Forced degradation studies of norepinephrine and epinephrine from dental anesthetics: Development of stability-indicating HPLC method and in silico toxicity evaluation.

Injectable solutions containing epinephrine (EPI) and norepinephrine (NE) are not stable, and their degradation is favored mainly by the oxidation of catechol moiety. As studies of these drugs under forced degradation conditions are scarce, herein, we report the identification of their degradation products (DP) in anesthetic formulations by the development of stability-indicating HPLC method. Finally, the risk assessment of the major degradation products was evaluated using in silico toxicity approach. HPLC method was developed to obtain a higher selectivity allowing adequate elution for both drugs and their DPs. The optimized conditions were developed using a C18 HPLC column, sodium 1-octanesulfonate, and methanol (80:20, v/v) as mobile phase, with a flow rate of 1.5 mL/min, UV detection at 199 nm. The analysis of standard solutions with these modifications resulted in greater retention time for EPI and NE, which allow the separation of these drugs from their respective DPs. Then, five DPs were identified and analyzed by in silico studies. Most of the DPs showed important alerts as hepatotoxicity and mutagenicity. To the best of our acknowledgment, this is the first report of a stability-indicating HPLC method that can be used with formulations containing catecholamines.

Validated chromatographic method for the simultaneous determination of eight drugs (morphine, ropivacaine, bupivacaine, baclofen, clonidine, sufentanil, fentanyl and ziconotide) for intrathecal analgesia.

Intrathecal analgesia has increased over the past two decades in various indications: chronic refractory pain from cancerous or non-cancerous origins, spasticity. These different indications involve the use of different molecules alone or in combination such as morphine, ropivacaine, bupivacaine, fentanyl, sufentanil, clonidine, baclofen and ziconotide. Pump refills are prepared at the pharmacy under a laminar flow hood. An analytical control should be carried out before release of the preparation. A new method of analytical control by chromatography has been developed and validated according to the International Conference on Harmonization guideline in order to secure the production process.

Anesthetic synergy between two n-alkanes.

OBJECTIVE: N-butane and n-pentane can both produce general anesthesia. Both compounds potentiate γ-aminobutyric acid type A (GABAA) receptor function, but only butane inhibits N-methyl-d-aspartate (NMDA) receptors. It was hypothesized that butane and pentane would exhibit anesthetic synergy due to their different actions on ligand-gated ion channels. STUDY DESIGN: Prospective experimental study. ANIMALS: A total of four Xenopus laevis frogs and 43 Sprague-Dawley rats. METHODS: Alkane concentrations for all studies were determined via gas chromatography. Using a Xenopus oocyte expression model, standard two-electrode voltage clamp techniques were used to measure NMDA and GABAA receptor responses in vitro as a function of butane and pentane concentrations relevant to anesthesia. The minimum alveolar concentrations (MAC) of butane and pentane were measured separately in rats, and then pentane MAC was measured during coadministration of 0.25, 0.50 or 0.75 times MAC of butane. An isobole with 95% confidence intervals was constructed using regression analysis. A sum of butane and pentane that was statistically less than the lower-end confidence bound isobole indicated a synergistic interaction. RESULTS: Both butane and pentane dose-dependently potentiated GABAA receptor currents over the study concentration range. Butane dose-dependently inhibited NMDA receptor currents, but pentane did not modulate NMDA receptors. Butane and pentane MAC in rats was 39.4±0.7 and 13.7±0.4 %, respectively. A small but significant (p<0.03) synergistic anesthetic effect with pentane was observed during administration of either 0.50 or 0.75×MAC butane. CONCLUSIONS: Butane and pentane show synergistic anesthetic effects in vivo consistent with their different in vitro receptor effects. CLINICAL RELEVANCE: Findings support the relevance of NMDA receptors in mediating anesthetic actions for some, but not all, inhaled agents.

Determination of eugenol in fish and shrimp muscle tissue by stable isotope dilution assay and solid-phase extraction coupled gas chromatography-triple quadrupole mass spectrometry.

In this study, we developed a new method for the accurate quantification of eugenol in fish samples based on stable isotope dilution assay (SIDA) and solid-phase extraction (SPE) coupled gas chromatography-triple quadrupole mass spectrometry (SIDA-SPE-GC-MS/MS). Due to the difference of matrix effect (ME), it was difficult to determine accurately the level of eugenol residue in different fish and shrimp samples based on external standard calibration method. SIDA was applied to compensate matrix effect (ME) that eugenol-d3 was used as internal standard (IS). Freshwater fish (carp, channel catfish), marine fish (turbot), and shrimp (Penaeus vannawei) were used for the method validation. The average recoveries of eugenol were in the range of 94.7 to 109.78 % when the spiking levels were 10, 50, and 200 µg kg(-1). The inter-day and intra-day precisions were in the range of 1.15-8.19 and 0.71-8.45 %. The limit of detection (LOD) and the limit of quantification (LOQ) were approximately 2.5 and 5.0 µg kg(-1). This method was applied to the real fish samples assay obtained from aquaculture markets in Beijing, China. Eugenol residue was found in two fish samples with the levels at 6.2 and 7.7 µg kg(-1), respectively. Graphical abstract Determination of eugenol in fish and shrimp muscle tissue.

Anesthetic constituents of Zanthoxylum bungeanum Maxim.: A pharmacokinetic study.

A sensitive and selective ultra high performance liquid chromatography with tandem mass spectrometry method was established and validated for the simultaneous determination of hydroxy-α-sanshool, hydroxy-ß-sanshool, and hydroxy-γ-sanshool in rat plasma after the subcutaneous and intravenous administration of an extract of the pericarp of Zanthoxylum bungeanum Maxim. Piperine was used as the internal standard. The analytes were extracted from rat plasma by liquid-liquid extraction with ethyl acetate and separated on a Thermo Hypersil GOLD C18 column (2.1 mm × 50 mm, 1.9 µm) with a gradient elution system at a flow rate of 0.4 mL/min. The mobile phase consisted of acetonitrile/0.05% formic acid in water and the total analysis time was 4 min. Positive electrospray ionization was performed using multiple reaction monitoring mode for the analytes. The calibration curves of the three analytes were linear over the tested concentration range. The intra- and interday precision was no more than 13.6%. Extraction recovery, matrix effect, and stability were satisfactory in rat plasma. The developed and validated method was suitable for the quantification of hydroxy-α-sanshool, hydroxy-ß-sanshool, and hydroxy-γ-sanshool and successfully applied to a pharmacokinetic study of these analytes after subcutaneous and intravenous administration to rats.

Determination of levels of current drugs in hospital and urban wastewater.

A rapid, sensitive and highly specific HPLC-MS/MS method with direct on-line preparation was applied for the determination of 20 common pharmaceuticals in hospital and urban wastewater. Median drug concentrations were quite similar in the majority of samples, cerca 1 µg L⁻¹ ranging from 0.06 to 2.67 µg L⁻¹ in both water. Pharmaceutical hospital contribution, below 1 %, was negligible, as compared to the huge amount in the municipal plant flow. Due to only partial elimination in the plant, hundreds of kilograms of harmful waste per year are discharged in the River Seine. Therefore, to reduce potential human and environmental exposure, a topic of major concern, an efficient drug treatment procedure should be used at the municipal plant stage in order to reduce urban wastewater pollution. The HPLC-MS/MS method could be a very useful tool to optimize the pharmaceutical wastewater treatment process.

Effects of Anesthetic Administration on Rat Hypothalamus and Cerebral Cortex Peptidome.

Prohormone-derived neuropeptides act as cell-cell signaling molecules to mediate a wide variety of biological processes in the animal brain. Mass spectrometry-based peptidomic experiments are valuable approaches to gain insight into the dynamics of individual peptides under different physiological conditions or experimental treatments. However, the use of anesthetics during animal procedures may confound experimental peptide measurements, especially in the brain, where anesthetics act. Here, we investigated the effects of the commonly used anesthetics isoflurane and sodium pentobarbital on the peptide profile in the rodent hypothalamus and cerebral cortex, as assessed by label-free quantitative peptidomics. Our results showed that neither anesthetic dramatically alters peptide levels, although extended isoflurane exposure did cause changes in a small number of prohormone-derived peptides in the cerebral cortex. Overall, our results demonstrate that acute anesthetic administration can be utilized in peptidomic experiments of the hypothalamus and cerebral cortex without greatly affecting the measured peptide profiles.

Development of an Analytical Method for Detection of Anesthetics and Sedatives in Fish.

BACKGROUND: Anesthetics and sedatives are frequently used to prevent abrasions caused by stress and to facilitate fish management. However, drug residues may persist and cause changes in fish conditions and induce side effects. In addition, drugs that are not permitted for use in edible fish are sometimes potentially used in fish. The drugs can also be found in wastewater and are likely to be detected in fish. OBJECTIVE: The purpose of this study was to establish a quantitative analytical method for 10 anesthetic and sedative (azaperone, chlorpromazine, diazepam, estazolam, haloperidol, nitrazepam, nordiazepam, oxazepam, perphenazine, and temazepam) residues in fish sold in Korean markets. METHOD: Shrimp, flounder, and eel samples were selected as matrices. Acetonitrile (ACN) containing 0.1% formic acid was selected as an extraction solvent for shrimp and 100% ACN for flounder and eel. The QuEChERS method with C18 and primary secondary amine (PSA) was used as the extraction procedure, and the analysis was performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). RESULTS: Limit of quantitation, recovery, accuracy, and precision were validated, and satisfactory results were obtained for the drugs. All results applied to the real samples were negative. CONCLUSIONS: An optimal validation method was studied. Since the results for all samples were negative, it is considered that additional studies are needed by increasing the number of drugs. HIGHLIGHTS: The most effective QuEChERS pretreatment method and conditions of LC-MS/MS for the analysis of anesthetics and sedatives in fish were established.

Optical detection of the anesthetic agent propofol in the gas phase.

The anesthetic agent propofol (2,6-diisopropylphenol) is the most widely used intravenously administered drug in general anesthesia. However, a viable online capability to monitor metabolized levels of propofol in patients does not currently exist. Here we show for the first time that optical spectroscopy has good potential to detect metabolized propofol from patients' exhaled breath. We present quantitative absorption measurements of gas phase propofol both in the ultraviolet and middle-infrared spectral regions. We demonstrate that a detection limit in the subparts-per-billion concentration range can be reached with photoacoustic spectroscopy in the UV spectral region, paving the way for the development of future optical monitors.

Effects of Occupational Exposure to Waste Anesthetic Gas on Oxidative Stress and DNA Damage.

OBJECTIVE: The aim of the study was to investigate the potential effects of waste anesthetic gas (WAG) on oxidative stress, DNA damage, and vital organs. METHODS: A total of 150 members of the staff at a hospital were assigned to an exposure group or control group. The 68 operating room (OR) staff in the exposure group were exposed to WAG, and the 82 non-OR staff in the control group were not exposed to WAG. Air samples were collected in the OR, and the sevoflurane concentrations in the samples were determined. Superoxide dismutase (SOD), glutathione peroxidase (GSH-px), and malondialdehyde (MDA) in plasma from the participants were determined to assess oxidative stress. Western blot analysis was used to detect γH2AX in peripheral blood to assess DNA damage. Hematopoietic parameters, liver function, kidney function, and changes in electrophysiology were assessed to identify the effects on the vital organs. RESULTS: The mean (±standard deviation) sevoflurane concentration in 172 air samples from 22 operating rooms was 1.11 ± 0.65 ppm. The superoxide dismutase activity and vital organ parameters (lymphocyte, hemoglobin, and total protein concentrations and heart rate) were significantly lower (P < 0.05) in the exposed group than the control group. The malondialdehyde, total bilirubin, and creatinine concentrations and QT and QTc intervals were significantly higher (P < 0.05) in the exposed group than the control group. There were no significant differences between the glutathione peroxidase activities and γH2AX concentrations for the exposed and control groups. CONCLUSIONS: Long-term occupational exposure to waste anesthetic gas may affect the antioxidant defense system and probably affects vital organ functions to some extent. No correlation between DNA damage and chronic exposure to WAG was observed.

Anaesthetic gas monitoring comparison between two side-stream monitors.

End-tidal gas monitoring has become standard of care during inhaled general anaesthesia. We studied the performance of a new side stream gas monitor the ISA multi-gas monitor. The performance was studied at constant low flow of calibration gas and end-tidal anaesthetic measure was studied during routine day case anaesthesia. Pair wise readings of end-tidal halogenated anaesthetic concentration were recorded during low flow anaesthesia. Performance was found to be high; all calibration gas measures were within 0.1 vol% deviation. During routine anaesthesia mean bias was -0.036 vol% and 93 out of 97 pair-wise readings were within the agreement limits as compared to the reference Datex instrument.

Evaluation of benzocaine-based anesthetic gel in anuran skins extracts: A case study using the frog Lithodytes lineatus (Anura: Leptodactylidae).

Extracts made from the skin of dead Lithodytes lineatus frog individuals with the application of the benzocaine-based anesthetic gel, introduced into the oral cavity, were analyzed by 1H Nuclear Magnetic Resonance to investigate whether the application of this product (oral) can make studies that use extracts from the skins of these animals unfeasible. For comparison, we used skins of another species of anuran following the same death protocol. No trace of the benzocaine substance was found in the 1H-NMR spectra of the skin extracts from any of the tested anuran species. Still, using the hierarchical clustering model, it was possible to observe the formation of well-defined groups between the skin extracts of anurans and the anesthetic used to kill these animals. Our results suggest that the lethal dose of benzocaine in gel used inside the mouth of frogs may have no influence on potential results regarding the chemical composition or even bioassays using extracts made from the skin of these animals killed under this protocol since there was no detection of this substance for the analyzed samples.

Fast log P determination by ultra-high-pressure liquid chromatography coupled with UV and mass spectrometry detections.

Ultra-high-pressure liquid chromatography (UHPLC) systems able to work with columns packed with sub-2 microm particles offer very fast methods to determine the lipophilicity of new chemical entities. The careful development of the most suitable experimental conditions presented here will help medicinal chemists for high-throughput screening (HTS) log P(oct) measurements. The approach was optimized using a well-balanced set of 38 model compounds and a series of 28 basic compounds such as beta-blockers, local anesthetics, piperazines, clonidine, and derivatives. Different organic modifiers and hybrid stationary phases packed with 1.7-microm particles were evaluated in isocratic as well as gradient modes, and the advantages and limitations of tested conditions pointed out. The UHPLC approach offered a significant enhancement over the classical HPLC methods, by a factor 50 in the lipophilicity determination throughput. The hyphenation of UHPLC with MS detection allowed a further increase in the throughput. Data and results reported herein prove that the UHPLC-MS method can represent a progress in the HTS-measurement of lipophilicity due to its speed (at least a factor of 500 with respect to HPLC approaches) and to an extended field of application.

Determination of tricaine residues in fish by liquid chromatography.

Tricaine methanesulfonate (MS-222) is approved by the U.S. Food and Drug Administration, Center for Veterinary Medicine (CVM), as an anesthetic drug for select aquaculture species. It was approved for use as a handling aid with a 3 week withdrawal time. The drug is rapidly metabolized and excreted; therefore, CVM approved its use without requiring a regulatory method for drug residues in tissues. However, there are concerns that the drug may be used to sedate fish during transport to slaughter. A regulatory method will enable monitoring for unsafe residues of this drug resulting from extralabel use. We present a quantitative method, using LC at a target level of 0.1 mg/kg (ppm), for three different farmed species: salmon (Salmo salar); tilapia (Oreochromis spp.); and catfish (Ictalurus punctatus). The assay begins with an acetonitrile extraction, followed by filtration and mixed-mode cation-exchange solid-phase extraction cleanup. The extracts are analyzed by reversed-phase LC with UV detection at 320 nm. The method was validated by using fish fillets with incurred residues, control fish fillets, and fish fillets fortified at half the target level, the target level, and twice the target level (0.05, 0.1, and 0.2 ppm, respectively). For all species, accuracy is > or =80% and the RSD is < or =10%. The method complies with CVM performance criteria for the determination of veterinary drug residues.

A special case of medicine in disguise: Tattoo inks containing anaesthetics.

This paper describes a case of medicine in disguise: seized tattoo inks containing lidocaine and tetracaine at high concentration. Identification of anaesthetics was performed by LC MS Q-TOF with ESI+ source, by accurate mass measurement and by comparing the fragmentation patterns of molecular ions, at 30 V and 10 V of collision-offset voltage, with reference standards. Quantification was also performed by LC MS Q-TOF on the chromatographic peaks in the extracted ion chromatograms, by calibration curves obtained at different standard concentrations and by standard additions approach. The measurement uncertainty was estimated from validation data. The paper gives also chromatographic parameters, MS and MS/MS data and a quantitation method, with a full validation, of other six "caines". Thus the paper intends to provide a tool for identification and quantitation of the most common local anaesthetics that could be fraudulently added to tattoo inks. The results here reported show that the seized samples of inks represent a serious health risk owing to the high anaesthetic content - therapeutic-like dosage - found.

Evaluation of a method for determining concentrations of isoeugenol, an AQUI-S residue, in fillet tissue from freshwater fish species.

AQUI-S is a fish anesthetic/sedative that is approved for use in a number of countries throughout the world and has the potential for use in the United States. The active ingredient in AQUI-S is isoeugenol. A method for determining isoeugenol concentrations in edible fillet tissue is needed for regulatory purposes, including surveillance and potential use in studies fulfilling human food safety data requirements if U.S. Food and Drug Administration approval is pursued. A method was developed and evaluated for determining isoeugenol concentrations in fillet tissue using relatively common procedures and equipment. The method produced accurate and precise results with fillet tissue from 10 freshwater fish species. The percentage of isoeugenol recovered from samples fortified with isoeugenol at nominal concentrations of 1, 50, and 100 microg/g for all species was always >80 and <97%. Within-day precision for samples fortified at those same concentrations was < or =10%, and day-to-day precision was < or =4.0%. Method precision with fillet tissue containing biologically incurred isoeugenol was < or =8.1%. There were no or minimal chromatographic interferences in control fillet tissue extracts from 9 of the 10 species. The method detection limits for all but one species ranged from 0.004 to 0.014 microg/g, and the quantitation limits ranged from 0.012 to 0.048 microg/g.

[Anaesthetics and breast feeding]. / Anestesiprosedyrer og amming.

Many women undergo anaesthetic procedures related to childbirth or during the period of lactation. Most anaesthetic drugs are lipophilic and are thus excreted into breast milk. This article summarises available knowledge regarding anaesthetics, their excretion into breast milk and possible effects on the suckling infant. The consequences of such an exposure are discussed in terms of whether breast-feeding should be allowed or not after anaesthetic procedures.

Was Mafeisan an Anesthetic in Ancient China?

According to the Chinese historical books, Records of the Three Kingdoms () and Book of the Later Han (), Hua Tuo (, 140 - 208), a Traditional Chinese medicine (TCM) physician invented Mafeisan, an oral herbal general anesthetic, more than 1800 years ago during Eastern Han Dynasty. However, no written record of ingredients of the original Mafeisan has been found anywhere so far although there have been several similar anesthetic prescriptions published in TCM books later. There has been controversy over the existence of Mafeisan and even Hua Tuo in Chinese literature. We did extensive literature search and analysis, and believe that there indeed was Mafeisan in Hua Tuo's time.

Rapid detection of five anesthetics in tilapias by in vivo solid phase microextraction coupling with gas chromatography-mass spectrometry.

The concentration of five rapidly metabolized anesthetics in living tilapias was determined in this study, by the presented method coupling in vivo solid phase microextraction (SPME) to gas chromatography-mass spectrometry (GC-MS), which was the first time that in vivo sampling method was adapted in detecting the anesthetic residue in the living aquatic product. The analytical performance of the developed method was evaluated in homogenized tilapia dorsal muscle, and the results demonstrated that the present method possessed low detection limits 1.7-9.4ngg-1), wide linear ranges (10 or 30-5000ngg-1), and satisfactory reproducibility (relative standard deviations no more than 8.1% and 10.8% for inter-fiber and intra-fiber assays, respectively). Standard curves were established in homogenized tilapia dorsal muscle for calibrating in vivo SPME in living tilapias. And the concentrations determined by in vivo SPME were close to those determined by the liquid extraction. By using the present method, one anesthetic residue was detected above the detection limit in tilapias from the local markets. Comparing to traditional methods, the present one exhibited superior time-efficiency and cost performance, as the extraction time was only ten minutes, which was short to successfully avoid the possible loss of analytes caused by elimination and sample storage. In addition, owing to the time-efficiency of the present method, the elimination of the anesthetics in tilapias was traced successfully in the laboratory.