Effects of Changing from Oral to Subcutaneous Methotrexate on Red Blood Cell Methotrexate Polyglutamate Concentrations and Disease Activity in Patients with Rheumatoid Arthritis

Abstract

Changing to SC MTX results in increased long-chain MTXGlu(n). However, it takes at least 6 months for RBC steady-state concentrations to be achieved. Increased long-chain MTXGlu(n) concentrations were significantly associated with reduced disease activity.