Huang Xinfan, Tanojo Hanafi, Lenn Jon, Deng C Helen, Krochmal Lincoln
Center for Skin Biology, Connetics Corp, Palo Alto, California 94303, USA.
J Am Acad Dermatol. 2005 Jul;53(1 Suppl 1):S26-38. doi: 10.1016/j.jaad.2005.04.028.
Skin, particularly the uppermost layer--the stratum corneum--presents a formidable, largely impassable barrier to the entry of most compounds. Recently, a novel thermolabile, low-residue foam vehicle, VersaFoam (Connetics Corp, Palo Alto, Calif), has emerged that offers a number of clinical and cosmetic advantages for the delivery of therapeutic agents through the skin. Two corticosteroids--mid-potency betamethasone valerate and ultra-high-potency clobetasol propionate--are now available in this formulation, and other products are in development to deliver clindamycin and ketoconazole in the foam vehicle. A series of in vitro studies have demonstrated that the new foam has the ability to deliver the active drug at an increased rate compared with other vehicles. These findings suggest that the new foam utilizes a nontraditional "rapid-permeation" pathway for the delivery of drugs. It is likely that components within the foam (probably the alcohols) act as penetration enhancers, and reversibly alter the barrier properties of the outer stratum corneum, thus driving the delivered drug across the skin membrane via the intracellular route. This is in contrast to traditional topical delivery vehicles, which must first rely on hydration of the intercellular spaces in the stratum corneum to achieve drug delivery. The latter mechanism reflects a hydration-dependent process, which may result in comparatively slower drug permeation.
皮肤，尤其是最外层——角质层，对大多数化合物的进入构成了巨大的、基本上无法逾越的屏障。最近，一种新型的热不稳定、低残留泡沫载体VersaFoam（加利福尼亚州帕洛阿尔托的Connetics公司）出现了，它在通过皮肤递送治疗剂方面具有许多临床和美容优势。两种皮质类固醇——中效的戊酸倍他米松和超强效的丙酸氯倍他索——现在有这种剂型，并且正在开发其他产品以在泡沫载体中递送克林霉素和酮康唑。一系列体外研究表明，与其他载体相比，这种新型泡沫能够以更快的速度递送活性药物。这些发现表明，这种新型泡沫利用了一种非传统的“快速渗透”途径来递送药物。泡沫中的成分（可能是醇类）可能作为渗透促进剂，可逆地改变角质层外层的屏障特性，从而通过细胞内途径驱动递送的药物穿过皮肤膜。这与传统的局部递送载体形成对比，传统载体必须首先依靠角质层细胞间空间的水合作用来实现药物递送。后一种机制反映了一个依赖水合作用的过程，这可能导致药物渗透相对较慢。
