Study design
This was a single-center double-blind, placebo-controlled, double-dummy clinical trial with four interventions: i.d. adalimumab (40 mg Humira, AbbVie, Maidenhead, UK), i.d. saline (0.9%), s.c. adalimumab, and s.c. saline. i.d. injections were given using a hollow microneedle (MicronJet600 from Nanopass Technologies Ltd., Ness Ziona, Israel), s.c. injections using a regular needle (Microlance 3 from Becton, Dickenson, and Company (BD), Franklin Lakes, United States of America); both devices were connected to a syringe (1 mL Luer-LokTM, BD). The length of the three needles of a MicronJet600 device is 600 µm. Injections were given according to standard operating procedures and the manufacturer’s instruction. All subjects received one placebo injection and one adalimumab injection of 40 mg in 0.4 ml in the right and left upper lateral thigh by the same physician. Given the nature of the study, the physician administering the injection could not be blinded to the method of administration but was blinded to treatment, i.e., adalimumab or placebo. Therefore, this physician was not involved in the assessment of any of the pre-defined outcomes (evaluator-blinded). The subjects were in a prone position during and in between injections to ensure blinding (subject-blinded). Injections were spaced five minutes apart. Prior to administration, the sites of injection were annotated using a surgical marker (Purple Surgical, Shenley, England). Subjects were instructed to maintain the marking while at home, and to prevent excessive sun exposure to the injection site to limit possible interference with the exploratory measurements.