Chemical transdermal enhancers

For example, the permeability coefficients of intact stratum corneum for lipophilic compounds such as corticosterone are in the order of 2 x lO cm/sec in an aqueous system. The aqueous solubility of corticosterone is approximately 0.3mg/mL.f A simple calculation using Eqs. (1) and (2) show why only potent drug of a required dose less than 1 mg per day can utilize the transdermal route via passive delivery. Physical and chemical transdermal enhancers are required for most drugs. Table 1 provides a list of transdermal enhancement methods and companies involved in the development of technologies related to these methods. The readers are encouraged to view the company websites listed in the table, but caution must be taken because the information and claims provided in a company website are subjective and not peer-reviewed. 

Weichers J. Use of chemical penetration enhancers in transdermal drug delivery—possibilities and difficulties. Acta Pharmeceutica Nordica 1992 4 123-123. 

Kanikkannan N, Kandimalla K, Lamba S, Singh M. Structure-activity relationship of chemical penetration enhancers in transdermal drug delivery. Curr Med Chem 2000 7 593-608. 

Karande, P., et al. 2005. Design principles of chemical penetration enhancers for transdermal drug delivery. PNAS 102 4688. 

Karande, P. Jain, A. Ergun, K. Kispersky, V. Mitragotri, S. Design principles of chemical penetration enhancers for transdermal drug dehvery. Proc. Natl. Acad. Sci. USA 2005, 102, 4688 693. 

Transdermal Electrophoretic (iontophoresis), electroporation, chemical permeation enhancers, prodrugs, ultrasonics ... 

Murthy, S.N. and Hiremath, R.R. (2001) Physical and chemical permeation enhancers in transdermal delivery of terbutaline sulphate . AAPS PharmSciTech. 2, 1-5. 

Pathan I. B., Setty C. M. (2009). Chemical penetration enhancers for transdermal drug delivery s5tstems. 2i2Ci.L i212IL fi 173-179. 

The human skin itself hinders the widespread use of transdermal drug dehvery (TDD) for administration of medications. Despite the different strategies devised and employed to reversibly overcome the skin barrier, this noninvasive dehvery mode is restricted to potent, low molar mass therapeutic agents. As most drugs would not be able to penetrate the skin in a sufficient quantity to reach the desired therapeutic level, chemical penetration enhancers (CPE) are commonly used to breach the skin barrier and increase dmg permeation. Over the years, extensive screening and testing have identified different classes of chemicals as potential... 

Terpenes have been utilized for a number of therapeutic purposes, such as in antispasmodics, carminatives, and perfumery. They have been found to be useful when incorporated into topical and transdermal pharmaceutical formulations as they act as chemical penetration enhancers facilitating the permeation of drugs through the skin barrier, both healthy and diseased in comprehensive reviews [26, 27]. 

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). 

The use of skin permeation enhancers in combination for synergistic effects has been studied in the transdermal literature (70). Such synergistic methods can be grouped in three categories (i) combination of two physical methods, e.g., ultrasound and iontophoresis (71-75) (ii) combination of a physical method with a chemical enhancer, e.g., use of ultrasound with sodium lauryl sulfate or isopropyl myristate (76-80) and (iii) combination of two chemicals, e.g., terpenes and propylene glycol (46,81-88). Numerous studies have been published on using combination of two physical methods or use of a physical method in conjunction with a chemical enhancer. Use of a physical method, by itself or in combination with another physical method, increases application cost for delivery purposes as mentioned before. In addition, there are unexplored safety and membrane recovery issues associated with these methods. A few reports have also been published on the use of a mixture of chemical enhancers for enhancing transdermal delivery. Typically, such studies use... 

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