Biological Activity
Darapladib is a potent inhibitor of lipoprotein-associated phospholipase A2 (Lp-PLA2) with IC50 of 0.25 nM.
In Vitro
Mechanistic studies using steady state and transient kinetics indicate Darapladib (SB-480848) to be a freely reversible, non-covalently bound, inhibitor of rhLp-PLA2 with a Ki of 110 pM and an off-rate of 27 min. Potent inhibition of the enzyme in whole human plasma is confirmed (IC50=5±2 nM). Furthermore, the presence of Darapladib during the copper catalysed oxidation of human LDL prevents the production of lyso-PtdCho (IC50=4±3 nM) and subsequent monocyte chemotaxis (IC50=4±1 nM)[1].
In Vivo
Additional in vivo studies with Darapladib indicated an oral bioavailability of 11±2% in the fed rat. The oral bioavailability of Darapladib is 28±4% in the dog. Furthermore excellent inhibition of Lp-PLA2 within the atherosclerotic plaque is achieved for Darapladib, with 95±1% inhibition observed 2 h after an oral dose of 30 mg/kg to the WHHL rabbit[1]. Darapladib, a specific inhibitor of lipoprotein-associated phospholipase A2 (lp-PLA2), on inflammation and atherosclerotic formation in the low density lipoprotein receptor (LDLR)-deficient mice. the activity of serum lp-PLA2 is inhibited by more than 60% in LDLR-deficient mice after oral administration of 50 mg/kg once daily of Darapladib for 6 weeks. Darapladib significantly inhibits serum lp-PLA2 activity in LDLR-deficient mice[2].
References & source
Published experimental findings depend on the model and assay conditions. They do not guarantee equivalent performance in every application. For laboratory research use only.