This study aims to evaluate the influence of the phase behavior of microemulsions in the transdermal administration (“spot-on”) of ivermectin, an antiparasitic drug widely used in the treatment of endoparasites and ectoparasites in dogs. In this regard, pseudoternary phase diagrams composed of water (aqueous phase), isopropyl myristate (oil phase), tween 80 (surfactant) and labrasol (cosurfactant) were obtained in a different surfactant: cosurfactant (S:CS) ratios. S:CS in 1:3 ratio presented a larger region of microemulsion formation and three microemulsions were selected from it and characterized. Subsequently, in vitro permeation and retention studies were conducted using canine skin as membrane. SAXS, rheology and conductivity data were employed to confirm the phase behavior of the microemulsions (w/o, bicontinuous or o/w). The cutaneous permeation and retention tests showed that the w/o microemulsion, followed by bicontinuous microemulsion, resulted in a higher amount of drug permeated through canine skin, suggesting better transdermal permeation. On the other hand, o/w microemulsion resulted in a higher amount of drug accumulated into the skin, suggesting better topical activity. Thus, it can be concluded that phase behavior of microemulsions influenced the drug permeation in the canine skin differently from other animal models. Microemulsions, especially w/o and bicontinuous, can be promising vehicles regarding the transdermal delivery of ivermectin.

这项研究旨在评估微乳剂的相行为对依维菌素的透皮给药（“ spot-on”）的影响，伊维菌素是一种广泛用于治疗犬体内寄生虫和体外寄生虫的抗寄生虫药。在这方面，以不同的表面活性剂：辅助表面活性剂（S：CS）比例获得了由水（水相），肉豆蔻酸异丙酯（油相），吐温80（表面活性剂）和拉布拉索尔（辅助表面活性剂）组成的假三元相图。比例为1：3的S：CS表现出较大的微乳液形成区域，并从中选择了三种微乳液并进行了表征。随后，在体外使用犬皮肤作为膜进行渗透和保留研究。使用SAXS，流变学和电导率数据来确认微乳液的相行为（w / o，双连续或o / w）。皮肤渗透和保留测试表明，无水微乳，然后是双连续微乳，导致犬科动物皮肤中药物的渗透量更高，表明透皮渗透性更好。另一方面，o / w微乳导致药物在皮肤中积累的量增加，表明具有更好的局部活性。因此，可以得出结论，与其他动物模型不同，微乳的相行为对犬皮肤中药物的渗透有不同的影响。关于伊维菌素的透皮递送，微乳剂，尤其是无/双连续乳剂，可能是有希望的载体。