Oleic acid and oleyl alcohol are commonly used permeation and penetration enhancers to facilitate topical drug delivery. Here, we aimed to better understand the mechanism of their enhancing effects in terms of their interactions with the human skin barrier using diclofenac diethylamine (DIC-DEA), a nonsteroidal anti-inflammatory drug for topical pain management. Oleic acid promoted DIC-DEA permeation through ex vivo human skin more rapidly than oleyl alcohol (both applied at 0.75%) due to fluidization of stratum corneum lipids as revealed by infrared spectroscopy. After 12 h, the effect of these enhancers on DIC-DEA permeation leveled off, fluidization was no longer evident, and skin permeabilization was mainly due to the formation of fluid enhancer-rich domains. Contrary to oleyl alcohol, oleic acid adversely affected two indicators of the skin barrier integrity, transepidermal water loss and skin electrical impedance. The content of oleyl alcohol in the stratum corneum was lower than that of oleic acid (even 12 h after the enhancers were removed from the skin surface), but it caused higher DIC-DEA retention in both epidermis and dermis compared to oleic acid. The effects of oleyl alcohol and oleic acid on DIC-DEA permeation and retention in the skin were similar after a single and repeated application (4 doses every 12 h). Thus, oleyl alcohol offers several advantages over oleic acid for topical drug delivery.
- MeSH
- aplikace kožní MeSH
- kožní absorpce * MeSH
- kůže metabolismus MeSH
- kyselina olejová * farmakologie metabolismus MeSH
- lidé MeSH
- mastné alkoholy metabolismus farmakologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Overcoming the skin barrier properties efficiently, temporarily, and safely for successful transdermal drug delivery remains a challenge. We synthesized three series of potential skin permeation enhancers derived from natural amino acid derivatives proline, 4-hydroxyproline, and pyrrolidone carboxylic acid, which is a component of natural moisturizing factor. Permeation studies using in vitro human skin identified dodecyl prolinates with N-acetyl, propionyl, and butyryl chains (Pro2, Pro3, and Pro4, respectively) as potent enhancers for model drugs theophylline and diclofenac. The proline derivatives were generally more active than 4-hydroxyprolines and pyrrolidone carboxylic acid derivatives. Pro2-4 had acceptable in vitro toxicities on 3T3 fibroblast and HaCaT cell lines with IC50 values in tens of μM. Infrared spectroscopy using the human stratum corneum revealed that these enhancers preferentially interacted with the skin barrier lipids and decreased the overall chain order without causing lipid extraction, while their effects on the stratum corneum protein structures were negligible. The impacts of Pro3 and Pro4 on an in vitro transepidermal water loss and skin electrical impedance were fully reversible. Thus, proline derivatives Pro3 and Pro4 have an advantageous combination of high enhancing potency, low cellular toxicity, and reversible action, which is important for their potential in vivo use as the skin barrier would quickly recover after the drug/enhancer administration is terminated.
- MeSH
- aplikace kožní MeSH
- hydroxyprolin metabolismus MeSH
- kožní absorpce * MeSH
- kůže metabolismus MeSH
- kyseliny karboxylové metabolismus MeSH
- léčivé přípravky metabolismus MeSH
- lidé MeSH
- organické látky metabolismus MeSH
- permeabilita MeSH
- prolin * metabolismus MeSH
- pyrrolidinony farmakologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Skin penetration/permeation enhancers are compounds that improve (trans)dermal drug delivery. We designed hybrid terpene-amino acid enhancers by conjugating natural terpenes (citronellol, geraniol, nerol, farnesol, linalool, perillyl alcohol, menthol, borneol, carveol) or cinnamyl alcohol with 6-(dimethylamino)hexanoic acid through a biodegradable ester linker. The compounds were screened for their ability to increase the delivery of theophylline and hydrocortisone through and into human skin ex vivo. The citronellyl, bornyl and cinnamyl esters showed exceptional permeation-enhancing properties (enhancement ratios up to 82) while having low cellular toxicities. The barrier function of enhancer-treated skin (assessed by transepidermal water loss and electrical impedance) recovered within 24 h. Infrared spectroscopy suggested that these esters fluidized the stratum corneum lipids. Furthermore, the citronellyl ester increased the epidermal concentration of topically applied cidofovir, which is a potent antiviral and anticancer drug, by 15-fold. In conclusion, citronellyl 6-(dimethylamino)hexanoate is an outstanding enhancer with an advantageous combination of properties, which may improve the delivery of drugs that have a limited ability to cross biological barriers.
- MeSH
- alkoholy chemie farmakologie MeSH
- aplikace kožní MeSH
- buňky 3T3 MeSH
- chemie farmaceutická MeSH
- cidofovir aplikace a dávkování chemie farmakokinetika MeSH
- epidermis účinky léků metabolismus MeSH
- estery chemie farmakologie MeSH
- farmaceutické pomocné látky chemie farmakologie MeSH
- hydrokortison aplikace a dávkování chemie farmakokinetika MeSH
- keratinocyty MeSH
- lidé MeSH
- metabolismus lipidů účinky léků MeSH
- monoterpeny chemie MeSH
- myši MeSH
- permeabilita účinky léků MeSH
- perspiratio insensibilis účinky léků MeSH
- příprava léků metody MeSH
- terpeny chemie farmakologie MeSH
- testy akutní toxicity MeSH
- theofylin aplikace a dávkování chemie farmakokinetika MeSH
- vztahy mezi strukturou a aktivitou MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
PURPOSE: To study new skin penetration/permeation enhancers based on amphiphilic galactose derivatives. METHODS: Two series of alkyl and alkenyl galactosides were synthesized and evaluated for their enhancing effect on transdermal/topical delivery of theophylline (TH), hydrocortisone (HC) and cidofovir (CDV), reversibility of their effects on transepidermal water loss (TEWL) and skin impedance, interaction with the stratum corneum using infrared spectroscopy, and cytotoxicity on keratinocytes and fibroblasts. RESULTS: Initial evaluation identified 1-(α-D-galactopyranosyl)-(2E)-pentadec-2-ene A15 as a highly potent enhancer - it increased TH and HC flux through human skin 8.5 and 5 times, respectively. Compound A15 increased the epidermal concentration of a potent antiviral CDV 7 times over that reached by control and Span 20 (an established sugar-based enhancer). Infrared spectroscopy of human stratum corneum indicated interaction of A15 with skin barrier lipids but not proteins. These effects of A15 on the skin barrier were reversible (both TEWL and skin impedance returned to baseline values within 24 h after A15 had been removed from skin). In vitro toxicity of A15 on HaCaT keratinocytes and 3T3 fibroblasts was acceptable, with IC50 values over 60 μM. CONCLUSIONS: Galactosyl pentadecene A15 is a potent enhancer with low toxicity and reversible action.
- MeSH
- alkeny aplikace a dávkování chemie MeSH
- aplikace kožní MeSH
- cytosin aplikace a dávkování analogy a deriváty chemie MeSH
- epidermis metabolismus MeSH
- fibroblasty účinky léků metabolismus MeSH
- galaktosa analogy a deriváty chemie MeSH
- galaktosidy aplikace a dávkování chemie MeSH
- hydrokortison aplikace a dávkování chemie MeSH
- keratinocyty účinky léků metabolismus MeSH
- kožní absorpce účinky léků MeSH
- kůže metabolismus MeSH
- lidé MeSH
- lipidy chemie MeSH
- organofosfonáty aplikace a dávkování chemie MeSH
- permeabilita MeSH
- theofylin aplikace a dávkování chemie MeSH
- uvolňování léčiv MeSH
- voda MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Ceramides based on phytosphingosine, sphingosine and dihydrosphingosine are essential constituents of the skin lipid barrier that protects the body from excessive water loss. The roles of the individual ceramide subclasses in regulating skin permeability and the reasons for C4-hydroxylation of these sphingolipids are not completely understood. We investigated the chain length-dependent effects of dihydroceramides, sphingosine ceramides (with C4-unsaturation) and phytoceramides (with C4-hydroxyl) on the permeability, lipid organization and thermotropic behavior of model stratum corneum lipid membranes composed of ceramide/lignoceric acid/cholesterol/cholesteryl sulfate. Phytoceramides with very long C24 acyl chains increased the permeability of the model lipid membranes compared to dihydroceramides or sphingosine ceramides with the same chain lengths. Either unsaturation or C4-hydroxylation of dihydroceramides induced chain length-dependent increases in membrane permeability. Infrared spectroscopy showed that C4-hydroxylation of the sphingoid base decreased the relative ratio of orthorhombic chain packing in the membrane and lowered the miscibility of C24 phytoceramide with lignoceric acid. The phase separation in phytoceramide membranes was confirmed by X-ray diffraction. In contrast, phytoceramides formed strong hydrogen bonds and highly thermostable domains. Thus, the large heterogeneity in ceramide structures and in their aggregation mechanisms may confer resistance towards the heterogeneous external stressors that are constantly faced by the skin barrier.
