Evaluation of the Pharmacokinetics of the Pancreastatin Inhibitor PSTi8 Peptide in Rats: Integration of In Vitro and In Vivo Findings

PSTi8 is a pancreastatin inhibitory peptide that is effective in the treatment of diabetic models. This study investigates the pharmacokinetic (PK) properties of PSTi8 in Sprague Dawley rats, for the first time. In vitro and in vivo PK studies were performed to evaluate the solubility, stability in plasma and liver microsomes, plasma protein binding, blood–plasma partitioning, bioavailability, dose proportionality, and gender difference in PK. Samples were analyzed using the validated LC-MS/MS method. The solubility of PSTi8 was found to be 9.30 and 25.75 mg/mL in simulated gastric and intestinal fluids, respectively. The protein binding of PSTi8 was estimated as >69% in rat plasma. PSTi8 showed high stability in rat plasma and liver microsomes and the blood–plasma partitioning was >2. The bioavailability of PSTi8 after intraperitoneal and subcutaneous administration was found to be 95.00 ± 12.15 and 78.47 ± 17.72%, respectively, in rats. PSTi8 showed non-linear PK in dose proportionality studies, and has no gender difference in the PK behavior in rats. The high bioavailability of PSTi8 can be due to high water solubility and plasma protein binding, low clearance and volume of distribution. Our in vitro and in vivo findings support the development of PSTi8 as an antidiabetic agent.

Improvement of in vitro antioxidant activity of kaempferol by encapsulation in copolymer micelles

Antioxidant capacity of poorly soluble natural antioxidant kaempferol, in particular free or loaded in two types of cationic micelles, was studied on non-enzyme induced lipid peroxidation (LPO) in vitro. The micelles were based on triblock copolymers - poly(2-(dimethylamino)ethyl methacrylate-b-poly(propylene oxide)-b-poly(2-(dimethylamino)ethyl methacrylate (PDMAEMA-PPO-PDMAEMA) and poly(2-(dimethylamino)ethyl methacrylate-b-poly(ε-caprolactone)-b-poly(2-(dimethylamino)ethyl methacrylate (PDMAEMA-PCL-PDMAEMA). The lipid peroxidation was induced by incubating of rat liver microsomes with iron sulphate and ascorbic acid (Fe2+/AA). The effect of free and micellar kaempferol (at concentrations 25, 50 and 75 μg/ml) was assessed after 20 min incubation time. In the non-enzyme lipid peroxidation model, the kaempferol-loaded micelles significantly decreased the formation of malondialdehyde (MDA). The effect of kaempferol loaded in PDMAEMA-PCL-PDMAEMA micelles was more pronounced, showing an improved antioxidant activity in the conditions of oxidative stress and lipid peroxidation in vitro.

Clinical pharmacology of lorazepam in infants and children

Lorazepam is a benzodiazepine has antiepileptic activity; it may be administered intravenously, intramuscularly, orally, by intranasal or buccal application and following oral dosing it is well absorbed. In infants, the initial intravenous dose of lorazepam is 100 µg/kg and in children the initial oral and intravenous dose is 50 to 100 µg/kg and the dose varies according to the child age. Lorazepam has been found efficacy and safe in infants and children but it may induce adverse-effects. Lorazepam is a racemate and the R and S enantiomers are conjugated with glucuronic acid in human liver microsomes and the respective Km and Vmax values are 29+8.9 and 36+10 µM and 7.4+1.9 and 10+3.8 pmol/min*mg. Lorazepam interacts with drugs and the interaction may affect the activity or metabolism of lorazepam. The pharmacokinetics of lorazepam have been studied in infants and children and in diseased children. In infants and children the elimination half-life is about 15 hours and it is about 24 hours and about 37 hours in children with severe malaria and convulsions following intravenous and intramuscular administration, respectively. The treatment and trials with lorazepam have been studied in infants and children. Lorazepam freely crosses the human placenta and poorly migrates into the breast-milk. The aim of this study is to review the published data on lorazepam dosing, efficacy and safety, adverse-effects, metabolism, interaction with drugs, pharmacokinetics, treatment and trials in infants and children and the lorazepam transfer across the human placenta and migration into the breast-milk.

Eco-Friendly, Simple, Fast, and Sensitive UPLC-MS/MS Method for Determination of Pexidartinib in Plasma and Its Application to Metabolic Stability

Pexidartinib is the first drug approved by the U.S. Food and Drug Administration specifically to treat the rare joint tumor tenosynovial giant cell tumor. In the current study, a validated, selective, and sensitive UPLC-MS/MS assay was developed for the quantitative determination of pexidartinib in plasma samples using gifitinib as an internal standard (IS). Pexidartinib and IS were extracted by liquid-liquid extraction using methyl tert-butyl ether and separated on an acquity BEH C18 column kept at 40 °C using a mobile phase of 0.1% formic acid in acetonitrile: 0.1% formic acid in de-ionized water (70:30). The flow rate was 0.25 mL/min. Multiple reaction monitoring (MRM) was operated in electrospray (ESI)-positive mode at the ion transition of 418.06 > 165.0 for the analyte and 447.09 > 128.0 for the IS. FDA guidance for bioanalytical method validation was followed in method validation. The linearity of the established UPLC-MS/MS assay ranged from 0.5 to 1000 ng/mL with r > 0.999 with a limit of quantitation of 0.5 ng/mL. Moreover, the metabolic stability of pexidartinib in liver microsomes was estimated.

Phase I-metabolism studies of the synthetic cannabinoids PX-1 and PX-2 using three different in vitro models

Purpose Synthetic cannabinoids (SCs), highly metabolized substances, are rarely found unmodified in urine samples. Urine screening relies on SC metabolite detection, requiring metabolism knowledge. Metabolism data can be acquired via in vitro assays, e.g., human hepatocytes, pooled human liver microsomes (pHLM), cytochrome P450 isoforms and a fungal model; or in vivo by screening, e.g., authentic human samples or rat urine. This work describes the comprehensive study of PX-1 and PX-2 in vitro metabolism using three in vitro models. 5F-APP-PICA (PX-1) and 5F-APP-PINACA (PX-2) were studied as they share structural similarity with AM-2201, THJ-2201 and 5F-AB-PINACA, the metabolism of which was described in the literature. Methods For SC incubation, pHLM, cytochrome P450 isoenzymes and the fungal model Cunninghamella elegans LENDNER (C. elegans) were used. PX-1 and PX-2 in vitro metabolites were revealed comprehensively by liquid chromatography–high-resolution mass spectrometry measurements. Results In total, 30 metabolites for PX 1 and 15 for PX-2 were detected. The main metabolites for PX-1 and PX-2 were the amide hydrolyzed metabolites, along with an indole monohydroxylated (for PX-1) and a defluorinated pentyl-monohydroxylated metabolite (for PX-2). Conclusions CYP isoforms along with fungal incubation results were in good agreement to those obtained with pHLM incubation. CYP2E1 was responsible for many of the metabolic pathways; particularly for PX-1. This study shows that all three in vitro assays are suitable for predicting metabolic pathways of synthetic cannabinoids. To establish completeness of the PX-1 and PX-2 metabolic pathways, it is not only recommended but also necessary to use different assays.

Design, Synthesis, and Antidepressant Activity Study of Novel Aryl Piperazines Targeting Both 5-HT1A and Sigma-1 Receptors

A total of 20 novel aryl piperazine derivatives were designed and synthesized, and their structures were confirmed by mass spectrometry and nuclear magnetic resonance analyses. Their 5-HT1A and sigma-1 receptor affinities were determined, and six of them showed high affinities (K i < 20 nmol/L) to both 5-HT1A and sigma-1 targets. Then, metabolic stability (T 1/2) tests of six compounds in rat and human liver microsomes were performed. Our data indicated that compound 27 has both high affinity for 5-HT1A and sigma-1 receptors (5-HT1A: K i = 0.44 nmol/L; sigma-1: K i = 0.27 nmol/L), and good metabolic stability (T 1/2 values are 21.7 and 24.6 minutes, respectively). Interestingly, results from the forced swimming test, mouse tail suspension test, and preliminary pharmacokinetic test suggested the marked antidepressant activity, good pharmacokinetic characteristics, and low toxicity of compound 27 in the two models. In conclusion, compound 27 has great value of further study as an active molecule of antidepressant drugs.

Design, Synthesis and Anti-Lung Cancer Evaluation of 1, 2, 3-Triazole Tethered Dihydroartemisinin-Isatin Hybrids

A series of 1,2,3-triazole tethered dihydroartemisinin-isatin hybrids 8a-c and 9a-k were designed and synthesized. Their antiproliferative activity against A549, doxorubicin-resistant A549 (A549/DOX) as well as cisplatin-resistant A549 (A549/DDP) lung cancer cell lines was also investigated in this study. All hybrids (half maximal inhibitory concentration/IC50: 7.54–73.8 μM) were more potent than the parent drug dihydroartemisinin (IC50: 69.4–88.0 μM) and also non-cytotoxic towards mouse embryonic fibroblast cells NIH/3T3 (IC50: &gt;100 μM). The structure-activity relationships illustrated that the substituents on C-3 and C-5 position of isatin moiety influenced the activity significantly. Imine at C-3 position decreased the activity, whereas fluoro at C-5 position enhanced the activity. In particular, hybrids 8a,c (IC50: 7.54–12.1 μM) and 9i (IC50: 9.10–15.9 μM) were comparable to cisplatin (IC50: 7.54–15.9 μM vs 9.38–19.7 μM) against A549 and A549/DOX, but 4.6–7.6 folds more potent than that of cisplatin (IC50: 8.77–14.3 μM vs 66.9 μM) against A549/DDP cells. Moreover, hybrids 8a,c exhibited excellent stability (liver microsomes: 68–83%) in mouse/human microsomes and good pharmacokinetic properties, demonstrating their potential as a novel anti-lung cancer chemotherapeutic candidates.