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.

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.

[Preparation of total matrine controlled release micropellet capsules]

OBJECTIVE

To prepare total matrine controlled release micropellet capsules.

METHODS

The capsules were prepared by the technology of film-coating with surelease as matrix, and judged by the release behavior.

RESULTS

The drug had completely been coated into a homogeneous and continuous film, and the results repeated in three batches showed that the release behavior of the pellet capsules followed zero-equation.

CONCLUSION

The capsules have good sustained release effect and the process of the preparation is available.

[Studies on cutaneous permeation in vitro of Kushen recipe gel]

OBJECTIVE

To establish a suitable dosage form for a traditional anti-anaphylaxis Chinese medicine of Kushen recipe, and investigate the effect of cutaneous permeation in vitro of the recipe.

METHOD

Techniques of extracting with ethanol and purifying with absorbent resin to obtain alkaloids from Kushen recipe were adopted, while volatile oil was extracted by steam distillation. The extraction was made to gel. The skin from SD rats' abdomen was used as permeability barriers. Then effects of permeation of the aqueous extraction, the purifying extraction and the gel were compared by Valia-Chien and Franz diffusion cell method. HPLC was utilized to quantitate the alkaloids in permeating liquid.

RESULT

In view of the permeation cumulation quantity, the permeation velocity and the lag time of the four kinds of alkaloids, the effect of permeation of purifying extraction was better than the aqueous extraction, and the purifying extraction gel surpassed both the aqueous extraction and the purifying extraction.

CONCLUSION

It was certified that the purifying extraction gel had improved the effect of cutaneous permeation of alkaloids, and it is the befitting dosage form for Kushen recipe to treat anaphylaxis disease in skin.

Development of a method for the determination of ibafloxacin in plasma by HPLC with flourescence detection and its application to a pharmacokinetic study

A simple, rapid, and sensitive high-performance liquid chromatographic method is developed for the determination of ibafloxacin in rabbit plasma. Plasma proteins are precipitated with acetonitrile, and after extraction with methylene chloride followed by desecation, ibafloxacin is determined by reversed-phase chromatography with fluorescence detection exciting at 330 nm and emission at 368 nm. Peaks corresponding to ibafloxacin and the internal standard (salycilic acid) are obtained at 9.8 and 5.2 min, respectively. The method is validated for a limit of quantitation of 10 ng/mL. The intraday relative standard deviation ranges from 4.78-7.15%, and the interday precision ranges from 1.32-4.03%. The method shows linearity for the two calibration curves used (10-100 ng/mL and 100-2000 ng/mL). The procedure described is applied successfully to a pharmacokinetics study of ibafloxacin in rabbits.

Sensitive quantitative determination of oxymatrine and matrine in rat plasma by capillary electrophoresis with stacking induced by moving reaction boundary

A quantitative method of capillary electrophoresis with sample stacking induced by moving reaction boundary (MRB) was developed for sensitive determination of oxymatrine (OMT) and matrine (MT) in rat plasma. The experimental conditions were optimized firstly. Below are the optimized experimental conditions: 20 mM sodium formate solution (HCOONa, adjusted to pH 10.70 by ammonia) as sample solution, 3 min 14 mbar sample injection, 40 mM formic buffer (HCOOH-HCOONa, pH 2.60) as stacking buffer, 7 min 14 mbar injection of stacking buffer, 100 mM HCOOH-HCOONa (pH 4.80) as separation buffer, 73 cm capillary (effective length 64 cm), 21 kV voltage, 210 nm wavelength. Under the optimized conditions, higher than 60-fold sensitivity improvement of the stacking was simply achieved as compared with capillary zone electrophoresis, and the detectable limits obtained for OMT and MT were 0.26 and 0.19 microg mL(-1), respectively. Then, numerous demonstrations were carefully performed for the methodological validations of OMT and MT in rate plasma, including high specificity of method, good linearity (r=0.9993 for OMT, r=0.9991 for MT), fair wide linear concentration range (1.30-65.00 microg mL(-1) for OMT, 0.84-42.00 microg mL(-1) for MT), low limit of detection (1.03 microg mL(-1) for OMT, 0.38 microg mL(-1) for MT), less than 5% intra- and inter-day variance value, and higher than 96% recovery of OMT and MT in plasma. The developed method could be used for the trace analyses of OMT and MT in plasma and was finally used for the investigation on pharmacokinetic study of OMT in rat plasma.

Postnatal upregulation of alpha4 and alpha3 nicotinic receptor subunits in the brain of alpha7 nicotinic receptor-deficient mice

The nicotinic receptor subtypes are important for several physiological functions in brain and may therefore play a critical role in brain development. The alpha7 nicotinic receptors which have high Ca2+ permeability are important for cognitive, neuroprotective and trophic functions. In this study, the brain development and the expression of alpha4, alpha3, alpha7, alpha5 and beta2 nicotinic receptors were investigated in the brains of alpha7 deficient (alpha7 -/-), alpha7 heterozygous null (alpha7 +/-) and alpha7 wild-type (alpha7 +/+) mice from postnatal days (P) 7-84. The specific binding of [3H] cytisine and [3H] epibatidine, as well as the expressions of alpha4 and alpha3 nicotinic receptor subunits at mRNA and protein levels, were significantly increased in the cortex and hippocampus of alpha7 -/- and alpha7 +/- mice compared with alpha7 +/+ mice. Furthermore, the alpha4 and alpha3 nicotinic acetylcholine receptor (nAChR) subunits appeared to co-assemble with the alpha5 nAChR subunit in these above brain regions of these mice. No significant change in synaptophysin level was observed. These data suggest that increased levels of alpha4, alpha3-containing nAChRs, co-assembled with the alpha5 nAChR subunit, may contribute to the normal brain development of alpha7 -/- and alpha7 +/- mice.

Are all 5-HT3 receptor antagonists the same?

The 5-hydroxytryptamine type 3 (5-HT3) receptor antagonists have become the cornerstone for preventing and treating chemotherapy-induced nausea and vomiting. Four 5-HT3 antagonists are commercially available in the United States, and numerous reports have been published comparing 2 or more agents. The studies ranged from randomized, double-blinded to open-label or retrospective trials; included chemotherapy-naïve and -non-naïve patients; and covered a range of doses and routes of administration with and without concomitant steroids, for preventing and treating nausea and vomiting after highly and moderately high emetogenic chemotherapy. With few exceptions, the studies uniformly show an equivalent efficacy rate and side effect profile among the various agents at equivalent doses. This article reviews the pharmacology of the class for insight into minor differences among the agents that could possibly influence drug selection for certain patients, and considers data on the absorption, half-life, metabolism, and receptor activity. Clinical trials support the claim of various guidelines that the 5-HT3 receptor antagonists are therapeutically similar in safety and efficacy, particularly because the current best practice for preventing nausea and vomiting after highly and moderately high emetogenic chemotherapy is a combination of a 5-HT3 antagonist, steroids, and aprepitant.

Impaired attention is central to the cognitive deficits observed in alpha 7 deficient mice

alpha7-Nicotinic acetylcholine receptors (alpha7-nAChR) have been implicated in a range of cognitive deficits in schizophrenia. Therefore we examined alpha7-nAChR knockout (KO), heterozygote (HT) and wildtype (WT) littermate mice in the 5-CSR (a rodent model of sustained attention) and odour span (a novel mouse working memory paradigm) tasks, and related performance to nAChR density. Whilst there was no difference between groups in baseline 5-CSR task performance, alpha7-nAChR KO's exhibited significantly higher omission levels compared to WT mice on increasing the attentional load, with HT mice performing at an intermediate level. Furthermore, alpha7-nAChR KO mice were significantly impaired in the odour span task when compared to WT mice, in a pattern consistent with impaired attention. These behavioural deficits were associated with the loss of alpha7-nAChRs, as alpha4beta2-nAChR density was unaltered in these mice. Thus these studies intimate that the attentional impairment in alpha7-nAChR transgenic mice maybe core to other deficits in cognition.

Simultaneous determination and pharmacokinetic study of oxymatrine and matrine in beagle dog plasma after oral administration of Kushen formula granule, oxymatrine and matrine by LC-MS/MS

A rapid, specific and sensitive LC-MS/MS method was developed for the determination of oxymatrine (OMT) and matrine (MT) in beagle dog plasma. The method was applied to study the pharmacokinetics of OMT and MT after oral administration of OMT, MT and Kushen formula granule (KFG) containing equivalent amounts of OMT and MT in a three-period crossover design. The analysis was carried out on an Acquity UPLC BEH C(18) column by linear gradient elution with 0.01% acetic acid-water-methanol as mobile phase. Detection was by positive ion electrospray ionization (ESI) mass spectrometry with multiple-reaction monitoring (MRM). Linear calibration curves were both obtained over the concentration range 15-2000 ng/mL, with a limit of quantification of 15 ng/mL. The matrix effect was minimized. The intra- and inter-day precisions (RSDs) were less than 12.4 and 14.7%, respectively, and the accuracy (RE) was from -2.1 to 2.7%. The validated method was used to determine the concentration-time profiles of OMT and MT. The results indicated that the absorption of OMT and MT after oral administration of KFG was significantly greater than that after oral administration of pure components.

Pharmacokinetics and milk penetration of ibafloxacin after intravenous administration to lactating goats

The pharmacokinetic behavior of ibafloxacin was studied after intravenous administration of a single dose of 15 mg/kg to 6 healthy lactating goats. Plasma concentrations of ibafloxacin were determined by high-performance liquid chromatography with fluorescence detection. The data for concentration versus time could best be described by a 2-compartment model. The mean plasma ibafloxacin clearance (and standard error) was 1.05 (0.10) L/h x kg. The mean steady-state volume of distribution was 1.65 (0.42) L/kg. The mean elimination half-life was 3.76 (0.30) h. Ibafloxacin penetration from the blood to the milk was poor. The ratio between the areas under the concentration-time curve of milk and plasma was 0.20 (0.01), indicating scant penetration of ibafloxacin into the milk.

A rapid reversed phase high-performance liquid chromatographic method for determination of sophoridine in rat plasma and its application to pharmacokinetics studies

A high-performance liquid chromatography (HPLC) method for determining sophoridine in rat plasma was developed for application in the pharmacokinetic studies. The plasma was deproteinized with acetonitrile that contained an internal standard (ephedrine) and was separated from the aqueous layer by adding sodium chloride and sodium carbonate. The HPLC assay was carried out using a YMC-ODS column. The mobile phase was methanol-ethanol-0.01 moll(-1) ammonium acetate buffer-triethylamine (10:0.5:89.5:0.03, v/v/v/v) (pH 6.80). The flow rate was 0.8 ml min(-1). The detection wavelength was set at 210 nm. The method was used to determine the concentration-time profiles of sophoridine in the plasma following oral administration or injection of sophoridine aqueous solution. The fractions of sophoridine reaching the systemic circulation were estimated for the first time by a deconvolution method.

Nadifloxacin: a quinolone for topical treatment of skin infections and potential for systemic use of its active isomer, WCK 771

Nadifloxacin is a potent, broad-spectrum, quinolone agent approved for topical use in acne vulgaris and skin infections in Japan. As exposure of pathogenic and colonising bacteria to antibiotics results in drug resistance, it is not desirable to use an important, broad-spectrum antibiotic, which belongs to a class of agents widely used systemically to treat a wide variety of infections, as a topically applied preparation. On this basis, nadifloxacin is not a good option for topical treatment of acne when other effective non-antibiotic treatments are available. Nadifloxacin has potential as a topical agent for short-term treatment of skin infections. The arginine salt of its (-)-(S)-isomer is being developed as a parenteral agent based on its potency against methicillin and quinolone-resistant Staphylococcus aureus.

Cholinergic receptor subtypes in the olfactory bulbectomy model of depression

The connection between smoking and depression, the antidepressant actions of nicotine and the targeting of nicotinic acetylcholine receptors (nAChRs) by monoamine re-uptake inhibitors all point to a potential role of nAChRs in the etiology and/or symptomatology of depression. In the current study, we evaluated nAChR subtypes in brain regions of rats subjected to olfactory bulbectomy (OBX), a standard animal model that recapitulates many of the behavioral and neurochemical alterations thought to underlie human depression. Comparisons were made both to sham-operated controls and unoperated animals. OBX led to upregulation of cerebrocortical alpha4beta2 nAChRs and downregulation of striatal alpha7 nAChRs as compared to either the sham-operated or unoperated groups. Striatal alpha4beta2 nAChRs were also downregulated but the sham surgery by itself produced a partial effect, masking the contribution of the OBX lesion. In agreement with earlier studies, we also found downregulation of muscarinic AChRs (both m1 and m2 subtypes) in the striatum when comparing the OBX group to sham-operated controls, but because sham surgery evoked mAChR upregulation, the effect was not apparent when the OBX animals were contrasted to the unoperated group. Accordingly, caution needs to be exercised in interpreting studies of cholinergic function in the OBX model that do not include unoperated animals as an additional comparison group. Our results reinforce a relationship between depression and nAChR expression and point to the need for parallel studies in human depression that might lead to the design of novel therapies targeting specific nAChR subtypes.

Antiviral effects of sophoridine against coxsackievirus B3 and its pharmacokinetics in rats

Coxsackievirus B3 (CVB3) is a major pathogen for acute and chronic viral myocarditis. The aim of this study was to investigate the antiviral effects of sophoridine, an alkaloid extracted from Chinese medicinal herb, Sophora flavescens, against CVB3, and the underlying pharmacokinetics. First, we determined the antiviral effects of sophoridine against CVB3 in in vitro (primarily cultured myocardial cells), in vivo (BALB/c mice) and serum pharmacological experiments. Then, we determined the pharmacokinetic behavior in serum samples of SD rats after oral administration by HPLC. Finally, we determined the effects of sophoridine on the production of cytokines in a murine viral myocarditis model by measuring mRNA expression of some important cytokines in hearts of infected BALB/c mice by RT-PCR. We found that sophoridine exhibited obvious antiviral effects both in vitro and in vivo, and serum samples obtained from rats with oral administration of sophoridine reduced the virus titers in infected myocardial cells. The serum concentration profile correlated closely with antiviral activity profile. Moreover, sophoridine significantly enhanced mRNA expression of IL-10 and IFN-gamma, but decreased TNF-alpha mRNA expression. In conclusion, sophoridine possesses antiviral activities against CVB3, by regulating cytokine expression, and it is likely that sophoridine itself, not its metabolites, is mainly responsible for the antiviral activities. Therefore, sophoridine may represent a potential therapeutic agent for viral myocarditis.

[HPLC-electrospray ionization ion trap tandem mass spectrometry analysis of oxymatrine and its metabolites in rat urine]

AIM

To identify the main metabolites of oxymatrine (OMT) in rats.

METHODS

To optimize the conditions of LC/ESI-ITMS' chromatograms and spectra by oxymatrine and matrine (MT), and summarize their ionization and cleavage rules in ESIMS, then serving as the basis for the metabolite analyses of oxymatrine in rats. To collect the 0-24 h urine samples of the rats after ip 40 mg x kg(-1) oxymatrine, the samples were enriched and purified through C18 solid-phase extraction cartridge. The purified samples were analyzed by LC/ESI-ITMS. The structures of OMT metabolites were identified according to their retention times and ESI-ITMSn rules.

RESULTS

Six phase I metabolites and the parent drug OMT were found in the rat urine, and the main metabolite was MT. No phase II metabolites were found.

CONCLUSION

The developed LC/ESI-ITMSn methods to identify the metabolites of oxymatrine in rats is not only simple and rapid but also sensitive and specific. This technology is one of the most efficient methods for the analysis of drug metabolites.

Pharmacokinetics of ibafloxacin in healthy cats

The pharmacokinetics of ibafloxacin following single and repeated administration of an oral gel formulation and the effect of food intake were investigated in cats. Ibafloxacin is a chiral fluoroquinolone available for clinical use as a racemic mixture of the R- and S-enantiomers. Plasma concentrations of ibafloxacin and its metabolites were determined using microbiological, LC-MS-MS and enantioselective capillary zone electrophoresis assays. Ibafloxacin was absorbed rapidly [time of maximum concentration (tmax) 2-3 h], reaching a mean maximum concentration (Cmax) of approximately 2.1 and 1.6 microg/mL for R- and S-ibafloxacin, respectively, following a single oral administration of the racemate at 15 mg/kg. Once absorbed, ibafloxacin was metabolized to 7-hydroxy-ibafloxacin and mainly to 8-hydroxy-ibafloxacin. Following repeated oral administration, significant increases in Cmax and AUC of ibafloxacin and its less active metabolites (racemic or enantiomers) were observed between the first and the tenth day of treatment. This twofold exposure increase in concentrations of ibafloxacin and its metabolites may contribute additionally to the efficacy of this drug in the treatment of feline bacterial infections. Single and repeated doses of ibafloxacin were well tolerated by cats. Food promoted the absorption of ibafloxacin, doubling Cmax and increasing AUC and slightly delaying tmax. High concentrations of the metabolites, mainly 8-hydroxy- and 7-hydroxy-ibafloxacin were excreted in urine, either unchanged or as glucurono-conjugates.

Pharmacodynamics of ibafloxacin in micro-organisms isolated from cats

The pharmacodynamic properties of ibafloxacin were investigated in micro-organisms isolated from cats. Minimal inhibitory concentrations (MIC) of ibafloxacin (racemate, R- and S-enantiomers) and its metabolites (7-hydroxy- and 8-hydroxy-ibafloxacin) and time-kill kinetics were determined against Gram-negative and Gram-positive bacteria isolated from dermal and respiratory and urinary tract infections in cats. Racemic ibafloxacin has a broad spectrum of bactericidal activity against Gram-negative and some Gram-positive bacteria. Escherichia coli and Pasteurella, Klebsiella and Staphylococcus spp. are commonly isolated from feline infections and all are susceptible to ibafloxacin (MIC90 < or = 0.5 microg/mL), whereas Pseudomonas aeruginosa, Proteus mirabilis and Streptococcus spp. are considered intrinsic resistant. Microbiological activity resides primarily in the S-enantiomer of ibafloxacin whereas the R-enantiomer is less active. Killing curves using concentrations of racemic ibafloxacin and 8-hydroxy-ibafloxacin, which are representative of the in vivo situation observed in cats, showed at least 99.9% reduction in viable bacterial isolates from feline clinical samples over 24 h. Bacterial eradication was achieved in cats with Cmax/MIC and AUC/MIC values much lower than the target values previously established in man and laboratory animals. Additional studies in dogs and cats are necessary to define more clearly the surrogate markers of antibacterial activity (i.e. Cmax/MIC, AUC/MIC ratios), which are associated with a good clinical response.

Antistaphylococcal activity of WCK 771, a tricyclic fluoroquinolone, in animal infection models

WCK 771, the arginine salt of S-(-)-nadifloxacin, was evaluated in animal models of staphylococcal infection and in vitro. For 302 methicillin-susceptible strains the MIC at which 50% of isolates are inhibited (MIC50) and the MIC90 of WCK 771 were 0.03 and 0.03 microg/ml, respectively, and for 198 methicillin-resistant strains the MIC50 and the MIC90 were 0.5 and 1.0 microg/ml, respectively. All methicillin-susceptible staphylococci were quinolone susceptible, and almost all methicillin-resistant staphylococci were quinolone resistant. WCK 771 was more potent than moxifloxacin, trovafloxacin, levofloxacin, and ciprofloxacin and had potency comparable to that of clinafloxacin. Only WCK 771 and clinafloxacin demonstrated strong potencies against vancomycin-intermediate Staphylococcus aureus strains (MICs = 1 microg/ml). WCK 771 is not a substrate of the NorA pump, as evident from the lack of an effect of reserpine on the MICs and similar protective doses against infections caused by efflux-positive and -negative staphylococci. WCK 771 was effective by both the oral and the subcutaneous routes in mice infected intraperitoneally with quinolone-susceptible methicillin-susceptible S. aureus (MSSA) strains. For infections caused by quinolone-resistant methicillin-resistant S. aureus (MRSA) strains, the activity of WCK 771 administered subcutaneously was superior to those of trovafloxacin and sparfloxacin, with a 50% effective dose range of 27.8 to 46.8 mg/kg of body weight. The activity of WCK 771 was superior to those of moxifloxacin, vancomycin, and linezolid in a mouse cellulitis model of infection caused by one MSSA and two MRSA strains, with effective doses of 2.5 and 5 mg/kg for the MSSA strain and 10-fold higher effective doses for MRSA strains. WCK 771, like vancomycin and linezolid, eradicated MRSA from mouse liver, spleen, kidney, and lung when it was administered subcutaneously at a dose of 50 mg/kg for four doses. These studies have demonstrated the effectiveness of WCK 771, administered orally and parenterally, for the treatment of diverse staphylococcal infections in mice, including those caused by quinolone-resistant strains.

Subunit Composition of Nicotinic Receptors in Monkey Striatum: Effect of Treatments with 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine or l-DOPA

Nicotinic acetylcholine receptors (nAChRs) represent an important modulator of striatal function both under normal conditions and in pathological states such as Parkinson's disease. Because different nAChR subtypes may have unique functions, immunoprecipitation and ligand binding studies were done to identify their subunit composition. As in the rodent, alpha2, alpha4, alpha6, beta2, and beta3 nAChR subunit immunoreactivity was identified in monkey striatum. However, distinct from the rodent, the present results also revealed the novel presence of alpha3 nAChR subunit-immunoreactivity in this same region, but not that for alpha5 and beta4. Relatively high levels of alpha2 and alpha3 subunits were also identified in monkey cortex, in addition to alpha4 and beta2. Experiments were next done to determine whether striatal subunit expression was changed with nigrostriatal damage. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine treatment decreased alpha6 and beta3 subunit immunoreactivity by approximately 80% in parallel with the dopamine transporter, suggesting that they are predominantly expressed on nigrostriatal dopaminergic projections. In contrast, alpha3, alpha4, and beta2 subunit immunoreactivity was decreased approximately 50%, whereas alpha2 was not changed. These data, together with those from dual immunoprecipitation and radioligand binding studies ([(3)H]cytisine, (125)I-alpha-bungarotoxin, and (125)I-alpha-conotoxin MII) suggest the following: that alpha6beta2beta3, alpha6alpha4beta2beta3, and alpha3beta2* nAChR subtypes are present on dopaminergic terminals and that the alpha4beta2 subtype is localized on both dopaminergic and nondopaminergic neurons, whereas alpha2beta2* and alpha7 receptors are localized on nondopaminergic cells in monkey striatum. Overall, these results suggest that drugs targeting non-alpha7 nicotinic receptors may be useful in the treatment of disorders characterized by nigrostriatal dopaminergic damage, such as Parkinson's disease.

Treatment of canine pyoderma with ibafloxacin and marbofloxacin - fluoroquinolones with different pharmacokinetic profiles

Dogs with superficial or deep pyoderma (n = 228) presented to first opinion veterinarians (n = 20) were treated orally with either ibafloxacin, at a dosage of 15 mg/kg, or marbofloxacin, at a dosage of 2 mg/kg, once daily for 3-16 weeks. On initial presentation, 35% of the cases were classified as having recurrent pyoderma and 40% as having deep pyoderma. Staphylococci (mainly Staphylococcus intermedius) were isolated from over 90% of the cases. The average treatment periods were 41 +/- 26 and 38 +/- 21 days in the ibafloxacin and marbofloxacin groups, respectively. One week after the cessation of treatment, 74 and 81% of dogs (P > 0.05) in the ibafloxacin and marbofloxacin groups, respectively, were classified as having responded to treatment. One month after the cessation of treatment, 70% of the dogs in each group were still classified as cured or improved, and 3 and 11% (P < 0.05) in the ibafloxacin and marbofloxacin groups, respectively, were classified as having relapsed. Despite having different pharmacokinetic profiles, ibafloxacin and marbofloxacin produced similar results when used under field conditions at the recommended dosages.

The bryophyte Fontinalis antipyretica Hedw. bioaccumulates oxytetracycline, flumequine and oxolinic acid in the freshwater environment

In recent years, the fate of pharmacological substances in the aquatic environment have been more and more studied. Oxolinic acid (OA), flumequine (FLU) and oxytetracycline (OTC) are commonly used antibacterial agents. A large amount of these drugs is released into water directly by dissolved fraction and indirectly in urine and feces. Monitoring these compounds in the freshwater environment is difficult because of the lack of suitable indicators. The aim of this work was to evaluate the OA, FLU and OTC bioaccumulation abilities of Fontinalis antipyretica Hedw., known for heavy metal bioaccumulation. The experiment described was decomposed for two times: a 10-days accumulation period during which bryophytes were in contact with antibiotics and a 15-days post-exposure period during which bryophytes were in water with no antibiotic. This experiment showed that this bryophyte strongly accumulates OA, FLU and OTC in freshwater. Bioaccumulation factors (ratio of concentrations in bryophyte and water) ranged between 75 and 450. Moreover, OA, FLU and OTC persisted in the bryophyte for a long time with clearance between 0.19 and 3.04 ng/g/day. Mean residence times ranged between 18 and 59 days. Accumulation and decontamination mechanism models were proposed.

Granisetron: new insights into its use for the treatment of chemotherapy-induced nausea and vomiting

Granisetron (Kytril, Roche) is a 5-hydroxytryptamine 3 (5-HT(3))-receptor antagonist indicated for the prevention of nausea and/or vomiting associated with initial and repeat courses of emetogenic chemotherapy, including high-dose cisplatin. Its indication expanded in August 2002, with approval from the FDA for the prevention and treatment of postoperative nausea and vomiting. Granisetron strongly and selectively binds to the 5-HT(3) receptor with a binding constant of 0.26 nM and exhibits a 4000 - 40,000 times greater binding affinity for the 5-HT(3) receptor than other binding sites, including other 5HT subtypes and adrenergic, histaminergic and opioid receptors. Its selectivity to the 5-HT(3) receptor over other receptor types is > 1000:1. Granisetron noncompetitively binds to the 5-HT(3) receptor and is associated with a long duration of action as shown by the inhibition of a 5-HT axonal response flare for up to 24 h. Granisetron is unique among the 5-HT(3)-receptor antagonists because it is not metabolised via the cytochrome P450 (CYP) 2D6 pathway and is, therefore, less susceptible to variation in patient response because of factors such as pharmacogenomic differences. Granisetron and other 5-HT(3)-receptor antagonists are first-line agents for acute chemotherapy-induced nausea and vomiting (CINV), whereas combination therapy with 5-HT(3)-receptor antagonists, dexamethasone and neurokinin (NK)-1 receptor antagonism (i.e., with the recently approved aprepitant) is an effective approach to prevent delayed CINV. Granisetron has been shown to be an effective within-class rescue antiemetic for prophylactic failures, which may be linked to its pharmacological properties including non-competitive, insurmountable binding to the 5-HT(3) receptor. As with other 5-HT(3)-receptor antagonists, granisetron is well-tolerated with adverse events of mild severity including headache, asthenia and constipation. Overall, data demonstrate that granisetron is an efficacious, safe and cost-effective member of the 5HT(3)-receptor antagonist class for the prevention of CINV.

Patient outcomes after therapeutic interchange of dolasetron for granisetron

The impact of using therapeutic interchange (TI) of dolasetron for granisetron for the prevention of chemotherapy-induced nausea and vomiting (CINV) was evaluated. An outcomes evaluation was conducted in two cohorts of adult outpatients who had not previously received chemotherapy. Before the interchange, 20 patients were enrolled in a granisetron cohort, and after the interchange to dolasetron, 42 patients were matched to the initial cohort. Evaluations using the modified Functional Life Index--Emesis (MFLIE) compared changes in functional status before and after treatment. Nausea and vomiting frequency, satisfaction with antiemetics, reported adverse effects, changes in antiemetic therapy, and the use of antiemetics postchemotherapy were also evaluated. Success, defined as no vomiting and less than a 2.5-unit change in MFLIE score, was demonstrated in 45% of granisetron patients and 40% of dolasetron patients (p = 0.461). While functional status declined in both groups in response to chemotherapy, the changes in MFLIE scores did not differ between agents (-16.8 +/- 20.16 versus -19.39 +/- 26.36 in granisetron and dolasetron patients, respectively) (p = 0.650). Patients were equally satisfied with their prescribed antiemetic therapy, although less than half of patients achieved antiemetic success in the 72-hour study period. Self-reported adverse events attributed to serotonin type 3-receptor antagonist use were minimal and not significantly different between groups. The TI did not negatively affect patient outcomes and produced savings of $143,534 in the first year of the program. TI of dolasetron for granisetron for CINV did not affect functional status, nausea control, or patient satisfaction with antiemetic therapy.

Utility of hepatocytes in predicting drug metabolism: comparison of hepatic intrinsic clearance in rats and humans in vivo and in vitro

We investigated hepatic in vitro intrinsic clearance (CL(int,in vitro)) in freshly isolated or cryopreserved hepatocytes and compared with CL(int,in vivo) by using nine model compounds, FK1052, FK480, diazepam, diltiazem, troglitazone, quinotolast, FK079, zidovudine, and acetaminophen, in rats and humans. The compounds showed a broad range of in vivo hepatic extraction ratios (rat, 0.05-0.93; humans, 0.03-0.76) and were metabolized by hepatic P450, UDP-glucuronosyltransferase, sulfotransferase, and/or esterase. CL(int,in vitro) was determined from substrate disappearance rate at 1 microM in hepatocytes. CL(int,in vivo) was calculated from in vivo pharmacokinetic data using two frequently used mathematical models (the well stirred and dispersion models). When estimating rat CL(int,in vitro) in freshly isolated hepatocytes, the rat scaling factor values (CL(int,in vivo)/CL(int,in vitro)) showed marked difference among the model compounds (0.2-73.1-fold). The rat CL(int,in vitro) values in freshly isolated hepatocytes were in good agreement with these in cryopreserved hepatocytes. Human CL(int,in vitro) were determined by use of cryopreserved hepatocytes. When human CL(int,in vitro) was regarded as the predicted CL(int,in vivo), the observed and predicted CL(int,in vivo) for FK1052, FK480, troglitazone, and FK079 differed markedly (12.4-199.0-fold). In contrast, using human CL(int,in vitro) corrected with the rat scaling factors yielded better predictions of CL(int,in vivo) that were mostly within 5-fold of the actual values. These results make the evaluation using hepatocytes more useful and provide a basis for predicting hepatic clearance using hepatocytes.

Pharmacokinetics of flumequine and in vitro activity against bacterial pathogens of gilthead sea bream Sparus aurata

The present study investigated the kinetic profile of flumequine (FLU) in gilthead sea bream Sparus aurata (170 g) held at 19 degrees C and evaluated its in vitro efficacy against important bacterial diseases in Mediterranean mariculture. Following a single intravascular injection (10 mg kg(-1) fish), the distribution half-life (t1/2alpha) and the half-life of the terminal phase of elimination (t1/2gamma) of the drug were 0.2 and 30 h respectively. Tissue penetration of FLU was low, since both the apparent distribution volume of the drug at steady-state (Vd(SS)) and the apparent volume of the central compartment (Vc) were small (0.57 and 0.15 l kg(-1)). The mean residence time (MRT) was short (11 h) and the total clearance (CL(T)) of the drug was slow (0.05 l kg(-1) h(-1)). Following oral administration (20 mg kg(-1)), the bioavailability (F %) of FLU was 29% and the maximum plasma concentration was 1.7 microg ml(-1). The minimum inhibitory concentration (MIC) of the drug in distilled water supplemented with 2% NaCl against Vibrio anguillarum Serotype 1b, Photobacterium damsela ssp. piscicida, V. alginolyticus, V. damsela and V. fluvialis was 0.15, 0.3, 1.2, 0.019 and 0.15 microg ml(-1) respectively. The addition however of 10 mM Ca2+ and 55 mM Mg2+ to the medium resulted in an 8- to >120-fold reduction in FLU activity. The results indicate that FLU has an adequate kinetic profile in gilthead sea bream and that marine cations induce a significant impact on the activity of FLU, rendering its use against bacterial pathogens questionable.

Flumequine in Atlantic salmon Salmo salar: disposition in fish held in sea water versus fresh water

14C-labeled flumequine was administered as a single oral (5 mg kg(-1), 86 microCi kg(-1)) or intravenous (5 mg kg(-1), 82 microCi kg(-1)) dose to Atlantic salmon Salmo salar held in sea water or in fresh water. The absorption, tissue distribution and elimination were determined by means of liquid scintillation counting and whole-body autoradiography. The drug was rapidly absorbed and extensively distributed in all groups of fish. Radiolabeled compound was present in blood and muscle for more than 8 wk in the freshwater groups. In the seawater groups, however, no radioactivity was detected in the blood and muscle after 4 d and 2 wk, respectively. It was concluded that flumequine was eliminated at a substantially higher rate from Atlantic salmon in sea water than in fresh water.

Disposition of 14C-flumequine in eel Anguilla anguilla, turbot Scophthalmus maximus and halibut Hippoglossus hippoglossus after oral and intravenous administration

The absorption, distribution and elimination of 14C-labelled flumequine were studied using whole body autoradiography and liquid scintillation counting. Flumequine was administered to eel Anguilla anguilla, turbot Scophthalmus maximus and halibut Hippoglossus hippoglossus intravenously and orally as a single dose of 5 mg kg(-1), corresponding to 0.1 mCi kg(-1). The turbot and halibut studies were performed in salt water (salinity of 32%) at temperatures of 16 +/- 1 degrees C (turbot) and 9.5 +/- 0.5 degrees C (halibut). The eel study was conducted in fresh water at 23 +/- 1 degrees C. In the intravenously administered groups flumequine was rapidly distributed to all major tissues and organs. After oral administration flumequine also appeared to have rapid and extensive absorption and distribution in all 3 species. After the distribution phase, the level of flumequine was higher in most organs and tissues than in the blood, except in muscle and brain. The most noticeable difference between the species was the slow elimination of flumequine from eel compared to turbot and halibut. In orally administered eels, substantial amounts of flumequine remained in all major organs/tissues for 7 d. At 28 d significant levels of flumequine were present in liver, kidney and skin (with traces in muscle), and at the last sampling point (56 d) in eye, bone, bile and posterior intestine. In orally administered turbot significant levels of flumequine were observed over 96 h in bile, urine, bone, skin, intestine and eye, and traces were detected over 28 d in bone and eye in addition to a significant level in bile. In orally administered halibut, significant levels of flumequine were observed in bile, skin, intestine and eye over 96 h. Traces were present in skin and eye over 7 d. The maximal flumequine concentrations in blood were calculated to be 2.5 mg equivalents l(-1) (eel at 12 h), 0.8 mg l(-1) (turbot at 6 h) and 0.6 mg l(-1) (halibut at 6 h) after oral administration.