Nanosized ethosomal dispersions for enhanced transdermal delivery of Nebivolol using intradermal/transfollicular sustained reservoir: in vitro evaluation, confocal laser scanning microscopy and in vivo pharmacokinetic studies.

Nebivolol (NBV), a BCS class-II anti-hypertensive drug that suffers from limited solubility and oral bioavailability. Nanosized ethosomes were adopted as an approach to solubilize and deliver NBV transdermally, as a substitute to oral route. Ethosomal dispersions were prepared employing thin film hydration method. Formulation variables were adjusted to obtain entrapment efficiency; EE > 50%, particle size; PS < 100 nm, zeta potential; ZP > ± 25 mV and polydispersity index; PDI < 0.5. The optimized ethosomal dispersion (OED) showed accepted EE 86.46 ± 0.15%, PS 73.50 ± 0.08 nm, ZP 33.75 ± 1.20 mV, and PDI 0.31 ± 0.07. It also showed enhanced cumulative amount of NBV permeated at 8h (Q8 ) 71.26 ± 1.46%, and 24h (Q24 ) 98.18 ± 1.02%. TEM images denoted spherical vesicles with light colored lipid bilayer and dark core. Confocal laser scanning microscopy showed deeply localized intradermal and transfollicular permeation of the fluorolabelled OED (FL-OED). Nanosized FL-OED (< 100 nm) can permeate through hair follicles creating a drug reservoir for enhanced systemic absorption. OED formulated into transdermal patch (OED-TP1) exhibited accepted physicochemical properties including; thickness 0.14 ± 0.01 mm, folding endurance 151 ± 0.07, surface pH 5.80 ± 0.15, drug content 98.64 ± 2.01%, mucoadhesion 8534 ± 0.03, Q8 87.61 ± 0.11% and Q24 99.22 ± 0.24%. In vivo pharmacokinetic studies showed significantly enhanced bioavailability of OED-TP1 by 7.9 folds compared to oral Nevilob® tablets ( p  = 0.0002). It could be concluded that OED-TP1 can be a promising lipid nanocarrier TDDS for NBV and an efficacious alternative route of administration for hypertensive patients suffering from dysphagia.