Assessing usability, label comprehension, pen robustness and pharmacokinetics of a self-administered prefilled autoinjector pen of methotrexate in patients with rheumatoid arthritis

OBJECTIVE To assess usability, bioavailability, and safety of subcutaneous self-administration of 0.3 mL of methotrexate 50 mg/mL solution via a prefilled autoinjector pen (methotrexate pen) in patients with rheumatoid arthritis. METHODS The study enrolled methotrexate-naïve and methotrexate-experienced patients aged ≥16 years. Visit 1 (Day 1) included methotrexate pen usage training with documentation, patient self-injection, and a patient-training questionnaire completed by the healthcare professional. Visit 2 (Days 8-10) included evaluation of patient self-injection through four scenarios: holding needle in place for 5 s, confirming methotrexate delivery, skin pinch, and pen disposal. At Visit 2, patient opinion and training retention (since Visit 1) were also assessed. Pharmacokinetic parameters were assessed in 25 patients, who were stratified by body weight and randomized to receive injections in the abdomen or the upper thigh. RESULTS At Visit 1, 12 of 106 patients had questions about the pen, and 4 required self-injection assistance. At Visit 2, the mean performance rating for all scenarios was ≥9.8 (scale: 1 (very difficult)-10 (very easy)). Successful completion rates were 96.2%-100%; 91.3%-100% of patients required no assistance. Impressions of the pen were favorable; 98.1% of patients passed the written examination. All methotrexate pens effectively delivered 0.3 mL methotrexate and were intact after use. Body weight >100 kg significantly decreased total and peak methotrexate exposure when administered abdominally. No adverse effects resulted in drug discontinuation. CONCLUSION The methotrexate pen was used with a high degree of effectiveness, satisfaction, and safety, indicating that this delivery system may be a viable option for patients requiring subcutaneous methotrexate.