Penetration enhancer alcohols

A wide variety of long-chain fatty acids increase transdermal delivery the most popular is oleic acid. It is relevant that many penetration enhancers contain saturated or unsaturated hydrocarbon chains and some structure-activity relationships have been drawn from the extensive studies of Aungst et al. [22,23] who employed a range of fatty acids and alcohols, sulfoxides, surfactants, and amides as enhancers for naloxone. From these experiments, it appears that saturated alkyl chain lengths of around Cio to C12 attached to a polar head... 

Southwell, D., and B.W. Barry. 1983. Penetration enhancers for human skin Mode of action of 2-pyrrolidone and dimethylformamide on partition and diffusion of model compounds water, -alcohols and caffeine. J Invest Dermatol 80 507. 

The most extensively studied amphiphilic and lipophilic penetration enhancers are oleic acid, oleyl surfactants, terpenes, alcohols, azone, azone analogues [84— 86], and FFAs. 

Patel, D.C. Chang, Y. Penetration Enhancement with Binary System of Oleic Acid, Oleins, and Oleyl Alcohol with Lower Alcohols. US Patent 4,863,970, September 5, 1989. 

Stearyl alcohol is used in cosmetics and topical pharmaceutical creams and ointments as a stiffening agent. By increasing the viscosity of an emulsion, stearyl alcohol increases its stability. Stearyl alcohol also has some emollient and weak emulsifying properties and is used to increase the water-holding capacity of ointments, e.g. petrolatum. In addition, stearyl alcohol has been used in controlled-release tablets, " suppositories, and microspheres. It has also been investigated for use as a transdermal penetration enhancer. ... 

Formulations containing an absorption promoting substance, such as propylene glycol or sodium lauryl sulphate, may increase the permeability of the stratum comeum to water-soluble drugs. Propylene glycol is a commonly used vehicle in topical corticosteroid preparations for veterinary use. Various aprotic solvents, which include dimethylacetamide, dimethylformamide, dimethylsulphoxide, tetrahydrofurfuryl alcohol, and 2-pyrrolidone, serve as penetration enhancers of polar drugs (Barry, 1983). Dimethylsulphoxide... 

An approach published in 2001 based on research out of the Klibanov laboratory at MIT is to use ethanol [5]. Ethanol, isopropanol, and other alcohols have long been used successfully as penetration enhancers for medical applications. Ethanol is one of the first molecules to have been used as a transdermal enhancer, because its effects are so easily and well characterized and its systemic and local toxicities are understood. It is currently contained in commercial delivery systems for estradiol [17] and other bioactive molecules. Ethanol and isopropanol have been used in a variety of studies based on their effects on drug transport. More applications can be found in the patent literature [18]. 

Fatty alcohols Widely used as emulsifying agents Penetration enhancing effects have been reported... 

Selected adjuvants are used to aid in delivering the pesticide. Herbicides usually benefit from a surface tension reduction and penetration enhancer. Adjuvants are from the three classes of surfactants nonionic alkyl polyethylene oxide alcohols, organosilicones, and anionic surfactants such as... 

Penetration into the skin can be enhanced by penetration enhancers. These excipients diffuse into the stratum comeum and interact with components of this layer. The barrier function of the skin decreases. The effect of penetration enhancers is based on two mechanisms. The penetration enhancer can change the stracture of the stratum comeum or the solubility of the active substance in the skin. Penetration enhancers should not damage the underlying skin layers and should not be toxic or allergenic. Moreover, the effect must be reversible. Because of the different properties and mechanisms of action of penetration enhancers it is difficult to predict which enhancer will be most effective for the penetration of a specific active substance. Substances such as dimethyl sulfoxide (DMSO), salicylic acid, urea, propylene glycol, ethanol, isopropyl alcohol and many acids can act as penetration enhancers. 

Also linalool alone, one of the most prominent monoterpene alcohols, is used in many dermal preparations as penetration enhancer. In a series of in vitro studies it was shown that linalool enhanced its own penetration (Cal and Sznitowska, 2003) as well as the absorption of other therapeutics, such as haloperidol (Vaddi et al., 2002a, 2002b), metoperidol (Komuru et al., 1999), propa-nolol hydrochloride (Kunta et al, 1997), and transcutol (Ceschel et al., 2000). Cal (2005) showed in another in vitro stndy the influence of linalool on the absorption and elimination kinetics and was able to prove that this monoterpene alcohol furnished the highest absorption ratio compared to an oily solution or an 0/W emulsion. 

Because skin exhibits many of the properties of a lipid membrane, dermal penetration can often be enhanced by increasing a molecule s lipophilicity. Preparation of an ester of an alcohol is often used for this purpose since this stratagem simultaneously time covers a hydrophilic group and provides a hydrophobic moiety the ready cleavage of this function by the ubiquitous esterase enzymes assures availability of the parent drug molecule. Thus acylation of the primary alcohol in flucinolone (65) with propionyl chloride affords procinonide (66) the same transform... 

A possible source of groundwater contamination, which has up to now almost been neglected, is associated with the introduction of surfactants into soils as pesticide additives (Table 6.7.3). Non-ionic surfactants composed of alcohols and fatty acids are most widely recommended as adjuvants to facilitate and enhance the absorbing, emulsifying, dispersing, wetting and penetrating properties of pesticides. Other pesticide adjuvants are silicone-based surfactants,... 

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