Prediction of Human Pharmacokinetics of Ulixertinib, a Novel ERK1/2 Inhibitor from Mice, Rats, and Dogs Pharmacokinetics.

Background And Objectives: Ulixertinib (BVD-523) is a novel and selective reversible inhibitor of ERK1/ERK2. The primary objectives of the study were to evaluate the pharmacokinetics of ulixertinib in mice, rats, and dogs followed by prediction of human pharmacokinetic profile by allometric equations with/without correction factors.

Methods: Oral and intravenous pharmacokinetic profiles of ulixertinib were generated in mice, rats, and dogs. The human intravenous pharmacokinetics profiles [volume of distribution (V) and clearance (CL)] were predicted employing simple allometry and using correction factors [maximum life span potential (MLP) and brain weight (BW)]. Pharmacokinetic data obtained from dogs were used to simulate human oral profile [area under the curve (AUC) and maximum plasma concentrations (C)].

Results: Post-intravenous administration the CL was moderate in dogs (15.5 mL/min/kg) and low in mice (6.24 mL/min/kg) and rats (1.67 mL/min/kg). V was 0.56, 0.36, and 1.61 L/kg in mice, rats, and dogs, respectively. The half-life (t) of ulixertinib ranged between 1.0 and 2.5 h across the animal species. Following oral administration ulixertinib attained maximum concentration in plasma (T) within 0.50-0.75 h in mice and rats, indicating that absorption was rapid; however, in dogs, T attained at 2 h. Absolute oral bioavailability in mice and rats was > 92%; however, in dogs, it was 34%. By different allometric approaches, simple method and brain weight correction factor shown clear improvement in the prediction efficiency of allometric scaling for V (1.34-1.70 L/kg) and CL (4.18-6.09 mL/min/kg), respectively, comparing with the MLP method and simple method for CL. Similarly, simulation of oral human profile was attained from scaled values and dog data to predict reported human profile (AUC and C).

Conclusions: The derived pharmacokinetic parameters (AUC and C at 600 mg dose) and simulated plasma concentration-time profiles of ulixertinib in humans were predicted with good confidence by allometric approach.