Occlusion effect on transcutaneous NSAID delivery from conventional and carrier-based formulations

We studied skin occlusion effects in vitro and in vivo on local and systemic delivery of ketoprofen across the organ, using the drug in a conventional non-occlusive topical gel (Togal Mobil-Gel), an occlusive tape (Mohrus), and the new targeted analgesic (Diractin), comprising ultradeformable, hydrophilic carriers in the form of a Transfersome vesicle. In vitro occluded skin permeability to ketoprofen from the tape (0.086cmh(-1)) marginally exceeds the value for the drug from carriers in a gel (0.058cmh(-1)), which resembles conventional gel on open excised skin (0.057cmh(-1)); smallness of occlusion-induced permeation enhancement ( approximately 1.5x) may be due to the high tested applied dose. In contrast, open skin permeability to the drug from the carriers in vitro is approximately 15xlower (0.004cmh(-1)). The benefit of ketoprofen association with the carriers for targeted transcutaneous delivery only shows-up in vivo after an non-occlusive epicutaneous application: the area under the curve (AUC) in peripheral deep muscle for the carrier-based gel then exceeds AUC for conventional gel approximately 35-fold. The AUC for occluded ultradeformable, hydrophilic carriers measured in living pigs is conversely approximately 10x lower, being 1.4-2.2x below that of the tape that is inferior to non-occluded carriers formulation (normalised cmax: approximately 200x). Occlusion thus disables ultradeformable, hydrophilic carriers by eliminating transcutaneous hydration gradient that normally drives the carriers across the skin. Compared with other non-steroidal anti-inflammatory agents (NSAIDs) for local usage, Diractin is thus evidently well differentiated and innovative.