Currently, there is a tendency for new forms of carrier-drug systems to appear with prolonged and controlled release. However, in order to design medical or pharmaceutical devices, which have to be characterized by high quality and the assumed parameters in real conditions, it is necessary to analyze this process based on in vitro release (IVR) testing methods. For this purpose, extracorporeal studies are carried out, which enable the determination of the release profiles of active substances using a simulated tissue-like environment. Here, we focused on the release tests of poorly water-soluble compounds (salicylic acid and fluocinolone acetonide) from the dual drug delivery system using the flow-through cell method (USP4). Additionally, bio-hybrid hydrogel matrix containing the system of thermosensitive nanocarrier with salicylic acid and fluocinolone acetonide was subjected to the following investigations: physicochemical (swelling ability, gel fraction), morphological (SEM analysis) and structural using FT-IR spectroscopy. On the basis of results, we can conclude that the USP4 method may be suitable, especially for the release tests of poorly water-soluble components introduced into modern forms of drug administration, such as polymeric matrices, hydrogels, nano- and microcarriers as well as hybrid systems.