Simultaneous detection of nitrosamines and other sartan-related impurities in active pharmaceutical ingredients by supercritical fluid chromatography.

Since July 2018, the pharmacological class of "sartans" has been the subject of considerable media and analytical interest, as it became known that they are contaminated with nitrosamines such as N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA) and N-nitrosodiisopropylamine (NDiPA). Previous compendial methods are not able to detect these new contaminants. Using the latest and innovative Quality-by-Design (QbD) approach, it has now been possible to develop an analytical method that enables to investigate sartans, such as valsartan and losartan. Also a large class of different nitrosamines in the ppb range and sartan-related impurities can thus be determined simultaneously in a single analysis using supercritical fluid chromatography (SFC). By using SFC, a broad spectrum of nonpolar and very polar impurities can be separated and analyzed in under 20 min. The analytical method developed is validated for limit testing according to ICH Q2(R1) and fulfills default thresholds of EMA and FDA for testing of drug substances and genotoxic impurities. Additionally, it can also be adapted to other pharmaceuticals that may be contaminated with nitrosamines, since tetrazole synthesis as the underlying cause of nitrosamine contamination is important for a set of other non-sartan drug substances.

Enzyme self-assembly on naked iron oxide nanoparticles for aminoaldehyde biosensing.

The preservation of enzymatic activity is a fundamental requirement for exploiting hybrid nano-bio-conjugates, and the control over protein-nanoparticle interactions, leading to stable and catalytically active hybrids, represents the key for designing new biosensing platforms. In this scenario, surface active maghemite nanoparticles (SAMNs) represent a new class of naked magnetic nanoparticles, displaying peculiar electrocatalytic features and the ability to selectively bind proteins. Recombinant aminoaldehyde dehydrogenase from tomato (SlAMADH1) was used as a model protein, and successfully immobilized by self-assembly on the surface of naked SAMNs, where its enzymatic activity resulted preserved for more than 6 months. The hybrid nanomaterial (SAMN@SlAMADH1) was characterized by UV-Vis spectroscopy, mass spectrometry, and TEM microscopy, and applied for the development of a biosensor for the determination of aminoaldehydes in alcoholic beverages. Measurements were carried out in a low volume electrochemical flow cell comprising a SAMN modified carbon paste electrode for the coulometric determination of the NADH produced during the enzymatic catalysis. The present findings, besides representing the first example of an electrochemical biosensor for aminoaldehydes in an alcoholic matrix, open the door to the use of immobilized enzymes on naked metal oxides nanomaterials for biosensing.

Mass poisoning with NPS: 2C-E and Bromo-DragonFly.

BACKGROUND: Reports of intoxications with new psychoactive substances (NPS) mostly involve young people, as they are the main consumers of these types of drugs. This report centers on a case that was unusual due to it being a mass-poisoning event involving middle-aged individuals who had consumed a combination of the two different new psychoactive drugs 2,5-dimethoxy-4-ethylphenethylamine (2C-E) and 1-(8-bromofuro[2,3-f][1]benzofuran-4-yl)-2-propanamine (Bromo-DragonFly, BDF). CASE HISTORY: The mass poisoning of 29 individuals (24-56 years old) resulted in their admission to six different hospitals with severe symptoms of intoxication. All symptoms manifested after consumption of an unknown drug formulation around lunchtime during an esoteric weekend seminar. INVESTIGATION: Urine (n = 11) and blood samples (n = 29), collected from the 29 individuals for police investigation, were analyzed with immunochemical techniques, GC/MS and LC-MS/MS. 2C-E was confirmed in seven urine samples, but not in blood. BDF was confirmed in all urine samples, and in 17 blood samples. The blood samples exhibited BDF concentrations between ca. 0.6 and ca. 2.0 µg/L, while urine concentrations of BDF ranged from ca. 1.6 to 35 µg/L. The concentration of 2C-E in urine was found to be between ca. 1.5 and 183 µg/L. All patients made a complete recovery, although some had required mechanical ventilation. CONCLUSION: The investigation and the presentation of this case illustrates not only mass intoxication with 2C-E and BDF, with corresponding blood and urine concentrations, but also the necessity of collecting urine samples in cases where NPS-consumption is suspected, in order to improve the chances of analytical detection.

Quantification and Stability Determination of Surface Amine Groups on Silica Nanoparticles Using Solution NMR.

Surface chemistry is a critical factor for determining the behavior of a nanomaterial after incorporation in composites, devices, and biomedical products, and is also important for nanotoxicology studies. We have developed an optimized protocol for dissolution of aminated silicas and determination of functional-group contents by quantitative 1H NMR (qNMR) analysis of the released amines. A number of variables were optimized for the dissolution protocol, including the base concentration, mass of silica, time, temperature, and method of sample agitation, in order to achieve adequate NMR signals for quantification. The protocol was tested using nanoparticles from a single commercial supplier with sizes ranging from 20 to 120 nm that were functionalized with 3-aminopropyl groups. Interestingly the batch-to-batch variability for some sizes of these aminated silicas was as high as 50%. Amine contents measured by a ninhydrin colorimetric assay were typically ∼20% lower than those measured by qNMR, consistent with measurement of only ninhydrin-reagent accessible amines. The dissolution-qNMR protocol was compatible with aminated silicas from other commercial suppliers, and in these cases, an even larger variability in surface coverage was observed. Silica nanoparticles with longer-chain amines and variable amine loadings were synthesized to demonstrate the ability to quantify amines with more complex structures and to assess the limit of quantification for the dissolution-qNMR method. Finally, the stability of the aminated nanoparticles was examined. Loss of 3-aminopropyl groups occurred in water at room temperature and was significantly more rapid at higher temperatures. Amine loss increased with increasing surface coverage and was slower for long-chain amines, consistent with studies of amine stability on planar silica. Overall, this work highlights the importance of developing methods for quantifying surface functionalization, particularly given the variability in surface coverage for commercial samples, and for ensuring that the amine group is stable under its usage conditions.

Skin Notations for Low-Molecular-Weight Amines: Development of a Testing Protocol with Isopropylamine as an Example.

Owing to their volatility, the most important occupational exposure route for low-molecular-weight amines is considered to be inhalation. However, dermal exposure is also possible in many workplace situations. There are limited data available on the dermal uptake of these amines through human skin, and existing exposure standard skin notations are typically based on acute toxicity animal studies or by chemical analogy. This gap in knowledge is in part due to a lack of standardized approach for assessing dermal uptake. We describe a relatively simple protocol for the determination of permeation of low-molecular-weight amines through human skin in vitro. Using isopropylamine as a test amine, it was found that isopropylamine vapour has limited capacity to absorb into, or penetrate through, the epidermal layer of human skin, even at lethal atmospheric concentrations. This protocol can be adapted for a range of exposure scenarios, including clothing effects, and may be used to determine whether skin notations are warranted.

Liquid chromatography-tandem mass spectrometry method for the analysis of N-(3-aminopropyl)-N-dodecylpropane-1,3-diamine, a biocidal disinfectant, in dairy products.

A novel and reliable method to quantify residual levels of N-(3-aminopropyl)-N-dodecylpropane-1,3-diamine in dairy products using ion-pairing reversed-phase liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed and fully validated. Sample extraction was done with salting-out technique using acetonitrile and sodium chloride. For LC-MS/MS, the analyte was detected using positive electrospray ionization (ESI+) and two multiple reaction monitoring (MRM) transitions were monitored. The method was validated in the 5-150 µg kg-1 range using total error approach. Thus, performance criteria of the method were evaluated. Relative standard deviations for trueness and precision were lower than 10%; with the exception of hard pressed cheese at 5 µg kg-1 for precision. The limit of quantification (LOQ) was around 5-7 µg kg-1 depending on the matrix of interest. The method was successfully applied to accurately quantify N-(3-aminopropyl)-N-dodecylpropane-1,3-diamine in 146 various dairy products with a maximum contamination level of 225 µg kg-1 in cheese.

Development of in situ product removal strategies in biocatalysis applying scaled-down unit operations.

An experimental platform based on scaled-down unit operations combined in a plug-and-play manner enables easy and highly flexible testing of advanced biocatalytic process options such as in situ product removal (ISPR) process strategies. In such a platform, it is possible to compartmentalize different process steps while operating it as a combined system, giving the possibility to test and characterize the performance of novel process concepts and biocatalysts with minimal influence of inhibitory products. Here the capabilities of performing process development by applying scaled-down unit operations are highlighted through a case study investigating the asymmetric synthesis of 1-methyl-3-phenylpropylamine (MPPA) using ω-transaminase, an enzyme in the sub-family of amino transferases (ATAs). An on-line HPLC system was applied to avoid manual sample handling and to semi-automatically characterize ω-transaminases in a scaled-down packed-bed reactor (PBR) module, showing MPPA as a strong inhibitor. To overcome the inhibition, a two-step liquid-liquid extraction (LLE) ISPR concept was tested using scaled-down unit operations combined in a plug-and-play manner. Through the tested ISPR concept, it was possible to continuously feed the main substrate benzylacetone (BA) and extract the main product MPPA throughout the reaction, thereby overcoming the challenges of low substrate solubility and product inhibition. The tested ISPR concept achieved a product concentration of 26.5 gMPPA · L-1 , a purity up to 70% gMPPA · gtot-1 and a recovery in the range of 80% mol · mol-1 of MPPA in 20 h, with the possibility to increase the concentration, purity, and recovery further. Biotechnol. Bioeng. 2017;114: 600-609. © 2016 Wiley Periodicals, Inc.

Rapid determination of cocamidopropyl betaine impurities in cosmetic products by core-shell hydrophilic interaction liquid chromatography-tandem mass spectrometry.

Cocamidopropyl betaine (CAPB) is a common surfactant widely used in personal care products. Dimethylaminopropylamine (DMAPA) and lauramidopropyldimethylamine (LAPDMA) are two chemicals present as impurities in CAPB and have been reported as skin sensitizers. A rapid and sensitive ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method, using a core shell hydrophilic interaction liquid chromatography (HILIC) column, has been developed to quantify DMAPA and LAPDMA in cosmetic products. Corresponding stable isotopically labeled analogues of the above native compounds were used as internal standards to compensate for matrix effect and for loss of recovery. Each sample was first screened to determine whether the sample needed to be diluted to minimize matrix effects as well as to fit the calibration range. The concept of matrix effect factor (MEF) was introduced to quantitatively evaluate each sample with a unique matrix using the internal standards. Recoveries at three spiking levels of low, medium, and high concentrations ranged from 98.4 to 112% with RSDs less than 5%. This method has been validated and is the first UHPLC-MS/MS method, which uses core shell HILIC column and stable isotopically labeled internal standards to simultaneously determine these two CAPB impurities in cosmetic products.

A solid device based on doped hybrid composites for controlling the dosage of the biocide N-(3-aminopropyl)-N-dodecyl-1,3-propanediamine in industrial formulations.

A colorimetric composite device is proposed to determine the widely used biocide N-(3-aminopropyl)-N-dodecyl-1,3-propanediamine (ADP).This sensing device is based on a film of 1,2-Naphthoquinone-4-sulfonate (NQS) embedded into polydimethylsiloxane-tetraethylortosilicate-SiO2 nanoparticles composite (PDMS-TEOS-SiO2NPs). Semiquantitative analysis can be performed by visual inspection. Digitalized image or diffuse reflectance (DR) measurements can be carried out for quantitative analysis. Satisfactory detection limit (0.018%, w/v) and relative standard deviations <12% were achieved. The proposed device has been applied for the determination of ADP in detergent industrial formulations with recovery values between 80% and 112%. The method has been successfully validated, showing its high potential to control and monitor this compound because the device is easy to prepare and use, robust, portable, stable over time and cost effective. This device allows a green, simple and rapid approach for the analysis of samples without pretreatment and does not require highly trained personnel. These advantages give the proposed kit good prospects for implementation in several industries.

Liquid chromatography-quadrupole time-of-flight mass spectrometry for screening in vitro drug metabolites in humans: investigation on seven phenethylamine-based designer drugs.

Phenethylamine-based designer drugs are prevalent within the new psychoactive substance market. Characterisation of their metabolites is important in order to identify suitable biomarkers which can be used for better monitoring their consumption. Careful design of in vitro metabolism experiments using subcellular liver fractions will assist in obtaining reliable outcomes for such purposes. The objective of this study was to stepwise investigate the in vitro human metabolism of seven phenethylamine-based designer drugs using individual families of enzymes. This included para-methoxyamphetamine, para-methoxymethamphetamine, 4-methylthioamphetamine, N-methyl-benzodioxolylbutanamine, benzodioxolylbutanamine, 5-(2-aminopropyl) benzofuran and 6-(2-aminopropyl) benzofuran. Identification and structural elucidation of the metabolites was performed using liquid chromatography-quadrupole-time-of-flight mass spectrometry. The targeted drugs were mainly metabolised by cytochrome P450 enzymes via O-dealkylation as the major pathway, followed by N-dealkylation, oxidation of unsubstituted C atoms and deamination (to a small extent). These drugs were largely free from Phase II metabolism. Only a limited number of metabolites were found which was consistent with the existing literature for other phenethylamine-based drugs. Also, the metabolism of most of the targeted drugs progressed at slow rate. The reproducibility of the identified metabolites was assessed through examining formation patterns using different incubation times, substrate and enzyme concentrations. Completion of the work has led to a set of metabolites which are representative for specific detection of these drugs in intoxicated individuals and also for meaningful evaluation of their use in communities by wastewater-based drug epidemiology.

Enhanced sensitivity of double gate junctionless transistor architecture for biosensing applications.

In the present work, we demonstrate the potential of double gate junctionless (JL) architecture for enhanced sensitivity for detecting biomolecules in cavity modulated field effect transistors (FETs). The higher values of body factor, achieved in asymmetric gate operation under impact ionization is utilized for enhanced sensing margin which is nearly five times higher than compared to symmetrical mode operation. The intrinsic detection sensitivity is evaluated in terms of threshold voltage change, and the ratio of drain current in the presence and absence of biomolecules in JL nanotransistors. It is shown that asymmetric mode JL transistor achieves a higher degree of detection sensitivity even for a partially filled cavity. The work demonstrates the potential of JL channel architecture for cavity based dielectric modulated FET biosensors.

Single-particle speciation of alkylamines in ambient aerosol at five European sites.

Alkylamines are associated with both natural and anthropogenic sources and have been detected in ambient aerosol in a variety of environments. However, little is known about the ubiquity or relative abundance of these species in Europe. In this work, ambient single-particle mass spectra collected at five sampling sites across Europe have been analysed for their alkylamine content. The aerosol time-of-flight mass spectrometer (ATOFMS) data used were collected in Ireland (Cork), France (Paris, Dunkirk and Corsica) and Switzerland (Zurich) between 2008 and 2013. Each dataset was queried for mass spectral marker ions associated with the following ambient alkylamines: dimethylamine (DMA), trimethylamine (TMA), diethylamine (DEA), triethylamine (TEA), dipropylamine (DPA) and tripropylamine (TPA). The fraction of ambient particles that contained detectable alkylamines ranged from 1 to 17 % depending on location, with the highest fractions observed in Paris and Zurich in the winter months. The lowest fractions were observed at coastal sites, where the influence of animal husbandry-related alkylamine emissions is also expected to be lowest. TMA was the most ubiquitous particle phase alkylamine detected and was observed at all locations. Alkylamines were found to be internally mixed with both sulphate and nitrate for each dataset, suggesting that aminium salt formation may be important at all sites investigated. Interestingly, in Corsica, all alkylamine particles detected were also found to be internally mixed with methanesulphonic acid (MSA), indicating that aminium methanesulphonate salts may represent a component of marine ambient aerosol in the summer months. Internal mixing of alkylamines with sea salt was not observed, however. Alkylamine-containing particle composition was found to be reasonably homogeneous at each location, with the exception of the Corsica and Dunkirk sites, where two and four distinct mixing states were observed, respectively.

Enantioseparation of benzofurys and other novel psychoactive compounds by CE and sulfobutylether ß-cyclodextrin as chiral selector added to the BGE.

The illicit drug market of psychoactive substances for human abuse is continuously expanding and developing. Besides already known substance classes like cathinones, amphetamines or synthetic cannabinoids, further derivatives such as benzofurys, thiophenes, and structural analogues of methylphenidate entered the global market recently. As many of these new compounds contain a stereogenic centre it is supposed that their isomers may differ in their pharmacological effects as it is the case with amphetamines or several chiral active pharmaceutical ingredients, for instance. In the course of this study, a method for the chiral separation of a set of 16 recreational drugs by CE was developed. The aim was to separate the analytes into their enantiomers at equal conditions within short time. Sulfobutylether ß-cyclodextrin served as chiral selector in an aqueous ammonium acetate solution containing ACN. For method optimization, methedrone and ethylphenidate were used as model compounds to find the appropriate concentration of chiral selector. Moreover, the influence of the pH value on enantioseparation was tested. Fourteen or 16 mM sulfobutylether ß-cyclodextrin, 50 mM ammonium acetate solution (pH 4.5) with 10% ACN were found to be optimal for enantioseparation of seven benzofurys, four cathinones, two diphenidines, ethylphenidate, methiopropamine, and thiothinone. Most of them were baseline resolved at migration times below 25 min.

Development of analytical methods for the quantification of metabolites of lesogaberan in a MIST investigation.

Analytical methods were developed for the determination of six metabolites of lesogaberan to be used in quantitative determinations of metabolites according to the guidelines of Metabolites in Safety Testing. The γ-amino butyric acid type B receptor agonist lesogaberan and its metabolites are small polar molecules and hydrophilic interaction liquid chromatography was found to be a suitable separation mode. The samples were prepared using protein precipitation and negative electrospray ionization tandem mass spectrometry was used for detection. Initially, exploratory methods for six metabolites were set up for analysis of human plasma samples taken after repeated administration of a high oral dose of lesogaberan. The purpose was to establish which metabolites were present at concentrations significant for further investigation. Four of the six metabolites were then found at clearly detectable concentrations. The analytical methods for these four metabolites were further elaborated and then taken through a qualification procedure, which showed acceptable accuracy (86-114%), precision (<9%) and good linearity in the range 0.03-5 µmol/L. No interferences were seen from endogenous plasma components.

Characterization and quantification of N-(3-aminopropyl)-N-dodecyl-1,3-propanediamine biocide by NMR, HPLC/MS and titration techniques.

The present paper reports the determination of the tri-amine N-(3-aminopropyl)-N-dodecyl-1,3-propanediamine (TA) present in a raw material called LONZABAC used to formulate various, widely used commercial biocides. The active principle, TA, is present in LONZABAC together with other molecules at lower concentration levels. Three independent analytical approaches, namely solution NMR spectroscopy, liquid chromatography coupled to high resolution mass spectrometry (LC/HRMS) and acid-base titration in mixed solvent, were used to overcome the problem of the non-availability of the active principle as high purity standard. NMR analysis of raw material, using a suitable internal standard, evidenced in all analyzed lots the presence of the active principle, the N-dodecyl-1,3-propanediamine (DA) and the n-dodecylamine (MA) and the absence of non-organic, NMR-inactive species. NMR peak integration led to a rough composition of the MA:DA:TA as 1:9:90. The LC/HRMS analysis allowed the accurate determination of DA and MA and confirmed in all samples the presence of the TA, which was estimated by difference: MA=1.4±0.3%, DA=11.1±0.7%, TA=87.5±1.3%. The obtained results were used to setup an easy, rapid and cheap acid-base titration method able to furnish a sufficiently accurate evaluation of the active principle both in the raw material and in diluted commercial products. For the raw material the results were: TA+MA=91.1±0.8% and DA-MA=8.9±0.8%, statistically coherent with LC/MS ones. The LC/MS approach demonstrated also its great potentialities to recognize trace of the biocide components both in environmental samples and in the formulated commercial products.

Medical management of a potentially toxic accidental trialkylamine ingestion during spaceflight.

INTRODUCTION: To reduce excessive iodine consumption by astronauts, the National Aeronautics and Space Administration (NASA) has developed various methods of removing residual iodine after iodine-based water purification aboard spacecraft. The Low Iodine Residual System (LIRS) was developed as an iodine removal system for use aboard the space shuttle. This is a case report of an accidental, potentially toxic ingestion by astronauts aboard a space shuttle mission following exposure to contaminated water from LIRS filtration and the medical response operations that followed. CASE REPORT: Astronauts ingested significant levels of trialkylamines from water that had passed through gamma-irradiated, de-iodination resin in the LIRS hardware. Medical response operations included crew evaluations, consultations with toxicologists and systems experts, hardware testing, contaminant evaluation, and close crewmember follow-up. DISCUSSION: Despite the significant ingestion there were no adverse clinical symptoms in any of the exposed astronauts; however, the case highlights a simple pitfall in the classification of hardware that ultimately lead to a potentially harmful toxic ingestion among the crewmembers, and the real-time response of medical personnel to ensure crew safety.

Surface-doping effect of InVO4 nanoribbons and the distinctive behavior as gas sensors.

Indium vanadate (InVO4) gas sensors were fabricated by depositing InVO4 nanoribbons aqueous suspension onto ceramic substrates. Their resistances distinctively increased in the detection of ammonia and propylamine, indicating an n-to-p semiconductor transition. This novel phenomenon of the InVO4-based sensor may be ascribed to the surface doping effect: electrons were trapped by H2O and O2 and produced OH(-) and O2(-) on the InVO4 surface, which resulted in holes overcompensation in the InVO4 valence band. Moreover, the sufficiently large surface-to-volume ratio of these nanoribbons enables fast carrier transfer on the sensor surface. The InVO4 nanoribbons-based sensors had optimum performance at room temperature and enjoyed good restorability. They also had great response to a wide range of target gas concentration, with ultrahigh sensitivities up to 1100% for ammonia and 760% for propylamine.

Sweat testing for the detection of atomoxetine from paediatric patients with attention deficit/ hyperactivity disorder: application to clinical practice.

Atomoxetine (ATX) is a selective norepinephrine reuptake inhibitor approved since 2002 for the treatment of attention deficit hyperactivity disorder (ADHD) in children, adolescents, and adults as an alternative treatment to methylphenidate. Within the framework of a project evaluating the use of alternative biological matrices for therapeutic monitoring of psychoactive drugs in paediatric and non-paediatric individuals, the excretion of ATX and its principal metabolites has been recently studied in oral fluid and hair. The aim of this study was to describe the excretion profile of ATX and its metabolites 4-hydroxyatomoxetine (4-OH-ATX) and N-desmethylatomoxetine (N-des-ATX) in sweat following the administration of different dosage regimens (60, 40, 35, and 18 mg/day) of ATX to six paediatric patients. Sweat patches were applied to the back of each participant and removed at timed intervals. ATX and its metabolites were measured in patches using a previously validated liquid chromatography-tandem mass spectrometric (LC-MS/MS) method. Independently from the administered dose, ATX appeared in the sweat patches 1 h post administration and reached its maximum concentration generally at 24 h. Peak ATX concentrations ranged between 2.31 and 40.4 ng/patch and did not correlate with the administered drug dose, or with body surface area. Total ATX excreted in sweat ranged between 0.008 and 0.121 mg, corresponding to 0.02 and 0.3% of the administered drug. Neither 4-OH-ATX, nor N-des-ATX was detected in either of the collected sweat patches. Measuring ATX in sweat patches can provide information on cumulative drug use from patch application until removal.

Concentrations of atomoxetine and its metabolites in plasma and oral fluid from paediatric patients with attention deficit/hyperactivity disorder.

Atomoxetine (ATX) is a non-stimulant drug approved for the treatment of children and adolescents with attention deficit/hyperactivity disorder (ADHD). We aimed to study the excretion profile of ATX and its principal metabolites 4-hydroxyatomoxetine (4-OH-ATX) and N-desmethylatomoxetine (desmethyl-ATX) in oral fluid and plasma of ADHD paediatric subjects, after administration of different dosage regimens. Oral fluid and plasma samples were obtained from one child and five adolescents treated with different ATX doses (18-60 mg/day). ATX and its metabolites were measured in oral fluid and plasma by liquid chromatography-mass spectrometry (LC-MS). Apparent pharmacokinetic parameters of ATX in oral fluid and plasma were estimated for each subject. All analytes under investigation were detected in plasma samples with concentrations from 0.6 to 1065.7 ng/ml for ATX, 0.7 to 17.1 ng/ml for 4-OH-ATX and 0.7 to 126.2 ng/ml for desmethyl-ATX. Only ATX and 4-OH-ATX were detected in oral fluid samples with concentrations from 0.5 to 36.0 ng/ml and 0.5 to 4.7 ng/ml, respectively. ATX concentrations in oral fluid were between one and two orders of magnitude lower than those in plasma. 4-OH-ATX was found in oral fluid at a peak concentration approximately one-fourth those in plasma with a mean tmax of 2.3 in plasma and 3.0 h in oral fluid. The correlations between ATX and 4-OH-ATX concentrations in the two biological fluids indicate that oral fluid concentrations of this drug and its principal metabolite may be a predictor of plasma concentrations, even if values are too low and variable to be considered an alternative to plasma.

Early pharmaceutical evaluation of a crystalline and hygroscopic GABAB receptor agonist.

Lesogaberan is a potent gamma amino butyric acid agonist and has been evaluated for its utility in treatment of gastroesophageal reflux disease. Lesogaberan is a crystalline substance that absorbs considerable amounts of water above 65% relative humidity (RH) where it also liquifies. As a result of the hygroscopicity of the zwitterionic form an investigation of different salt forms was performed. Since the test compound is polar and lacks ultraviolet (UV) chromophore, conventional separation and detection techniques could not be used to characterise the test compound and the impurities. The analytical techniques are described, focusing on the capillary electrophoresis method with indirect UV detection for purity, the liquid chromatographic method for enantiomeric separation with derivatisation with UV chromophore and two complementary nuclear magnetic resonance (NMR) approaches (¹9F-NMR and ¹H-NMR) for impurities. The stability study in solution showed that solutions between pH 5 and 7 were the most stable ones, but after some time degradation occurred at room temperature. When bulk lesogaberan was stored at 25°C/60% RH no chemical degradation was observed after 1 year. At 40°C/75% RH, where the compound liquefies, a significant degradation was observed after 1 month. However, in a closed container (= 40°C) or as a napsylate salt, no degradation of lesogaberan was observed at 40°C/75% RH.