Impact of Alkanediols on Stratum Corneum Lipids and Triamcinolone Acetonide Skin Penetration

Alkanediols are widely used as multifunctional ingredients in dermal formulations. In addition to their preservative effect, considering their possible impact on drug penetration is also essential for their use. In the present study, the influence of 2-methyl-2,4-pentanediol, 1,2-pentanediol, 1,2-hexanediol and 1,2-octanediol on the skin penetration of triamcinolone acetonide from four different semisolid formulations was investigated.

Furthermore, confocal Raman spectroscopy measurements were performed to examine the influence of the alkanediols on stratum corneum lipid content and order. Alkanediols were found to increase the penetration of triamcinolone acetonide. However, the extent depends strongly on the formulation used. In certain formulations, 1,2-pentanediol showed the highest effect, while in others the penetration-enhancing effect increased with the alkyl chain length of the alkanediol used.

None of the tested alkanediols extracted lipids from the stratum corneum nor reduced its thickness. Not withstanding the above, the longer-chained alkanediols cause the lipids to be converted to a more disordered state, which favors drug penetration. This behavior could not be detected for the shorter-chained alkanediols. Therefore, their penetration-enhancing effect is supposed to be related to an interaction with the hydrophilic regions of the stratum corneum.

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Materials: 1,2-Pentanediol, 2-methyl-2,4-pentanediol, and 1,2-hexanediol (Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany), polysorbate 60 (Kolliphor PS 60), cetostearyl alcohol (Kolliwax CSA), cetyl alcohol (Kolliwax CA), emulsifying cetostearyl alcohol type A (Kolliphor CSA) (BASF SE, Ludwigshafen, Germany), glycerol 85%, propylene glycol (Dr. Willmar Schwabe GmbH & Co. KG, Karlsruhe, Germany), white soft paraffin (Sasol Performance Chemicals, Hamburg, Germany), liquid paraffin (Hansen & Rosenthal KG, Hamburg, Germany), carbomer 50,000 (Fagron GmbH & Co. KG, Glinde, Germany), sodium hydroxide (Chemical supply of the University, Tuebingen, Germany), medium-chain triglycerides (Evonik Industries AG, Essen, Germany), glycerol monostearate 60, macrogol 20 glycerol monostearate, disodium hydrogen phosphate, potassium dihydrogen phosphate, sodium chloride, triamcinolone acetonide (micronized) (Caesar & Loretz GmbH, Hilden, Germany), bovine serum albumin (Carl Roth GmbH & Co. KG, Karlsruhe, Germany), acetonitril HPLC gradient grade (Honeywell Specialty Chemicals Seelze GmbH, Seelze, Germany), PTFE filters (pore size: 0.2 µm, diameter: 25 mm, Chromafil Xtra H-PTFE-20/25, Macherey-Nagel GmbH & Co. KG, Dueren, Germany), Neg-50 Frozen Section Medium (Thermo Fisher Scientific Inc., Waltham, MA, USA). 1,2-Octanediol (dermosoft Octiol) was kindly donated by Evonik Dr. Straetmans GmbH, Hamburg, Germany.

Article information: Sigg, M.; Daniels, R. Impact of Alkanediols on Stratum Corneum Lipids and Triamcinolone Acetonide Skin Penetration. Pharmaceutics 2021, 13, 1451. https://doi.org/10.3390/pharmaceutics13091451