peficitinib peficitinib peficitinib (trade name smyraf) is a pharmaceutical drug used for the treatment of rheumatoid arthritis. it belongs to the class of drugs known as janus kinase inhibitors (jak inhibitors). peficitinibclinical datatrade namessmyrafother namesasp015k; jnj-54781532atc codel04aa49 (who) legal statuslegal status us: not fda approved in general: ℞ (prescription only) identifierscas number944118-01-8pubchem cid57928403uniihph1166ckxkeggd10721chemical and physical dataformulac18h22n4o2molar mass326.400 g·mol−13d model (jsmol)interactive image smiles nc(=o)c1cnc2ccc2c1nc12cc3c1cc(o)(c3)c2 inchi inchi=1s/c18h22n4o2/c19-16(23)13-8-21-17-12(1-2-20-17)15(13)22-14-10-3-9-4-11(14)7-18(24,5-9)6-10/h1-2,8-11,14,24h,3-7h2,(h2,19,23)(h2,20,21,22)/t9?,10-,11+,1 ykey:dreijxjrtltgjc-jqclmnfqsa-n y peficitinib was approved for use in japan in 2019.