Surface-engineered nanoliposomes with lipidated and non-lipidated peptide-dendrimeric scaffold for efficient transdermal delivery of a therapeutic agent: Development, characterization, toxicological and preclinical performance analyses

The current study aimed to develop novel peptide dendrimer (PD)-conjugated nanoliposomal formulations of asenapine maleate (ASP) for improvement in the transdermal delivery and pharmacokinetic profile of the drug. Novel arginine-terminated PDs (+/-lipidation) were prepared by solid phase peptide synthesis, followed by conjugation onto ASP nanoliposomes. The nanoliposomes were characterized for particle size (and polydispersity index), zeta potential (ZP), drug entrapment efficiency, shape and morphology, differential scanning calorimetry and FT-IR spectroscopy. Ex vivo skin permeation and retention studies demonstrated considerably higher percutaneous permeation of ASP from the developed nanoliposomes (Q₂₄ = 794.31 ± 54.89 µg/cm², J_ss = 105.40 ± 4.8 µg/cm²/h, ER = 36.85 ± 2.89 for liposomes with lipidated peptide dendrimer (Lipo-PD2)) in comparison with passive diffusion studies (Q₂₄ = 63.09 ± 3.56 µg/cm², J_ss = 3.01 ± 0.23 µg/cm²/h). Confocal Laser Scanning Microscopy (CLSM) confirmed the higher percutaneous penetration of Lipo-PD2 in comparison with liposomes without the dendrimer. In vitro cytotoxicity determined on HaCaT cell line demonstrated CTC₅₀ of >1000 µg/mL for both the synthesized PDs and Lipo-PD2. Pharmacokinetic studies in male Sprague Dawley rats revealed considerably and significantly higher t_1/2 = 82.32 ± 14.48 h and AUC_0-t = 4403.34 ± 367.10 h.ng/mL, from the developed formulation, compared to orally administered ASP (t_1/2 = 21.64 ± 2.53 h and AUC_0-t = 2303.55 ± 444.5 h.ng/mL), demonstrating higher bioavailability and longer retention in vivo. Additionally, in vivo skin retention, brain uptake studies and pharmacodynamics of the developed formulations were investigated. Stability studies indicated that the formulations were stable up to relatively stable with respect to size, ZP and drug content for 4 months at the tested conditions. This study demonstrates that the developed PD-conjugated nanoliposomal formulations can effectively serve as a transdermal delivery strategy for ASP.