Salicylic acid permeation enhancer

Azone (laurocapram) is used extensively as a transdermal permeation enhancer, and has also found use in buccal drug delivery. It is a lipophilic surfactant in nature (Figure 10.4). Permeation of salicylic acid was enhanced by the pre-application of an Azone emulsion in vivo in a keratinized hamster cheek pouch model [35]. Octreotide and some hydrophobic compounds absorption have also been improved by the use of Azone [36], Azone was shown to interact with the lipid domains and alter the molecular moment on the surface of the bilayers [37], In skin it has been proposed that Azone was able to form ion pairs with anionic drugs to promote their permeation [38],... 

Many studies have been published on the use of various enhancers for the rectal absorption. They increase the absorption of an active substance by enhancing the membrane permeation, rather than increasing the solubility. Published examples of absorption enhancers are capric acid and sodium caprate, lauric acid and sodium laurate, sodium salicylate and sodium cholate. These enhancers however give an unpredictable and strongly variable improvement of the biological availability [5b]. Nevertheless they sometimes lead to a licensed medicine sodium caprate is already in use in a suppository product available in Japan [7]. 

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