Iontophoresis-facilitated delivery of prednisolone through throat skin to the trachea after topical application of its succinate salt

Skin Delivery of siRNA Using Sponge Spicules in Combination with Cationic Flexible Liposomes

We report the topical administration of sponge Haliclona sp. Spicules (SHS) combined with cationic flexible liposomes (CFL) to increase the delivery of small interfering RNA (siRNA) into viable skin cells in vitro and in vivo. SHS can be applied topically as novel microneedles to overcome skin barrier by creating plenty of new microchannels in stratum corneum. Subsequently, well-designed CFL can be also utilized topically as nanocarriers to overcome skin cells membrane by delivering siRNA to skin deep layers through these microchannels and thereby facilitating their cell internalization. The topical application of SHS in combination with CFL (0.05% of lipids, w/v), referred to as CFL(0.05%), enhanced siRNA skin penetration in vitro by 72.95 ± 2.97-fold compared to control group (p < 0.001). Further, the topical application of SHS in combination with CFL(0.05%) on female BALB/c mice skin resulted in 29.21% ± 1.41% of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) knockdown at all application area in vivo, which was not significantly different from the GAPDH protein knockdown rate in the subcutaneous injection center. However, the high knockdown rate only appears in the vicinity (<0.5 cm) of the injection center. In sum, this study provides a promising strategy of topical delivery of siRNA by the combined used of SHS and well-designed CFL.

Skin Delivery of Hydrophilic Biomacromolecules Using Marine Sponge Spicules

We report the development of sponge Haliclona sp. spicules, referred to as SHS, and its topical application in skin delivery of hydrophilic biomacromolecules, a series of fluorescein isothiocyanate-dextrans (FDs). SHS are silicious oxeas which are sharp-edged and rod-shaped (∼120 μm in length and ∼7 μm in diameter). SHS can physically disrupt skin in a dose-dependent manner and retain within the skin over at least 72 h, which allows sustained skin penetration of hydrophilic biomacromolecules. The magnitude of enhancement of FD delivery into skin induced by SHS treatment was dependent on its molecular weight. Specifically, SHS topical application enhanced FD-10 (MW: 10 kDa) penetration into porcine skin in vitro by 33.09 ± 7.16-fold compared to control group (p < 0.01). SHS dramatically increased the accumulation of FD-10 into and across the dermis by 62.32 ± 13.48-fold compared to the control group (p < 0.01). In vivo experiments performed using BALB/c mice also confirmed the effectiveness of SHS topical application; the skin absorption of FD-10 with SHS topical application was 72.14 ± 48.75-fold (p < 0.05) and 15.39 ± 9.91-fold (p < 0.05) higher than those from the PBS and Dermaroller microneedling, respectively. Further, skin irritation study and transepidermal water loss (TEWL) measurement using guinea pig skin in vivo indicated that skin disruption induced by SHS treatment is self-limited and can be recovered with time and efficiently. SHS can offer a safe, effective, and sustained skin delivery of hydrophilic biomacromolecules and presents a promising platform technology for a wide range of cosmetic and medical applications.

Efficient Transdermal Delivery of Alendronate, a Nitrogen-Containing Bisphosphonate, Using Tip-Loaded Self-Dissolving Microneedle Arrays for the Treatment of Osteoporosis

To improve the transdermal bioavailability and safety of alendronate (ALN), a nitrogen-containing bisphosphonate, we developed self-dissolving microneedle arrays (MNs), in which ALN is loaded only at the tip portion of micron-scale needles by a dip-coating method (ALN(TIP)–MN). We observed micron-scale pores in rat skin just after application of ALN(TIP)–MN, indicating that transdermal pathways for ALN were created by MN. ALN was rapidly released from the tip of MNs as observed in an in vitro release study. The tip portions of MNs completely dissolved in the rat skin within 5 min after application in vivo. After application of ALN(TIP)–MN in mice, the plasma concentration of ALN rapidly increased, and the bioavailability of ALN was approximately 96%. In addition, the decrease in growth plate was effectively suppressed by this efficient delivery of ALN in a rat model of osteoporosis. Furthermore, no skin irritation was observed after application of ALN(TIP)–MN and subcutaneous injection of ALN, while mild skin irritation was induced by whole-ALN-loaded MN (ALN–MN)—in which ALN is contained in the whole of the micron-scale needles fabricated from hyaluronic acid—and intradermal injection of ALN. These findings indicate that ALN(TIP)–MN is a promising transdermal formulation for the treatment of osteoporosis without skin irritation.