SB-209247

SB-209247 is a selective, high affinity and orally active leukotriene B4 (LTB4) receptor antagonist with a K_i of 0.78 nM. SB-209247 blocks LTB4-induced Ca²⁺ mobilization with an IC₅₀ of 6.6 nM. SB-209247 shows a potent anti-inflammatory activity^[1]. In Vitro:SB-209247 (Compound 3) demonstrates a high degree of selectivity for the LTB4 receptor. SB-209247 competes with [³H]-fMLP and [³H]LTD4 in respective receptor binding assays with IC₅₀ values of 3250 nM and 16800 nM and with another 14 ligands with IC₅₀ values greater than 10000 nM. Functional activity at the cellular level is demonstrated in human polymorphonuclear leukocytes (PMNs) by blocking the LTB4-induced Ca²⁺ mobilization and LTB4-induced degranulation with IC₅₀ values of 6.6 nM and 53 nM, respectively^[1]. In Vivo:SB-209247 (Compound 3) has an ED₅₀ of 14.8 mg/kg for inhibiting neutrophil influx in the murine model, and inhibits the fluid phase (edema) of the inflammatory response with an ED₅₀ of 18.7 mg/kg^[1].