Binding of pyridostigmine bromide,N,N-diethyl-m-toluamide and permethrin,alone and in combinations,to human serum albumin

In this study we examined the interaction of the anti-nerve agent drug pyridostigmine bromide (PB, 3,3-dimethylaminocarbonyloxy- N-methylpyridiniyum bromide), the insect repellent DEET ( N, N-diethyl- m-toluamide), and the insecticide permethrin [3-(2,2-dichloroethyl)-2,2-dimethylcyclopropanecarboxylic acid (3-phenoxyphenyl)methyl ester] in binding to human serum albumin (HSA). Concentrations between 500 ng/ml and 10 microg/ml PB, DEET and permethrin, alone or in combination, were incubated with HSA at 37 degrees C for 60 min. Concentrations of PB, DEET and permethrin were determined using high performance liquid chromatography (HPLC). The results showed that 81.2+/-4.2%, and 84.6+/-2.5% of the initial concentration of PB was bound to HSA when incubated alone or in combination with DEET or permethrin, respectively. DEET and permethrin did not significantly interact with HSA after 1 h of incubation. Incubation of combinations of two or three compounds did not significantly alter the binding pattern of any of the compounds with HSA. These results showed that PB is highly bound to albumin protein, while the competition between PB, DEET and permethrin on binding sites of HSA as a possible site of interaction following combined administration in vivo is not likely.     

Pyridostigmine bromide modulates topical irritant-induced cytokine release from human epidermal keratinocytes and isolated perfused porcine skin

Gulf War personnel were given pyridostigmine bromide (PB) as a prophylactic treatment against organophosphate nerve agent exposure, and were exposed to the insecticide permethrin and the insect repellent N,N-diethyl-m-toluamide (DEET). The purpose of this study was to assess the effects of PB to modulate release of inflammatory biomarkers after topical chemical exposure to chemical mixtures containing permethrin and DEET applied in ethanol or water vehicles. Treatments were topically applied to isolated perfused porcine skin flaps (IPPSFs). Concentrations of interleukin-8 (IL-8), tumor necrosis factor-alpha (TNF-alpha) and prostaglandin E(2) (PGE(2)) were assayed in perfusate to probe for potential inflammatory effects after complex mixture application. IPPSFs (n=4/treatment) were topically dosed with mixtures of permethrin, DEET, and permethrin/DEET, in ethanol. Each treatment was repeated with perfusate spiked with 50 ng/ml of PB. Perfusate was also spiked with 30 ng/ml diisopropylfluorophosphate to simulate low level organophosphate nerve agent exposure. Timed IPPSF venous effluent samples (0.5,1,2,4, and 8 h) were assayed by ELISA for IL-8 and TNF-alpha and by EIA for PGE(2). Overall, PB infusion caused a decrease or IL-8 and PGE(2) release. Effects on TNF-alpha were vehicle dependent. To probe the potential mechanism of this PB effect, human epidermal keratinocyte HEK cell cultures were exposed to permethrin DEET permethrin/DEET, with and without PB in DMSO. IL-8 was assayed at 1, 2, 4, 8, 12 and 24 h. PB suppressed IL-8 in permethrin and ethanol treatment from 4 to 24 h confirming the IPPSF results. In conclusion, these studies suggest that systemic exposure to PB suppressed IL-8 release at multiple time points in two skin model systems. This interaction merits further study.     

In vitro metabolism and interactions of pyridostigmine bromide, N,N-diethyl-m-toluamide, and permethrin in human plasma and liver microsomal enzymes

1. The in vitro human plasma activity and liver microsomal metabolism of pyridostigmine bromide (PB), a prophylactic treatment against organophosphate nerve agent attack, N,N-diethyl-m-toluamide (DEET), an insect repellent, and permethrin, a pyrethroid insecticide, either alone or in combination were investigated. 2. The three chemicals disappeared from plasma in the following order: permethrin > PB > DEET. The combined incubation of DEET with either permethrin or PB had no effect on permethrin or PB. Binary incubation with permethrin decreased the metabolism of PB and its disappearance from plasma and binary incubation with PB decreased the metabolism of permethrin and its clearance from plasma. Incubation with PB and/or permethrin shortened the DEET terminal half-life in plasma. These agents behaved similarly when studied in liver microsomal assays. The combined incubation of DEET with PB or permethrin (alone or in combination) diminished DEET metabolism in microsomal systems. 3. The present study evidences that PB and permethrin are metabolized by both human plasma and liver microsomal enzymes and that DEET is mainly metabolized by liver oxidase enzymes. Combined exposure to test chemicals increases their neurotoxicity by impeding the body's ability to eliminate them because of the competition for detoxifying enzymes.     

Simultaneous determination of malathion, permethrin, DEET (N,N-diethyl-m-toluamide), and their metabolites in rat plasma and urine using high performance liquid chromatography

A method was developed for the separation and quantification of the insecticide malathion (O,O-dimethyl-S-(1,2-carbethoxyethyl) phosphorodithioate), its metabolite malaoxon (O,O-dimethyl-S-(1,2-carbethoxyethyl) phosphorothioate), the insecticide permethrin (3-(2,2-dichloro-ethenyl)-2,2-dimethylcyclopropanecarboxylic acid(3-phenoxyphenyl)methylester), two of its metabolites m-phenoxybenzyl alcohol and m-phenoxybenzoic acid, the insect repellent N,N-diethyl-m-toluamide (DEET), and its metabolites m-toluamide and m-toluic acid in rat plasma and urine. The method used high performance liquid chromatography (HPLC) with reversed phase C(18) column, and UV detection at 210 nm. The compounds were separated using gradient of 45--99% acetonitrile in water (pH 3.5) at a flow rate ranging between 0.5 and 2 ml/min in a period of 15 min. The retention times ranged from 7.4 to 12.3 min. The limits of detection ranged between 20 and 100 ng/ml, while limits of quantitation were 50-150 ng/ml. Average percentage recovery of five spiked plasma samples were 80.1+/-4.2, 75.2+/-4.6, 84.5+/-4.0, 84.3+/-3.4, 82.8+/-3.9, 83.9+/-5.5, 82.2+/-6.0, 83.1+/-4.3, and from urine 78.8+/-3.9, 76.4+/-4.9, 82.3+/-4.5, 82.5+/-3.9, 81.4+/-4.0, 83.9+/-4.3, 81.5+/-5.0, and 84.5+/-3.8 for, malathion, malaoxon, DEET, m-toluamide, m-toluic acid, permethrin, m-phenoxybenzyl alcohol, and m-phenoxybenzoic acid, respectively. The method was reproducible and linear over range between 100 and 1000 ng/ml. This method was applied to analyze the above chemicals and metabolites following combined dermal administration in rats.     

Induction of urinary excretion of 3-nitrotyrosine, a marker of oxidative stress, following administration of pyridostigmine bromide, DEET (N,N-diethyl-m-toluamide) and permethrin, alone and in combination in rats

In this study, we determined levels of 3-nitrotyrosine in rat urine following administration of a single oral dose of 13 mg/kg pyridostigmine bromide (PB) (3-dimethylaminocarbonyloxy-N-methylpyridinum bromide), a single dermal dose of 400 mg/kg N,N-diethyl-m-toluamide (DEET) and a single dermal dose of 1.3 mg/kg permethrin, alone and in combination. Urine samples were collected from five treated and five control rats at 4, 8, 16, 24, 48, and 72 h following dosing. Solid-phase extraction coupled with high-performance liquid chromatography with ultraviolet detection at 274 nm was used for the determination of tyrosine and 3-nitrotyrosine. A single oral dose of PB and a single dermal dose of DEET or their combination significantly (P<0.05) increased levels of 3-nitrotyrosine starting 24 h after dosing compared with control urine samples. The maximum increase of 3-nitroytyrosine was detected 48 h after combined administration of PB and DEET. The ratio of 3-nitrotyrosine to tyrosine in urine excreted 48 h after dosing was 0.19+/-0.04, 0.20+/-0.05, 0.28+/-0.03, 0.32+/-0.04, 0.19+/-0.05, 0.42+/-0.04, 0.27+/-0.03, 0.36+/-0.04, and 0.48+/-0.04 following administration of water, ethanol, PB, DEET, permethrin, PB+DEET, PB+permethrin, DEET+permethrin, and PB+DEET+permethrin, respectively. The results indicate that an oral dose of PB and a dermal administration of DEET, alone and in combination, could generate free radical species, and thus increase levels of 3-nitrotyrosine in rat urine. Induction of 3-nitrotyrosine, a marker of oxidative stress, following exposure to these compounds could be significant in understanding the proposed enhanced toxicity following combined exposure to these compounds.     

In vitro metabolism and interactions of pyridostigmine bromide,N,N-diethyl-m-toluamide,and permethrin in human plasma and liver microsomal enzymes

1.?The in vitro human plasma activity and liver microsomal metabolism of pyridostigmine bromide (PB), a prophylactic treatment against organophosphate nerve agent attack, N,N-diethyl-m-toluamide (DEET), an insect repellent, and permethrin, a pyrethroid insecticide, either alone or in combination were investigated.

2.?The three chemicals disappeared from plasma in the following order: permethrin > PB > DEET. The combined incubation of DEET with either permethrin or PB had no effect on permethrin or PB. Binary incubation with permethrin decreased the metabolism of PB and its disappearance from plasma and binary incubation with PB decreased the metabolism of permethrin and its clearance from plasma. Incubation with PB and/or permethrin shortened the DEET terminal half-life in plasma. These agents behaved similarly when studied in liver microsomal assays. The combined incubation of DEET with PB or permethrin (alone or in combination) diminished DEET metabolism in microsomal systems.

3.?The present study evidences that PB and permethrin are metabolized by both human plasma and liver microsomal enzymes and that DEET is mainly metabolized by liver oxidase enzymes. Combined exposure to test chemicals increases their neurotoxicity by impeding the body's ability to eliminate them because of the competition for detoxifying enzymes.     

Co-exposure to pyridostigmine bromide, DEET, and/or permethrin causes sensorimotor deficit and alterations in brain acetylcholinesterase activity

Military personnel deployed in the Persian Gulf War (PGW) were exposed to a combination of chemicals, including pyridostigmine bromide (PB), DEET, and permethrin. We investigated the dose-response effects of these chemicals, alone or in combination, on the sensorimotor performance and cholinergic system of male Sprague-Dawley rats. Animals were treated with a daily dermal dose of DEET and/or permethrin for 60 days and/or PB (gavage) during the last 15 days. Neurobehavioral performance was assessed on day 60 following the beginning of the treatment with DEET and permethrin. The rats were sacrificed 24 h after the last treatment for biochemical evaluations. PB alone, or in combination with DEET, or DEET and permethrin resulted in deficits in beam-walk score and longer beam-walk times compared to controls. PB alone, or in combination with DEET, permethrin, or DEET and permethrin caused impairment in incline plane performance and forepaw grip strength. PB alone at all doses slightly inhibited plasma butyrylcholinesterase activity, whereas combination of PB with DEET or permethrin increased its activity. Brainstem acetylcholinesterase (AChE) activity significantly increased following treatment with combinations of either DEET or permethrin at all doses, whereas the cerebellum showed a significant increase in AChE activity following treatment with a combination of PB/DEET/permethrin. Co-exposure to PB, DEET, and permethrin resulted in significant inhibition in AChE in midbrain. PB alone or in combination with DEET and permethrin at all doses increased ligand binding for m2 muscarinic acetylcholine receptor in the cortex. In addition, PB and DEET together or a combination of PB, DEET, and permethrin significantly increased ligand binding for nicotinic acetylcholine receptor. These results suggest that exposure to various doses of PB, alone and in combination with DEET and permethrin, leads to sensorimotor deficits and differential alterations of the cholinergic system in the CNS.     

Locomotor and sensorimotor performance deficit in rats following exposure to pyridostigmine bromide, DEET, and permethrin, alone and in combination.

Since their return from Persian Gulf War (PGW), many veterans have complained of symptoms including muscle and joint pain, ataxia, chronic fatigue, headache, and difficulty with concentration. The causes of the symptoms remain unknown. Because these veterans were exposed to a combination of chemicals including pyridostigmine bromide (PB), DEET, and permethrin, we investigated the effects of these agents, alone and in combination, on the sensorimotor behavior and central cholinergic system of rats. Male Sprague-Dawley rats (200-250 gm) were treated with DEET (40 mg/kg, dermal) or permethrin (0.13 mg/kg, dermal), alone and in combination with PB (1.3 mg/kg, oral, last 15 days only), for 45 days. Sensorimotor ability was assessed by a battery of behavioral tests that included beam-walk score, beam-walk time, incline plane performance, and forepaw grip on days 30 and 45 following the treatment. On day 45 the animals were sacrificed, and plasma and CNS cholinesterase, and brain choline acetyl transferase, muscarinic and nicotinic acetylcholine receptors were evaluated. Animals treated with PB, alone or in combination with DEET and permethrin, showed a significant deficit in beam-walk score as well as beam-walk time as compared with controls. Treatment with either DEET or permethrin, alone or in combination with each other, did not have a significant effect on beam-walk score. All chemicals, alone or in combination, resulted in a significant impairment in incline plane testing on days 30 and 45 following treatment. Treatment with PB, DEET, or permethrin alone did not have any inhibitory effect on plasma or brain cholinesterase activities, except that PB alone caused moderate inhibition in midbrain acetylcholinesterase (AChE) activity. Treatment with permethrin alone caused significant increase in cortical and cerebellar AChE activity. A combination of DEET and permethrin or PB and DEET led to significant decrease in AChE activity in brainstem and midbrain and brainstem, respectively. A significant decrease in brainstem AChE activity was observed following combined exposure to PB and permethrin. Coexposure with PB, DEET, and permethrin resulted in significant inhibition in AChE in brainstem and midbrain. No effect was observed on choline acetyl transferase activity in brainstem or cortex, except combined exposure to PB, DEET, and permethrin caused a slight but significant increase in cortical choline acetyltransferase activity. Treatment with PB, DEET, and permethrin alone caused a significant increase in ligand binding for m2 muscarinic acetylcholine receptor (mAChR) in the cortex. Coexposure to PB, DEET, and permethrin did not have any effect over that of PB-induced increase in ligand binding. There was no significant change in ligand binding for nicotinic acetylcholine receptor (nAChR) associated with treatment with the chemical alone; a combination of PB and DEET or coexposure with PB, DEET, and permethrin caused a significant increase in nAChR ligand binding in the cortex. Thus, these results suggest that exposure to physiologically relevant doses of PB, DEET, and permethrin, alone or in combination, leads to neurobehavioral deficits and region-specific alterations in AChE and acetylcholine receptors.     

Increased 8-hydroxy-2'-deoxyguanosine, a biomarker of oxidative DNA damage in rat urine following a single dermal dose of DEET (N, N-diethyl-m-toluamide), and permethrin, alone and in combination

Levels of the biomarker of DNA oxidative damage 8-hydroxy-2'-deoxyguanosine (8-OHdG) in rat urine following dermal exposure to DEET (N,N-diethyl-m-toluamide) and permethrin, alone and in combination have been determined. A group of five rats for each time point were treated with a single dermal dose of 400 mg/kg of DEET, 1.3 mg/kg of permethrin or their combination. Urine samples were collected 2,4,8,16,24,48, and 72 h following application. Control urine samples of rats treated with ethanol were also collected at the same time intervals. Solid phase extraction coupled with high performance liquid chromatography (HPLC) with UV detection at 254 nm was used for determination of 2'-deoxyguanosine, and (8-OHdG). The limits of detection (LOD) were 0.5 ng of both 2'-deoxyguanosine and 8-OHdG. Their average percentage recoveries from urine samples were between 70-85%. A single dermal dose of DEET or in combination with permethrin significantly induced levels of (8-OHdG) that are excreted in the urine over the time course of the study compared to control urine samples. Permethrin did not cause significant increase in the amount of 8-OHdG in the urine. Levels of 8-OHdG in urine excreted at 24 h were 1009+/-342, 1701+/-321, 1140+/-316, and 1897+/-231 ng following treatment with ethanol, DEET, permethrin, and DEET+permethrin, respectively. The results indicate that dermal administration of DEET could generate free radical species hence cause DNA oxidative damage in rats.     

Simultaneous determination of chlorpyrifos, permethrin, and their metabolites in rat plasma and urine by high-performance liquid chromatography

A high-performance liquid chromatographic (HPLC) method was developed for the separation and quantitation of the insecticide chlorpyrifos (O,O-diethyl-O[3,5,6-trichloro-2-pyridinyl] phosphorothioate), its metabolites chlorpyrifos-oxon (O,O-diethyl-O[3,5,6-trichloro-2-pyridinyl] phosphate) and TCP (3,5,6-trichloro-2-pyridinol), the insecticide permethrin (3-(2,2-dichloro-ethenyl)-2,2-dimethylcyclopropanecarboxylic acid-(3-phenoxyphenyl) methylester), and two of its metabolites, m-phenoxybenzyl alcohol and m-phenoxybenzoic acid, in rat plasma and urine. The method is based on using C18 Sep-Pak cartridges for solid-phase extraction and reversed-phase HPLC. The compounds were separated using a gradient of 1 to 80% acetonitrile in water (pH 3.2) at a flow rate ranging between 1 and 1.5 mL/min in a period of 17 min and gradient UV detection ranging between 210 and 280 nm. The retention times ranged from 9.3 to 14.5 min. The limits of detection ranged between 20 and 150 ng/mL, whereas the limits of quantitation were 150-200 ng/mL. The respective average percentage recoveries of chlorpyrifos, chlorpyrifos-oxon, TCP, permethrin, m-phenoxybenzyl alcohol, and m-phenoxybenzoic were 78.6 +/- 6.4, 72.8 +/- 6.8, 84.8 +/- 8.0, 79.2 +/- 8.4, 80.5 +/- 7.2, and 82.3 +/- 7.1 from five spiked plasma samples and 77.5 +/- 8.1, 72.8 +/- 8.3, 79.9 +/- 6.4, 79.1 +/- 8.9, 80.5 +/- 7.6, and 81.4 +/- 7.8 from urine samples. The relationship between peak areas and concentration was linear for concentrations between 200 and 2,000 ng/mL. This method was used to analyze these chemicals and metabolites following dermal administration in rats.     

UPLC-MS/MS法同时测定人血浆中黄芩苷和绿原酸

建立UPLC-MS/MS法同时测定人血浆中黄芩苷和绿原酸的浓度，研究注射用银黄在健康人体的药代动力学。色谱柱为BEH C₁₈(50 mm×2.1 mm ID，1.7 μm)；流动相：A(水，0.1%甲酸)，B(甲醇，0.1%甲酸)，梯度洗脱；流速：0.35 mL·min^-1。电喷雾离子源，多反应监测。黄芩苷：［M+H］⁺，m/z 447→271；绿原酸：［M-H］^-，m/z 353→191；山柰素：［M+H］⁺，m/z 287→287。结果表明，黄芩苷和绿原酸血药浓度的线性范围分别为9.6～1 540和7.5～1 200 ng·mL^-1，日内、日间精密度均小于10.2%。志愿者静脉滴注注射用银黄后，黄芩苷和绿原酸的药时曲线分别符合二房室和三房室模型。该法简便、灵敏、特异，适用于血浆中黄芩苷和绿原酸浓度的测定。     

Combined exposure to DEET (N,N-diethyl-m-toluamide) and permethrin-induced release of rat brain mitochondrial cytochrome c.

The release of cytochrome c from the mitochondrial intermembrane space can induce apoptosis. The levels of mitochondrial cytochrome c in rat brain following a single dermal dose of 400 mg/kg of DEET, and of 1.3 mg/kg of permethrin, alone or in combination were determined. Rats were sacrificed at a time interval of 0.5, 1, 2, 4, 8, 16, 24, 48, or 72 h after dosing. Brain mitochondria were isolated and the levels of cytochrome c were measured using reversed-phase high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. Average percentage recovery of cytochrome c spiked with control rat brain mitochondria was 83.2 +/- 8.9%. Limits of detection and quantitation were 1 and 5 ng, respectively. The results showed that a single dermal dose of a combination of DEET and permethrin significantly increased the release of brain mitochondrial cytochrome c starting 24 h after treatment. DEET and permethrin alone did not affect the release of cytochrome c. The results indicate that combined exposure to DEET and permethrin might induce the apoptotic processes in rat brain as seen by the release of cytochrome c.     

LC-MS/MS法测定人血浆中加巴喷丁的浓度及其药动学研究

建立液相色谱串联质谱(LC-MS/MS)法测定人血浆中加巴喷丁的浓度并将其应用于人体药动学研究。取血浆样品经甲醇沉淀蛋白后,以甲醇0.2%甲酸水溶液(80∶20)为流动相,用Inertsil ODS-3 C18柱(50 mm×2.1 mm ID,3μm)分离,采用电喷雾离子源,以多反应监测(MRM)方式进行正离子检测,定量分析的离子反应分别为m/z 172→m/z 154(加巴喷丁)和m/z 130→m/z 71(内标二甲双胍)。加巴喷丁线性范围为40.8～8.16×103 ng.mL 1,定量限为40.8 ng.mL 1,每个样品测试时间仅2.2 min,日内、日间精密度(RSD)均小于12%,准确度(RE)在±6.4%范围内。应用此法研究了20名健康志愿者单剂量口服加巴喷丁胶囊600 mg后的药动学特点。该方法快速、专属、灵敏、适用性强,可应用于加巴喷丁的人体药动学研究。     

Solid-phase microextraction of human plasma samples for determination of sufentanil by gas chromatography-mass spectrometry

A solid-phase microextraction (SPME) method has been developed for the quantitative analysis of sufentanil from human plasma by gas chromatography-mass spectrometry (GC-MS). The immersion SPME sampling technique was optimized for the extraction of sufentanil from plasma. The influence of the pH and the ionic strength of the sample on the extraction of the analytes by the SPME fiber were investigated. Sufentanil and fentanyl (internal standard) were extracted from plasma with a 65-microm polydimethylsiloxane-divinylbenzene (PDMS-DVB) fiber for 30 minutes using salting out agents in basic conditions. The calibration curve was linear over a concentration range of 6-50 ng/mL. Intraday and interday relative standard deviations were 3.6% and 10.6%, respectively. The limit of quantification was 6 ng/mL for a plasma volume of 1 mL. With regard to selectivity, simplicity, and low cost, the SPME method described should be useful for a rapid extraction of sufentanil from human plasma.     

Determination of olanzapine in human plasma by reversed-phase high-performance liquid chromatography with ultraviolet detection

A sensitive high-performance liquid chromatographic method with ultraviolet absorbance detection for the determination of olanzapine in human plasma is described. Clozapine was used as internal standard. Analytes were concentrated from alkaline plasma by liquid-liquid extraction with n-hexane-isoamyl alcohol (90:10, vol/vol). The organic phase was back-extracted with 150 muL phosphate buffer (KH2PO4 with 25% H3PO4) 0.1 mol/L pH 2.2. The chromatographic separation required 6 minutes at a flow-rate of 1.0 mL/min and was carried out on a Water Spherisorb S5 C6 analytical column (250 mm x 4.6 mm ID) with a mobile phase water-acetonitrile 55:45 vol/vol containing 0.009 moL/L eptansulfonic acid sodium salt and 0.06 mol/L potassium phosphate monobasic pH 2.7. The peaks were detected at 254 nm. Mean recoveries for olanzapine and internal standard were 89.4+/-3.3% and 90.4+/-1.0%, respectively. Coefficient of variation value for intraday was 5.0% at concentrations of 10, 50, and 100 ng/mL and for interday was 4.0% at concentrations of 5 and 25 ng/mL. Accuracy, expressed as percent error, ranged from -8.00% to 1.24%. Limit of detection and limit of quantification for olanzapine were 2 and 5 ng/mL, respectively. The method is suitable for pharmacokinetic studies and therapeutic drug monitoring.     

HPLC—MS／MS法测定人体血浆中格列美脲及其活性代谢物

目的：建立同时测定格列美脲（Glimepiride,G）及其活性代谢物羟基格列美脲（Hydroxyl—glimepiride,M1）血浆浓度的高效液相色谱一串联质谱（HPLC—MS／MS）法。方法：血浆样品酸化后,经乙酸乙酯萃取后浓集进样,色谱柱为PhenomenexGeminiC18（50mill×3．0mm,5μm）,甲醇：水：甲酸（80：20：0．1）为流动相,流速为0．2mL／min,柱温为室温,采用电喷雾（ESI）离子源,多反应离子检测模式,以格列齐特（Gliclazide,IS）为内标。G、M1和IS的检测离子对分别为质荷比（仇／z）491．4—352．4、507．4—352．4、324．4—127．2。结果：G和M1的线性范围分别为1．25～400ng／mL和0．313～100ng／mL,最低定量限分别为1．25和0．313ng／mL;批内批间精密度均小于10％,方法回收率均在96．4％～102．5％之间。结论：该方法简便快速、特异性高,可用于同时测定G和M．血药浓度及其人体药代动力学的研究。     

Pyridostigmine bromide modulates the dermal disposition of [14C]permethrin

The cause of the Gulf War Syndrome may be related to soldiers being exposed to insecticides (e.g., permethrin (P)), insect repellents (e.g., N,N-diethyl-m-toluamide (DEET)), an organophosphate nerve agent simulant (e.g., diisopropyl fluorpohosphate (DFP)), and/or prophylactic treatment (e.g., pyridostigmine bromide (PB)) against potential nerve gas attacks. The purpose of this study was to assess the dermal disposition of [14C]permethrin in ethanol or ethanol:water (3:2) in the isolated perfused porcine skin flap (IPPSF) model with simultaneous dermal exposure to DEET or DFP. These IPPSFs were also simultaneously perfused arterially with or without PB, DFP, or DFP + PB. The results indicated that DFP + PB significantly increased [14C]permethrin absorption compared to controls (1.06% dose vs 0.14% dose). PB significantly increased [14C]permethrin disposition in the stratum corneum (SC) in aqueous mixtures only (9.40 vs 3.35% dose), while topical DEET or topical DFP reduced [14C]permethrin levels in the SC especially in nonaqueous mixtures. PB also significantly enhanced [14C]permethrin penetration into all skin tissues and perfusate in aqueous mixtures, while DEET reversed this effect. PB appeared to influence [14C]permethrin disposition in flowthrough diffusion cells, suggesting that the mechanism of this interaction may be associated predominantly with epidermal permeability, although muscarinic effects in the vasculature in IPPSFs should not be ruled out and requires further investigation. These experiments suggest that intraarterial perfusion of PB and/or DFP and topical application of DFP or DEET can alter the disposition of [14C]permethrin in skin and possibly its bioavailability in soldiers simultaneously exposed to these chemicals.     

Determination of 5-fluorouracil and its prodrug tegafur in plasma and tissue by high-performance liquid chromatography in a single injection: validation for application in clinical pharmacokinetic studies

Tegafur, a prodrug of 5-fluorouracil (5-FU), is an oral fluorouracil antitumor drug used for the management of adenocarcinomas. It has an efficacy similar to that of intravenous 5-FU, with potential advantages in terms of convenience and quality of life for the patient and cost-effectiveness as compared with intravenous chemotherapy. The authors developed a high-performance liquid chromatography (HPLC) assay for the determination of tissue or plasma tegafur and 5-FU concentration in a single step extraction and a single HPLC injection. The retention times of 5-FU and tegafur were 5 and 16.5 minutes, respectively, and the internal standard retention times were 11.5 and 17.5 minutes for 5-bromouracil (5-BU) and beta-hydroxyethyltheophylline, respectively. The limit of quantification was 0.0125 microg/mL for 5-FU and 0.05 microg/mL for tegafur. The assay had good recovery (96.5% +/- 9.45% and 97.5% +/- 7.89% for 5-FU in plasma and tissue, respectively, and 88.5% +/- 12.17% and 104.9% +/- 8.77% for tegafur in plasma and tissue, respectively). Precision was good: the within-day and between-day standard deviation of the mean (RSD) for 5-FU (0.0125-5 microg/mL) and tegafur (0.5-150 microg/mL) was always <8%. The authors conclude that the method described here is ideally suited for the therapeutic monitoring of 5-FU and tegafur.     

Analysis of 3-(2-(ethylamino)propyl)-1,2,3,4-tetrahydro-5H(1)benzopyrano (3,4-c)pyridin-5-one in plasma by liquid chromatographic column switching after derivatizing the secondary amine with fluorescein-6-isothiocyanate

A high-performance liquid chromatographic (HPLC) assay has been developed to quantify the bronchodilator 3-(2-ethylamino)propyl)-1,2,3,4-tetrahydro-5H(1)benzopyrano(3,4-c)pyridi n-5-one (CI-923) (1) in human plasma. The drug and internal standard (2) were extracted from plasma (pH 10.5) with ether, and the secondary amines were derivatized with fluorescein-6-isothiocyanate (F6ITC) (3). The derivatives were isolated from the mixture by on-line HPLC column switching and were quantified with fluorometric detection (Ex: 484 nm; Em: 518 nm). Linearity was observed over the range 0.5-50.0 ng/mL of 1, and the recovery of drug from plasma was greater than 86%. The precision of the method was 3.7-5.2% RSD based on the analysis of seeded control pools containing 0.8, 20.0 and 40.0 ng/mL of 1. The accuracy of the method was +/- 3.3% relative error for the same three pools.     

高效液相色谱-质谱/质谱联用法测定人血浆中莫沙必利

建立测定人血浆中莫沙必利的高效液相色谱-质谱/质谱联用法。取血浆样品经液-液萃取后，以乙腈为有机相，0.3%甲酸水溶液为水相，采用梯度洗脱的方式，用C₁₈柱分离，通过电喷雾离子化，以多反应监测(MRM)方式进行正离子检测。莫沙必利线性范围为0.17~68.00 ng·mL^-1，定量下限为0.17 ng·mL^-1，每个样品测试时间仅2.8 min，日内、日间精密度(RSD)均小于13%，准确度(RE)在±6.3%范围内。应用此法研究了20名志愿者单剂量口服枸橼酸莫沙必利片后的药代动力学特点。该方法、灵敏、准确、快速，适用于莫沙必利的药代动力学及生物等效性研究。