Enhancing effects of six chemical enhancers on the permeation of ketotifen through excised hairless mouse skin from aqueous donor solutions buffered at pH 5 and 10

Cationic Moieties in Polystyrene Gels Swollen with d-Limonene Improved Transdermal Delivery System

d-limonene, a terpene and natural compound, has been found to be an excellent penetration enhancer for transdermal drug delivery (TDD). It hence has been incorporated within various transdermal formulations. Herein, we report the application of polystyrene gel swollen with d-limonene and its derivatives for TDD. Poly(styrene-co-divinylbenzene) (PS gel), poly(styrene-co-divinylbenzene-co-4-vinylpyridine) (PS-4VP) gel and poly(styrene-co-divinylbenzene-co-(vinylbenzyl) trimethylammonium chloride) (PS-VBAC gel) were employed as chemical gels to improve the stability of the TDD substrates. The drug permeation properties from the PS gels swollen in limonene were examined, regarding the effect of its network density as well as their rheological properties. The lowest density of the network showed the highest steady flux of the permeation at 43.7 ± 0.3 μg/cm². FT-IR spectra were confirmed for PS-4VP and PS-VBAC, bearing cationic moieties and they could control the release of ibuprofen by the electrostatic interaction at the interface of organogel and skin. The steady state flux of skin permeation got low values from 55.2 ± 0.8 to 11.6 ± 2.0 μg/cm², when the cationic moieties were increased. Moreover, the chemical network of PS gel swollen in limonene showed high mechanical stability illustrated by elastic modulus (G') of about 98 kPa for 10% cross-linked PS gel. The developed PS gels swollen in limonene show highly promising results, suggesting their possible application in TDD.

Corneal targeted Sertaconazole nitrate loaded cubosomes: Preparation, statistical optimization, in vitro characterization, ex vivo permeation and in vivo studies

Sertaconazole nitrate (STZ) is a poorly soluble antifungal drug commonly used for treating fungal skin infections. Introducing it as a new treatment option for the management of fungal keratitis, requires the development of a delivery system capable of targeting the infected cornea with an adequate STZ concentration. Hence, Sertaconazole nitrate loaded cubosomes (STZ-CUBs) were prepared, characterized and optimized based on a 3³ central composite face-centred design. Optimized formulation (CUB-opt) showed maximum desirability (0.905), with solubilization efficiency (SE%) of 94.50 ± 0.51%, particle size (PS) of 216.55 ± 2.33 nm, polydispersity index (PDI) of 0.229 ± 0.11 and zeta potential (ZP) of 34.00 ± 6.93 mV. Under the transmission electron microscope, it showed discrete cubic shaped structures. Moreover, it exhibited a promising mucoadhesive behavior, terminal sterilization stability, and storage stability. Ex vivo corneal permeation study revealed its ability to enhance the steady state flux (J_ss) and the permeability coefficient (K_P) of STZ, compared to STZ-suspension. Finally, CUB-opt formulation was found to be safe on the corneal tissues in the in vivo corneal tolerance study, and demonstrated a superior corneal penetration power in the in vivo corneal uptake study.

Relationship between the enhancement effects of chemical permeation enhancers on the lipoidal transport pathway across human skin under the symmetric and asymmetric conditions in vitro

PURPOSE

Previously, the mechanisms of action of chemical permeation enhancers (CPEs) were studied, and a quantitative structure-enhancement relationship for the lipoidal transport pathway of the stratum corneum was established under symmetric and equilibrium conditions. The present study examined whether the effects of CPEs under the asymmetric conditions could be predicted by those determined using the symmetric transport experimental approach.

METHODS

Both symmetric (same CPE concentration in both donor and receiver chambers) and asymmetric (CPE in the donor chamber only and phosphate-buffered saline solution in the receiver) transport experiments were carried out in a two-chamber side-by-side diffusion cell with human epidermal membrane (HEM). Corticosterone was the model permeant to probe the effects of CPEs upon the HEM lipoidal pathway under these conditions.

RESULTS

A correlation between the experimental enhancement factors under the asymmetric conditions (E (Asym)) and those under the symmetric conditions (E (Sym)) was observed. The potencies of CPEs based on their donor concentrations are related to their lipophilicities.

CONCLUSIONS

The results suggest that the symmetric configuration findings in the previous studies can be used to explain the effects of CPEs under the asymmetric condition likely encountered in practice and to understand drug delivery enhancement in transdermal enhancer formulation development.