In vitro toxicity assessment of rivaroxaban degradation products and kinetic evaluation to decay process

Analysis of omarigliptin forced degradation products by ultra-fast liquid chromatography, mass spectrometry, and in vitro toxicity assay

Omarigliptin (OMG) is an antidiabetic drug indicated for the treatment of type 2 diabetes mellitus. Forced degradation studies are practical experiments to evaluate the stability of drugs and to establish degradation profiles. Herein, we present the investigation of the degradation products (DPs) of OMG formed under various stress conditions. OMG was subjected to hydrolytic (alkaline and acidic), oxidative, thermal, and photolytic forced degradation. A stability-indicating ultra-fast liquid chromatography method was applied to separate and quantify OMG and its DPs. Five DPs were adequately separated and detected in less than 6 min, while other published methods detected four DPs. MS was applied to identify and obtain information on the structural elucidation of the DPs. Three m/z DPs confirmed previously published research, and two novel DPs were described in this paper. The toxicity of OMG and its DPs were investigated for the first time using in vitro cytotoxicity assays, and the sample under oxidative conditions presented significant cytotoxicity. Based on the results from forced degradation studies, OMG was found to be labile to hydrolysis, oxidation, photolytic, and thermal stress conditions. The results of this study contribute to the quality control and stability profile of OMG.

Immunomodulatory effect of imidacloprid on macrophage RAW 264.7 cells

The neonicotinoid imidacloprid was promoted in the market because of widespread resistance to other insecticides, plus its low mammalian impact and higher specific toxicity towards insects. This study aimed to evaluate the immunomodulatory effect of imidacloprid on macrophages. RAW 264.7 cells were incubated to 0-4000mg/L of imidacloprid for 24 and 96h. Imidacloprid presented a concentration-dependent cytotoxicity after 24h and 96h incubation for MTT reduction (3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide) (EC₅₀ 519.6 and 324.6mg/L, respectively) and Neutral Red (3-amino-7-dimethylamino-2-methylphenazine hydrochloride) assays (EC₅₀ 1139.0 and 324.2mg/L, respectively). Moreover, imidacloprid decreased the cells' inflammatory response and promoted a mitochondrial depolarization. The complex II and succinate dehydrogenase (SDH) activities in RAW 264.7 cells incubated with imidacloprid increased more at 24h. These results suggest that imidacloprid exerts an immunomodulatory effect and mitochondria can act as regulator of innate immune responses in the cytotoxicity mediated by the insecticide in RAW 264.7 cells.

DNA damage in peripheral blood lymphocytes of severely ill COVID-19 patients in relation to inflammatory markers and parameters of hemostasis

Bearing in the mind that a variety of agents can contribute to genome instability, including viral infections, the aim of this study was to analyze DNA damage in hospitalized COVID-19 patients and its relationship with certain laboratory parameters. The potential impact of applied therapy and chest X-rays on DNA damage was also estimated. The study population included 24 severely COVID-19 patients and 15 healthy control subjects. The level of DNA damage was measured as genetic damage index (GDI) by comet assay. The standard laboratory methods and certified enzymatic reagents for the appropriate autoanalyzers were performed for the determination of the biochemical and hematological parameters. COVID-19 patients had significantly higher level of DNA damage compared with control subjects. The absolute number of neutrophil leukocytes was statistically higher, while the absolute number of lymphocytes was statistically lower in COVID-19 patients than in healthy controls. The analysis of the relationship between DNA damage and laboratory parameters indicated that GDI was positively correlated with interleukin 6 (IL-6) concentration and negatively with platelet count in COVID-19 patients. The level of DNA damage was slightly higher in female patients, in whom it was demonstrated a positive correlation of GDI with C-reactive protein (CRP) and procalcitonin. Likewise, there was a negative relationship of GDI and platelet count, and positive relationship of GDI and activated partial thromboplastin time (aPTT) in female population. The applied therapy (antibiotics, corticosteroid, anticoagulant, and antiviral therapy) as well as chest X rays has been shown to have genotoxic potential. The level of DNA damage significantly corresponds to the inflammatory markers and parameters of hemostasis in COVID-19 patients. In conclusion, inflammation, smoking habit, applied therapy, and chest X rays contribute to a higher level of DNA damage in COVID-19 patients.

Photodegradation of Bexarotene and Its Implication for Cytotoxicity

A detailed understanding of the stability of an active pharmaceutical ingredient and a pharmaceutical dosage form is essential for the drug-development process and for safe and effective use of medicines. Photostability testing as an inherent part of stability studies provides valuable knowledge on degradation pathways and structures of products generated under UV irradiation. Photostability is particularly important for topically administered drugs, as they are more exposed to UV radiation. Bexarotene is a more recent third-generation retinoid approved by the U.S. Food and Drug Administration and the European Medicines Agency as a topically applied anticancer agent. The present study aimed to assess bexarotene photostability, including the presence of UV filters, which have been permitted to be used in cosmetic products in Europe and the USA. The bexarotene photostability testing was performed in ethanol solutions and in formulations applied on PMMA plates. The UPLC-MS/MS technique was used to determine the tested substance. The presence of photocatalysts such as TiO₂ or ZnO, as well as the organic UV filters avobenzone, benzophenone-3, meradimate, and homosalate, could contribute to degradation of bexarotene under UV irradiation. Four photocatalytic degradation products of bexarotene were identified for the first time. The antiproliferative properties of the degradation products of bexarotene were assessed by MTT assay on a panel of human adherent cancer cells, and concentration-dependent growth inhibition was evidenced on all tested cell lines. The cytotoxicity of the formed products after 4 h of UV irradiation was significantly higher than that of the parent compound (p < 0.05). Furthermore non-cancerous murine fibroblasts exhibited marked concentration-dependent inhibition by bexarotene, while the degradation products elicited more pronounced antiproliferative action only at the highest applied concentration.