known beta-lactam class of antibiotics) is close to $1.0B and growing. By 2006, the carbapenem market is expected to grow by 50 percent due to the ever increasing need for safe, powerful, broad-spectrum antibiotics to treat increasingly difficult and serious hospital infections.

Source: Peninsula Pharmaceuticals, Inc.

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