Update on subcutaneous methotrexate for inflammatory arthritis and psoriasis

Area of Science:

• Rheumatology
• Dermatology
• Clinical Pharmacology

Background:

• Methotrexate (MTX) is a primary treatment for immune-mediated inflammatory diseases such as rheumatoid arthritis (RA) and psoriasis.
• Oral MTX exhibits interpatient variability due to pharmacogenomics, saturable absorption, and nonlinear pharmacokinetics, impacting bioavailability and efficacy.
• Parenteral MTX, particularly subcutaneous (SC) injection, demonstrates rapid absorption, higher serum levels, and less variable exposure than oral administration.

Purpose of the Study:

• To review literature data on subcutaneous MTX for inflammatory arthritis, focusing on RA and psoriasis.
• To compare the efficacy, safety, and pharmacokinetic profiles of SC MTX versus oral MTX.
• To examine pharmacodynamic and pharmacoeconomic aspects of SC MTX treatment.

Main Methods:

• Literature review of available data on SC MTX in inflammatory arthritis.
• Emphasis on studies involving rheumatoid arthritis and psoriasis patients.
• Analysis of pharmacokinetic, pharmacodynamic, and safety data comparing SC and oral MTX.

Main Results:

• SC MTX generally shows higher efficacy than oral MTX, especially in patients with inadequate response to oral therapy.
• SC MTX offers a similar safety profile to oral MTX, with potentially fewer gastrointestinal complaints.
• Parenteral administration leads to more predictable drug exposure and bioavailability compared to oral dosing.

Conclusions:

• Subcutaneous methotrexate is a promising alternative to oral MTX for managing RA and psoriasis, potentially improving treatment outcomes.
• The enhanced bioavailability and consistent exposure of SC MTX may translate to greater clinical benefit.
• Further research is warranted, particularly in juvenile idiopathic arthritis and psoriatic disease, to fully elucidate the benefits of SC MTX.