Novel thiazolopyridine derivatives of diflapolin as dual sEH/FLAP inhibitors with improved solubility.

Inflammatory responses are orchestrated by a plethora of lipid mediators, and perturbations of their biosynthesis or degradation hinder resolution and lead to uncontrolled inflammation, which contributes to diverse pathologies. Small molecules that induce a switch from pro-inflammatory to anti-inflammatory lipid mediators are considered valuable for the treatment of chronic inflammatory diseases. Commonly used non-steroidal anti-inflammatory drugs (NSAIDs) are afflicted with side effects caused by the inhibition of beneficial prostanoid formation and redirection of arachidonic acid (AA) into alternative pathways. Multi-target inhibitors like diflapolin, the first dual inhibitor of soluble epoxide hydrolase (sEH) and 5-lipoxygenase-activating protein (FLAP), promise improved efficacy and safety but are confronted by poor solubility and bioavailability. Four series of derivatives bearing isomeric thiazolopyridines as bioisosteric replacement of the benzothiazole core and two series additionally containing mono- or diaza-isosteres of the phenylene spacer were designed and synthesized to improve solubility. The combination of thiazolo[5,4-b]pyridine, a pyridinylen spacer and a 3,5-Cl2-substituted terminal phenyl ring (46a) enhances solubility and FLAP antagonism, while preserving sEH inhibition. Moreover, the thiazolo[4,5-c]pyridine derivative 41b, although being a less potent sEH/FLAP inhibitor, additionally decreases thromboxane production in activated human peripheral blood mononuclear cells. We conclude that the introduction of nitrogen, depending on the position, not only enhances solubility and FLAP antagonism (46a), but also represents a valid strategy to expand the scope of application towards inhibition of thromboxane biosynthesis.

Thiolated α-cyclodextrin: The likely smallest drug carrier providing enhanced cellular uptake and endosomal escape.

This study aimed to evaluate the effect of thiolated α-cyclodextrin (α-CD-SH) on the cellular uptake of its payload. For this purpose, α-CD was thiolated using phosphorous pentasulfide. Thiolated α-CD was characterized by FT-IR and 1H NMR spectroscopy, differential scanning calorimetry (DSC), and powder X-ray diffractometry (PXRD). Cytotoxicity of α-CD-SH was evaluated on Caco-2, HEK 293, and MC3T3 cells. Dilauryl fluorescein (DLF) and coumarin-6 (Cou) serving as surrogates for a pharmaceutical payload were incorporated in α-CD-SH, and cellular uptake was analyzed by flow cytometry and confocal microscopy. Endosomal escape was investigated by confocal microscopy and hemolysis assay. Results showed no cytotoxic effect within 3 h, while dose-dependent cytotoxicity was observed within 24 h. The cellular uptake of DLF and Cou was up to 20- and 11-fold enhanced by α-CD-SH compared to native α-CD, respectively. Furthermore, α-CD-SH provided an endosomal escape. According to these results, α-CD-SH is a promising carrier to shuttle drugs into the cytoplasm of target cells.

Solidification of self-emulsifying drug delivery systems (SEDDS): Impact on storage stability of a therapeutic protein.

Four solidification methods for self-emulsifying drug delivery systems (SEDDS) were compared to evaluate the impact of solidification on storage stability of an incorporated protein. Papain was loaded in SEDDS via hydrophobic ion pairing (HIP). Liquid SEDDS (l-SEDDS) were either solidified by adsorption to solid excipients such as magnesium-aluminometasilicate via wet granulation (ssilica-SEDDS) and carbohydrates via lyophilisation (scarbo-SEDDS) or by incorporation of high-melting PEG-surfactants (sPEG-SEDDS) and triglycerides (soil-SEDDS) in SEDDS preconcentrates. L- and s-SEDDS were compared regarding intrinsic emulsion properties, solid-state form of papain, enzyme stability and activity during storage. HIP with deoxycholate showed a precipitation efficiency of 82% and papain maintained 90% of its initial activity. Incorporated papain was present in an amorphous state, confirming a molecular dispersion in all preconcentrates. In comparison to l-SEDDS each solidification method investigated improved the storage stability of incorporated papain. Neither precipitation nor phase separation was observed for s-SEDDS. sPEG-SEDDS demonstrated with 87.8% the highest enzymatic activity and displayed according to the following rank order: sPEG-SEDDS > soil-SEDDS > ssilica-SEDDS > scarbo-SEDDS > l-SEDDS the highest remaining papain activity after 30 days of storage. This work clearly demonstrates that solidified SEDDS can provide a significantly improved storage stability for therapeutic proteins compared to corresponding liquid formulations.