2-Hydroxymethyl-4-[5-(4-methoxyphenyl)-3-trifluoromethyl-1H-1-pyrazolyl]-1-benzenesulfonamide (DRF-4367): an orally active COX-2 inhibitor identified through pharmacophoric modulation

Analogs of 1,5-diarylpyrazoles with a novel pharmacophore at N1 were designed, synthesized and evaluated for the in-vitro cyclooxygenase (COX-1/COX-2) inhibitory activity. The variations at/around position-4 of the C-5 phenyl ring in conjunction with a CF3 and CHF2 groups at C-3 exhibited a high degree of potency and selectivity index (SI) for COX-2 inhibition. The in-vivo evaluation of these potent compounds with a few earlier ones indicated the 4-OMe-phenyl analog 6 and the 4-NHMe-phenyl analog 9 with a CF3, and the 4-OEt-phenyl analog 19 with a CHF2 group at C-3 to possess superior potency than celecoxib. In addition to its impressive anti-inflammatory, antipyretic, analgesic and anti-arthritic properties, compound 6 (DRF-4367) was found to possess an excellent pharmacokinetic profile, gastrointestinal (GI) safety in the long-term arthritis study and COX-2 potency in human whole blood assay. Thus, compound 6 was selected as an orally active anti-inflammatory candidate for pre-clinical evaluation.