Citalopram and Cannabidiol: In Vitro and In Vivo Evidence of Pharmacokinetic Interactions Relevant to the Treatment of Anxiety Disorders in Young People.

BACKGROUND: Cannabidiol (CBD), a major nonintoxicating constituent of cannabis, exhibits anxiolytic properties in preclinical and human studies and is of interest as a novel intervention for treating anxiety disorders. Existing first-line pharmacotherapies for these disorders include selective serotonin reuptake inhibitor and other antidepressants. Cannabidiol has well-described inhibitory action on cytochrome P450 (CYP450) drug-metabolizing enzymes and significant drug-drug interactions (DDIs) between CBD and various anticonvulsant medications (eg, clobazam) have been described in the treatment of epilepsy. Here, we examined the likelihood of DDIs when CBD is added to medications prescribed in the treatment of anxiety. METHODS: The effect of CBD on CYP450-mediated metabolism of the commonly used antidepressants fluoxetine, sertraline, citalopram, and mirtazapine were examined in vitro. Cannabidiol-citalopram interactions were also examined in vivo in patients (n = 6) with anxiety disorders on stable treatment with citalopram or escitalopram who received ascending daily doses of adjunctive CBD (200-800 mg) over 12 weeks in a recent clinical trial. RESULTS: Cannabidiol minimally affected the metabolism of sertraline, fluoxetine, and mirtazapine in vitro. However, CBD significantly inhibited CYP3A4 and CYP2C19-mediated metabolism of citalopram and its stereoisomer escitalopram at physiologically relevant concentrations, suggesting a possible in vivo DDI. In patients on citalopram or escitalopram, the addition of CBD significantly increased citalopram plasma concentrations, although it was uncertain whether this also increased selective serotonin reuptake inhibitor-mediated adverse events. CONCLUSIONS: Further pharmacokinetic examination of the interaction between CBD and citalopram/escitalopram is clearly warranted, and clinicians should be vigilant around the possibility of treatment-emergent adverse effects when CBD is introduced to patients taking these antidepressants.

Pharmacological and pharmacokinetic effect of a polyherbal combination with Withania somnifera (L.) Dunal for the management of anxiety.

ETHNOPHARMACOLOGICAL RELEVANCE: In the Indian system of medicine, Withania somnifera (L.) Dunal, Hemidesmus indicus (R.Br.), Aegle marmelos (L.) Correa, Emblica officinalis Gaertn, Ocimum sanctum (L.) has been mentioned as a remedy for the treatment of anxiety related disorders. Based on their folklore use, a polyherbal combination was derived for the management of anxiety. AIM OF THE STUDY: The present study is aimed to find the best polyherbal combination (PHC), in terms of its pharmacological action, out of two PHC, namely PHC1 and PHC3, prepared based on the previous studies conducted and to carry out the pharmacokinetic (PK) study of the best combination (PHC3). MATERIALS AND METHODS: Pharmacological activities include elevated plus maze model and hole-board test for anti-anxiety screening, gamma amino-butyric acid (GABAA) measurement in brain tissues and superoxide dismutase, lipid peroxidation and reduced glutathione measurement for anti-oxidant screening. RESULTS: PHC3 (100 mg/kg) produced statistically significant (p < 0.05) effect on all the pharmacological outcome measures when compared to alprazolam standard. Therefore, it was chosen for PK study. PK study was carried out using Liquid Chromatography Mass Spectroscopy technique with respect to Withaferin-A. PK parameters such as maximum plasma concentration (Cmax), 16.78 ± 5.32 ng/mL; time of maximum concentration (Tmax), 18 ± 0.12min; half-life (T1/2) 61.20 ± 9.87min; mean residual time (MRT), 7.53 h s; area under the concentration versus time curve (AUC0-1), 1678 ± 34.13 ng/mL; area under the concentration versus time curve from zero to infinity (AUC0-∞), 1705 ± 28.87 ng/mL; total clearance (CL), 290.67 ± 15.89 mL/min and volume of distribution (Vd) 0.054 L were calculated. CONCLUSIONS: The results of the studies revealed that PHC3 possessed significant anxiolytic, anti-oxidant activities and enhanced expression of GABAA mediated inhibition when compared to PHC1. Withaferin-A in PHC3 exhibited a rapid oral absorption in rat plasma. The findings of this study greatly help to provide useful evidence for the development of suitable formulation using PHC3.

Flavonoids as therapeutic candidates for emotional disorders such as anxiety and depression.

Emotional disorders such as anxiety and depression are widespread psychological diseases that affect up to 20% of the world's population. There are many approaches to the discovery of novel agents for the treatment of depressive- and anxiety-like symptoms. However, the efficacy of existing drugs for emotional disorders is only exerted after a few weeks of treatment and have serious side effects. Due to this, new strategies to find suitable and safe options are being sought by many researchers. Among them, a lot of interest has been attracted by plant-derived natural compounds due to their wide range of beneficial effects for new agent development. Flavonoids are natural polyphenol-like compounds found commonly in plants, fruits, vegetables, and medicinal herbs. A diverse range of flavonoids have been studied to investigate their potential therapeutic activities for the treatment of brain-associated disorders, including anxiety and depression. The main aim of this review is to understand the associations between the various flavonoids and the emotional disorders and discuss the therapeutic effects of these natural compounds that were demonstrated during the conduction of recent studies. The current work shows advances in the latest research of some flavonoids as a potential candidate for the treatment of emotional disorders. We summarize their behavioral, molecular, physiological, and neurochemical effects in various in vitro and in vivo models. Therefore, in the present work, the latest studies were collected on the most important flavonoid compounds and their underlying mechanisms of action in emotion-related disorders were discussed.

Metabolism of a Novel Anxiolytic GML-1 in Rats.

Metabolism of a novel anxiolytic GML-1 (N-benzyl-N-methyl-1-phenylpyrrolo[1,2-a]pirazin-3-carboxamide) in rat blood plasma was studied by HPLC-mass spectrometry. Three biotransformation products with the corresponding molecular ions were detected. A conclusion was made that the main pathways of GML-1 metabolism are oxidative reactions yielding hydroxylated, methylated, and demethylated metabolites.

Anxiolytic actions of Nardostachys jatamansi via GABA benzodiazepine channel complex mechanism and its biodistribution studies.

Nardostachys jatamansi has profound applications against pharmacological interventions and is categorized as a hypno-sedative drug according to Ayurveda. In the present study probable mechanism of anxiolytic action of Nardostachys jatamansi extract (NJE) was studied using behavioral anxiolytic tests (Elevated plus maze, Open field test, Light dark box test, and Vogel's conflict test) in mice. Mice were treated orally with NJE (250 mg/kg) for 3, 7 and 14 days or diazepam (1 mg/kg) followed by behavioral assessment and estimation of monoamine neurotransmitters, GABA, and antioxidant enzymes. Treatment of mice for 7 days caused an increase in time spent in open arms in elevated plus maze, number of line crossings in open field test, increased time spent in lit compartment of light-dark box test, an increase in number of licks made and shocks accepted in Vogel's conflict test, with results comparable to diazepam and this treatment also caused a significant increase in monoamine neurotransmitters and GABA in brain and tissue antioxidant parameters. Co-treatment of NJE with flumazenil (GABA-benzodiazepine antagonist; 0.5 mg/kg i.p) or picrotoxin (GABAA gated chloride channel blocker; 1 mg/kg i.p) caused a blockage/antagonised anxiolytic actions of NJE by causing a significant reduction in time spent in open arms of elevated plus maze, an decrease in number of line crossing in open field test and also number of shocks and licks accepted in Vogel's conflict test. Further, NJE was radiolabelled with technetium99m at their hydroxyl groups following which purity as well as in vivo and in vitro stability of radiolabelled formulations was evaluated. The blood kinetics and in vivo bio-distribution studies were carried out in rabbits and mice respectively. Labeled formulation was found to be stable in vitro (96 to 93% stability) and in vivo (96 to 92% stability). The labeled compound was cleared rapidly from blood (within 24 h) and accumulated majorly in kidneys (11.65 ± 1.33), liver (6.07 ± 0.94), and blood (4.03 ± 0.63) after 1 h. However, a small amount was observed in brain (0.1 ± 0.02) probably because of its inability to cross blood-brain barrier. These results highlight biodistribution pattern of NJE, and also indicated that a 7-day treatment with NJE produced significant anxiolytic effects in mice and also a significant increase in brain monoamine and GABA neurotransmitter levels and suggests that anxiolytic effects of NJE are primarily and plausibly mediated by activating GABAergic receptor complex.

Effect of Benifuuki Tea on Cytochrome P450-mediated Metabolic Activity in Rats.

BACKGROUND/AIM: Benifuuki tea has recently been used as an alternative therapy for pollinosis, and it may be consumed with pharmaceutical drugs. This study aimed to examine cytochrome P450 (CYP)-mediated food-drug interactions with Benifuuki tea in rats. MATERIALS AND METHODS: The inhibitory effects of Benifuuki tea and (-)-epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3"Me) on CYP activities were evaluated in vitro. Midazolam pharmacokinetics was investigated after two treatments with Benifuuki tea. In an ex vivo study, CYP activities were determined after 1-week-treatment with the tea. RESULTS: Benifuuki tea and EGCG3"Me inhibited CYP2D and CYP3A activities in a concentration-dependent manner in vitro. However, MDZ metabolism did not change by Benifuuki treatment in vivo and ex vivo. In contrast, CYP2D activity was decreased ex vivo. CONCLUSION: Normal intake of Benifuuki tea is not likely to cause food-drug interactions by CYP3A inhibition or induction. In contrast, Benifuuki tea consumption may lead to food-drug interactions through the inhibition of CYP2D.

Pharmacokinetic Study of Biotransformation Products from an Anxiolytic Fraction of Tilia americana.

An anxiolytic fraction of Tilia americana standardized in tiliroside, rutin, quercitrin, quercetin glucoside, and kaempferol was obtained. After oral administration of the fraction, the above-mentioned flavonoids were not detected in plasma over 24 h. However, meta and para hydroxyphenylacetic acid and dihydroxyphenylacetic acid (m-HPAA, p-HPAA and DOPAC) were monitored. These are the biotransformation compounds of the aglycones of kaempferol and quercetin; these aglycones are products of the other flavonoids present in the anxiolytic fraction. The analytical methods (HPLC) for flavonoids and the related compounds (m-HPAA, p-HPAA and DOPAC) were validated, determining the parameters of accuracy, precision, specificity or selectivity, limit of detection, quantification range, and robustness. The pharmacokinetic assay was performed with ICR mice strains, which were given 200 mg/kg of the standardized active fraction. The results of validation of the analytical methods were obtained, allowing it to be established in a validated way that no flavonoids present in the anxiolytic fraction of T. americana were detected in plasma. However, detection and follow up was possible for the serum levels of m-HPAA, p-HPAA, and DOPAC. The three compounds follow a two-compartment model with very similar parameters between m-HPAA and p-HPAA, some being different from the ones characterized in the pharmacokinetics of DOPAC.

Intracerebral Distribution of a-Pinene and the Anxiolytic-like Effect in Mice Following Inhaled Administration of Essential Oil from Chamaecyparis obtuse.

The anxiolytic-like and stress reduction effects following inhaled administration of essential oil from Chamaecyparis obtusa (EOCO) have been reported. Volatile components are thought to produce these effects of EOCO by neurological transfer and pharmacological transfer. The regions of the brain in which inhaled compounds are found due to pharmacological transfer of EOCO are not known. This research was undertaken to clarify the relationship between the intracerebral distribution of α-pinene, which is the main component of EOCO, and emotional behavior. α-Pinene was detected as the main component of volatile EOCO. The amount of α-pinene in each region of the brain was measured following inhaled administration of EOCO. The amount of α-pinene was different in each region of the brain. With inhaled administration of 32 µL/L air EOCO, a high concentration of α-pinene was observed. However, no significant differences in the concentration of α-pinene among brain regions were found. A therapeutic concentration of α-pinene (8 µL/L air EOCO) in each region of the brain may induce an anxiolytic-like effect, and a high concentration of α-pinene (32 µL/L air EOCO) in each region of the brain may induce an excitatory-like effect. The increases in the concentration of α-pinene from 8 to 32 µL/L air EOCO in the striatum and the hippocampus were significantly lower compared with the increases in other brain regions. These results indicate that regions besides the striatum and the hippocampus participated in the increase in locomotor activity due to the high concentration of α-pinene in the brain.

Daily inhalation of α-pinene in mice: effects on behavior and organ accumulation.

In phytotherapy, essential oils tend to be used daily for a period of days or weeks, rather than in a single application. However, the literature contains very little information on repeated use of essential oils. In this study, we investigated the effects on behavior and the accumulation in the brain and liver of α-pinene, an essential oil component, when inhaled by mice. Animals were individually housed in cages for 1 week. Mice inhaled α-pinene or water vapor (negative control) for 90 min/day for 1 day, 3 days, or 5 days, and they were then submitted to the elevated plus maze test for 10 min. We used gas chromatography with flame ionization detection to quantify concentrations of α-pinene in the brain and liver. There was significant anxiolytic-like activity, which remained constant for the 5 days' inhalation of α-pinene. On the other hand, the accumulation of α-pinene in the brain and liver peaked on the third day of inhalation. The existence of stress related to the new environment appears to have affected the change in the accumulation of α-pinene in the internal organs, keeping the anxiolytic-like action constant.

The anxiolytic effects of a Valerian extract is based on valerenic acid.

BACKGROUND: Valerian is commonly used for the treatment of insomnia and anxiety. Valerian extracts allosterically modulate GABA-A receptors and induced an anxiolytic activity. This activity is closely related to valerenic acid. In the present experiments it was investigated whether acetoxy valerenic acid may interfere with the anxiolytic action of valerenic acid. METHODS: Situational anxiety was measured using male CD-1 mice in the elevated plus maze test after oral administration of the test substances. In addition the body core temperature was measured. For the 3H-GABA binding assay dissected tissue from frontal cortex of male RjHan:WI rats were used. Statistical evaluation was performed by means of the non-parametric Kruskal-Wallies H-test, followed by the two-tailed Mann-Whitney U-test. RESULTS: Adding of acetoxy valerenic acid abolished the anxiolytic action of valerenic acid. There was no effect on body core temperature. Moreover, the valerian extract did not show any affinity to benzodiazepine binding sites. CONCLUSION: The determining compound for the observed anxiolytic effect of the valerian extract is its content of valerenic acid.

GSK356278, a potent, selective, brain-penetrant phosphodiesterase 4 inhibitor that demonstrates anxiolytic and cognition-enhancing effects without inducing side effects in preclinical species.

Small molecule phosphodiesterase (PDE) 4 inhibitors have long been known to show therapeutic benefit in various preclinical models of psychiatric and neurologic diseases because of their ability to elevate cAMP in various cell types of the central nervous system. Despite the registration of the first PDE4 inhibitor, roflumilast, for the treatment of chronic obstructive pulmonary disease, the therapeutic potential of PDE4 inhibitors in neurologic diseases has never been fulfilled in the clinic due to severe dose-limiting side effects such as nausea and vomiting. In this study, we describe the detailed pharmacological characterization of GSK356278 [5-(5-((2,4-dimethylthiazol-5-yl)methyl)-1,3,4-oxadiazol-2-yl)-1-ethyl-N-(tetrahydro-2H-pyran-4-yl)-1H-pyrazolo[3,4-b]pyridin-4-amine], a potent, selective, and brain-penetrant PDE4 inhibitor that shows a superior therapeutic index to both rolipram and roflumilast in various preclinical species and has potential for further development in the clinic for the treatment of psychiatric and neurologic diseases. GSK356278 inhibited PDE4B enzyme activity with a pIC50 of 8.8 and bound to the high-affinity rolipram binding site with a pIC50 of 8.6. In preclinical models, the therapeutic index as defined in a rodent lung inflammation model versus rat pica feeding was >150 compared with 0.5 and 6.4 for rolipram and roflumilast, respectively. In a model of anxiety in common marmosets, the therapeutic index for GSK356278 was >10 versus <1 for rolipram. We also demonstrate that GSK356278 enhances performance in a model of executive function in cynomolgus macaques with no adverse effects, a therapeutic profile that supports further evaluation of GSK356278 in a clinical setting.

Interaction between different extracts of Hypericum perforatum L. from Serbia and pentobarbital, diazepam and paracetamol.

Herb-drug interactions are an important safety concern and this study was conducted regarding the interaction between the natural top-selling antidepressant remedy Hypericum perforatum (Hypericaceae) and conventional drugs. This study examined the influence of acute pretreatment with different extracts of Hypericum perforatum from Serbia on pentobarbital-induced sleeping time, impairment of motor coordination caused by diazepam and paracetamol pharmacokinetics in mice. Ethanolic extract, aqueous extract, infusion, tablet and capsule of Hypericum perforatum were used in this experiment. The profile of Hypericum perforatum extracts as well as paracetamol plasma concentration was determined using RP-HPLC analysis. By quantitative HPLC analysis of active principles, it has been proven that Hypericum perforatum ethanolic extract has the largest content of naphtodianthrones: hypericin (57.77 µg/mL) and pseudohypericin (155.38 µg/mL). Pretreatment with ethanolic extract of Hypericum perforatum potentiated the hypnotic effect of pentobarbital and impairment of motor coordination caused by diazepam to the greatest extent and also increased paracetamol plasma concentration in comparison to the control group. These results were in correlation with naphtodianthrone concentrations. The obtained results have shown a considerable influence of Hypericum perforatum on pentobarbital and diazepam pharmacodynamics and paracetamol pharmacokinetics.

Pharmacokinetic study in mice of galphimine-A, an anxiolytic compound from Galphimia glauca.

The aim of this study was to obtain pharmacokinetic data for the anxiolytic compound galphimine-A (G-A) from Galphimia glauca. G-A is the most abundant anxiolytic compound in this plant, while Galphimine-E (G-E) is the most abundant galphimine, but inactive. G-E was transformed chemically into G-A. The pharmacokinetic study was carried out in ICR mice, which were orally administered a single 200 mg/kg dose of G-A. Samples of blood and brain were taken at different times after administration of G-A. Previously, we established the validation of methods for determining the concentration of G-A. The G-A was detected in plasma 5 min after oral administration, and its concentration reached 2.47 µg/mL. Data from concentration-time curves allowed us to establish the main pharmacokinetic parameters in two models: one- and/or two-compartment. C(max) values were 3.33 and 3.42 µg/mL respectively, likewise AUC(0→1440 min) were 1,951.58 and 1,824.95 µg/mL·min. The G-A in brain tissue was noted to cross the blood-brain barrier, reaching C(max) 2.74 µg/mL, T(max) 81.6 min, and then drop gradually to 0.32 µg/mL detected at 24 h. The presence of G-A in brain tissue, confirmed that this anxiolytic compound can access the target organ and acts directly on the CNS.

Alterations in the CNS effects of anti-epileptic drugs by Chinese herbal medicines.

INTRODUCTION: Concomitant use of anti-epileptic drugs (AEDs) and Chinese herbal medicines (CHMs) is increasing globally. However, information summarizing how CHMs might alter the CNS effects of AEDs is lacking. AREAS COVERED: A systematic review of the English-language articles in evidence-based databases was performed. It identified CHMs that interact with AEDs and lead to alterations in the CNS effects of AEDs. This review provides a descriptive summary of the existing information on CHM-induced changes of both the therapeutic and adverse CNS effects of AEDs, including i) anti-epileptic effect, ii) sedative effect, iii) anxiolytic effect and iv) memory impairment effect. The proposed mechanisms behind the interactions are also summarized. EXPERT OPINION: Despite the popularity of both AEDs and CHMs, the availability of information on CHM-AED interactions that could result in altered CNS outcomes is considerably limited. Moreover, there are some insufficiencies in the study designs of the identified reports. More research, including both mechanistic and human studies, with improved study design is necessary to ensure the safety and efficacy of combinational use of AEDs with CHMs.

Is pomegranate juice a potential perpetrator of clinical drug-drug interactions? Review of the in vitro, preclinical and clinical evidence.

The area of fruit juice-drug interaction has received wide attention with numerous scientific and clinical investigations performed and reported for scores of drugs metabolized by CYP3A4/CYP2C9. While grapefruit juice has been extensively studied with respect to its drug-drug interaction potential, numerous other fruit juices such as cranberry juice, orange juice, grape juice, pineapple juice and pomegranate juice have also been investigated for its potential to show drug-drug interaction of any clinical relevance. This review focuses on establishing any relevance for clinical drug-drug interaction potential with pomegranate juice, which has been shown to produce therapeutic benefits over a wide range of disease areas. The review collates and evaluates relevant published in vitro, preclinical and clinical evidence of the potential of pomegranate juice to be a perpetrator in drug-drug interactions mediated by CYP3A4 and CYP2C9. In vitro and animal pharmacokinetic data support the possibility of CYP3A4/CYP2C9 inhibition by pomegranate juice; however, the human relevance for drug-drug interaction was not established based on the limited case studies.

Anxiolytic effect and tissue distribution of inhaled Alpinia zerumbet essential oil in mice.

The use of essential oils is common throughout the world, and clarification of their detailed effects and pharmaceutical potencies is necessary. Additionally, detailed information regarding the pharmacokinetics of essential oils is needed. In this report, GC-MS analysis was used to observe the tissue distribution of the multiple components of Alpinia zerumbet (Pers.) B.L. Burtt. et Sm. Anxiety-related behavior was evaluated by the light and dark box test (LD), open field test (OF), and elevated plus maze test (EPM). GC-MS quantification of the major components of A. zerumbet essential oil (AZEO) (alpha-pinene, p-cymene, 1,8-cineole, and limonene) was almost identical using either the injection or headspace injection method. All the behavioral assessments indicated that inhalation of AZEO had a positive anxiolytic effect. This was especially evident in the EPM (time spent in the open arms), where anxiolytic effects were clearly observed (P < 0.05). Alpha-Pinene accumulated in the brain at almost the same rate as in the liver. However, the oil components chiefly accumulated in the kidney. Therefore, the essential oil component in the largest proportion will not necessarily be distributed to organs throughout the body in the same quantities and/or ratios. It is necessary to consider tissue distribution for investigating the effects of essential oil inhalation.

St. John's wort components and the brain: uptake, concentrations reached and the mechanisms underlying pharmacological effects.

Hypericum perforatum L. (St. John's wort) extracts have gained popularity as an alternative to conventional antidepressant drugs for mild to moderate forms of depressive disorders. New potential psychiatric uses for extracts in obsessive-compulsive disorder, generalised anxiety disorder and alcohol dependence have also been suggested on the basis of animal studies. The neurochemical mechanisms of these central actions are still debated but several components have antidepressant-like and anxiolytic-like effects in animals, or interact with neurotransmitter systems believed to be causally involved in depression, anxiety and in psychiatric illness generally. However, these data should interpreted taking account of the pharmacokinetic data on the main components, particularly those of their brain distribution and concentrations and the relationships with blood concentrations; the (scant) data so far suggest that the acylphloroglucinol hyperforin, the flavonol quercetin and its glycosylated forms and their metabolites, the biflavones amentoflavone and its I3,II8-analog biapigenin and the naphthodianthrones hypericin and pseudohypericin pass the blood-brain barrier poorly in animals. The brain concentrations of all these high-molecular weight, poorly water-soluble compounds after pharmacologically effective doses of the extracts are therefore far below those effective on neurotransmitter receptors and the mechanisms which are obviously important in the central effects of conventional, pharmacologically related drugs. Additional pharmacokinetic data on the brain concentrations of these and other constituents and their metabolites are therefore required for a more meaningful interpretation of the central effects of St. John's Wort extracts.

Excretion of afobazole and its metabolites with urine and feces in rats.

The amount of afobazole and identified metabolites was measured in the urine and feces of rats after intraperitoneal and peroral administration of the drug in a dose of 25 mg/kg. Over 1 day after intraperitoneal or peroral treatment with afobazole, urine and feces contained 0.1% initial compound (from administered dose) and 42.1% metabolites.

Combined approach for high-throughput preparation and analysis of plasma samples from exposure studies.

In drug discovery today, drug exposure is determined in preclinical efficacy and safety studies and drug effects are related to measured concentrations rather than to the administered dose. This leads to a strong increase in the number of bioanalytical samples, demanding the development of higher throughput methods to cope with the increased workload. Here, a combined approach is described for the high-throughput preparation and liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis of drug levels in plasma samples from the preclinical efficacy and safety studies, i.e. exposure studies. Appropriate pharmacokinetic (PK) compartmental models were fitted to data from PK screening studies in the rat, which were subsequently used to simulate the expected plasma concentrations of the respective exposure studies. Information on the estimated drug concentrations was used to dilute the samples to appropriate concentration levels. A Tecan Genesis RSP liquid handling system was utilized to perform automated plasma sample preparation including serial dilution of standard solutions, dilution of plasma samples, addition of internal standard solution and precipitation with acetonitrile. This robotic sample preparation process permitted two studies of 1-96 samples each to be run simultaneously. To ensure the performance of this method the accuracy and precision for diazepam were examined. Two novel drugs were used to illustrate the suggested approach. In conclusion, our method for sample preparation of exposure samples, based on the combined use of PK simulations, a liquid handling system and a fast LC/MS/MS method, increased the throughput more than three times and minimized the errors, while maintaining the required accuracy and precision.

Rational design, synthesis, and structure-activity relationship of benzoxazolones: new potent mglu5 receptor antagonists based on the fenobam structure.

A novel class of potent and stable mGlu5 receptor antagonists was developed by combining information from a high-throughput screening campaign with the structure of the known anxiolytic fenobam. Representative compounds from this class show favorable pharmacokinetic properties and are active in an in vivo model of anxiety.