Chemical penetration enhancers combinations

Figure 2 (A) Design of a ternary formulation. (B) Activity phase map of a ternary combination of chemical penetration enhancers. Dark gray indicates highest skin permeabilization and light gray indicates lowest skin permeabilization.

The lack of significant impact of CPEs on transdermal delivery vehicles is related to the inherent nonspecific activity of CPEs in the different strata of the skin, as discussed earlier. This limitation may be overcome by utilization of mixtures of CPEs. Research has already shown that binary mixtures of CPEs provide increased permeation enhancement as well as increased safety compared to single enhancers. Such unique chemical combinations, called synergistic combinations of penetration enhancers or SCOPE formulations, offer new opportunities in transdermal drug delivery (46). 

Combined Chemical and Electroporation Methods of Skin Penetration Enhancement... 

The chemical composition of liposomes is an important parameter for their transdcrmal penetration. The most common phospholipid used for tlie preparation of topically applied liposomes is egg or soy derived phosphatidylcholine in mixtures with cholesterol. Phosholipids are very-attractive molecules for skin treatment as they combine penetration enhancement with skin hydration properties due to their tendency to bond water molecules. Their low toxicity makes them even more suitable for topical formulations. 

Low power ultrasound offers the possibility of enhancing the effects of chlorine. The results of a study of the combined effect of low power ultrasound and chlorination on the bacterial population of raw stream water are shown (Tab. 4.2). Neither chlorination alone nor sonication alone was able to completely destroy the bacteria present. When sonication is combined with chlorination however the biocidal action is significantly improved [10]. The effect can be ascribed partly to the break-up and dispersion of bacterial clumps and floes which render the individual bacteria more susceptible to chemical attack. In addition cavitation induced damage to bacterial cell walls will allow easier penetration of the biocide. 

Eriedman et al. have demonstrated enhanced brain penetrance under psychological stress of relatively small molecules such as anticholinesterases, as well as larger dye-protein complexes and DNA plasmids. This stress-induced process putatively explains some of the nervous system-associated sequelae reported by Gulf War veterans, who were exposed to unknown doses and combinations of potentially harmful xenobiotics, particularly anticholinesterases. The anticipated chemical warfare agents would have irreversibly blocked AChE. Eor prophylactic protection from these agents, Gulf War soldiers were administered pyridostigmine, a reversible carbamate... 

The heterogeneous process can be seen as a combination of physical absorption with chemical reaction. The reaction zone can penetrate in the liquid phase, if the reaction is relatively slow, or takes place only at the interface, if the reaction rate is infinite. The chemical reaction can accelerate considerably the pure physical process. The ratio of actual process rate by the physical process rate is known as enhancement factor E. In the case of a bimolecular reaction the enhancement factor can be expressed as function... 

A combination of CyDs with absorption enhancers can enhance bioavailabUity in various routes. A number of attempts have been made to enhance the absorption of Class III dmgs, induding not only prostaglandin but also peptides and proteins. One of the methods of improving their bioavailability is to use absorption enhancers. Prostaglandins are chemically unstable and poorly penetrative in epidermis and dermis, and some means of solving these defidencies of prostaglandins are required. 

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