CYP3A4 and rheumatoid arthritis: With an oral bioavailability of 74% and mean elimination half-life of 3 h, tofacitinib is metabolized via cytochrome P450 3A4 (CYP3A4) with 30% renally excreted; 5 mg bd Tofacitinib has recently been approved by the FDA for moderate to severe RA refractory to DMARDs based on recent efficacy studies, with the onset benefits associated with the treatment occurring earlier.145 Common adverse side effects were related to infection, hematologic and hepatic disorders, and association of tofacitinib, with carcinogenicity and infections debatable.