tcsc0275 Zosuquidar (trihydrochloride)

Zosuquidar trihydrochloride is an inhibitor of P-glycoprotein with a K_i value of 59 nM.

IC50 & Target: Ki: 59nM (P-glycoprotein)^[1].

In Vitro: Zosuquidar completely or partially restores drug sensitivity in all P-gp-expressing leukemia cell lines and enhances the cytotoxicity of anthracyclines (daunorubicin, idarubicin, mitoxantrone) and gemtuzumab ozogamicin (Mylotarg) in primary AmL blasts with active P-gp. In addition, P-gp inhibition by zosuquidar is found to be more potent than cyclosporine A in cells with highly active P-gp^[2].

In Vivo: Zosuquidar trihydrochloride is only moderately active as an inhibitor of P-gp at the blood-brain. An oral dose of 25 mg/kg of zosuquidar trihydrochloride increases the brain concentrations by about 2.5-fold at 1 h and 5-fold at 24 h after paclitaxel administrationbarrier^[3]. Zosuquidar enhances the brain uptake of nelfinavir in a dose-dependent manner. Brain tissue/plasma nelfinavir concentration ratios increase from 0.06±0.03 in the absence of zosuquidar administration and 0.09±0.02 between 2 and 6 h after a 2 mg/kg intravenous dose of zosuquidar to 0.85±0.19 after 6h and 1.58±0.67 after 20 mg/kg zosuquidar^[4].