P-glycoprotein is responsible for the poor intestinal absorption and low toxicity of oral aconitine: in vitro, in situ, in vivo and in silico studies.

Aconitine (AC) is a highly toxic alkaloid from bioactive plants of the genus Aconitum, some of which have been widely used as medicinal herbs for thousands of years. In this study, we systematically evaluated the potential role of P-glycoprotein (P-gp) in the mechanisms underlying the low and variable bioavailability of oral AC. First, the bidirectional transport of AC across Caco-2 and MDCKII-MDR1 cells was investigated. The efflux of AC across monolayers of these two cell lines was greater than its influx. Additionally, the P-gp inhibitors, verapamil and cyclosporin A, significantly decreased the efflux of AC. An in situ intestinal perfusion study in rats showed that verapamil co-perfusion caused a significant increase in the intestinal permeability of AC, from 0.22×10(-5) to 2.85×10(-5) cm/s. Then, the pharmacokinetic profile of orally administered AC with or without pre-treatment with verapamil was determined in rats. With pre-treatment of verapamil, the maximum plasma concentration (Cmax) of AC increased sharply, from 39.43 to 1490.7 ng/ml. Accordingly, a 6.7-fold increase in the area under the plasma concentration-time curve (AUC0-12h) of AC was observed when co-administered with verapamil. In silico docking analyses suggested that AC and verapamil possess similar P-gp recognition mechanisms. This work demonstrated that P-gp is involved in limiting the intestinal absorption of AC and attenuating its toxicity to humans. Our data indicate that potential P-gp-mediated drug-drug interactions should be considered carefully in the clinical application of aconite and formulations containing AC.

Metabolism of novel anti-HIV agent 3-cyanomethyl-4-methyl-DCK by human liver microsomes and recombinant CYP enzymes.

AIM: To investigate the metabolism of 3-cyanomethyl-4-methyl-DCK (CMDCK), a novel anti-HIV agent, by human liver microsomes (HLMs) and recombinant cytochrome P450 enzymes (CYPs). METHODS: CMDCK was incubated with HLMs or a panel of recombinant cytochrome P450 enzymes including CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6, 3A4, and 3A5. LC-ion trap mass spectrometry was used to separate and identify CMDCK metabolites. In the experiments with recombinant cytochrome P450 enzymes, specific chemical inhibitors combined with CYP antibodies were used to identify the CYP isoforms involved in CMDCK metabolism. RESULTS: CMDCK was rapidly and extensively metabolized by HLMs. Its intrinsic hepatic clearance estimated from the in vitro data was 19.4 mL·min(-1)·kg(-1), which was comparable to the mean human hepatic blood flow rate (20.7 mL·min(-1)·kg(-1)). The major metabolic pathway of CMDCK was oxidation, and a total of 14 metabolites were detected. CYP3A4 and 3A5 were found to be the principal CYP enzymes responsible for CMDCK metabolism. CONCLUSION: CMDCK was metabolized rapidly and extensively in human hepatic microsomes to form a number of oxidative metabolites. CYP3A4 and 3A5 were the predominant enzymes responsible for the oxidation of CMDCK.

Pharmacokinetic properties of albiflorin and paeoniflorin after oral administration of pure compound, Radix Paeoniae alba extract and danggui-shaoyao-san extract to rats.

This study compared the pharmacokinetics of albiflorin (ALB) and paeoniflorin (PAE), respectively, after oral administration of ALB, PAE, Radix Paeoniae alba (RPA) extract, and Danggui-Shaoyao-San (DSS) extract to rats on separate occasions. Analytes were detected simultaneously with liquid chromatography-tandem mass spectrometry. Noncompartmental pharmacokinetic parameters were calculated. After oral administration of RPA and DSS extract to rats, ALB reached maximum concentrations of 4637 ± 2774 ng/ml (0.40 ± 0.14 h) and 226 ± 122 ng/ml (0.35 ± 0.14 h) and PAE reached maximum concentrations of 2132 ± 560 ng/ml (0.40 ± 0.14 h) and 143 ± 65 ng/ml (0.45 ± 0.11 h), respectively. Compared to the AUC(0 - t) value (1122 ± 351 and 722 ± 158 ng h/ml for ALB and PAE, respectively) after administration of monomers, larger AUC(0 - t) value of ALB (4755 ± 2560 ng h/ml) and PAE (2259 ± 910 ng h/ml) after administration of RPA extract and smaller AUC(0 - t) value of ALB (411 ± 118 ng h/ml) and PAE (242 ± 126 ng h/ml) after administration of DSS extract were obtained. The C(max), AUC, and K(el) of ALB and PAE were remarkably increased (P < 0.05, 0.01 or 0.005) during oral administration of RPA extract in comparison to that of DSS extract.

[Research progress of enhancing quantitative sensitivity by using LC-MS(n) with derivatization method in bio-matrices].

Liquid chromatography/mass spectrometry (LC-MS(n)) has been essential to a large number of quantitative analytical applications in drug research, and especially in the drug PK/PD research, due to its high sensitivity and high specificity. But following the appearance of drugs with high activity and low dosage and the especial structural compounds, a number of limitations of LC-MS(n) have been noted. Derivatization changes the structure of drugs and therefore changes their physical and chemical properties, resulting in high ionization efficiency, low matrix effect and low disturbance by inorganic salts and endogenous compounds in LC-MS(n). In this article, recent progress in the research of the chemical derivatization strategy with LC-MS(n) is reviewed on breakthrough of some LC-MS(n) limitations, in particular focusing on the applications involving some drugs in bio-matrices.

Metabolic stability of human parathyroid hormone peptide hPTH (1-34) in rat tissue homogenates: kinetics and products of proteolytic degradation.

The present study aim to investigate the metabolic stability and degradation of cleavage sites of human parathyroid hormone peptide, hPTH (1-34), in rat tissue homogenate, and to identify the types of proteases involved in hPTH (1-34) processing degradation. The stability of hPTH (1-34) in rat kidney, lung and liver homogenates was evaluated by LC-ESI-MS, and the structures of the major degradation products were identified by MALDI-TOF MS and LC-ESI-MS/MS. The ability of protease inhibitors to inhibit hPTH (1-34) degradation was used to identify the class of proteases involved in the metabolism of hPTH (1-34). hPTH (1-34) peptide was readily degraded in rat kidney, liver, and lung homogenates, with half-lives of 5.7, 32.2, and 18.9 min, respectively. The degradation of hPTH (1-34) in each tissue can be inhibited by inhibitors of serine and metalloproteases. The major degradation products of hPTH (1-34) are similar in each tissue and suggest that hPTH (1-15) and hPTH (16-34) appear as the major degradation products. The degradation patterns of hPTH (1-34) incubated in rat kidney, liver and lung homogenates are largely overlapping, and a majority of the fragments are generated via cleavages at sites of Leu15-Asn16 peptide bond.

An HPLC-ultraviolet detection method for the determination of Z24 in mouse whole blood and its application to pharmacokinetic studies.

A sensitive and reproducible high-performance liquid chromatography (HPLC)-UV method for the determination of Z24, a tumorigenesis and angiogenesis inhibitor, has been developed and validated in mouse whole blood. Blood samples were extracted with ether, evaporated, and the residue was reconstituted in mobile phase. An aliquot was separated by isocratic reversed-phase HPLC on a Hypersil ODS-2 column and quantified using UV detection at 390 nm. The mobile phase was 50% (v/v) acetonitrile/water with a flow rate of 0.8 ml/min. A linear curve over the concentration range of 0.05-6 microg/ml (r(2)=0.9976) was obtained. The coefficient of the variation for the intra- and inter-day precision ranged from 3.0 to 10.9% and 5.7 to 10.3%, respectively. The absolute recovery of Z24 was 89.2-108.5%. The method is simple, economical and sufficient for in vivo pharmacokinetic studies on Z24. Nonlinear pharmacokinetics was found in mice at doses from 20 to 80 mg/kg.

Structural elucidation of in vivo metabolites of penehyclidine in rats by the method of liquid chromatography-mass spectrometry, gas chromatography-mass spectrometry and isotope ion cluster.

The structural elucidation of metabolites of penehyclidine in rats, a novel anti-cholinergic drug, by the method of liquid chromatography-electrospray ionization mass spectrometry, gas chromatography-mass spectrometry with electron impact ion source and stable isotope ion cluster was described. Identification and elucidation of the phase I and phase II metabolites were performed by comparing the daughter ion pairs of stable isotope cluster, changes of the protonated molecular masses, full scan MS(n) spectra and retention times with those of the parent drug, penehyclidine and penehyclidine deuterium-labeled. Penehyclidine was easily biotransformed by the pathways of oxidative, hydroxylated, methoxylated and phase II conjugated reactions to form several metabolites that retained the some features of the parent molecules. Twelve metabolites (penehyclidine monoxide, hydroxypenehyclidine, penehyclidine dioxide, hydroxypenehyclidine monoxide, dihydroxypenehyclidine, dihydroxypenehyclidine (position isomer), dihydroxypenehyclidine monoxide, trihydroxypenehyclidine, methoxypenehyclidine dioxide, dimethoxypenehyclidine, trihydroxymethoxypenehyclidine and glucuronide conjugated hydroxypenehyclidine) were identified. The results from electrospray ion and electron impact ion data with the stable isotope cluster showed the qualitative differences in the mass spectral patterns, suggesting that these technologies should be used in parallel to ensure comprehensive metabolites detection and characterization. The described method has wide applicability to rapidly screen and provide structural information of metabolites.

Comparative pharmacokinetics and distribution kinetics in brain of phencynonate enantiomers in rats.

To investigate the pharmacokinetics in blood and the distribution kinetics in brain of enantiomers of novel anticholinergic agent phencynonate (N-methyl-9alpha-(3-azabicyclo[3,3,1]nonanyl)-2'-cyclopentyl-2'-hydroxyl-2'-phenylacetate), we collected blood and implanted microdialysis probes in the cerebral frontal cortex of rats. Phencynonate enantiomers (0.35 mg/kg, i.m.) were then cross administered, and the microdialysates were collected using in situ microdialysis sampling in the brain of freely moving rats, and the concentration of phencynonate enantiomers was determined by the validated method of liquid chromatography-mass spectrometry. Pharmacokinetic parameters were calculated from the blood and the brain dialysate concentrations of phencynonate enantiomers versus time data. The disposition profiles of the phencynonate enantiomers were best fitted to a first order absorption, two-compartment open model in rats. In general, there were some differences when comparing the mean kinetic parameters of S- and R-phencynonate in the blood and brain, but the distinct diversity between individual animals made the statistical difference not obvious. Therefore, stereoselective disposition of phencynonate isomers was not obviously observed in rat.

Degradation of salmon calcitonin in rat kidney and liver homogenates.

Salmon calcitonin (sCT), a 32-amino-acid peptide, is the active component in many pharmaceuticals used for the management of bone diseases. In this study, the stability of sCT in rat kidney and liver homogenates were evaluated by LC-ESI-MS, and the structures of the major degradation products were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The results show that the half life of sCT was 13.18 min in rat kidney homogenate (2.5 mg/ml, protein concentration) and 43.07 min in rat liver homogenate (2.5 mg/ml, protein concentration). MALDI-TOF MS results indicated that sCT was initially cleaved at Leu9-Gly10 and Gly10-Lys11 bonds in rat kidney homogenate in vitro, at the same time, the major degradation fragment, Lys11-Pro32-NH2 Was metabolized at the C-terminal amide by deamidation, whereas in rat liver homogenate, the initial cleavage sites were at Val8-Leu9 and His17-Lys18. The results indicated that the metabolism of sCT proceeds by initial endoproteolytic cleavage and subsequent exoproteolytic digestion.

[Determination of decapeptide LXT-101 in plasma by HPLC-MS/MS and its pharmacokinetics in Beagle dogs].

This paper developed a sensitive and specific liquid chromatography-electrospray ionization mass spectrometry (HPLC-MS/MS) method for the determination of decapeptide LXT-101 in Beagle dog plasma. Plasma samples spiked with internal standard (IS) were treated with acetonitrile to precipitate the protein. Selected reaction monitoring (SRM) using the precursor --> product ion combinations of m/z 472.1-->587.9 and m/z 502.8-->633.8 were used to quantify LXT-101 and IS, respectively. The linear calibration curves were obtained in the concentration range of 0.5 - 500.0 ng x mL(-1). The limit of quantification (LOQ) was 0.5 ng x mL(-1). The inter-day and intra-day precision (RSD) across three validation run over the entire concentration range was below 10.9%, and the accuracy (RE) was within +/- 1.8%. The main pharmacokinetic parameters of LXT-101 after muscle injection of 20 microg x kg(-1) were as follows, AUC(0-t): (176.8 +/- 116.7) microg x h x L(-1), MRT(0-t): (2.52 +/- 0.53) h, T(1/2): (1.4 +/- 0.3) h; CL: (0.16 +/- 0.09) L x h(-1) x kg(-1), and Vd: (0.30 +/- 0.16) L x kg(-1), respectively. The method is proved to be specific, sensitive and suitable for the investigation of LXT-101 pharmacokinetics in Beagle dog.

Liquid chromatography-tandem electrospray mass spectrometry method for determination of serial chiral novel anticholinergic compounds of phencynonate in rat plasma.

A sensitive and selective liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method was developed for the determination of serial chiral novel anticholinergic compounds of phencynonate in rat plasma. After a simple protein-precipitation using methanol, the post-treatment samples were separated on a CAPCELL UG120 column with a mobile phase of a mixture of methanol and water (35:65) containing 0.1% formic acid. The serial chiral analytes and internal standard (IS) were all detected by the use of selected reaction monitoring mode (SRM). The method of all serial chiral analytes developed was validated in rat plasma with a daily working range of 0.5-100 ng/ml with correlation coefficient, R(2) > or = 0.99 and a sensitivity of 0.5 ng/ml as lower limit of quantification, respectively. This method was fully validated for the accuracy, precision and stability studies for all serial chiral analytes. The method proved to be accurate and specific, and was applied to the pharmacokinetic study of serial chiral novel anticholinergic compounds of phencynonate in rat plasma.

Simultaneous determination of thienorphine and its active metabolite thienorphine glucuronide in rat plasma by liquid chromatography-tandem mass spectrometry and its application to pharmacokinetic studies.

A simple, sensitive and reliable method was developed to determine simultaneously the concentrations of thienorphine and its metabolite thienorphine glucuronide conjugate in rat plasma by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The metabolite was identified by MS: thienorphine glucuronide conjugate. Sample preparation involved protein precipitation with methanol. Analytes were separated on Finnigan BetaBasic-18 column (150 mm x 2.1mm i.d., 5 microm) using methanol: water: formic acid (56:44:0.1, v/v/v) as mobile phase at a flow rate of 0.2 ml/min. The method had a linear calibration curve over the concentration range of 0.1-50 ng/ml for thienorphine and 2-1000 ng/ml for thienorphine glucuronide conjugate, respectively. LOQ of thienorphine and thienorphine glucuronide conjugate was 0.1 and 2 ng/ml, respectively. The intra- and inter-batch precisions were less than 12% and their recoveries were greater than 80%. Pharmacokinetic data of thienorphine and its metabolite thienorphine glucuronide conjugate obtained with this method following a single oral dose of 3mg/kg thienorphine to rats were also reported for the first time.

Suppression of perfluoroisobutylene induced acute lung injury by pretreatment with pyrrolidine dithiocarbamate.

Perfluoroisobutylene (PFIB) is produced as a main by-product in large quantities by the fluoropolymer industry. As a highly toxic compound, even the case of brief inhalation of PFIB can result in acute lung injury (ALI), pulmonary edema and even death. To test for any preventive or therapeutic effects of pyrrolidine dithiocarbamate (PDTC), a NF-kappaB activation inhibitor, against PFIB inhalation-induced ALI, mice were exposed in a flow-past exposure system to PFIB and the prophylactic and therapeutic effects of PDTC were studied. The inhibitory effects of PDTC on ALI, the activation of NF-kappaB, as well as the expression of cytokines (IL-1beta and IL-8) after PFIB exposure were evaluated. The results demonstrated that pretreatment with PDTC (120 mg/kg, 30 min before PFIB exposure) could significantly lower the lung coefficient (wet lung-to-body weight ratio, dry lung-to-body weight ratio, water content in the lung, and lung wet-to-dry weight ratio) and protein content in bronchoalveolar lavage fluid (BALF), but no effects of PDTC were found when PDTC was treated after PFIB inhalation, suggesting a preventative effect rather than a therapeutic effect of PDTC. Furthermore, the above preventative effects of PDTC (when given at 30 min before PFIB exposure) on PFIB-induced lung injury were achieved in a dose-dependent manner. In support of these preventive effects of PDTC, our toxicological studies demonstrated that PFIB-inhalation induced a quick activation of NF-kappaB (0.5 h post PFIB exposure) and expression of IL-1beta and IL-8 (0.5 h and 1 h post PFIB exposure, respectively). Pretreatment with PDTC (120 mg/kg, 30 min before PFIB exposure) resulted in a significant inhibitive effect on the activation of NF-kappaB (0.5 h post PFIB exposure) and expression of IL-1beta and IL-8 (1 h post PFIB exposure). The mortality, the extent of lung injury of the mice indexed by lung coefficients, the content of total protein and albumin in BALF, as well as the lung histopathologic changes, were dramatically alleviated in PFIB exposure after pretreatment with PDTC, clearly suggesting that PDTC has a prophylactic role against PFIB inhalation-induced ALI, and that NF-kappaB activation might play a central role in initiating an acute inflammatory response and in causing injury to the lungs after PFIB inhalation.

[Effect of Danxiongfang and its components on experimental liver injury models induced by CCl4 in mice].

OBJECTIVE: The study investigates the protective effect on liver of Danxionfang and its components. METHOD: Mice are injected with CCl4 to establish liver injured model. ALT, AST, serum albumin, globulin in serum and SOD, MDA in liver and liver histological changes were measured to confirm the ability of protecting liver of Danxiongfang. RESULT: The results show Danxiongfang can inhibit obviously the abnormal increase of ALT, AST in serum and MDA in liver, enhance SOD activity in liver, total protein, albumin, globulin in serum, and decrease liver pathological changes, which suggests Danxiongfang can protect injured liver induced by CCl4. CONCLUSION: Danxiongfang showed powerful protective effect against liver damage induced by CCl4.

Determination of penehyclidine by gas chromatographic-mass spectrometry and its application to pharmacokinetics in humans, rabbits and mice.

A sensitive and specific gas chromatographic-mass spectrometry with the extracted ion chromatograms (GC-MS/EIC) method has been developed and validated for the identification and quantification of penehyclidine (PH) in human and animal blood. The chromatography was on HP-5 capillary column (12 m x 0.2 mm x 0.3 microm). PH-d(5) was selected as the internal standard (IS). Simultaneous MS detection of PH and IS was performed at m/z 315 (PH) and m/z 320 (PH-d(5)), and the EIC of the two compounds was at 175 and 180. PH and PH-d(5) eluted at approximately 8.2 min and no endogenous materials interfered with their measurement. Linearity was obtained over the concentration range of 0.1-100 ng/ml in the blood. The lower limit of quantification (LLOQ) was reproducible at 50 pg/ml in both human and animal blood. The within-day and between-day precisions were no more than 9.1%. This method was successfully applied to quantification and pharmacokinetic studies of PH in the subjects. The concentration-time profiles of PH in humans, rabbits and mice were all fitted to first order absorption two-compartment open model after i.m. a single dose. The differences in absorption, distribution and elimination of PH among the species were found. The results provided the important information for developing a novel anti-cholinergic drug and for obtaining a more effectual remedy in clinical practice.

A simplified model to predict P-glycoprotein interacting drugs from 3D molecular interaction field.

A new two components partial least squares discriminant analysis (PLS) model for the prediction of P-glycoprotein-associated ATPase activity of drugs by using VolSurf compute theoretical molecular descriptors derived from 3D molecular interaction field was reported in the present study. By using 27 diverse drugs from literature, two models were constructed (R(2)=0.9003, 0.8150; Q(2)=0.7165, 0.7630) in this paper, which were similar to models that utilized MolSurf parametrization (R(2)=0.7760, 0.7180; Q(2)=0.7420, 0.6950) by using 22 drugs reported in the same literature. The results investigated VolSurf software was superior to MolSurf in its simplicity. Properties associated with the volume, polarizability, and hydrogen bond could have important impact on the P-glycoprotein-associated ATPase activity.

Determination of thiencynonate by liquid chromatographic-mass spectrometry and its application to pharmacokinetics in rats.

A sensitive and specific high-performance liquid chromatography-tandem mass spectrometry method (LC/ESI/MS) was developed and validated for the identification and quantification of the novel lead compound of anticholinergic drug thiencynonate in rat plasma. The analytes were determined using positive electrospray ionization mass spectrometry in the selected reaction ion monitoring (SRM). The chromatography separation was on BetaBasic-18 column (150 mm x 2.1 mm i.d., 3 microm). The mobile phase was composed of methanol-water (70:30, v/v), containing 0.5 per thousand formic acid, which was pumped at a flow rate of 0.2 ml/min. Phencynonate was selected as the internal standard (IS). Simultaneous MS detection of thiencynonate and IS was performed at m/z 364.4 (thiencynonate), m/z 358 (phencynonate), and the SRM of the two compounds were both at 156. Thiencynonate eluted at approximately 2.8 min, phencynonate eluted at approximately 2.9 min and no endogenous materials interfered with their measurement. Linearity was obtained over the concentration range of 1-100 ng/ml in rat plasma. The lower limit of quantification (LLOQ) was reproducible at 1 ng/ml in rat plasma. The precision measured was obtained from 2.47 to 9.28% in rat plasma. Extraction recoveries were in the range of 67.63-76.76% in plasma. This method was successfully applied to the identification and quantification of thiencynonate in pharmacokinetic studies.

Anticonvulsant effects of phencynonate hydrochloride and other anticholinergic drugs in soman poisoning: neurochemical mechanisms.

Previous studies have paid little attention to the anticonvulsant effect of anticholinergic drugs that act on both muscarinic (M) and nicotinic (N) receptors during soman-induced seizures. Therefore, with the establishment of a soman-induced seizures model in rats, this study evaluated the efficacy in preventing soman-induced convulsions of two antagonists of both the M and N receptors, phencynonate hydrochloride (PCH) and penehyclidine hydrochloride (8018), which were synthesized by our institute, and of other anticholinergic drugs, and investigated the mechanisms of their antiseizures responses. Male rats, previously prepared with electrodes to record electroencephalographic (EEG) activity, were pretreated with the oxime HI-6 (125 mg kg-1, i.p.) 30 min before they were administered soman (180 microg kg-1, s.c.). All animals developed seizures subsequent to this treatment. Different drugs were given at different times (5, 20 and 40 min after seizures onset) and their anticonvulsant effects were monitored and compared using the two variables, i.e. the dose that could totally control the ongoing seizures, as well as the speed of seizures control. The anticonvulsant effects of atropine, scopolamine and 8018 decreased with the progression of the seizures, and they eventually lost their anticonvulsant activity when the seizures had progressed for 40 min. In contrast, PCH showed good anticonvulsant effectiveness at 5 and 20 min, and especially at 40 min after seizures onset. Of the anticholinergic drugs tested, atropine, scopolamine, and 8018 showed no obvious protection against pentylenetetrazol (PTZ)-induced convulsions or N-methyl-D-aspartate (NMDA)-induced lethality in mice. However, PCH antagonized the PTZ-induced convulsions in a dose-dependant manner with an ED50 of 10.8 mg kg-1, i.p. (range of 7.1-15.2 mg kg-1) and partly blocked the lethal effects of NMDA in mice. PCH also dose-dependently inhibited NMDA-induced injury in rat primary hippocampal neuronal cultures, suggesting a possible neuroprotective action in vivo. In conclusion, our study suggests that the mechanisms of PCH action against soman-induced seizures might differ from those of the M receptor antagonists atropine and scopolamine, and that of the antagonist of both the M and N receptors, 8018. The pharmacological profile of PCH might include anticholinergic and anti-NMDA properties. Compared with the currently recommended anticonvulsant drug diazepam, with known NMDA receptor antagonists such as MK-801 and with conventional anticholinergics such as scopolamine and atropine, the potent anticonvulsant effects of PCH during the entire initial 40 min period of soman poisoning, and its fewer adverse effects, all suggest that PCH might serve as a new type of anticonvulsant for the treatment of seizures induced by soman.

Liquid chromatography-tandem mass spectrometry method for determination of phencynonate in rat blood and urine.

A sensitive and specific high-performance liquid chromatographic assay with electrospray ionization mass spectrometry detection (LC-ESI-MS) has been developed and validated for the identification and quantification of the novel anticholinergic drug phencynonate in rat blood and urine. The sample pretreatment involves basification and iterative liquid-liquid extraction with ethyl ether-dichloromethane (2:1, v/v) solution, followed by LC separation and positive electrospray ionization mass spectrometry detection. The chromatography was on BetaBasic-18 column (150 mm x 2.1mm i.d., 3 microm). The mobile phase was composed of methanol-water (85:15, v/v), containing 0.5 per thousand formic acid, which was pumped at a flow-rate of 0.2 ml/min. Thiencynonate was selected as the internal standard (IS). Simultaneous MS detection of phencynonate and IS was performed at m/z 358.4 (phencynonate), m/z 364 (thiencynonate), and the selected reaction ion monitoring (SRM) of the two compounds was at 156. Phencynonate eluted at approximately 5.25 min, thiencynonate eluted at approximately 5.10 min and no endogenous materials interfered with their measurement. Linearity was obtained over the concentration range of 1-100 ng/ml in rat blood and 1-500 ng/ml in rat urine. The lower limit of quantification (LLOQ) was reproducible at 1 ng/ml in both of rat blood and urine. The precision measured was obtained from 2.92 to 9.76% in rat blood and 4.17 to 9.76% in rat urine. Extraction recoveries were in the range of 69.57-79.49% in blood and 56.85-64.86% in urine. This method was successfully applied to the identification and quantification of phencynonate in pharmacokinetic studies.

The prophylactic and therapeutic effects of cholinolytics on perfluoroisobutylene inhalation induced acute lung injury.

Perfluoroisobutylene (PFIB) is a kind of fluoro-olefin that is ten times more toxic than phosgene. The mechanisms of the acute lung injury (ALI) induced by PFIB inhalation remain unclear. To find possible pharmacological interventions, mice and rats were exposed to PFIB, and the prophylactic or therapeutic effects of 3-quinuclidinyl benzilate (QNB) and anisodamine were studied and confirmed. It was observed that the wet lung/body weight and the dry lung/body weight ratios at 24 h after PFIB exposure (130 mg/m(3) for 5 min) were significantly decreased when a single dose of QNB (5 mg/kg) was administered intraperitoneally either 30 min before exposure or 10 h after exposure. Anisodamine was without any prophylactic or therapeutic effects at single doses below 30 mg/kg. The effects of QNB against PFIB inhalation induced ALI were well evidenced by the significantly decreased mice mortality at 72 h, the total protein concentration in bronchoalveolar lavage fluid at 24 h after the PFIB exposure, as well as the ultrastructural observations. The analysis of the time courses of lung sulfhydryl concentration, myeloperoxidase (MPO) activity and hemorheology assay showed that the toxicity of PFIB may be due to consumption of lung protein sulfhydryl, influx of polymorphonuclear leukocytes (PMNs) into the lung, and increased peripheral blood viscosity at a low shear rate, all of which were partially blocked by QNB intervention except for PMN influx. The results suggest that cholinolytics might have prophylactic and therapeutic roles in PFIB inhalation induced ALI.