A multidrug-resistance modulator; restores sensitivity of MDR-P388 murine leukemia cells to various cytostatic agents from 26-70 nM; inhibits basal-to-apical transport and increases apical-to-basal transport of [14C]docetaxel in LLC-GA5-COLO150 cells that overexpress human P-gp; increases survival time in MDR-P388 tumor-bearing mice and in an MDR-L1210 leukemia mouse xenograft model when administered in combination with doxorubicin; prolongs the anti-hyperalgesic effects of intraperitoneally administered pregabalin in a mouse model of cold stress-induced central pain