Esters of 6-aminohexanoic acid as skin permeation enhancers: The effect of branching in the alkanol moiety
✍ Scribed by Alexandr Hrabálek; Kater̆ina Vávrová; Pavel Dolez̆al; Miloš Machác̆ek
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 114 KB
- Volume
- 94
- Category
- Article
- ISSN
- 0022-3549
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✦ Synopsis
In order to investigate the effect of branching and cyclization in the hydrophobic part of skin permeation enhancers, 17 novel branched-chain and cyclic 6-aminohexanoic acid esters were prepared. Their permeation enhancing activity was evaluated in vitro using human skin and theophylline as a model drug, and compared to that of the corresponding linear-chain analogues. The results showed that chain branching and cyclization has a negative influence on the enhancing activity of 6-aminohexanoates. For example, the enhancement ratios (ERs) of dodecan-1-yl, dodecan-2-yl, dodecan-4-yl, and cyclododecyl ester were 39.7, 29.3, 3.1, and 2.2, respectively. No significant change in the optimum length of the chain was observed. Dodecan-2-yl 6-aminohexanoate, the most active branched derivative, still maintains a remarkable enhancing activity (ER 29.3). Presumably, the relatively small degree of branching of these molecules does not prevent them from interacting with the lipid components of the stratum corneum. However, a higher degree of branching, cyclization of the chain, and presence of an aromatic ring resulted in a loss of activity.