Minoxidil permeation

Fig. 6 Minoxidil permeation from ethosome systems and appropriate control vehicles. Data are expressed as the cumulative permeation across male nude mouse skin in vitro over 24 h. (Figure plotted from data given in Ref l)...

Dermac SR-38 is one of a series of oxazolidinones, cyclic urethane compounds, evaluated as transdermal enhancers. The compound was designed to mimic natural skin lipids (such as ceramides), to be nonirritating, and to be rapidly cleared from the systemic circulation following absorption. In animal and human safety studies, Dermac SR-38 demonstrated a good skin tolerance (no observed irritancy or sensitization at levels of 1-10 wt% moderate to severe irritation in rabbit at 100%), and a low degree of acute toxicity (LD50(rat oral) > 5.0g/kg). The compound was evaluated for its ability to enhance the human skin permeation of diverse drugs from dermal and transdermal delivery systems. Data for minoxidil indicated an enhancer concentration-dependent effect for permeation enhancement. Dermac SR-38 was also found to enhance the skin retention of both retinoic acid when applied in Retin A cream, and dihydroxyacetone when applied in a hydrophilic cream. ... 

On the other hand, SEPA (2-n-nonyl-l,3-dioxolane) has been shown to be a more versatile penetration enhancer in terms of its ease of formulation, chemical stability and its ability to enhance the skin penetration of a wide variety of compounds of varying physicochemical characteristics. Permeants that have been evaluated include indomethacin, ibuprofen, minoxidil, acyclovir, caffeine, econazole, papaverine, progesterone and estradiol. The degree of skin penetration enhancement using SEPA is dependent on the physicochemical characteristics of the permeant. For example, following application of indomethacin in a simple ethanol-propylene glycol vehicle to human skin in vitro, cumulative absorption over 24 h amounted to 0.7 percent of the applied dose. The addition of 2 percent SEPA to the vehicle increased the 24 h absorption value to 23 percent of the applied dose (Marty et al. 1989). Furthermore, in comparative studies between SEPA and Azone, SEPA was shown to be a more effective human skin permeation enhancer for indomethacin (Figure 14.6, Marty et al. 1989). 

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