TY - JOUR T1 - Preclinical Metabolism and Disposition of SB939 (Pracinostat), an Orally Active Histone Deacetylase Inhibitor, and Prediction of Human Pharmacokinetics JF - Drug Metabolism and Disposition JO - Drug Metab Dispos SP - 2219 LP - 2232 DO - 10.1124/dmd.111.041558 VL - 39 IS - 12 AU - Ramesh Jayaraman AU - Venkatesh Pilla Reddy AU - Mohammed Khalid Pasha AU - Haishan Wang AU - Kanda Sangthongpitag AU - Pauline Yeo AU - Chang Yong Hu AU - Xiaofeng Wu AU - Liu Xin AU - Evelyn Goh AU - Lee Sun New AU - Kantharaj Ethirajulu Y1 - 2011/12/01 UR - http://dmd.aspetjournals.org/content/39/12/2219.abstract N2 - The preclinical absorption, distribution, metabolism, and excretion (ADME) properties of Pracinostat [(2E)-3-[2-butyl-1-[2-(diethylamino) ethyl]-1H-benzimidazol-5-yl]-N-hydroxyarylamide hydrochloride; SB939], an orally active histone deacetylase inhibitor, were characterized and its human pharmacokinetics (PK) was predicted using Simcyp and allometric scaling. SB939 showed high aqueous solubility with high Caco-2 permeability. Metabolic stability was relatively higher in dog and human liver microsomes than in mouse and rat. The major metabolites formed in human liver microsomes were also observed in preclinical species. Human cytochrome P450 (P450) phenotyping showed that SB939 was primarily metabolized by CYP3A4 and CYP1A2. SB939 did not significantly inhibit human CYP3A4, 1A2, 2D6, and 2C9 (>25 μM) but inhibited 2C19 (IC50 = 5.8 μM). No significant induction of human CYP3A4 and 1A2 was observed in hepatocytes. Plasma protein binding in mouse, rat, dog, and human ranged between ∼84 and 94%. The blood-to-plasma ratio was ∼1.0 in human blood. SB939 showed high systemic clearance (relative to liver blood flow) of 9.2, 4.5, and 1.5 l · h−1 · kg−1 and high volume of distribution at steady state (>0.6 l/kg) of 3.5, 1.7, and 4.2 l/kg in mouse, rat, and dog, respectively. The oral bioavailability was 34, 65, and ∼3% in mice, dogs, and rats, respectively. The predicted oral PK profile and parameters of SB939, using Simcyp and allometric scaling, were in good agreement with observed data in humans. Simcyp predictions showed lack of CYP3A4 and 2C19 drug-drug interaction potential for SB939. In summary, the preclinical ADME of SB939 supported its preclinical and clinical development as an oral drug candidate. ER -