Article

Synergistic effect of low-frequency ultrasound and surfactants on skin permeability.

Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, USA.
Journal of Pharmaceutical Sciences (impact factor: 3.06). 02/2002; 91(1):91-100.
Source: PubMed

ABSTRACT Low-frequency ultrasound (20 kHz) and surfactants have been individually shown to enhance transdermal drug transport. In this study, we investigated the synergistic effect of ultrasound and surfactants on transdermal drug delivery. Surfactants with different head group chemistries including anionic, cationic, and nonionic with varying tail lengths (8-16-carbon atoms) were studied. We found that surfactants possessing anionic and cationic head groups were more potent than those possessing nonionic head groups in increasing skin conductivity in the presence of ultrasound. Furthermore, for surfactants possessing the same head group, those with a 14-carbon tail length were found to be most effective in enhancing skin permeability. The data presented in this report show that ultrasound and surfactants synergistically enhance skin permeability. Two mechanisms are shown to play a role in this synergistic effect. First, ultrasound enhances surfactant delivery (enhanced delivery) into the skin and, second, ultrasound disperses surfactant (enhanced dispersion) within the skin. In general, surfactants that are potent enhancers by themselves are potent enhancers in the presence of ultrasound as well. We performed imaging experiments to assess the effect of ultrasound on delivery of a model permeant, sulforhodamine B, into the skin. These experiments show that ultrasound enhances surfactant delivery and dispersion in the skin.

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Keywords

14-carbon tail length
 
8-16-carbon atoms
 
cationic head groups
 
different head group chemistries
 
head group
 
imaging experiments
 
Low-frequency ultrasound
 
model permeant
 
possessing nonionic head groups
 
potent enhancers
 
skin conductivity
 
skin permeability
 
sulforhodamine B
 
surfactants
 
surfactants synergistically
 
synergistic effect
 
transdermal drug delivery
 
transdermal drug transport
 
ultrasound enhances surfactant delivery
 
varying tail lengths
 

Ahmet Tezel