Safety, tolerability, and pharmacokinetics of fluoropezil (DC20), a novel acetylcholinesterase inhibitor: A phase I study in healthy young and elderly Chinese subjects.

The present study evaluated the safety, tolerability, and pharmacokinetics of fluoropezil (DC20), a novel acetylcholinesterase inhibitor under development for the treatment of Alzheimer's disease (AD) in otherwise healthy young and elderly Chinese subjects. The study of young subjects included the multiple ascending dose (MAD) arm (2 and 6 mg, N = 24) and the food effect arm (4 mg, N = 12) and was followed by the study of elderly subjects who were given (2 and 4 mg, N = 11). The noncompartmental analysis method was used to determine the pharmacokinetic parameters. The pharmacokinetics of fed versus fasted dose administration in the same subjects was assessed by 90% confidence interval. In the MAD arm, the accumulation ratios of DC20 in vivo were 2.29 and 2.15, respectively. In the food effect arm, compared with fasting administration, an area under the concentration-time curve from zero to t after a standard and high-fat diet orally administered slightly increased by about 19% and 29%, and the time to maximum concentration (Tmax ) was delayed by around 1 h. For elderly study subjects, Tmax was 1.5 and 1.25 h, and terminal half-life (t1/2 ) was 77.1 and 74.2 h, respectively. There were no serious adverse events (AEs), whereas gastrointestinal reactions were the most common AEs associated with the study drug. We predicted the safety risks of DC20 in the clinical treatment of AD, which were well-tolerated by the healthy young and elderly subjects. The elimination of DC20 from the body was slower in elderly subjects than in young subjects. This study was approved by the Center for Drug Evaluation, National Medical Products Administration (CTR20181428, CTR20190664, CTR20191878, and CTR20192724).

LC-MS/MS assay of fluoropezil and its two major metabolites in human plasma: an application to pharmacokinetic studies.

Background: LC-MS/MS methods were developed for pharmacokinetic analysis and verified to measure fluoropezil, a new AchE inhibitor for Alzheimer's disease treatment, and its two primary metabolites (N-debenzyl fluoride fluoropezil [M1] and N-oxidized fluoropezil [M11]) in human plasma. Methods & results: Analytes were extracted from 50 µl plasma using protein precipitation and separated by HPLC using a bridged ethyl hybrid column and gradient elution procedure. Analytical detection was performed with a triple quadrupole mass spectrometer and electrospray ionization source in multiple reaction monitoring mode. The LC-MS/MS method was fully validated. The quantification linear ranges were 0.100-50.0 ng/ml (fluoropezil), 0.0500-25.0 ng/ml (M1) and 0.0500-25.0 ng/ml (M11). Conclusion: A sensitive, reliable LC-MS/MS method was established and used successfully to explore the pharmacokinetics of fluoropezil.

Non-cytochrome P450 enzymes involved in the oxidative metabolism of xenobiotics: Focus on the regulation of gene expression and enzyme activity.

Oxidative metabolism is one of the major biotransformation reactions that regulates the exposure of xenobiotics and their metabolites in the circulatory system and local tissues and organs, and influences their efficacy and toxicity. Although cytochrome (CY)P450s play critical roles in the oxidative reaction, extensive CYP450-independent oxidative metabolism also occurs in some xenobiotics, such as aldehyde oxidase, xanthine oxidoreductase, flavin-containing monooxygenase, monoamine oxidase, alcohol dehydrogenase, or aldehyde dehydrogenase-dependent oxidative metabolism. Drugs form a large portion of xenobiotics and are the primary target of this review. The common reaction mechanisms and roles of non-CYP450 enzymes in metabolism, factors affecting the expression and activity of non-CYP450 enzymes in terms of inhibition, induction, regulation, and species differences in pharmaceutical research and development have been summarized. These non-CYP450 enzymes are detoxifying enzymes, although sometimes they mediate severe toxicity. Synthetic or natural chemicals serve as inhibitors for these non-CYP450 enzymes. However, pharmacokinetic-based drug interactions through these inhibitors have rarely been reported in vivo. Although multiple mechanisms participate in the basal expression and regulation of non-CYP450 enzymes, only a limited number of inducers upregulate their expression. Therefore, these enzymes are considered non-inducible or less inducible. Overall, this review focuses on the potential xenobiotic factors that contribute to variations in gene expression levels and the activities of non-CYP450 enzymes.

Desorption electrospray ionization (DESI) source coupling ion mobility mass spectrometry for imaging fluoropezil (DC20) distribution in rat brain.

Fluoropezil (DC20) is a new selective acetylcholinesterase inhibitor, and it was developed for the treatment of Alzheimer's disease patients. In this study, a desorption electrospray ionization source coupling ion mobility mass spectrometry imaging (DESI/IMS-MSI) method was developed to explore the distribution of DC20 in brain tissue following oral administration. Rat brain coronal slices obtained 1 h and 3 h following drug dosing were used in the study. D6-DC20 was used as internal standard and sprayed by matrix sprayer on the brain slices to calibrate the matrix effect. Ion mobility separation was used to reduce the interference from background noise and the biological matrix. By optimizing DESI-MSI parameters for improved sensitivity, the limit of quantitation of the method was 1.45 pg/mm2 with a linear range from 1.45 to 72.7 pg/mm2. DESI-MSI data showed that DC20 could quickly enter and diffuse across whole brain and tended to be much more enriched in striatum than cerebral cortex and hippocampus, which was consistent with quantitative analysis using high-performance liquid chromatography-electrospray tandem mass spectrometry to measure DC20 concentration in each homogenized brain sub-region. The workflow of tissue imaging method optimization and strategy were established, and for the first time, the DESI-MSI technique and optimized method were used to explore the distribution characteristics of DC20 in rat brain, which could help elucidate pharmacological effect mechanisms and improve clinical outcomes.

Dual Action of Acidic Microenvironment on the Enrichment of the Active Metabolite of Disulfiram in Tumor Tissues.

Disulfiram, an antialcoholism drug, could potentially be repurposed as an anticancer drug because of the formation of copper(II) diethyldithiocarbamate (CuET) from dithiocarb (DTC, a reduced metabolite of disulfiram) and Cu2+ CuET exhibited preferential distribution to tumor tissues. This study investigated the mechanism of CuET accumulation in tumor tissues by employing MDA-MB-231 human breast cancer cells. The concentration of CuET in cells treated with DTC and Cu2+ in acidic culture medium (pH 6.8) was significantly higher than that of the control group (pH 7.4). Subsequently, the effects of pH on the uptake of DTC, Cu2+, and CuET were investigated separately. The acidic environment significantly increased the uptake rate of DTC and Cu2+ but had no effect on CuET. MDA-MB-231 cells overexpressing copper transporter hCTR1 were constructed to evaluate its intermediate role in CuET accumulation. After treatment with CuCl2 followed by DTC for 15 minutes, the levels of CuET and Cu2+ in hCTR1-overexpressed cells were 2.5 times as much as those of vector group. In the tumors of cancer xenograft models constructed by hCTR1-MDA-MB-231 cells, the concentrations of CuET and Cu were also significantly higher than those of control group. In conclusion, the acidic microenvironment of tumors can promote the enrichment of CuET in tumors through dual action. On the one hand, it can promote transmembrane transport of DTC by converting ionic DTC into molecular state. On the other hand, it enhances Cu2+ uptake by activating hCTR1, which ultimately leads to the enrichment of CuET. SIGNIFICANCE STATEMENT: Increasing evidence suggests that the antitumor activity of disulfiram is related to the formation of a copper(II) diethyldithiocarbamate (CuET) of its reducing metabolite dithiocarb with copper(II) ion, which is preferentially distributed in tumor tissues. We showed that the acidic microenvironment, a common feature of many solid tumor tissues, could promote intracellular CuET accumulation through dual action without changing CuET uptake. This result is helpful for the formulation of clinical dosage regimens of disulfiram in cancer treatment.