Characterization of metabolic fate of phellodendrine and its potential pharmacological mechanism against diabetes mellitus by ultra-high-performance liquid chromatography-coupled time-of-flight mass spectrometry and network pharmacology

RATIONALE

Characterizing the functional mechanism of quality control marker (Q-marker) was of great importance in revealing the primary pharmacological mechanism of herbs or the other complex system, and drug-related metabolites always contribute to the pharmacological functions. Cortex Phellodendri was used as a core herb in the treatment of diabetes mellitus (DM). As a Q-marker of Cortex Phellodendri, the role of phellodendrine in DM was still unclear. Thus, the characterization of phellodendrine-related metabolites in vivo and the subsequent induced functional mechanism exerted great importance in elucidating the anti-DM mechanism of Cortex Phellodendri.

METHODS

An ultra-high-performance liquid chromatography-coupled time-of-flight mass spectrometry (UHPLC/Q-TOF MS) method was developed to profile metabolites of phellodendrine in rats. The potential pharmacological mechanism against DM was predicted by network pharmacology.

RESULTS

A total of 19 phellodendrine-related metabolites were screened out in rats for the first time. Among them, M4, M5, M9, and M12 were regarded as the primary metabolites. Meanwhile, phase I metabolic reactions of hydroxylation, demethylation, and isomerization and phase II reactions of glucuronidation and sulfation occurred to phellodendrine; glucuronidation and hydroxylation were the two main metabolic reactions. Moreover, the potential targets of phellodendrine and three main metabolites (M4, M5, and M12) were predicted by a network pharmacological method, and they mainly shared 52 targets, including PDE5A, CHRNA3, SIGMAR1, F3, ESR1, DRD1, DRD2, DRD3, and DRD4. Furthermore, Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that calcium signaling pathway, cGMP-PKG signaling pathway, and cAMP signaling pathway were regarded as the core mechanism of phellodendrine to treat DM.

CONCLUSION

The metabolic feature of phellodendrine in vivo was revealed for the first time, and its anti-DM mechanism information for further pharmacological validations was also supplied. It also gave a direction to further elucidation of pharmacological mechanism of Cortex Phellodendri in treating DM.

Pharmacokinetic Characterization and Bioavailability Barrier for the Key Active Components of Botanical Drug Antitumor B (ATB) in Mice for Chemoprevention of Oral Cancer

This study aims to characterize the pharmacokinetic (PK) profiles and identify important bioavailability barriers and pharmacological pathways of the key active components (KACs) of Antitumor B (ATB), a chemopreventive agent. KACs (matrine, dictamine, fraxinellone, and maackiain) of ATB were confirmed using the antiproliferative assay and COX-2 inhibition activities in oral cancer cells. The observed in vitro activities of KACs were consistent with their cell signaling pathways predicted using the in silico network pharmacology approach. The pharmacokinetics of KACs were determined after i.v., i.p., and p.o. delivery using ATB extract and a mixture of four KACs in mice. Despite good solubilities and permeabilities, poor oral bioavailabilities were estimated for all KACs, mostly because of first-pass metabolism in the liver (for all KACs) and intestines (for matrine and fraxinellone). Multiple-dose PK studies showed 23.2-fold and 8.5-fold accumulation of dictamine and maackiain in the blood, respectively. Moreover, saliva levels of dictamine and matrine were found significantly higher than their blood levels. In conclusion, the systemic bioavailabilities of ATB-KACs were low, but significant levels of dictamine and matrine were found in saliva upon repeated oral administration. Significant salivary concentrations of matrine justified its possible use as a drug-monitoring tool to track patient compliance during chemoprevention trials.

Matrine: A review of its pharmacology, pharmacokinetics, toxicity, clinical application and preparation researches

ETHNOPHARMACOLOGICAL RELEVANCE

"Dogel ebs" was known as Sophora flavescens Ait., which has been widely utilized in the clinical practice of traditional Chinese Mongolian herbal medicine for thousands of years. Shen Nong's Materia Medica (Shen Nong Ben Cao Jing in Chinese pinyin) recorded that it is bitter in taste and cold in nature with the effect of clearing heat and eliminating dampness, insecticide, diuresis. Due to its extensive application in the fields of ethnopharmacological utilization, the pharmaceutical researches of Sophora flavescens Ait.s keeps deepening. Modern pharmacological studies have exhibited that matrine, which is rich in this traditional herbal medicine, mediates its main biological properties.

AIMS OF THE REVIEW

This review aimed at summarizing the latest and comprehensive information of matrine on the pharmacology, pharmacokinetics, toxicity, clinical application and preparation researches to explore the therapeutic potential of this natural ingredient. In addition, outlooks and perspective for possible future researches that related are also discussed.

MATERIALS AND METHODS

Related information concerning matrine was gathered from the internet database of Google scholar, Pubmed, ResearchGate, Web of Science and Wiley Online Library with the keywords including "matrine", "pharmacology", "toxicology" and "pharmacokinetics", "clinical application", etc. RESULTS: Based on literatures, matrine has a variety of pharmacological effects, including anti-cancer, anti-inflammatory, anti-microbial, detoxification and so on. Nevertheless, there are still some doubts about it due to the toxicity and questionable bioavailability that does exist.

CONCLUSIONS

Future researches directions probably include elucidate the mechanism of its toxicity and accurately tracing the in vivo behavior of its drug delivery system. Without doubt, integration of toxicity and efficiency and structure modification based on it are also pivotal methods to enhance pharmacological activity and bioavailability.

Polysaccharides of vinegar-baked radix bupleuri promote the hepatic targeting effect of oxymatrine by regulating the protein expression of HNF4α, Mrp2, and OCT1

ETHNOPHARMACOLOGICAL RELEVANCE

Vinegar-baked Radix Bupleuri (VBRB) is a processed form of Bupleurum chinense DC. As a well-known meridian-guiding drug, it is traditionally used as a component of traditional Chinese medicine formulations indicated for the treatment of liver diseases. However, the liver targeting component in VBRB remains unclear. Therefore, this study aims to explore the efficacy and mechanism of PSS (polysaccharides in Vinegar-baked Radix Bupleuri) in enhancing liver targeting.

MATERIALS AND METHODS

Drug distribution of OM alone or combined with PSS was investigated in vivo. Relative uptake efficiency (RUE) and relative targeting efficiency (RTE) were calculated to evaluate liver targeting efficiency. The mRNA and protein expression of organic cation transporter 1 (OCT1), multi-drug resistance protein 2 (Mrp2), and hepatocyte nuclear factor 4α (HNF4α) in the liver were determined by q-PCR and Western blot. Then, AZT, the inhibitor of OCT1 and BI6015, the inhibitor of HNF4α were used to investigate regulatory mechanisms involved in the uptake of OM in the cell. At last, the role of PSS in the anti-hepatitis B virus (HBV) was explored on HepG2.2.15.

RESULTS

PSS increased the AUC of OM in the liver and increase the RUE and RTE in the liver which indicated a liver targeting enhancing effect. The mRNA and protein expression of OCT1 was increased while Mrp2 and HNF4α decreased. PSS could increase the uptake of OM in HepG2 by increasing the protein expression of HNF4α and OCT1, while inhibited Mrp2. Moreover, PSS combined with OM could enhance the anti-HBV effect of OM.

CONCLUSION

PSS enhanced the liver targeting efficiency and the underlying mechanism related to up-regulating the expression of OCT1 and HNF4α, while down-regulating of Mrp2. These results suggest that PSS may become a potential excipient and provide a new direction for new targeted research.

Pharmacokinetics of vatinoxan in male neutered cats anesthetized with isoflurane

OBJECTIVE

To characterize the pharmacokinetics of vatinoxan in isoflurane-anesthetized cats.

STUDY DESIGN

Prospective experimental study.

ANIMALS

A group of six adult healthy male neutered cats.

METHODS

Cats were anesthetized using isoflurane in oxygen. Venous catheters were placed to administer the drug and sample blood. Vatinoxan, 1 mg kg^-1, was administered intravenously over 5 minutes. Blood was sampled before and at various times during and up to 8 hours after vatinoxan administration. Plasma vatinoxan concentration was measured using liquid chromatography/tandem mass spectrometry. Compartment models were fitted to the time-concentration data using population methods and nonlinear mixed effect modeling.

RESULTS

A three-compartment model best fitted the data. Typical value (% interindividual variability) for the three volumes (mL kg^-1), the metabolic clearance and two distribution clearances (mL minute^-1 kg^-1) were 34 (55), 151 (35), 306 (18), 2.3 (34), 42.6 (25) and 5.6 (0), respectively. Hypotension increased the second distribution clearance to 10.6.

CONCLUSION AND CLINICAL RELEVANCE

The pharmacokinetics of vatinoxan in anesthetized cats were characterized by a small volume of distribution and a low clearance. An intravenous bolus of 100 μg kg^-1 of vatinoxan followed by constant rate infusions of 55 μg kg^-1 minute^-1 for 20 minutes, then 22 μg kg^-1 minute^-1 for 60 minutes and finally 10 μg kg^-1 minute^-1 for the remainder of the infusion time is expected to maintain the plasma concentration within 90%-110% of the plasma vatinoxan concentration previously shown to attenuate the cardiovascular effects of dexmedetomidine (25 μg kg^-1) in conscious cats.

Effects of vatinoxan on cardiorespiratory function, fecal output and plasma drug concentrations in horses anesthetized with isoflurane and infusion of medetomidine

A constant rate infusion (CRI) of medetomidine is used to balance equine inhalation anesthesia, but its cardiovascular side effects are a concern. This experimental crossover study aimed to evaluate the effects of vatinoxan (a peripheral α2-adrenoceptor antagonist) on cardiorespiratory and gastrointestinal function in anesthetized healthy horses. Six horses received medetomidine hydrochloride 7μg/kg IV alone (MED) or with vatinoxan hydrochloride 140μg/kg IV (MED+V). Anesthesia was induced with midazolam and ketamine and maintained with isoflurane and medetomidine CRI for 60min. Heart rate, carotid and pulmonary arterial pressures, central venous pressure, cardiac output and arterial and mixed venous blood gases were measured. Selected cardiopulmonary parameters were calculated. Plasma drug concentrations were determined. Fecal output was measured over 24h. For statistical comparisons, repeated measures analysis of covariance and paired t-tests were applied. Heart rate decreased slightly from baseline in the MED group. Arterial blood pressures decreased with both treatments, but significantly more dobutamine was needed to maintain normotension with MED+V (P=0.018). Cardiac index (CI) and oxygen delivery index (DO₂I) decreased significantly more with MED, with the largest difference observed at 20min: CI was 39±2 and 73±18 (P=0.009) and DO₂I 7.4±1.2 and 15.3±4.8 (P=0.014)mL/min/kg with MED and MED+V, respectively. Fecal output or plasma concentrations of dexmedetomidine did not differ between the treatments. In conclusion, premedication with vatinoxan induced hypotension, thus its use in anesthetized horses warrants further studies. Even though heart rate and arterial blood pressures remained clinically acceptable with MED, cardiac performance and oxygen delivery were lower than with MED+V.

Effects of dexmedetomidine, with or without vatinoxan (MK-467), on minimum alveolar concentration of isoflurane in cats

OBJECTIVE

To characterize the effects of dexmedetomidine, with or without vatinoxan, on the minimum alveolar concentration of isoflurane (MACISO) in cats.

STUDY DESIGN

Randomized crossover experimental study.

ANIMALS

A group of six adult healthy male neutered cats.

METHODS

Cats were anesthetized with isoflurane in oxygen and instrumented. Dexmedetomidine was administered using a target-controlled infusion system to achieve 10 target plasma concentrations ranging from 0 to 40 ng mL-1. Additionally, vatinoxan or an equivalent volume of saline was administered using a target-controlled infusion system to achieve a target plasma concentration of 4 μg mL-1. Pulse rate (PR), respiratory rate, systolic arterial pressure (SAP), hemoglobin oxygen saturation, body temperature, end-tidal partial pressure of carbon dioxide and drug concentrations were measured. MACISO was determined at each target plasma dexmedetomidine concentration using the bracketing method and the tail clamp technique. Pharmacodynamic models were fitted to the plasma dexmedetomidine concentration-MACISO. Pharmacodynamic parameters were tested for equivalence, and if rejected, for difference.

RESULTS

Dexmedetomidine alone decreased MACISO in a plasma concentration-dependent manner. Maximum reduction was 77 ± 4%; the dexmedetomidine concentration producing 50% of the maximum decrease (IC50) was 0.77 ng mL-1. Vatinoxan increased MACISO in the absence of dexmedetomidine, decreased the potency of dexmedetomidine for its MACISO-reducing effect (IC50 = 12 ng mL-1) and lessened the maximum MACISO reduction (60 ± 14%). PR decreased less and SAP increased less when dexmedetomidine was administered with vatinoxan compared with saline.

CONCLUSION AND CLINICAL RELEVANCE

Vatinoxan altered the effect of dexmedetomidine on MACISO. A high plasma dexmedetomidine concentration in the presence of vatinoxan resulted in a large decrease in MACISO, with attenuation of dexmedetomidine-induced cardiovascular effects. The vatinoxan-dexmedetomidine combination may provide clinical benefits in isoflurane-anesthetized cats.

Preliminary pharmacokinetics of intravenous and subcutaneous dolasetron and pharmacodynamics of subcutaneous dolasetron in healthy cats

Objectives The objectives were to evaluate the pharmacokinetics (PK) of subcutaneous (SC) and intravenous (IV) dolasetron and the pharmacodynamics (PD) of SC dolasetron in healthy cats. Methods Five cats with unremarkable complete blood count, serum biochemistry and urinalyses were utilized. In the PK study, cats received 0.8 mg/kg SC and IV dolasetron in a crossover format. Serum samples were obtained via a jugular catheter at 0, 0.25, 0.5, 1, 2, 4, 8, 12, 24, 36 and 48 h after the administration of dolasetron. Dolasetron and the active metabolite hydrodolasetron were measured using liquid chromatography/tandem mass spectrometry. Non-compartmental PK analysis was performed. In the PD study, SC dolasetron (0.8 mg/kg and 1.0 mg/kg) and saline were administered 30 mins prior to administration of 0.44 mg/kg intramuscular xylazine in a randomized three-way crossover. Number of emetic events, lip licks, time to onset of emesis and visual nausea score were scored by a blinded observer. Results In the PK study, dolasetron was quickly metabolized to the active metabolite hydrodolasetron, limiting assessment of dolasetron PK parameters. Median (range) PK parameters for IV hydrodolasetron were as follows: maximum serum concentration (Cmax) 116 ng/ml (69-316 ng/ml), time to maximum concentration (Tmax) 0.5 h (0.3-0.5 h), half-life 3.3 h (2.9-7.2 h) and area under the curve until the last measurable concentration (AUClast) 323 h/ng/ml (138-454 h/ng/ml). Median (range) PK parameters for SC hydrodolasetron were as follows: Cmax 67.9 ng/ml (60.4-117 ng/ml), Tmax 0.5 h (0.5-1.0 h), half-life 3.8 h (2.9-5.3 h) and AUClast 437 h/ng/ml (221.5-621.8 h/ng/ml). There was no significant difference in exposure to hydrodolasetron between the routes of administration. With regard to PD, when dolasetron was administered prior to xylazine, there was no significant difference in the mean number of emetic events, lip licks, time to onset of emesis or visual nausea score when compared with saline. Conclusions and relevance Administration of 0.8 mg/kg dolasetron does not maintain serum concentrations of active metabolite for 24 h. Administration of dolasetron at 0.8 mg/kg and 1 mg/kg did not prevent xylazine-induced vomiting. Additional feline dose studies are needed to determine if a higher dose is efficacious.

The role of active transport in the transcellular movement of the peripheral α2-adrenoceptor antagonist, MK-467: An in vitro pilot study

MK-467 is a peripherally acting α₂-adrenoceptor antagonist due to its low lipid solubility and poor penetration of the blood-brain barrier (BBB). The aim of this study was to assess whether MK-467 could be a substrate of an active efflux transport mechanism. Using Madin-Darby Canine Kidney cells (MDCKII) and MDCKII cells transfected with the human multidrug resistance gene 1, drug transport was assessed in apical-basolateral and basolateral-apical directions. MK-467 was studied at 2 concentrations: 200 and 1000 ng/mL. Samples for analysis were taken at 15, 30, 45, 60, and 90 min after drug application. Drug concentrations were measured using liquid chromatography and mass spectrometry. MK-467 showed no apparent permeability in the apical-basolateral direction, transport in the basolateral-apical direction occurred in both cell lines. Efflux ratios were not calculated. However, MK-467 appeared to undergo active cellular transport. The identity of the transporter requires further investigation.

A ten fold reduction of nicotine yield in tobacco smoke does not spare the central cholinergic system in adolescent mice

The tobacco industry has gradually decreased nicotine content in cigarette smoke but the impact of this reduction on health is still controversial. Since the central cholinergic system is the primary site of action of nicotine, here, we investigated the effects of exposure of adolescent mice to tobacco smoke containing either high or low levels of nicotine on the central cholinergic system and the effects associated with cessation of exposure. From postnatal day (PN) 30 to 45, male and female Swiss mice were exposed to tobacco smoke (whole body exposure, 8h/day, 7 days/week) generated from 2R1F (HighNic group: 1.74mg nicotine/cigarette) or 4A1 (LowNic group: 0.14mg nicotine/cigarette) research cigarettes, whereas control mice were exposed to ambient air. Cholinergic biomarkers were assessed in the cerebral cortex and midbrain by the end of exposure (PN45), at short- (PN50) and long-term (PN75) deprivation. In the cortex, nicotinic cholinergic receptor upregulation was observed with either type of cigarette. In the midbrain, upregulation was detected only in HighNic mice and remained significant in females at short-term deprivation. The high-affinity choline transporter was reduced in the cortex: of HighNic mice by the end of exposure; of both HighNic and LowNic females at short-term deprivation; of LowNic mice at long-term deprivation. These decrements were separable from effects on choline acetyltransferase and acetylcholinesterase activities, suggesting cholinergic synaptic impairment. Here, we demonstrated central cholinergic alterations in an animal model of tobacco smoke exposure during adolescence. This system was sensitive even to tobacco smoke with very low nicotine content.

Pharmacokinetic study of 14-(3-methylbenzyl)matrine and 14-(4-methylbenzyl)matrine in rat plasma using liquid chromatography-tandem mass spectrometry

A rapid, sensitive and selective high-performance liquid chromatography-tandem mass spectrometric method (HPLC-MS) was developed and validated to determine the 14-(3-methylbenzyl)matrine (3MBM) and 14-(4-methylbenzyl)matrine (4MBM) levels in rat plasma in the present study. The analytes were separated using a C18 column (1.9 μm, 2.1 mm × 100 mm) equipped with a Security Guard C18 column (5 μm, 2.1 mm × 10 mm), followed by detection via triple-quadrupole mass spectrometry using an electrospray ionization (ESI) source. Sample pretreatment involved one-step protein precipitation with isopropanol:ethyl acetate (v/v, 25:75), and pseudoephedrine hydrochloride was used as an internal standard. The method was linear in the concentration range of 5-2000 ng/ml for both compounds. The intra-day and inter-day relative standard deviations (RSDs) were less than 15%, and all relative errors (REs) were within 15%. The proposed method enables the unambiguous identification and quantification of these two compounds in vivo. This study is the first to determine the 3MBM and 4MBM levels in rat plasma after oral administration of these compounds. These results provide a meaningful basis for evaluating the clinical applications of these medicines.

[Study on preparation of matrine double-sensitive colon-specific pellets and in vitro release]

OBJECTIVE

To prepare matrine double-sensitive colon-specific pellets and study the factors affecting its quality and evaluateing the colon-specific effects of preparation.

METHOD

Matrine enzyme-sensitive pellets core were prepared by carboxymethyl konjac glucomannan as the main carrier material, and coated the core by acrylic resin II and III to prepare matrine double-sensitive colon-specific pellets. The prescription and technology of the matrine colon-specific pellets were studied by the single factor investigation, through the in vitro release test and coating rate determination.

RESULT

The optimized process conditions: FeCl3 concentration is 4.0 g x L(-1), chitosan concentration is 3.0 g x L(-1), carboxymethyl konjac glucomannan concentration is 20 g x L(-1), mixed gel solution pH value is 3. The release of matrine is less than 30% in the simulation of the upper gastrointestinal medium. The release of matrine is close to 100% in simulated full gastrointestinal medium, the coating weight is 7%.

CONCLUSION

The prepared pellets have good colon positioning effect in vitro.

Protective effects of oxymatrine on experimental diabetic nephropathy

Diabetic nephropathy, one of the most common and serious vascular complications of both type 1 and type 2 diabetes mellitus, has become a major contributor of end-stage renal failure. The aims of this study were to investigate the effects and possible underlying action mechanism(s) of oxymatrine on renal damage in diabetic rats. Diabetes was induced in male Sprague-Dawley rats by administering a high-fat diet and an intraperitoneal 30 mg/kg streptozotocin injection. The animals were treated orally with saline, metformin hydrochloride, and oxymatrine at 50, 100, and 150 mg/kg/day for 11 weeks. At the end of the treatment, renal tissue, blood, and urine samples were collected for histological and biochemical examination. The results revealed that oxymatrine significantly decreased blood glucose, urinary protein and albumin excretion, serum creatinine, and blood urea nitrogen in diabetic rats, and ameliorated diabetes-induced glomerular and tubular pathological changes. Furthermore, oxymatrine significantly prevented oxidative stress and reduced the contents of renal advanced glycation end products, transforming growth factor-β1, connective tissue growth factor, and inflammatory cytokines in diabetic rats. All these results indicate that oxymatrine has protective effects on experimental diabetic nephropathy by multiple mechanisms.

Monitoring cholinergic activity during attentional performance in mice heterozygous for the choline transporter: a model of cholinergic capacity limits

Reductions in the capacity of the human choline transporter (SLC5A7, CHT) have been hypothesized to diminish cortical cholinergic neurotransmission, leading to risk for cognitive and mood disorders. To determine the acetylcholine (ACh) release capacity of cortical cholinergic projections in a mouse model of cholinergic hypofunction, the CHT+/- mouse, we assessed extracellular ACh levels while mice performed an operant sustained attention task (SAT). We found that whereas SAT-performance-associated increases in extracellular ACh levels of CHT+/- mice were significantly attenuated relative to wildtype littermates, performance on the SAT was normal. Tetrodotoxin-induced blockade of neuronal excitability reduced both dialysate ACh levels and SAT performance similarly in both genotypes. Likewise, lesions of cholinergic neurons abolished SAT performance in both genotypes. However, cholinergic activation remained more vulnerable to the reverse-dialyzed muscarinic antagonist atropine in CHT+/- mice. Additionally, CHT+/- mice displayed greater SAT-disrupting effects of reverse dialysis of the nAChR antagonist mecamylamine. Receptor binding assays revealed a higher density of α4β2* nAChRs in the cortex of CHT+/- mice compared to controls. These findings reveal compensatory mechanisms that, in the context of moderate cognitive challenges, can overcome the performance deficits expected from the significantly reduced ACh capacity of CHT+/- cholinergic terminals. Further analyses of molecular and functional compensations in the CHT+/- model may provide insights into both risk and resiliency factors involved in cognitive and mood disorders.

N-substituted benzyl matrinic acid derivatives inhibit hepatitis C virus (HCV) replication through down-regulating host heat-stress cognate 70 (Hsc70) expression

Heat-stress cognate 70 (Hsc70) is a host factor that helps hepatitis C virus (HCV) to complete its life cycle in infected hepatocytes. Using Hsc70 as a target for HCV inhibition, a series of novel N-substituted benzyl matrinic/sophoridinic acid derivatives was synthesized and evaluated for their anti-HCV activity in vitro. Among these analogues, compound 7c possessing N-p-methylbenzyl afforded an appealing ability to inhibit HCV replication with SI value over 53. Furthermore, it showed a good oral pharmacokinetic profile with area-under-curve (AUC) of 13.4 µM·h, and a considerably good safety in oral administration in mice (LD₅₀>1000 mg/kg). As 7c suppresses HCV replication via an action mode distinctly different from that of the marketed anti-HCV drugs, it has been selected as a new mechanism anti-HCV candidate for further investigation, with an advantage of no or decreased chance to induce drug-resistant mutations.

Lack of Effect of Aprepitant on Hydrodolasetron Pharmacokinetics in CYP2D6 Extensive and Poor Metabolizers

To prevent chemotherapy-induced nausea and vomiting, aprepitant is given with a corticosteroid and a 5-hydroxytryptamine type 3 antagonist, such as dolasetron. Dolasetron is converted to the active metabolite hydrodolasetron, which is cleared largely via CYP2D6. The authors determined whether aprepitant, a moderate CYP3A4 inhibitor, alters hydrodolasetron pharmacokinetics in CYP2D6 poor and extensive metabolizers. Six CYP2D6 poor and 6 extensive metabolizers were randomized in an open-label, crossover fashion to treatment A (dolasetron 100 mg on day 1) and treatment B (dolasetron 100 mg plus aprepitant 125 mg on day 1, aprepitant 80 mg on days 2-3). For hydrodolasetron area under the concentration-versus-time curve (AUC0-infinity) and peak plasma concentration (Cmax), geometric mean ratios (B/A) and 90% confidence intervals (CIs) fell below the predefined limit (2.0) for clinical significance (AUC0-infinity, 1.09 [90% CI, 1.01-1.18], Cmax, 1.08 [90% CI, 0.94-1.24]). Aprepitant did not affect the pharmacokinetics of hydrodolasetron, regardless of CYP2D6 metabolizer type, and was generally well tolerated when coadministered with dolasetron in volunteers.

[Preparation of sustained release microspheres containing oxymatrine and their release characteristics in vitro]

OBJECTIVE

To prepare poly(lactide-co-glycolide) (PLGA) microspheres containing Oxymatrine (OMT-PLGA-MS) and study their release characteristics in vitro.

METHODS

OMT-PLGA-MS was prepared with PLGA as carriers using double emulsion solvent evaporation method (W/O/W). The preparation technology of microspheres was optimized by orthogonal design, and the microspheres were characterized in terms of morphology, the rate of drug loading, encapsulation efficiency, and in vitro drug release.

RESULTS

The formed microspheres were spherical with smooth surfaces and the average size was (98.3 +/- 3.4) microm. The encapsulation efficiency and rate of drug loading were (70.14 +/- 3.47)% and (21.59 +/- 1.07)%, respectively. In vitro release study revealed that 84.63% of OMT was released from OMT-PLGA-MS in 240 hours, and the Higuchi model fitted OMT release pattern best.

CONCLUSION

OMT-PLGA-MS is prepared successfully and shows good sustained release characteristics.

[Preparation and pharmaceutical characterization of Marine-SSL]

OBJECTIVE

To prepare and characterize marine sterically stabilized liposomes (Marine-SSL).

METHODS

Liposomes were prepared by ethanol injection technique. An orthogonal test was utilized to optimize the formulation and preparation of Marine-SSL The unencapsulated marine and liposomes were separated by sephadex gel G-50, the encapsulation efficiency was detected by HPLC. The morphological examination of Marine-SSL was performed using transmission electron microscopy. The particle size and Zeta potential of the liposomes were measured. The in vitro release rate of marine from liposomes was tested.

RESULTS

The liposomes with spherical or ellipsoidal shape and better stability featured the encapsulation efficiency of (85.39 +/- 1.21)%, the mean partical size of (156 +/- 10) nm, and Zeta potential of (- 39.0 +/- 3.06) mv. The release kinetics in vitro obeyed Higuchi equation. The stability of Marine-SSL was better.

CONCLUSION

The selected formulation and preparation technic of Marine-SSL are rational and stable and liposomes feature a sustained release in vitro.

Identification of phenanthroindolizines and phenanthroquinolizidines as novel potent anti-coronaviral agents for porcine enteropathogenic coronavirus transmissible gastroenteritis virus and human severe acute respiratory syndrome coronavirus

The discovery and development of new, highly potent anti-coronavirus agents and effective approaches for controlling the potential emergence of epidemic coronaviruses still remains an important mission. Here, we identified tylophorine compounds, including naturally occurring and synthetic phenanthroindolizidines and phenanthroquinolizidines, as potent in vitro inhibitors of enteropathogenic coronavirus transmissible gastroenteritis virus (TGEV). The potent compounds showed 50% maximal effective concentration (EC₅₀) values ranging from 8 to 1468 nM as determined by immunofluorescent assay of the expression of TGEV N and S proteins and by real time-quantitative PCR analysis of viral yields. Furthermore, the potent tylophorine compounds exerted profound anti-TGEV replication activity and thereby blocked the TGEV-induced apoptosis and subsequent cytopathic effect in ST cells. Analysis of the structure-activity relations indicated that the most active tylophorine analogues were compounds with a hydroxyl group at the C14 position of the indolizidine moiety or at the C3 position of the phenanthrene moiety and that the quinolizidine counterparts were more potent than indolizidines. In addition, tylophorine compounds strongly reduced cytopathic effect in Vero 76 cells induced by human severe acute respiratory syndrome coronavirus (SARS CoV), with EC₅₀ values ranging from less than 5 to 340 nM. Moreover, a pharmacokinetic study demonstrated high and comparable oral bioavailabilities of 7-methoxycryptopleurine (52.7%) and the naturally occurring tylophorine (65.7%) in rats. Thus, our results suggest that tylophorine compounds are novel and potent anti-coronavirus agents that may be developed into therapeutic agents for treating TGEV or SARS CoV infection.

[Pharmacokinetics and bioavailability of sustained-release tablets of matrine in dogs]

OBJECTIVE

To study the pharmacokinetics and bioavailability of sustained-release tablets of Matrine in dogs.

METHODS

6 dogs were randomly assigned to receive sustained-release tablets or commercial capsules 300 mg, then a crossover trial was conducted 1 week later. Plasma samples were taken at different time points and the plasma concentration of Oxymatrine and Matrine in dogs was determined by HPLC.

RESULTS

The pharmacokinetic parameters of self-made sustained-release tablets versus those of its control preparation were as follows: Tmax: (6.17 +/- 2.04) (M), (3.25 +/- 0.61) (OM), (4.75 +/- 1.17) (M), (2.42 +/- 0.38) (OM) h; Cmax: (3.79 +/- 1.11) (M), (4.76 +/- 0.60) (OM), (5.35 +/- 0.72) (M), (7.04 +/- 0.47) (OM) microg/mL; AUC(0-->infinity): (45.15 +/- 11.77) (M), (32.38 +/- 4.60) (OM) and (44.71 +/- 5.52) (M), (29.11 +/- 4.41) (OM) microg x h/mL.

CONCLUSION

The self-made sustained-release tablets and commercial capsules bioequivalent.

Effect of casopitant, a novel NK-1 antagonist, on the pharmacokinetics of dolasetron and granisetron

OBJECTIVE

The objective of this study was to characterize the impact of casopitant, a novel neurokinin-1 receptor antagonist under investigation for the prevention of postoperative and chemotherapy-induced nausea and vomiting, on the pharmacokinetics of the commonly prescribed 5-hydroxytryptamine receptor 3 receptor antagonists, dolasetron or granisetron.

MATERIALS AND METHODS

In a phase I, open-label, two-part, two-period, single-sequence study, two cohorts of healthy subjects received either oral dolasetron (100 mg once daily for 3 days) or oral granisetron (2 mg once daily for 3 days) alone (period 1) and combined with oral casopitant, 150 mg day 1, 50 mg days 2 and 3 (period 2). Pharmacokinetics of hydrodolasetron and granisetron were assessed on days 1 and 3 of each period. Log-transformed area under the curve (AUC) and Cmax were statistically analyzed by performing an analysis of variance. Eighteen subjects were enrolled in the dolasetron cohort; nine subjects were CYP2D6 extensive metabolizers (EMs) and nine subjects were CYP2D6 poor metabolizers. Nineteen subjects were enrolled in the granisetron cohort.

RESULTS

The largest changes in hydrodolasetron exposure after coadministration with casopitant were seen in CYP2D6 EMs, with a 24% increase in hydrodolasetron AUC on day 1 and 30% increase in Cmax on days 1 and 3. All other changes in hydrodolasetron exposure were <20%, and granisetron exposure was not altered to any relevant extent (<11%).

CONCLUSION

None of the changes observed are considered clinically meaningful, and coadministration of casopitant with dolasetron or granisetron was well tolerated.

[Study on pharmacokinetics and tissue distribution of stealth matrine liposomes in rats]

OBJECTIVE

To determine the concentration of matrine in rats plasma and tissue and study the pharmacokinetics and tissues distribution of matrine solution (MS), regular matrine liposome (ML) and stealth matrine liposome (LML) after the intravenous administration at a single dose of 15 mg x kg(-1) to rats.

METHOD

Reversed-phase HPLC was used to determine matrine concentration in rats plasma and tissues.

RESULT

The concentration-time curves of MS, ML and LML were fitted to a two-compartment model. The terminal half-life of LML was 2.7-fold higher than MS and 2-fold higher than ML. The area under the plasma concentration curve (AUC) of LML was 63-fold higher than MS and 2.3-fold higher than ML. Tissues distribution results proved that the area under the plasma concentration curve of LML was significantly different from ML and MS (P<0.05). The area under the liver and spleen curve of LML was significantly different from ML (P<0.05). The ratio between the area under the curve of plasma and the area under the curve of reticulo-endothelial system (Blood/RES) of LML was 5.4-fold higher than ML.

CONCLUSION

Our present studies demonstrate that, compared to MS and ML, LML significantly alters its pharmacokinetics in plasma and tissues targeting.

[Simultaneous determination of matrine, oxysophocarpin and oxymatrine in rat plasma by HPLC-MS and its application in the pharmacokinetic study]

To establish an HPLC-MS method for simultaneous determination of matrine, oxymatrine and oxysophocarpine in rat plasma after oral administration of herbal preparation, namely Sanwu Huangqin decoction, and the pharmacokinetic porameters were calculated as well. Matrine, oxymatrine, oxysophocarpine, and internal standard pseudoephedrine were extracted from plasma with liquid-liquid extraction, then separated on a Kromasil C18 column by using acetonitrile-0.1% aqueous formic acid (10 : 90) as mobile phase. Electrospray ionization (ESI) source was applied and operated in positive ion mode. The linear calibration curve was obtained in the concentration range of 10 -5 000 ng x mL(-1) for matrine, 2 - 1 000 ng x mL(-1) for oxymatrine, and 2 - 1 000 ng x mL(-1) for oxysophocarpine. The extraction recovery was 89.1% - 93.5%, 83.9% - 91.3%, and 85.4% - 88.0% accordingly. The inter- and intra- day precision (RSD) was below 15.0% calculated from quality control (QC) samples. Matrine, oxymatrine and oxysophocarpine concentration time profile conformed to a two-compartment pharmacokinetic model. The method was shown to be effective, convenient, and suitable for simultaneous pharmacokinetic study of matrine, oxymatrine, and oxysophocarpine in rat.

Cytisine for smoking cessation: a research agenda

Cytisine has a molecular structure somewhat similar to that of nicotine and varenicline. The concept for the new smoking cessation drug varenicline was based partly on cytisine. Like varenicline, cytisine is a partial agonist of nicotinic acetylcholine receptors, with high affinity for alpha4beta2 receptors. Cytisine has been used since the 1960s as a smoking cessation drug in Eastern and Central Europe, but has remained largely unnoticed elsewhere. Three placebo-controlled trials, conducted in East and West Germany in the 1960s and 1970s, suggest that cytisine, even with minimal behavioural support, may be effective in aiding smoking cessation. Cytisine tablets are very inexpensive to produce and could be a more affordable treatment than nicotine replacement, bupropion and varenicline. There is however a dearth of scientific research on the properties of cytisine, including safety, abuse liability and efficacy. This paper seeks to identify research priorities for molecular, animal and clinical studies. In particular, new studies are necessary to define the nicotinic receptor interaction profile of cytisine, to establish its pharmacokinetics and pharmacodynamics in humans, to determine whether animals self-administer cytisine, and to ascertain whether cytisine is safe and effective as a smoking cessation drug. Potentially, this research effort, contributing to wider use of an inexpensive drug, could save many lives.

[Study on bioavilability of oxymatrine-phospholipid complex in rats]

OBJECTIVE

To study the plasma concentration-time curve, pharmacokinetic parameters and bioavilability of oxymatrine-phospholipid complex and to compare with oxymatrine in rats.

METHOD

Rats were given oxymatrine-phospholipid 100 mg x kg(-1). Blood samples were collected at different times after oral administration. The internal standard was cimetidine. Protein in plasma was precipitated with merhanol and centrifuged at high speed. The supernatant was directly injected and assayed by CE method. The running buffer was 0.04 mol x L(-1) Tris-10 mmol x L(-1) sodium phosphate monobasic-40% isopropanol pH to 7.6 with phosphoric acid. The wavelength of detection was 205 nm.

RESULT

The AUC of oxymatrine and oxymatrine-phospholipid complex were 4.52 mg x mL(-1) x h(-1) and 6.21 mg x mL(-1) x h(-1), respectively. The oxymatrine-phospholipid bioavailability enhanced 1.4 times.

CONCLUSION

It is concluded that after oral administration of oxymatrine-phospholipid complex in rats the bioavailability of oxymatrine is increased greatly. This is mainly due to an obvious improvement of the lipophilic property of oxymatrine-phospholipid complex compared with oxymatrine material and an increase in gastrointestinal absorption.