Embedding of active substances in supramolecular systems has as the main goal to ensure the controlled release of the active ingredients. Whatever the final architecture or entrapment mechanism, modeling of release is challenging due to the moving boundary conditions and complex initial conditions. Despite huge diversity of formulations, diffusion phenomena are involved in practically all release processes. The approach in this paper starts, therefore, from mathematical methods for solving the diffusion equation in initial and boundary conditions, which are further connected with phenomenological conditions, simplified and idealized in order to lead to problems which can be analytically solved. Consequently, the release models are classified starting from the geometry of diffusion domain, initial conditions, and conditions on frontiers. Taking into account that practically all solutions of the models use the separation of variables method and integral transformation method, two specific applications of these methods are included. This paper suggests that “good modeling practice” of release kinetics consists essentially of identifying the most appropriate mathematical conditions corresponding to implied physicochemical phenomena. However, in most of the cases, models can be written but analytical solutions for these models cannot be obtained. Consequently, empiric models remain the first choice, and they receive an important place in the review.

In this study a novel type of in vitro–in vivo correlation (IVIVC) is proposed: The correlation of the in vitro parent drug dissolution data with the in vivo pharmacokinetic data of drug’s metabolite after the oral administration of the parent drug. The pharmacokinetic data for the parent drug diltiazem (DTZ) and its desacetyl diltiazem metabolite (DTZM) were obtained from an in vivo study performed in 19 healthy volunteers. The pharmacokinetics of the parent drug and its metabolite followed a pseudomono-compartmental model and deconvolution of the DTZ or DTZM plasma concentration profiles was performed with a Wagner–Nelson-type equation. The calculated in vivo absorption fractions were correlated with the in vitro DTZ dissolution data obtained with USP 2 apparatus. A linear IVIVC was obtained for both DTZ and DTZM, with a better correlation observed for the case of the metabolite. This type of correlation of the in vitro data of the parent compound with the in vivo data of the metabolite could be useful for the development of drugs with active metabolites and prodrugs.

The Black Sea offers underutilized marine bioresources with potential for the development of materials intended for wound healing and skin tissue repair. In this study, new composite biomaterials were created using collagen peptides extracted from the jellyfish Rhizostoma pulmo (JPC) and hydroalcoholic extracts from the seaweeds Ulva lactuca (ALGU) and Enteromorpha intestinalis (ALGE). The marine-derived ingredients and resulting biocomposites were physicochemically and rheologically characterized and evaluated for antioxidant, antimicrobial, and biological activities on cell cultures relevant to wound healing. Two hydrogel biocomposites, B1 (JPC–ALGU 20%) and B2 (JPC–ALGE 20%), exhibited antioxidant activity of 65.2% and 63.5%, respectively, in the DPPH assay at a concentration of 400 mg/mL, and values of 1.26 μg/mg AAE and 1.15 μg/mg AAE, respectively, in the reducing power assay at a concentration of 800 µg/mL. Antibacterial activity was investigated against several Gram-positive and Gram-negative bacteria. The strongest effects were observed against Staphylococcus aureus. In vitro tests conducted on fibroblast and keratinocyte cultures revealed concentration-dependent cellular responses, while scratch assays confirmed the formulations’ potential to promote cell migration. These results support further investigation of jellyfish collagen–green algae biocomposites for wound-healing and skin tissue-repair applications, although additional dose optimization and in vivo validation are required.