Development of microneedles containing gamma-aminobutyric acid for skin delivery

Abstract

Gamma-aminobutyric acid (GABA) has been reported to have several skin benefits. Since GABA is a small water soluble molecule which may have problems getting through stratum corneum to its site of action. Therefore, newly invented microneedles (MNs) fabrication of polypropylene (PP) plastic was investigated as a delivery system for GABA. Physical and chemical properties of fabricated MNs and GABA loaded MNs with height 1 mm and two different dipping distances (i.e., 1 mm and 1.5 mm) were studied. PP MNs were successfully produced. Physical properties including MNs physical appearance, the strength of MNs against axial force and skin penetration were studied. Both MNs made from different dipping distances showed no significant difference in needle height with means of 1.03 ± 0.15 and 1.01 ± 0.15 mm, respectively but showed significant difference in drug pocket depth with means of 0.96 ± 0.09 and 1.46 ± 0.09 mm, respectively. These MNs could withstand applied force (6 N/needle against axial force) without significant deformation or fracture in the failure strength tests. About the chemical property, different GABA loadings were found with MNs made from 1 and 1.5 mm dipping distances which were 551.25 and 715.25 µg GABA/piece, respectively. Loading capacities were correlated with the drug pocket size where larger pocket size could load more GABA than smaller one. These primitive fabricated MNs has noticeably wider tip radiuses (i.e., 252.22 ± 13.79 µm for 1 mm dipping distance and 233.51 ± 9.45 µm for 1.5 mm dipping distance). As a result, two produced MNs did not penetrate through the pig skin even using pressing force of 7 kg/piece. Further development of this primitive prototype of PP MNs is needed to be able to break into the skin. However, promising early results showed that the developed MNs can be a potential delivery system of small and water soluble molecule through the skin.