Allergic contact dermatitis (ACD) can easily develop once sensitization is established by exposure to small amounts of antigen, and steroids are used for treatment. In this study, we evaluated the therapeutic efficacy of prednisolone (PSL)-loaded poly(DL-lactide-co-glycolide) (PLGA) nanoparticles (NPs) on a mouse model of contact dermatitis (CHS). Nanoparticles were prepared using a poor solvent diffusion method, and particle size distribution and mean particle size were measured using dynamic light scattering. Treatment experiments with PSL-loaded PLGA NPs were performed before and after sensitization with 1-fluoro-2,4-dinitrobenzene (DNFB), and evaluation was performed by quantifying intracutaneous IL-4 and TNF-α levels in a mouse model of CHS using ELISA. When PSL-loaded PLGA NPs were administered before sensitization, IL-4 expression was significantly decreased, and TNF-α tended to decrease in the group treated with PSL-loaded PLGA NPs compared to the non-treated group. When PSL-loaded PLGA NPs were administered after sensitization, IL-4 expression was significantly decreased in the group treated with PSL-loaded PLGA NPs compared to the non-treated group. In both cases, there were no significant differences between the PSL-loaded PLGA NP treatment group and the PSL-containing ointment group. These results suggest that, in the treatment of CHS, PSL-loaded PLGA NPs show a certain therapeutic effect when preadministration.

This study aimed to evaluate the feasibility and safety of pulsed-current iontophoresis (IP) for the transdermal delivery of teriparatide, a therapeutic peptide for osteoporosis. Female rats were subjected to in vivo iontophoretic administration under constant or pulsed-current conditions. Serum teriparatide concentrations, skin irritation scores, and transepidermal water loss (TEWL) were assessed. After 2 h of IP, serum teriparatide concentrations reached 53.3 ± 4.0 pg/mL with pulsed current and 48.8 ± 12.6 pg/mL with constant current, confirming successful transdermal absorption of teriparatide (≈4 kDa) into systemic circulation. Skin irritation was significantly reduced under pulsed-current conditions, as indicated by lower erythema, edema, and TEWL values, despite identical total current exposure. These results suggest that intermittent current application during pulsed-current IP alleviates local electrical stress through partial depolarization and may provide a delivery efficiency comparable to that of constant direct current IP while improving tolerability. Overall, pulsed-current IP enables noninvasive and effective systemic delivery of peptide drugs with minimized skin irritation, representing a promising alternative to injection-based administration for macromolecular therapeutics.

This study focused on the poly(DL-lactide-co-glycolide)-block-poly(ethylene glycol)-block-poly(DL-lactide-co-glycolide) (PLGA-PEG-PLGA) triblock copolymer, which was recently reported as a novel material for polymeric nanoparticles to replace poly(DL-lactide-co-glycolide) (PLGA) as a drug carrier for prednisolone (PSL), and aimed to evaluate the efficacy of PSL-loaded PLGA-PEG-PLGA nanoparticles (NPs) against allergic contact dermatitis (ACD). PSL-loaded PLGA-PEG-PLGA NPs were prepared using the nanoprecipitation method, and their particle size distribution and mean particle size were measured using dynamic light scattering. 1-Fluoro-2,4-dinitrobenzene (DNFB) was used to create a mouse model of contact hypersensitivity (CHS). PSL-loaded PLGA-PEG-PLGA NPs were administered before sensitization with DNFB, and the therapeutic effect was evaluated by quantifying intracutaneous TNF-α and IL-4 levels suing ELISA. When PSL-loaded PLGA-PEG-PLGA NPs were administered before sensitization, TNF-α expression and IL-4 statements were significantly lower in the PSL-loaded PLGA-PEG-PLGA NP group than in the non-treated group. No significant difference was observed between the PSL-loaded PLGA-PEG-PLGA NP and PSL-loaded ointment groups, even though the steroid dose was 40 times lower than in the PSL-containing ointment. These results suggest that PSL-loaded PLGA-PEG-PLGA NPs may have a better effect in the treatment of ACD than PSL-loaded PLGA NPs.

Tinea is a superficial fungal infection of keratinized structures caused by specific filamentous fungi called dermatophytes. Terbinafine, a drug used to treat tinea, is poorly soluble in water, and its delivery into the skin via nanoparticle formulation usingpoly(lactic-co-glycolic acid) (PLGA) has been demonstrated. In this study, we investigated the preparation conditions for nanoparticles (NPs) to achieve efficient intradermal delivery of terbinafine. Terbinafine-loaded PLGA NPs were prepared using the nanoprecipitation method, and the particle size distribution and average particle size were measured using dynamic light scattering. Skin permeability tests were conducted using mouse dorsal skin, and the amount of terbinafine delivered into the skin was measured to evaluate the release behavior in the skin. In the preparation of terbinafine-loaded PLGA NPs, under conditions where the external solution was purified water, the mean volume diameter was 40.49 ± 15.63 nm, the terbinafine-loaded content was 3.31 ± 0.29%, and the entrapment efficiency was 55.08 ± 4.88%. Under conditions of an external solution containing 1.0 × 10⁻³ w/v% arginine(Arg) aq. solution, the mean volume diameter was 41.71 ± 16.08 nm, the terbinafine-loaded content was 5.17 ± 0.37%, and the entrapment efficiency was 86.48 ± 6.01%. The entrapment efficiency and content were higher under the condition using 1.0 × 10⁻³ w/v% Arg aq. solution compared to purified water. In addition, in the skin permeability test, no drug was detected in the receptor solution sampled from both the NPs suspension group and the simple solution group, and no drug was detected in the intradermal solution in the simple solution group. The intradermal drug concentration was 77.94 ± 10.66 µg/g under conditions where purified water was used as the dialysate, and 96.42 ± 61.62 µg/g under conditions using 1.0 × 10⁻³ w/v% arginine, exceeding the reported minimum inhibitory concentration (MIC) of 8.87 µg/g, suggesting the efficacy of terbinafine-loaded PLGA NPs for the treatment of tinea versicolor. Since tinea treatment is a long-term process, it is desirable to deliver a stable amount of drug to the treatment site at all times. Therefore, the nanoparticle preparation conditions using purified water as the external solution, where the intradermal drug concentration exceeded the MIC and remained stable in the skin permeability test, were suggested to be suitable for tinea treatment.