Oxyphenisatine (Oxyphenisatin) is a laxative. Oxyphenisatin acetate is the pro-drug of oxyphenisatin with anticancer activity. In Vitro: Oxyphenisatin has been shown to have antiproliferative activity. Oxyphenisatin acetate (OXY, NSC 59687) is the pro-drug of oxyphenisatin. OXY inhibits the growth of the breast cancer cell lines MCF7, T47D, HS578T, and MDA-MB-468 (IC₅₀=0.8, 0.6, 2.1, 1.8 μM). This effect is associated with selective inhibition of translation accompanied by rapid phosphorylation of the nutrient sensing eIF2α kinases, GCN2 and PERK^[1]. In Vivo: Toxicity studies demonstrate that mice tolerate IP administration of OXY at 300 mg/kg once daily or 200 mg/kg twice daily. Administration of OXY at 300 mg/kg IP once daily for 10 days results in significantly smaller tumors from day 33 to day 52^[1].