Fosaprepitant dimeglumine (MK-0517) is the dimeglumine salt form of fosaprepitant, the water-soluble, N-phosphorylated prodrug of aprepitant, with antiemetic activity. Upon intravenous administration and rapid conversion to aprepitant, this agent binds selectively to the human substance P/neurokinin 1 (NK1) receptors in the central nervous system (CNS). This inhibits receptor binding of the endogenous substance P and prevents substance P-induced emesis.

Fosaprepitant (MK-0517，L-758,298) 可作为 aprepitant 的磷酸酯前药。Aprepitant 是一种选择性物质P（NK-1受体）拮抗剂，用于与皮质类固醇和5-HT 3受体拮抗剂组合治疗，预防急性及延迟的化疗引起的恶心和呕吐。[1]

Fosaprepitant通过静脉注射后，由于广泛存在的磷酸酶的作用，在30分钟内转化为aprepitant。Fosaprepitant在150 mg（1 mg/ml）剂量下具有良好的耐受性，而Fosaprepitant 115 mg在其AUC上与aprepitant 125 mg生物等效。Fosaprepitant 115 mg已作为3天口服aprepitant方案第1天的替代方案提交FDA审批，其中第2天和第3天采用口服aprepitant。[1]

Biochemical Methods: EPZ-6438 is incubated for 30 min with 40 μL per well of 5 nM PRC2 (final assay concentration in 50 μL is 4 nM ) in 1X assay buffer (20 mM Bicine [pH 7.6], 0.002% Tween-20, 0.005% Bovine Skin Gelatin and 0.5 mM DTT). 10 μL per well of substrate mix comprising assay buffer 3 H-SAM, unlabeled SAM, and peptide representing histone H3 residues 21-44 containing C-terminal biotin (appended to a C-terminal amide-capped lysine) are added to initiate the reaction (both substrates are present in the final reaction mixture at their respective Km values, an assay format referred to as ‘‘balanced conditions''. The final concentrations of substrates and methylation state of the substrate peptide are indicated for each enzyme Reactions are incubated for 90 min at room temperature and quenched with 10 μL per well of 600 μM unlabeled SAM, Then transferred to a 384-well flashplate and washed after 30 min.