Solutol HS15 based binary mixed micelles with penetration enhancers for augmented corneal delivery of sertaconazole nitrate: optimization, in vitro, ex vivo and in vivo characterization

Keratomycosis is a serious corneal disease that can cause a permanent visual disability if not treated effectively. Sertaconazole nitrate (STZ), a novel broad spectrum antifungal drug, was suggested as a promising treatment. However, its utility in the ocular route is restricted by its poor solubility, along with other problems facing the ocular delivery like short residence time, and the existing corneal barrier. Therefore, the objective of this study was to formulate STZ loaded binary mixed micelles (STZ-MMs) enriched with different penetration enhancers using thin-film hydration method, based on a 3¹.2² mixed factorial design. Different formulation variables were examined, namely, type of auxiliary surfactant, type of penetration enhancer, and total surfactants: drug ratio, and their effects on the solubility of STZ in MMs (S_M), particle size (PS), polydispersity index (PDI), and zeta potential (ZP) were evaluated. STZ-MMs enhanced STZ aqueous solubility up to 338.82-fold compared to free STZ. Two optimized formulations (MM-8 and MM-11) based on the desirability factor (0.891 and 0.866) were selected by Design expert^® software for further investigations. The optimized formulations were imaged by TEM which revealed nanosized spherical micelles. Moreover, they were examined for corneal mucoadhesion, stability upon dilution, storage effect, and ex vivo corneal permeation studies. Finally, both in vivo corneal uptake and in vivo corneal tolerance were investigated. MM-8 showed superiority in the ex vivo and in vivo permeation studies when compared to the STZ-suspension. The obtained results suggest that the aforementioned STZ loaded mixed micellar system could be an effective candidate for Keratomycosis-targeted therapy.

Fabrication of novel elastosomes for boosting the transdermal delivery of diacerein: statistical optimization, ex-vivo permeation, in-vivo skin deposition and pharmacokinetic assessment compared to oral formulation

Diacerein (DCN) is a hydrophobic osteoarthritis (OA) drug with short half-life and low oral bioavailability. Furthermore, DCN oral administration is associated with diarrhea which represents obstacle against its oral use. Hence, this article aimed at developing elastosomes (edge activator (EA)-based vesicular nanocarriers) as a novel transdermal system for delivering DCN efficiently and avoiding its oral problems. For achieving this goal, elastosomes were prepared according to 41.21 full factorial design using different EAs in varying amounts. The prepared formulae were characterized regarding their entrapment efficiency percentage (EE%), particle size (PS), polydispersity index (PDI), zeta potential (ZP) and deformability index (DI). Desirability function was employed using Design-Expert® software to select the optimal elastosomes (E1) which showed EE% of 96.25 ± 2.19%, PS of 506.35 ± 44.61 nm, PDI of 0.46 ± 0.09, ZP of -38.65 ± 0.91 mV, and DI of 12.74 ± 2.63 g. In addition, E1 was compared to DCN-loaded bilosomes and both vesicles exhibited superior skin permeation potential and retention capacity compared to drug suspension. In-vivo histopathological study was performed which ensured the safety of E1 for topical application. Furthermore, the pharmacokinetic study conducted in albino rabbits demonstrated that there was no significant difference in the rate and extent of DCN absorption from topically applied E1 compared to oral suspension. Multiple level C in-vitro in-vivo correlation showed good correlation between in-vitro release and in-vivo drug performance for E1 and DCN oral suspension. Overall, results confirmed the admirable potential of E1 to be utilized as novel carrier for transdermal delivery of DCN and bypassing its oral side effects.

Effect of fixed aqueous layer thickness of polymeric stabilizers on zeta potential and stability of aripiprazole nanosuspensions

The aim of this study was to evaluate the effect of the thickness of adsorbed polymer layer (also known as Fixed Aqueous Layer Thickness, FALT) of polymeric stabilizers on zeta potential and stability of nanoparticles in a suspension. Aripiprazole, a poorly water soluble drug was used as a model drug to evaluate rationale for increased FALT and to understand the effect of hydrophilicity and hydrophobicity of polymeric stabilizers on FALT of aripiprazole nanosuspensions. The nanosuspensions were prepared by media milling and Pluronic F68, Pluronic F127, Hydroxypropyl methylcellulose (HPMC) and Hydroxypropyl cellulose (HPC) were used as polymeric stabilizers. The particle size (immediately after preparation and after 1 week of storage at 25°C) and zeta potential of aripiprazole nanosuspensions were determined. For Pluronics, FALT was determined theoretically whereas for HPMC and HPC it was calculated as Debye Huckel parameter from the zeta potential dependence on the ionic strength. An increase in FALT resulted in reduced zeta potential. With an increase in FALT of polymers used, the stability of nanosuspensions showed improvement. Furthermore, a linear correlation was shown to exist between the FALT and length of hydrophilic chains in Pluronics.