The effect of diethylene glycol monoethyl ether as a vehicle for topical delivery of ivermectin

The effect of diethylene glycol monoethyl ether (DGME; Transcutol) on the permeation of ivermectin, a broad-spectrum antiparasitic agent, through bovine skin was evaluated by in vitro permeation experiments followed by serial sectioning of the skin to assess the amount of ivermectin retained in the skin. Ivermectin permeation through bovine skin was enhanced by DGME and this enhancement was DGME-concentration-dependent. Permeation of ivermectin was effectively enhanced in vehicles with low proportions of DGME, but the magnitude of permeation enhancement decreased as the proportion of DGME increased. The permeation was accompanied by the formation of cutaneous depots of ivermectin. Furthermore, the data indicated that the flux and the cutaneous accumulation of ivermectin were sensitive to the concentration gradient of DGME across the skin. This suggested that ivermectin was permeating with DGME, in which it is very soluble. Hence, the enhancing mechanism involves solubilization of the ivermectin by DGME and the transport of DGME itself across the skin. Based on these results, DGME appears to be a potential vehicle for topical delivery of ivermectin by transport through the skin and through formation of cutaneous depots of ivermectin.