Pharmacodynamic behaviour of the selective cyclooxygenase-2 inhibitor lumiracoxib in the lipopolysaccharide-stimulated rat air pouch model.

PURPOSE: To investigate the pharmacodynamic behaviour of the selective cyclooxygenase-2 inhibitor, lumiracoxib, in the rat air pouch. METHODS: Air pouches were injected with lipopolysaccharide to stimulate prostaglandin E2 (PGE2) production 1h after lumiracoxib treatment. Pouch fluid samples were collected 6 or 24 h after lumiracoxib administration to measure PGE2 levels. Lumiracoxib concentrations in pouch fluid and plasma were measured by mass spectrometry. RESULTS: Oral administration of lumiracoxib resulted in dose-dependent inhibition of PGE2 production 6 and 24 h post-dose. The estimated ED50 values for inhibition of PGE2 production were 0.1 and 2.0 mg/kg at 6 and 24 h, respectively. Lumiracoxib concentrations in plasma and pouch fluid increased in proportion to dose. There was a strong positive correlation between lumiracoxib concentrations in plasma and pouch fluid compartments. Lumiracoxib concentrations were higher in plasma than in pouch fluid 6 h post-dose, but at 24 h post-dose, pouch fluid concentrations were > or =4-fold greater than plasma concentrations. CONCLUSIONS: Lumiracoxib readily enters the air pouch and persists in this extravascular compartment for a longer period of time than in plasma. This distribution profile may contribute to the ability of lumiracoxib to inhibit PGE2 production up to 24 h after dosing.

N-alkyl urea hydroxamic acids as a new class of peptide deformylase inhibitors with antibacterial activity.

Peptide deformylase (PDF) is a prokaryotic metalloenzyme that is essential for bacterial growth and is a new target for the development of antibacterial agents. All previously reported PDF inhibitors with sufficient antibacterial activity share the structural feature of a 2-substituted alkanoyl at the P(1)' site. Using a combination of iterative parallel synthesis and traditional medicinal chemistry, we have identified a new class of PDF inhibitors with N-alkyl urea at the P(1)' site. Compounds with MICs of 200 micro M for matrilysin and other mammalian metalloproteases. Structure-activity relationship analysis identified preferred substitutions resulting in improved potency and decreased cytotoxity. One of the compounds (VRC4307) was cocrystallized with PDF, and the enzyme-inhibitor structure was determined at a resolution of 1.7 A. This structural information indicated that the urea compounds adopt a binding position similar to that previously determined for succinate hydroxamates. Two compounds, VRC4232 and VRC4307, displayed in vivo efficacy in a mouse protection assay, with 50% protective doses of 30.8 and 17.9 mg/kg of body weight, respectively. These N-alkyl urea hydroxamic acids provide a starting point for identifying new PDF inhibitors that can serve as antimicrobial agents.