Formulation development of tazarotene-loaded PLGA nanoparticles for follicular delivery in the treatment of inflammatory skin diseases.

Tazarotene is a widely prescribed topical retinoid for acne vulgaris and plaque psoriasis and is associated with skin irritation, dryness, flaking, and photosensitivity. In vitro permeation of tazarotene was studied across the dermatomed human and full-thickness porcine skin. The conversion of tazarotene to the active form tazarotenic acid was studied in various skin models. Tazarotene-loaded PLGA nanoparticles were prepared using the nanoprecipitation technique to target skin and hair follicles effectively. The effect of formulation and processing variables on nanoparticle properties, such as particle size and drug loading, was investigated. The optimized nanoparticle batches with particle size <500 µm were characterized further for FT-IR analysis, which indicated no interactions between tazarotene and PLGA. Scanning electron microscopy analysis showed uniform, spherical, and non-agglomerated nanoparticles. In vitro release study using a dialysis membrane indicated a sustained release of 40-70 % for different batches over 36 h, following a diffusion-based release mechanism based on the Higuchi model. In vitro permeation testing (IVPT) in full-thickness porcine skin showed significantly enhanced follicular and skin delivery from nanoparticles compared to solution. The presence of tazarotenic acid in the skin from tazarotene nanoparticles indicated the effectiveness of nanoparticle formulations in retaining bioconversion ability and targeting follicular delivery.

Development of 4-phenylbutyric acid microsponge gel formulations for the treatment of lewisite-mediated skin injury.

Lewisite, a chemical warfare agent, causes skin blisters, erythema, edema, and inflammation, requiring mitigation strategies in case of accidental or deliberate exposure. 4-phenyl butyric acid (4-PBA), a chemical chaperone, reduces endoplasmic reticulum stress and skin inflammation. The study aimed to encapsulate 4-PBA in microsponges for effective, sustained delivery against lewisite injury. Porous microsponges in a topical gel would potentially sustain delivery and improve residence time on the skin. Microsponges were developed using the quasi-emulsion solvent diffusion method with Eudragit RS100. Optimized formulation showed 10.58%w/w drug loading was incorporated in a carboxymethylcellulose (CMC) and Carbopol gel for in vitro release and permeation testing using dermatomed human skin. A sustained release was obtained from all vehicles in the release study, and IVPT results showed that compared to the control (41.52 ± 2.54 µg/sq.cm), a sustained permeation profile with a reduced delivery was observed for microsponges in PBS (14.16 ± 1.23 µg/sq.cm) along with Carbopol 980 gel (12.55 ± 1.41 µg/sq.cm), and CMC gel (10.09 ± 1.23 µg/sq.cm) at 24 h. Optimized formulation showed significant protection against lewisite surrogate phenyl arsine oxide (PAO) challenged skin injury in Ptch1+/-/SKH-1 hairless mice at gross and molecular levels. A reduction in Draize score by 29%, a reduction in skin bifold thickness by 8%, a significant reduction in levels of IL-1ß, IL6, and GM-CSF by 54%, 30%, and 55%, respectively, and a reduction in apoptosis by 31% was observed. Thus, the translational feasibility of 4-PBA microsponges for effective, sustained delivery against lewisite skin injury is demonstrated.

Fabrication of Polymeric Microneedles using Novel Vacuum Compression Molding Technique for Transdermal Drug Delivery.

PURPOSE: To demonstrate the feasibility of vacuum compression molding as a novel technique for fabricating polymeric poly (D, L-lactic-co-glycolic acid) microneedles. METHODS: First, polydimethylsiloxane molds were prepared using metal microneedle templates and fixed in the MeltPrep® Vacuum Compression Molding tool. Poly (D, L-lactic-co-glycolic acid) (EXPANSORB® DLG 50-5A) was added, enclosed, and heated at 130°C for 15 min under a vacuum of -15 psi, cooled with compressed air for 15 min, followed by freezing at -20°C for 30 min, and stored in a desiccator. The microneedles and microchannels were characterized by a variety of imaging techniques. In vitro permeation of model drug lidocaine as base and hydrochloride salt was demonstrated across intact and microporated dermatomed human skin. RESULTS: Fabricated PLGA microneedles were pyramid-shaped, sharp, uniform, and mechanically robust. Scanning electron microscopy, skin integrity, dye-binding, histology, and confocal laser microscopy studies confirmed the microchannel formation. The receptor delivery of lidocaine salt increased significantly in microporated (270.57 ± 3.73 µg/cm2) skin as compared to intact skin (142.19 ± 13.70 µg/cm2) at 24 h. The receptor delivery of lidocaine base from microporated skin was significantly higher (312.37 ± 10.57 µg/cm2) than intact skin (169.68 ± 24.09 µg/cm2) up to 8 h. Lag time decreased significantly for the base (2.24 ± 0.17 h to 0.64 ± 0.05 h) and salt (4.76 ± 0.31 h to 1.47 ± 0.21 h) after microporation. CONCLUSION: Vacuum compression molding was demonstrated as a novel technique to fabricate uniform, solvent-free, strong polymer microneedles in a short time.