Encequidar mesylate (HM30181A mesylate) is a competitive P-glycoprotein inhibitor.

Treatment of 0.1 or 1 nM Encequidar lead to 20 and 42% inhibition of survival at the 100 nM and 1000 nM NSC 125973 treatment, respectively [2].

The plasma concentrations of Encequidar are higher for the simultaneous administration with the microcapsule than with the powder; providing significant differences from 1 to 2 h. The microcapsule has about a 1.7-fold faster Tmax and a 1.6-fold higher AUC value compared with the powder (2.5±0.6 vs. 4.3±0.9 h; 107.7±20.1 vs. 64.3±18.0 h ng/mL). The faster and overall improved absorption of Encequidar in microcapsule form might be due to the remarkable enhancement of the aqueous solubility and dissolution resulting from its crystalline conversion to the amorphous form and particle size reduction [1].