A Single Center Single Dose Open-label Randomized Two Period Crossover Study to Determine the Bioavailability of Two Formulations of Methotrexate 25 mg Administered by Needle Injection and a Pre-filled Needle-free Device in at Least 48 Healthy Volunteers.

ABSTRACT Objective: Zeneo1 is a needle-free injection device. We performed a pharmacokinetic study to investigate the bioequivalence of methotrexate administered subcutaneously using either the needle-free injection device or a conventional needle and syringe.

Research design and methods: This was a single-dose, open-label, laboratory-blind, randomized crossover study performed in adult healthy volunteers. Each participant received two methotrexate injections (each 25mg), one via needle-free injection device and one via conventional injection, with a 21-28 day wash-out interval between dosing. For each participant, the administration site for both injections was either the abdomen or the thigh.

Main outcome measures: The primary pharmacokinetic outcome parameters were AUC(0-t) and Cmax.

Bioequivalence was assessed by standard criteria: whether 90% confidence intervals of geometric mean ratios for the two administration methods were within 80-125%.

Results: Fifty-two individuals completed the study. Bioequivalence criteria were met for AUC(0-t), for the overall analysis (both injection sites: 90% confidence interval: 99.4-103.1%), and for each injection site separately. Bioequivalence was similarly demonstrated with AUC(0-1). Bioequivalence criteria for Cmax were fulfilled for abdominal administration but not for the overall analysis. Injection via the needle- free injection device was well tolerated.