Pharmacokinetics of sinomenine hydrochloride cubic liquid crystal injection based on microdialysis technology

Development of an integrated strategy for comprehensive characterization of Sinomenii Caulis extract and metabolites in rats based on UPLC/Q-TOF-MS

Sinomenii Caulis (SC), a commonly used traditional Chinese medicine for its therapeutic effects on rheumatoid arthritis, contains rich chemical components. At present, most studies mainly focus on sinomenine, with little research on other alkaloids. In this study, a comprehensive profile of compounds in SC extract, and biological samples of rats (including bile, urine, feces, and plasma) after oral administration of SC extract was conducted via ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS). The fragmentation patterns and potential biotransformation pathways of six main types of alkaloids in SC were summarized, and the corresponding characteristic product ions, relative ion intensity, and neutral losses were obtained to achieve rapid classification and identification of complex components of SC from in vitro to in vivo. As a result, a total of 114 alkaloid compounds were identified, including 12 benzyl alkaloids, 4 isoquinolone alkaloids, 32 aporphine alkaloids, 28 protoberberine alkaloids, 34 morphinan alkaloids and 4 organic amine alkaloids. After administration of SC extract to rats, a total of 324 prototypes and metabolites were identified from rat plasma, urine, feces and bile, including 81 aporphines, 95 protoberberines, 117 morphinans and 31 benzylisoquinolines. The main types of metabolites were demethylation, hydrogenation, dehydrogenation, aldehydation, oxidation, methylation, sulfate esterification, glucuronidation, glucose conjugation, glycine conjugation, acetylation, and dihydroxylation. In summary, this integrated strategy provides an additional approach for the incomplete identification caused by compound diversity and low abundance, laying the foundation for the discovery of new bioactive compounds of SC against rheumatoid arthritis.

A liquid crystal in situ gel based on rotigotine for the treatment of Parkinson's disease

One of the most common neurodegenerative illnesses is Parkinson's disease (PD). Rotigotine (RTG) is a dopamine agonist that exerts anti-Parkinsonian effects through dopamine receptor agonism to improve motor symptoms and overall performance in PD patients. In this study, an in situ liquid crystal gel called rotigotine-gel (RTG-gel) was developed using soya phosphatidyl choline (SPC) and glycerol dioleate (GDO) to provide long-acting slow-release benefits of rotigotine while minimizing side effects. This study prepared the RTG-gel precursor solution using SPC, GDO, and ethanol (in the ratio of 54:36:10, w/w/w). The internal structures of the gel were confirmed by crossed-polarized light microscopy (PLM), small-angle X-ray scattering (SAXS), and differential scanning calorimetry (DSC). The rheological properties of the RTG-gel precursor solution indicate a favorable combination of low viscosity and excellent flowability. The gel that produced during water absorption was also highly viscous and structurally stable, which helped to maintain the drug delayed release at the injection site. In vitro release assays showed that the in vitro release of RTG-gel followed Ritger-Peppas. The RTG-gel precursor solution was administered by subcutaneous injection, and the results of in vivo pharmacokinetic tests in SD rats showed that the plasma elimination half-life (t1/2) was 59.28 ± 16.08 h; the time to peak blood concentration (Tmax) was 12.00 ± 10.32 h, and the peak concentration (Cmax) was 29.9 ± 10.10 ng/mL. The blood concentration remained above 0.1 ng/mL for 20 days after administration and was still detectable after 31 days of administration, and the bioavailability of RTG can reach 72.59%. The results of in vitro solvent exchange tests showed that the RTG-gel precursor solution undergoes rapid exchange upon contact with PBS, and the diffusion of ethanol can reach 48.1% within 60 min and 80% within 8 h. The results of cytotoxicity test showed 89.27 ± 4.32% cell survival after administration of the drug using RTG-gel. The results of tissue extraction at the administration site showed that healing of the injection site without redness and hemorrhage could be observed after 14 days of injection. The results of tissue section of the administered site showed that the inflammatory cells decreased and granulation tissue appeared after 14 days of administration, and there was basically no inflammatory cell infiltration after 35 days of administration, and the inflammatory reaction was basically eliminated. It shows that RTG-gel has some irritation to the injection site, but it can be recovered by itself in the later stage, and it has good biocompatibility. In summary, RTG-gel might be a potential RTG extended-release formulation for treating PD.

Lipidic lyotropic liquid crystals: Insights on biomedical applications

Liquid crystals (LCs) possess unique physicochemical properties, translatable into a wide range of applications. To date, lipidic lyotropic LCs (LLCs) have been extensively explored in drug delivery and imaging owing to the capability to encapsulate and release payloads with different characteristics. The current landscape of lipidic LLCs in biomedical applications is provided in this review. Initially, the main properties, types, methods of fabrication and applications of LCs are showcased. Then, a comprehensive discussion of the main biomedical applications of lipidic LLCs accordingly to the application (drug and biomacromolecule delivery, tissue engineering and molecular imaging) and route of administration is examined. Further discussion of the main limitations and perspectives of lipidic LLCs in biomedical applications are also provided. STATEMENT OF SIGNIFICANCE: Liquid crystals (LCs) are those systems between a solid and liquid state that possess unique morphological and physicochemical properties, translatable into a wide range of biomedical applications. A short description of the properties of LCs, their types and manufacturing procedures is given to serve as a background to the topic. Then, the latest and most innovative research in the field of biomedicine is examined, specifically the areas of drug and biomacromolecule delivery, tissue engineering and molecular imaging. Finally, prospects of LCs in biomedicine are discussed to show future trends and perspectives that might be utilized. This article is an ampliation, improvement and actualization of our previous short forum article "Bringing lipidic lyotropic liquid crystal technology into biomedicine" published in TIPS.

Injectable Lipid-Based Depot Formulations: Where Do We Stand?

The remarkable number of new molecular entities approved per year as parenteral drugs, such as biologics and complex active pharmaceutical ingredients, calls for innovative and tunable drug delivery systems. Besides making these classes of drugs available in the body, injectable depot formulations offer the unique advantage in the parenteral world of reducing the number of required injections, thus increasing effectiveness as well as patient compliance. To date, a plethora of excipients has been proposed to formulate depot systems, and among those, lipids stand out due to their unique biocompatibility properties and safety profile. Looking at the several long-acting drug delivery systems based on lipids designed so far, a legitimate question may arise: How far away are we from an ideal depot formulation? Here, we review sustained release lipid-based platforms developed in the last 5 years, namely oil-based solutions, liposomal systems, in situ forming systems, solid particles, and implants, and we critically discuss the requirements for an ideal depot formulation with respect to the used excipients, biocompatibility, and the challenges presented by the manufacturing process. Finally, we delve into lights and shadows originating from the current setups of in vitro release assays developed with the aim of assessing the translational potential of depot injectables.