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To prepare a topical formulation of bimatoprost (BIM) with high skin permeability, we designed a solvent mixture system composed of ethanol, diethylene glycol monoethyl ether, cyclomethicone, and butylated hydroxyanisole, serving as a volatile solvent, nonvolatile co-solvent, spreading agent, and antioxidant, respectively. The ideal topical BIM formulation (BIM–TF#5) exhibited 4.60-fold higher human skin flux and a 529% increase in dermal drug deposition compared to BIM in ethanol. In addition, compared to the other formulations, BIM–TF#5 maximally activated human dermal papilla cell proliferation at a concentration of 5 μM BIM, equivalent to 10 μM minoxidil. Moreover, BIM–TF#5 (0.3% [w/w] BIM) significantly promoted hair regrowth in the androgenic alopecia mouse model and increased the area covered by hair at 10 days by 585% compared to the vehicle-treated mice, indicating that entire telogen area transitioned into the anagen phase. Furthermore, at day 14, the hair weight of mice treated with BIM–TF#5 (5% [w/w] BIM) was 8.45- and 1.30-fold greater than in the 5% (w/w) BIM in ethanol and 5% (w/v) minoxidil treated groups, respectively. In the histological examination, the number and diameter of hair follicles in the deep subcutis were significantly increased in the BIM–TF#5 (0.3 or 5% [w/w] BIM)-treated mice compared to the mice treated with vehicle or 5% (w/w) BIM in ethanol. Thus, our findings suggest that BIM–TF#5 is an effective formulation to treat scalp alopecia, as part of a novel therapeutic approach involving direct prostamide F2α receptor-mediated stimulation of dermal papilla cells within hair follicles.

In this study, a system for oral delivery of etoposide (ETP) was designed to avoid the problems associated with low and variable bioavailability of a commercially available ETP emulsion comprised of polyethylene glycol, glycerol, and citric acid anhydrous. ETP was complexed with low-molecular-weight methylcellulose (ETP/LMC) and loaded into a water-in-oil-in-water multiple nanoemulsion to formulate an ETP/LMC-nanoemulsion (ELNE). To further enhance the oral bioavailability, an ionic complex formed by anionic lipid 1,2-didecanoyl-sn-glycero-3-phosphate (sodium salt) and cationic N α -deoxycholyl- l -lysyl-methylester was incorporated into ELNE, yielding ELNE#7. As expected, ELNE#7 showed 4.07- and 2.25-fold increases in artificial membrane and Caco-2/HT29-MTX-E12 permeability ( P app ), respectively, resulting in 224% greater oral bioavailability compared with the commercially available ETP emulsion. In contrast, inhibition of clathrin- and caveola-mediated endocytosis, macropinocytosis, and bile acid transporters by chlorpromazine, genistein, amiloride, and actinomycin D in Caco-2/HT-29-MTX-E12 monolayers reduced the P app by 45.0%, 20.5%, 28.8%, and 31.1%, respectively. These findings suggest that these routes play important roles in enhancing the oral absorption of ELNE#7. In addition, our mechanistic study suggested that P-glycoprotein did not have an inhibitory effect on the permeation of ELNE#7. Notably, ELNE#7 showed significantly enhanced toxicity in LLC and A549 cells compared with ETP-E. These observations support the improved oral absorption of ETP in ELNE#7, suggesting that it is a better alternative than ETP emulsion.

In this study, a stable and highly skin-permeable topical delivery system for itraconazole (ITZ) was designed to provide effective treatment against superficial mycosis. Herein, ITZ was incorporated into a solution composed of ethanol, benzyl alcohol, hydrochloric acid, Transcutol P, and cyclomethicone as a delivery vehicle, solubilizer, protonating agent, permeation enhancer, and spreading agent, respectively. At 72 h, the optimal topical ITZ formulation (ITZ–TF#11) exhibited 135% enhanced skin permeability, which led to increases in drug deposition in the stratum corneum, epidermis, and dermis of 479%, 739%, and 2024%, respectively, compared with the deposition of 1% ITZ in ethanol (control). Moreover, on day 7, ITZ–TF#11 demonstrated 2.09- and 2.30-fold enhanced nail flux and drug deposition, compared with the control. At a dose of 40 mg/kg/day, ITZ–TF#11 showed 323% greater lesion recovery, a 165% lower mean erythema severity score, and a 37% lower mean logarithm of viable fungal cells in skin in the treated area, compared with mice that received oral ITZ at the same dose. Overall, the findings imply that ITZ–TF#11 is a superior alternative to oral ITZ for treatment of superficial mycosis.

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