2.3 Experimental design

Participants received three microneedle patches – one self-administered and two investigator-administered. Participants were provided a brief overview of the study and watched a short instructional audiovisual presentation on self-administration of microneedle patches. An outline of the microneedle patch administration process is shown in Figure 1.

Procedure to apply a microneedle patch to the skin. (A) The subject or investigator picks up the patch and removes the protective cap. (B) The subject forms a fist in the other hand and then the subject or investigator places the patch on the forearm. The subject or investigator pushes on the patch with the thumb and continues to apply force until hearing a ‘click’ sound, indicating that enough force has been applied. (C) The subject leaves the patch on the skin for 20 min, after which the subject or investigator peels the patch off the skin and the investigator saves the patch for additional analysis.

Each participant first self-administered a microneedle patch to his or her forearm without assistance from the investigator. After the patch removal, the investigator stained this skin site (see below). The investigator then applied two microneedle patches to the participant, one on each forearm. Only one of these skin sites was stained by the investigator. The site not stained was used to make measurements of skin tolerability (see below). The two stained sites were used for usability measurements (see below).

Participants then answered a survey about microneedle patch administration to assess acceptability of the microneedle patches. Participants returned to the study site 1, 2, 3, 4 and 7 days after microneedle patch administration for skin tolerability measurements.