A Target-Mediated Drug Disposition Model to Explain Nonlinear Pharmacokinetics of the 11β-Hydroxysteroid Dehydrogenase Type 1 Inhibitor SPI-62 in Healthy Adults

SPI-62 is a selective and potent small-molecule inhibitor of 11β-hydroxysteroid dehydrogenase type 1 (HSD-1). SPI-62 has demonstrated substantial and complex nonlinear pharmacokinetics (PK) in humans that is characterized by unusually low plasma exposure at low doses, dose-dependent volume of distribution, nonlinear PK following the first dose, and dose-proportional PK at steady state, as well as unusually high accumulation ratios at low doses.