Doripenem: S 4661.

Doripenem [S 4661] is a new parenteral carbapenem antibacterial undergoing clinical trials in Japan and North America. It is characterised by a 1beta-methyl group and a sulfamoylaminomethyl substituted pyrrolidylthio group at the C2 position. The compound has good activity against both Gram-positive and Gram-negative bacteria and superior activity to meropenem and imipenem against Pseudomonas aeruginosa. It possesses higher stability than imipenem or meropenem against animal dehydropeptidase I. The compound is stable to most beta-lactamases produced by Gram-negative bacteria. Shionogi has stated that doripenem is expected to be effective at low doses. In May 2003, Shionogi and Peninsula Pharmaceuticals (USA) entered a licensing agreement for doripenem under which Peninsula obtained exclusive rights (including sublicense rights) to market and develop the product in North America. Shionogi will manufacture doripenem for worldwide distribution. Doripenem is currently undergoing phase III trials in Japan for pneumonia, chronic respiratory tract infections (RTIs) and urinary tract infections (UTIs). In its November 2002 pipeline, Shionogi stated that it plans to file a NDA in Q4 of 2003. Doripenem is also in phase II studies in hospitalised patients with complicated urinary tract infections including pyelonephritis. In September 2003, Peninsula announced it had completed enrolment in this trial, and results are expected later in the year. Doripenem has also completed two phase I studies in healthy volunteers with a number of different dosing regimens.