[Influence of penetration enhancers on in vitro transdermal permeation of L-tethrahydropalmatine].
OBJECTIVE
To study the effect of different penetration enhancers on the in vitro transdermal permeation of 1-tethrahydropalmatine (L-THP) through rat skin.


METHODS
Both natural and chemical synthesis penetration enhancers were applied singly or jointly to investigate the skin permeation rates of l-THP. The skin permeation profiles were evaluated by Valian-Chien permeation cells with isolated rat skin. HPLC-UV method was established to determine the concentration of l-THP in samples.


RESULTS
As chemical synthesis penetration enhancer was used alone, 8% azone was observed to be the optimal penetration enhancer with the maximal penetration rate of 21.153 microg x cm(-20 x h(-1). Although 2% menthol crystal or 5% eucalyptus oil was effective as a natural penetration enhancer when used alone, the average penetration rate reached only half of that of 8% azone. The penetration potency of either menthol oil or menthol crystal combined with 8% azone was more effective than that of azone alone (P < 0.05).


CONCLUSIONS
Either menthol oil or menthol crystal combined with 8% azone is effective on transdermal penetration of l-THP in vitro. There is significant synergistic effect when natural penetration enhancers combined with chemical synthesis penetration enhancers.
Institute of Materia Medica, Zhejiang Academy of Medical Sciences, Hangzhou 310013, China. zoe-051@163.com
Li
L
Qian
Zhen
Z
Ma
Wanggang
W
Zhang
Qiao
Q
Wang
D000279:Administration, Cutaneous; D000818:Animals; D001381:Azepines / Q000494:pharmacology*; D001600:Berberine Alkaloids / Q000032:analysis / Q000493:pharmacokinetics*; D004357:Drug Synergism; D005052:Eucalyptus / Q000737:chemistry; D008297:Male; D008610:Menthol / Q000494:pharmacology*; D009822:Oils, Volatile / Q000494:pharmacology*; D010539:Permeability / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012867:Skin / Q000187:drug effects / Q000378:metabolism*; D012869:Skin Absorption / Q000187:drug effects*
D001381:Azepines; D001600:Berberine Alkaloids; D009822:Oils, Volatile; D008610:Menthol; C035229:laurocapram; C005413:palmatine