Untitled

Abstract

Ethanol-water systems enhance permeation of ionic solutes through human stratum corneum. Optimum enhancement of salicylate ion permeation has been observed with ethanol volume fractions near 0.63. The mechanism of action of ethanol-water systems enhancing skin permeation was investigated by in vitro skin permeation studies combined with Fourier transform infrared spectroscopy experiments. The increased skin permeation of the ionic permeant by the ethanol-water systems may be associated with alterations involving the polar pathway. Polar pathway alterations may occur in either or both the lipid polar head and proteinaceous regions of the stratum corneum. Ion-pair formation may also contribute to increased permeation. However, the decreased permeation of salicylate ion observed at higher volume fractions of ethanol may be attributed to decreased uptake of permeant into the stratum corneum.

Transdermal Delivery of Dideoxynucleoside-Type Anti-HIV Drugs. 2. The Effect of Vehicle and Enhancer on Skin Permeation

“…Volume fractions of 60-70% (v/v) or below improved drug flux across the skin, whereas permeation decreased with higher concentrations. 19,24,25 In this study using EtOH/water and EtOH/TCP cosolvent systems, the permeation rate of DDC, DDI, and AZT also reached maximum value at 50-60% (v/v) ethanol (Table 2 and 3), and decreased with further increases in the volume fraction of ethanol. Many researchers have investigated the mechanism of the enhancing effect of ethanol on skin permeability.…”

“…Many researchers have investigated the mechanism of the enhancing effect of ethanol on skin permeability. [23][24][25][26][27] Some have demonstrated an ethanol concentration-dependent enhancement mechanism: the ethanol vehicle alters the lipid pathway at a low ethanol fraction, while the pore pathway is significantly affected at higher ethanol fractions. It has also been recognized that the enhancement of the skin permeability of a drug by ethanol at low concentrations comes from physical perturbation of the lipoidal barrier region of the stratum corneum, while that at high concentration is caused by conformational changes within the keratinized protein component and partial extraction of the stratum corneum lipid.…”

Penetration route of functional molecules in stratum corneum studied by time-resolved small- and wide-angle x-ray diffraction

“…As a typical hydrophilic or hydrophobic molecule we applied ethanol [4,5] or d-limonene [6][7][8][9], respectively. For this purpose we have developed an x-ray diffraction method which can perform the SAXD and WAXD measurements successively for a single SC sample as a function of time after applying the functional molecules [10].…”

Quantitative Evaluation of Aqueous Isopropyl Alcohol Enhancement on Skin Flux of Terbutaline (Sulfate). 2. Permeability Contributions of Equilibrated Drug Species across Human Skin in Vitro

“…[1][2][3][4][5][6][7] The process of skin permeation for ionizable permeants is complicated by the simultaneous presence of both ionized and un-ionized species in solution, among which the ionized penetrates through stratum corneum much slower than the un-ionized. [3][4][5][6] In aqueous solution, the total flux of drug can be maximized by adjusting the solution pH to balance the concentration of the un-ionized fraction and the total solubility of the drug.…”

“…While iontophoresis can largely deliver the charged permeants through skin, the simple use of penetration-enhancing solvents is valuable for passive transdermal delivery of ionizable compounds. [6][7][8][9] For aqueous-miscible solvents, ethanol and isopropyl alcohol are the most acceptable in terms of toxicology and widely used in pharmaceuticals and cosmetics. 10,11 Ethanol is well known to enhance the transport of both lipophilic and ionic compounds across hairless mouse skin and human skin.…”