Discovery of highly selective and potent p38 inhibitors based on a phthalazine scaffold.

Investigations into the structure-activity relationships (SAR) of a series of phthalazine-based inhibitors of p38 are described. These efforts originated from quinazoline 1 and through rational design led to the development of a series of orally bioavailable, potent, and selective inhibitors. Kinase selectivity was achieved by exploiting a collection of interactions with p38alpha including close contact to Ala157, occupation of the hydrophobic gatekeeper pocket, and a residue flip with Gly110. Substitutions on the phthalazine influenced the pharmacokinetic properties, of which compound 16 displayed the most desirable profile. Oral dosing (0.03 mg/kg) of 16 in rats 1 h prior to LPS challenge gave a >50% decrease in TNFalpha production.

Trisubstituted pyrimidines as transient receptor potential vanilloid 1 (TRPV1) antagonists with improved solubility.

A series of trisubstituted pyrimidines were synthesized to improve aqueous solubility of our first TRPV1 clinical candidate (1; AMG 517), while maintaining potent TRPV1 inhibitory activity. Structure-activity and structure-solubility studies led to the identification of compound 26. The aqueous solubility of 26 (>or=200microg/mL, 0.01 HCl; 6.7microg/mL, phosphate buffered saline (PBS); 150microg/mL, fasted-state simulated intestinal fluid (SIF)) was significantly improved over 1. In addition, compound 26 was found to be orally bioavailable (rat F(oral)=24%) and had potent TRPV1 antagonist activity (capsaicin IC(50)=1.5nM) comparable to that of 1.