Assessment of micropore closure after microneedle application in diverse skin types

Microneedles (MNs) Microneedles (MNs) are micron scale projections that allow for improved drug delivery through the skin via formation of transient micropores. For successful transdermal drug delivery, it is crucial that the micropores remain open as drug delivery ceases rapidly after micropore closure, usually within ~48-72 hrs. Delaying micropore closure would be advantageous by allowing a longer period of drug delivery from each MN treatment. Previous methods that have been explored for delaying micropore closure timeframes did not account for the biochemical differences seen in diverse skin types; further, previous studies did not address the physiological processes that impact micropore closure. We showed that darker skin types have longer micropore closure timeframes. This could result in altered therapeutic outcomes from unexpected drug delivery windows in diverse skin types, which may be especially problematic for drugs with narrow therapeutic windows.