Skin, drug penetration through

Model II. The Use of Zeolite-Polystyrene Disks as Models in the Study of Drug Penetration through Skin... 

Lippold GC (1992) How to optimize drug penetration through the skin. Pharm Acta Helv 67 294-300. 

Ghafourian, T., et al. 2004. The effect of penetration enhancers on drug delivery through skin A QSAR study. J Control Release 99 113. 

This approach consists of transiently increasing the permeability characteristics of the cornea by appropriate substances, known as penetration enhancers or absorption promoters. It bears a strict analogy to techniques aimed at facilitating drug penetration through the skin and other epithelia such as the buccal, nasal, intestinal, or rectal. 

Orally administered isosorbide dinitrate shows clear hemodynamic and anti-anginal effects, but it undergoes a rapid hepatic first-pass metabolism, with a plasma half-life of ca. 40 min. Its major metabolites are isosorbide-2-mononitrate and isosorbide-5-mononitrate, with half-lives of 2 and 4 h, respectively [16]. A transdermal spray of isosorbide dinitrate can be administered in order to avoid the first-pass effect, and the unchanged drug penetrates through the skin within 20 min so that it is slowly released into the capillaries in therapeutically effective amounts [24]. A very recent study showed intravenously infused isosorbide dinitrate to be ideal anti-anginal agent, especially in acute conditions [25]. 

Studies were performed in vivo on two volunteers as well as in vitro using porcine skin. Although not directly related to tablet evaluation, the work is notable for its contribution to the transdermal delivery of drugs, potential NIR prediction of drug penetration through the skin, and conclusions regarding moisturizer use on the skin. 

Okamoto, H., Yamashita, E, Saito, K., and Hashida, M. (1989). Analysis of drug penetration through the skin by the two-layer skin model. Pharmaceutical Research, 6 931-937. 

Menthol is a natural compound present in mentha and rose oil. It acts as a mild inhibitor of inflammation processes and a promoter of drug penetration through the skin [7]. The menthol skeleton has three chiral centers and therefore 2 = 8 stereoisomers, i.e., four diastereometic racemates. In nature, both (+)- and (—)-menthol are present O ig. 9.1). 

Many studies have employed phospholipids as liposomes (vesicles) to transport drugs into and through human skin. However, a few investigations have also employed phospholipids in a nonvesicular form as penetration enhancers. For example, 1% phosphatidylcholine in PG, a concentration at which liposomes would not form, enhanced theophylline penetration through hairless mouse skin [64]. Similarly, indomethacin flux was enhanced through rat skin by the same phospholipid and hydrogenated soybean phospholipids increased diclofenac permeation through rat skin in vivo. 

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