Penetration enhancers chemical

While there are limitations associated with the use of an in vitro permeability model for assessing the transport of compounds across the buccal mucosa, it can still be useful in assessing and comparing the permeability of compounds under different conditions, such as pH, temperature, and osmolarity, which provide valuable information on the mechanisms involved in drug transport. Additionally, the preliminary effects of potential chemical penetration enhancers or formulation excipients may be assessed, and these may provide a substantial rationale for subsequently assessing the effect of these agents in man. 

The buccal mucosa does serve as an alternative route for administering compounds systematically however, to ensure particular compounds are candidates for delivery across this biological tissue, preclinical screening is essential. While in vivo human permeability studies are ideal, due to their costs and associated issues, it is necessary to perform such screening in vitro. Assessment of compound permeability across porcine buccal mucosa has been widely used and can provide the preclinical biopharmaceutical scientist with much information relating to permeability, routes of transport, and effects of various chemical penetration enhancers. 

CHALLENGES IN DESIGNING MULTICOMPONENT CHEMICAL PENETRATION ENHANCER FORMULATIONS... 

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.

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. 

The literature describing such synergy between electrical enhancement techniques with chemical penetration enhancers was reviewed recently [2] and is beyond the scope of this chapter. 

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

It is therefore desirable to devise strategies both to enhance the penetration of molecules, which can already breach the skin barricade passively to some extent, and also to widen the spectrum of drug molecules that can penetrate the skin at therapeutically beneficial doses. Many tactics have been utilized to help overcome the barrier function. These include chemical means (e.g., chemical penetration enhancers or entrapment of molecules within lipid vesicles) or physical methods (such as ultrasound, microneedles, or electrical methods). Two important electrical methods are iontophoresis and electroporation. 

Chemical Penetration Enhancers of Electroporation-Mediated Delivery.331... 

Figure 8.9 Structures of selected chemical penetration enhancers...

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