Figure legends
Figure 1 CONSORT flow diagram of clinical trial . For PK and population PK analysis subjects in which any spillage occurred during injection were excluded. Other analyses were done with all subjects who completed the study (N=24).
Figure 2 Volunteer reported outcomes indicate preference for s.c. administration versus i.d. administration. Healthy volunteers were injected with a single dose of adalimumab in the upper thigh and placebo in the contralateral upper thigh administered i.d. using a hollow microneedle or s.c. using a conventional needle. Pain scores were measured during insertion of the needle (insertion pain) and during infusion of the compound (injection pain) using a 100 points VAS. Insertion and injection pain were normalized to the pain score during a Mantoux which the volunteers received during screening. (A) VAS pain scores for insertion pain. No differences were observed between s.c. and i.d. insertion pain (p=0.68). (B) VAS pain scores for injection and post-injection pain. Injection pain was significantly (p<0.0001) higher for i.d. compared to s.c. injection. Post-injection pain was not present. After injection, subjects were asked multiple choice questions about their preference, for (C) how they experienced the injection, (D) how they would like to get a hypothetical future injection, (E) and for which injection they had fear. (A-E): N=12 per group, except for Mantoux where n=24. (A-B): mean ± SD; repeated measures ANOVA; **** p<0.0001. NA: not available because not measured. VAS: visual analogue scale.
Figure 3 Pharmacokinetics of adalimumab and anti-adalimumab antibodies after i.d. or s.c. Injection . Mean anti-adalimumab levels after (A) s.c. and (B) i.d. administration (n=12 per administration type). (C) Average anti-adalimumab levels for subjects with anti-adalimumab antibodies (n=10 for s.c. administration and n=6 for i.d. administration). (D) Serum adalimumab concentrations over time (D, n=10 for s.c. administration and n=9 for i.d. administration, non-compartmental analysis). (C-D) Mean ± SD. (E) Schematic depiction of population PK model. (F) Adalimumab absorption kinetics over time after adalimumab administration following microneedle (i.d.) or s.c. administration (typical population PK model). F: bioavailability; ID: intradermal; ka: absorption rate constant; SC: subcutaneous.
Figure 4 Similar cytokine production after i.d. or s.c. adalimumab administration (A) TNFα, (B) IL-1β, (C) IL-8, (D) IFNγ, and (E) IL-6 release after ex vivostimulation with LPS/aluminium hydroxide of whole blood samples. No gender effect was observed. Mean ± SD. A-E: N=12 per group, repeated measures ANOVA.
Figure 5 Characterization of skin reaction following i.d. and s.c. injection. (A-C) 3D photography; (A) Typical bleb after i.d. injection. (B) Maximum height and volume of injection site. Volume was determined by outlining bleb circumference and height and calculated using the DermaPix (QuantifiCare, USA) algorithm for volume (σ = 5). Bleb height and volume did not differ between i.d. adalimumab and i.d. placebo (height p=0.26, volume p=0.29). (D) Redness of the injection sites, determined using a multispectral camera, displayed using the CIELAB *a ratio (green colours are negative, red colours positive). The more positive the CIELAB *a ratio, the redder the injection site. I.d. adalimumab and placebo injections induced significantly more redness of the skin compared to s.c. adalimumab and placebo injections (p<0.0001). Within i.d. administration, skin redness induced by adalimumab injection was significantly higher than for placebo injection (p=0.0014) (E-F) Representative OCT images of i.d. injection 10 minutes post injection; (D-E) Cross-sectional planes of i.d. injection, and (F) top view of skin surface with three puncture holes. (G) LSCI was used to quantify skin perfusion in arbitrary PU 10 minutes post-injection. (H) Injection site surface area 10 minutes post injection. Area was calculated based on values above an arbitrary threshold of 90 PU. A significant difference in skin perfusion and surface area 10 minutes post injection was observed for both administration method (p<0.0001) and treatment (p<0.0001). (I) Representative LSCI images of both injection methods and treatments 10 minutes post injection. LSCI: laser speckle contrast imaging; OCT: optical coherence tomography; PU: perfusion units; B, D, G, H: mean ± SD, N=12 per group, repeated measures ANOVA, **** p<0.0001.