Evaluation of Clinical Outcomes Associated With Phenobarbital With Taper Compared to No Taper for the Management of Alcohol Withdrawal Syndrome.

BACKGROUND: Phenobarbital (PHB) has been shown to be an effective treatment of alcohol withdrawal syndrome (AWS), with multiple dosing strategies used (e.g., single-dose and symptom-triggered). Studies have often used tapered doses, typically following a front-loaded dose, despite PHB's long half-life which should lead to an ability to auto-taper. OBJECTIVE: The purpose of this study was to compare clinical outcomes associated with two PHB dosing strategies (taper [T], no taper [NT]) for AWS. METHODS: This retrospective cohort study compared adult patients admitted to the ICU from October 2017 to May 2019 who received an initial loading dose of PHB for AWS. The use of PHB was at the discretion of the clinician per our institutional guidelines. Prior to November 2018, patients were prescribed a PHB taper, while after this period, the taper was no longer recommended. The primary outcome was the proportion of patients requiring rescue PHB or adjunctive medications for AWS. Secondary outcomes included number of adjunctive agents used, prevalence of severe manifestations of AWS, ICU and hospital lengths of stay, and incidence of potentially significant drug interactions. RESULTS: A total of 172 patients were included (T: n = 81, NT: n = 91). Baseline characteristics were similar between groups, including history of severe AWS and cumulative benzodiazepine dose pre-PHB. There was no difference in the primary outcome between groups (T: 70.4% vs NT: 59.3%, P = 0.152). The median number of adjunctive agents per patient, severe manifestations, and ICU and hospital length of stay did not differ between groups. Twenty-five patients (14.5%) had potentially significant drug interactions. CONCLUSION AND RELEVANCE: The use of a PHB loading dose without a taper may be comparable to a taper strategy on clinical outcomes. Prospective studies are needed to further delineate the optimal dose of PHB for AWS.

Sedation Therapy in Intensive Care Units: Harnessing the Power of Antioxidants to Combat Oxidative Stress.

In critically ill patients requiring intensive care, increased oxidative stress plays an important role in pathogenesis. Sedatives are widely used for sedation in many of these patients. Some sedatives are known antioxidants. However, no studies have evaluated the direct scavenging activity of various sedative agents on different free radicals. This study aimed to determine whether common sedatives (propofol, thiopental, and dexmedetomidine (DEX)) have direct free radical scavenging activity against various free radicals using in vitro electron spin resonance. Superoxide, hydroxyl radical, singlet oxygen, and nitric oxide (NO) direct scavenging activities were measured. All sedatives scavenged different types of free radicals. DEX, a new sedative, also scavenged hydroxyl radicals. Thiopental scavenged all types of free radicals, including NO, whereas propofol did not scavenge superoxide radicals. In this retrospective analysis, we observed changes in oxidative antioxidant markers following the administration of thiopental in patients with severe head trauma. We identified the direct radical-scavenging activity of various sedatives used in clinical settings. Furthermore, we reported a representative case of traumatic brain injury wherein thiopental administration dramatically affected oxidative-stress-related biomarkers. This study suggests that, in the future, sedatives containing thiopental may be redeveloped as an antioxidant therapy through further clinical research.

Pharmacological Analysis of GABAA Receptor and Sigma1R Chaperone Interaction: Research Report I-Investigation of the Anxiolytic, Anticonvulsant and Hypnotic Effects of Allosteric GABAA Receptors' Ligands.

Two groups of facts have been established in previous drug development studies of the non-benzodiazepine anxiolytic fabomotizole. First, fabomotizole prevents stress-induced decrease in binding ability of the GABAA receptor's benzodiazepine site. Second, fabomotizole is a Sigma1R chaperone agonist, and exposure to Sigma1R antagonists blocks its anxiolytic effect. To prove our main hypothesis of Sigma1R involvement in GABAA receptor-dependent pharmacological effects, we performed a series of experiments on BALB/c and ICR mice using Sigma1R ligands to study anxiolytic effects of benzodiazepine tranquilizers diazepam (1 mg/kg i.p.) and phenazepam (0.1 mg/kg i.p.) in the elevated plus maze test, the anticonvulsant effects of diazepam (1 mg/kg i.p.) in the pentylenetetrazole-induced seizure model, and the hypnotic effects of pentobarbital (50 mg/kg i.p.). Sigma1R antagonists BD-1047 (1, 10, and 20 mg/kg i.p.), NE-100 (1 and 3 mg/kg i.p.), and Sigma1R agonist PRE-084 (1, 5, and 20 mg/kg i.p.) were used in the experiments. Sigma1R antagonists have been found to attenuate while Sigma1R agonists can enhance GABAARs-dependent pharmacological effects.

Estado actual y perspectivas futuras en el manejo de la hipertensión intracraneal posterior a traumatismo craneoencefálico: craniectomía descompresiva, hipotermia terapéutica y barbitúricos / Current status and outlook for the management of intracranial hypertension after traumatic brain injury: decompressive craniectomy, therapeutic hypothermia, and barbiturates

Introducción: El aumento de la presión intracraneal se ha asociado a un pronóstico neurológicodesfavorable y a un incremento en la mortalidad en pacientes con traumatismo craneoencefálico grave. Tradicionalmente, las terapias para disminuir la presión intracraneal se administranutilizando un enfoque progresivo, reservando el uso de opciones más agresivas para los casossin respuesta a intervenciones de primer nivel, o de hipertensión intracraneal refractaria. Desarrollo: El valor terapéutico de las intervenciones de rescate para la hipertensión intracraneal, así como el momento adecuado para su uso ha sido debatido constantemente en laliteratura. En esta revisión, discutiremos las principales opciones de tratamiento para la hipertensión intracraneal refractaria posterior a un traumatismo craneoencefálico grave en adultos.Tenemos la intención de llevar a cabo una revisión en profundidad de los ensayos controladosaleatorios más representativos sobre las diferentes intervenciones terapéuticas de rescate,incluyendo la craniectomía descompresiva, hipotermia terapéutica y barbitúricos. Además,discutiremos las perspectivas futuras de estas opciones de tratamiento. Conclusiones: La evidencia parece mostrar que se puede reducir la mortalidad al utilizar estasintervenciones de rescate como terapia de último nivel, sin embargo, este beneficio vieneacompanado de una discapacidad severa. La decisión de realizar o no estas intervencionesdebe ser individualizada y centrada en el paciente. El desarrollo e integración de diferentesvariables fisiológicas a través de monitorización multimodal es de suma importancia para poderproporcionar información pronóstica más sólida a los pacientes que enfrentan este tipo dedecisiones.(AU)

Introduction: Increased intracranial pressure has been associated with poor neurological out-comes and increased mortality in patients with severe traumatic brain injury. Traditionally,intracranial pressure-lowering therapies are administered using an escalating approach, withmore aggressive options reserved for patients showing no response to first-tier interventions,or with refractory intracranial hypertension. Development: The therapeutic value and the appropriate timing for the use of rescue treat-ments for intracranial hypertension have been a subject of constant debate in literature. Inthis review, we discuss the main management options for refractory intracranial hypertensionafter severe traumatic brain injury in adults. We intend to conduct an in-depth revision of themost representative randomised controlled trials on the different rescue treatments, includingdecompressive craniectomy, therapeutic hypothermia, and barbiturates. We also discuss futureperspectives for these management options. Conclusions: The available evidence appears to show that mortality can be reduced whenrescue interventions are used as last-tier therapy; however, this benefit comes at the cost ofsevere disability. The decision of whether to perform these interventions should always bepatient-centred and made on an individual basis. The development and integration of differentphysiological variables through multimodality monitoring is of the utmost importance to providemore robust prognostic information to patients facing these challenging decisions.(AU)

Covalently Modified MoS2 Bearing a Hamilton-Type Receptor for Recognizing a Redox-Active Ferrocene-Barbiturate Guest via Multiple H-Bonds.

The covalent modification of the metallic phase of MoS2 with a Hamilton-type ligand is presented, transforming MoS2 to a recognition platform which is able to embrace barbiturate moieties via hydrogen bonding. The successful hydrogen bonding formation is easily monitored by simple electrochemical assessments, if a ferrocene-labeled barbiturate analogue is utilized as a proof of concept. Full spectroscopic, thermal, and electron microscopy imaging characterization is provided for the newly formed recognition system, along with valuable insights concerning the electrochemical sensing. The given methodology expands beyond the sensing applications, confidently entering the territory of supramolecular interactions on the surface of 2D transition metal dichalcogenides. The well-designed host-guest chemistry presented herein, constitutes a guide and an inspiration for hosting customized-structured functional building blocks on MoS2 and its relatives via hydrogen bonding, opening up new opportunities regarding potential applications.

Current status and outlook for the management of intracranial hypertension after traumatic brain injury: decompressive craniectomy, therapeutic hypothermia, and barbiturates.

INTRODUCTION: Increased intracranial pressure (ICP) has been associated with poor neurological outcomes and increased mortality in patients with severe traumatic brain injury (TBI). Traditionally, ICP-lowering therapies are administered using an escalating approach, with more aggressive options reserved for patients showing no response to first-tier interventions, or with refractory intracranial hypertension. DEVELOPMENT: The therapeutic value and the appropriate timing for the use of rescue treatments for intracranial hypertension have been a subject of constant debate in literature. In this review, we discuss the main management options for refractory intracranial hypertension after severe TBI in adults. We intend to conduct an in-depth revision of the most representative randomised controlled trials on the different rescue treatments, including decompressive craniectomy, therapeutic hypothermia, and barbiturates. We also discuss future perspectives for these management options. CONCLUSIONS: The available evidence appears to show that mortality can be reduced when rescue interventions are used as last-tier therapy; however, this benefit comes at the cost of severe disability. The decision of whether to perform these interventions should always be patient-centred and made on an individual basis. The development and integration of different physiological variables through multimodality monitoring is of the utmost importance to provide more robust prognostic information to patients facing these challenging decisions.

New approach for barbiturates, phenytoin, methyprylon and glutethimide determination and fragmentation (UHPLC-MS/MS).

Barbiturates which are old pharmaceutical drugs are still widely used in medical treatment of epilepsy and for general anesthesia. To date, more than 2500 different barbituric acid analogs have been synthesized, and 50 of them were introduced into medical use over the last century. Due to their highly addictive properties, pharmaceuticals containing barbiturates are under strict control in many countries. However, by considering the worldwide problem with new psychoactive substances (NPS) the introduction of new designer barbiturate analogs into the dark market might serve a serious public health problem in the near future. For this reason there is an increasing need for application methods for barbiturates monitoring in biological samples. The UHPLC-QqQ-MS/MS method for determination of 15 barbiturates, phenytoin, methyprylon and glutethimide was developed and fully validated. The biological sample volume was reduced to only 50 µL. A simple LLE (pH 3 with ethyl acetate) was successfully applied. The lower LOQ was 10 ng/mL. The method enables differentiation of structural isomers: hexobarbital and cyclobarbital; as well as amobarbital and pentobarbital. Chromatographic separation was achieved with the use of the alkaline mobile phase (pH 9) and Acquity UPLC BEH C18 column. Furthermore, the novel fragmentation mechanism of barbiturates was proposed, which may have a great impact in identification of novel barbiturates analogs introduced to illegal marketplaces. The presented technique has a great potential to be applied in forensic, clinical and veterinary toxicological laboratories, as was evidenced by the positive results of international proficiency tests.

Barbiturates and pyrazolopyridines for the treatment of postpartum depression-repurposing of two drug classes.

Zulresso (brexanolone) is an aqueous formulation of the neurosteroid, allopregnanolone, and the only FDA-approved medication for the treatment of postpartum depression (PPD). While brexanolone is effective for the treatment of PPD, lengthy infusion time and high cost can be prohibitive. Failure of GABAA receptors to adapt to fluctuating neurosteroid levels is considered to predispose women to mood disorders in the postpartum period. Brexanolone is thought to act via stimulation of δ subunit-containing GABAA receptors, which are extrasynaptic and localized to particular brain regions. Neurosteroid stimulation of δ subunit-containing GABAA receptors leads to sustained inhibition (hyperpolarization) of GABAergic neurons, which makes δ subunit-containing GABAA receptors a potentially important pharmacologic target. Barbiturates and pyrazolopyridines are potent stimulators of δ subunit-containing GABAA receptors and therefore potentially cost-effective treatments for PPD. Barbiturates are often not prescribed, owing to risk of dependence and respiratory depression. The pyrazolopyridines were tested several decades ago for anxiety and depression but never developed commercially. Herein we use the FDA-approved dosing schedule of brexanolone and GABAA receptor binding data from various animal models to examine the safety, efficacy, and potential clinical utility of barbiturates and pyrazolopyridines for the treatment of PPD. We suggest consideration of repurposing barbiturates and pyrazolopyridines as safe and readily available treatment alternatives for PPD.

Phenobarbital in Status epilepticus - Rediscovery of an effective drug.

Phenobarbital (PB) is one of the oldest Antiseizure Medicines (ASMs), which is in clinical use since 1912. Its value in the treatment of Status epilepticus is currently discussed controversially. Phenobarbital has fallen out of favor in many countries across Europe because of reports of hypotension, arrhythmias, and hypopnea. Phenobarbital has a strong antiseizure effect with remarkably little sedation. It exerts its clinical effects, through the increase of GABE-ergic inhibition and decrease of glutamatergic excitation by inhibition of AMPA receptors. Despite good preclinical evidence, there are remarkably few randomized controlled studies on humans in SE, which suggest, that it is at least as good as lorazepam in first-line treatment in early SE, and significantly better than valproic acid in benzodiazepine-resistant SE. Data from randomized trials and large non-randomized prospective and retrospective studies suggest, that Phenobarbital is well tolerated even if used in very high dose protocols. Thus, despite its decline in its popularity at least in Europe and North America, it should be considered a highly cost-effective treatment for early and established SE, not only in resource-limited settings. This paper was presented at the 8th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures held in September 2022.

DARK Classics in Chemical Neuroscience: Methaqualone.

Commonly known as "Quaaludes," methaqualone (1) is a sedative-hypnotic medication, with effects resembling barbiturates and other downers, that exerts its effects through modulation of γ-aminobutyric acid type A receptors (GABAAR). Following the discovery of the sedative and euphoric effects of methaqualone (1), it was quickly adopted by pharmaceutical companies and promoted by clinicians around the world as a "safe" sleeping pill option, and for a period it was available over the counter. The popularity of methaqualone (1) soared worldwide, and many people began to use it recreationally for its sedative-hypnotic-like psychoactive effects. Not long after its introduction, many individuals began to misuse the drug leading to overdoses and drug dependence which brought to light methaqualone's (1) addictive nature. In this review, the background, synthesis, pharmacology, metabolism, and pharmacokinetics of methaqualone (1) will be covered along with its discovery, history, and the derivatives that are currently available around the world through manufacture in clandestine laboratories.

Phenobarbital to manage severe gamma-hydroxybutyrate withdrawal: A case series.

INTRODUCTION: Management of a withdrawal syndrome following cessation of regular gamma-hydroxybutyrate (GHB) use, and its precursors, can represent a clinical challenge due to rapid onset delirium and/or seizures. Severe GHB withdrawal can be characterised by persistent or worsening features despite increasing benzodiazepine doses and regular baclofen. Barbiturates, such as phenobarbital, are an appealing option in this context due to their unique GABA-A receptor action. CASE SERIES: This series describes the use of phenobarbital in 13 cases, 12 patients, across two hospitals in Sydney, Australia, with persistent or progressive GHB withdrawal despite benzodiazepine-based management. A median cumulative dose of oral diazepam prior to commencing phenobarbital was 120 mg (range 80-255 mg). The median time from the last GHB use to the first dose of phenobarbital was 24 h (range 7-57 h). Eight cases received phenobarbital orally on a general ward and 5 intravenously in intensive care units. An improvement in GHB withdrawal symptoms was observed after phenobarbital in all cases and there were no adverse events related to phenobarbital. DISCUSSION AND CONCLUSION: This case series suggests that phenobarbital for the management of benzodiazepine-resistant GHB withdrawal can be safe, even in general inpatient settings, and may avert the progression of delirium. Most data on the management of GHB withdrawal comes from case reports or series, such as this one. This highlights the need for prospective trials to establish an evidence base for therapeutic approaches, including validated measures of withdrawal severity and more information relating to the safe and effective dosing of phenobarbital.

Opioid-Free Anaesthesia Improves Anaesthesia Recovery when Compared with that of Opioid-Based Anaesthesia. Systematic Review and Meta-Analysis of Clinical Trials.

INTRODUCTION: Opioid Free Anesthesia (OFA) is a relatively new technique that has been questioned due to the lack of evidence regarding its benefit-risk balance. METHODS: Four international databases were searched for clinical trials comparing OFA with opioid based anesthesia. The primary outcome was pain control and the secondary included postoperative nausea and vomiting (PONV), gastrointestinal recovery, respiratory depression, urinary retention, length of hospital stay, surgical complications, number of patients with cessation of the intervention and other side effects. RESULTS: Pain was better controlled in the OFA group in all the measurements made (VAS 1h: Md = -0.81, CI95% = -0.48- -1.14, VAS 24h: Md = -1.25, CI95% =-2.41- -0.1, VAS >24h: Md = -1.36, CI95% = -1.73- -1). In the opioid group there was an increase in the risk of nausea (RR=2.69, CI95% = 2-3.61) and vomiting (RR = 3.99, CI95% = 2.06-7.74), whilst in the OFA group, there was an increased risk of bradycardia (RR= 1.62, CI95% = 1.02-2.57). The rest of the variables showed no differences between groups or could not be analyzed. CONCLUSION: There is a clear benefit of OFA in pain control and PONV, but there is also a higher risk of bradycardia. This technique should be considered in patients with a special risk of difficult postoperative pain control or PONV. However, the best drug combination to perform OFA is still unknown, as well as the type of patient that benefits more with less risk.

Pentobarbital overdose: A case of contract killing.

Suicides by pentobarbital overdose have increased since about 2012, which appear to be influenced by technical information on active euthanasia that has spread over the Internet. We encountered a pentobarbital poisoning case of a patient with amyotrophic lateral sclerosis. A caregiver found the patient unconscious immediately after two visitors left the room. The patient was immediately transferred to the emergency hospital but eventually declared dead. A fatal concentration of pentobarbital was detected in peripheral blood samples collected in the emergency hospital and during autopsy (53.8 µg/mL and 29.4 µg/mL, respectively). Because the ratios of pentobarbital concentrations between the gastric contents and peripheral blood were 35 and 29 in the hospital and autopsy samples, respectively, it is likely that pentobarbital was administered via the gastrostomy tube. The patient had contacted the visitors through social media. Although the patient had requested the doctor perform active euthanasia and expressed a desire to end their life on social media, nobody had noticed the plan to commit suicide.

Topiramate and other kainate receptor antagonists for depression: A systematic review of randomized controlled trials.

BACKGROUND: Depression is a common disorder that affects patients' quality of life and incurs health system costs. Due to the resistance to treat depression, better understanding of neurophysiology was considered; one of the implications is the glutamatergic system. This study aims to systematically review clinical trials investigating the antidepressant effects of kainate receptor antagonists. METHODS: The study protocol was registered in PROSPERO (CRD42021213912). Scopus, ISI, Embase, PubMed, Cochrane Library, Google Scholar, and two trial registries were searched for randomized controlled trials on the effectiveness of topiramate, phenobarbital, and other ten barbiturates in depression. The difference with control groups in terms of changing depressive symptoms was the primary outcome. RESULTS: Nine trials were identified, in which 784 patients were studied. The efficacy of thiopental was comparable to that of imipramine, with fewer side effects. When administered with electroconvulsive therapy, it had fewer to similar effects and fewer side effects than ketamine. Both monotherapy and adjunctive therapy with topiramate were effective and tolerable in treating depressed patients. Phenobarbital had therapeutic effects compared to imipramine and amitriptyline with fewer side effects. CONCLUSION: Regarding the glutamatergic hypothesis of depression and obtained promising results, further studies of kainate receptor antagonists in high-quality trials are recommended. Given the high prevalence of depression in epileptic patients, more problems with its treatment, and the fact that the studied agents were anticonvulsants, it is recommended that future studies prioritize depressed-epileptic patients.

A concise SAR-analysis of antimicrobial cationic amphipathic barbiturates for an improved activity-toxicity profile.

An amphipathic barbiturate mimic of the marine eusynstyelamides is reported as a promising class of antimicrobial agents. We hereby report a detailed analysis of the structure-activity relationship for cationic amphipathic N,N'-dialkylated-5,5-disubstituted barbiturates. The influence of various cationic groups, hydrocarbon linkers and lipophilic side chains on the compounds' antimicrobial potency and haemolytic activity was studied. A comprehensive library of 58 compounds was prepared using a concise synthetic strategy. We found cationic amine and guanidyl groups to yield the highest broad-spectrum activity and cationic trimethylated quaternary amine groups to exert narrow-spectrum activity against Gram-positive bacteria. n-Propyl hydrocarbon linkers proved to be the best compromise between potency and haemolytic activity. The combination of two different lipophilic side chains allowed for further fine-tuning of the biological properties. Using these insights, we were able to prepare both, the potent narrow-spectrum barbiturate 8a and the broad-spectrum barbiturates 11lG, 13jA and 13jG, all having low or no haemolytic activity. The guanidine derivative 11lG demonstrated a strong membrane disrupting effect in luciferase-based assays. We believe that these results may be valuable in further development of antimicrobial lead structures.

Enhancing GABA inhibition is the next generation of medications for essential tremor.

γ-Aminobutyric acid (GABA) is the most prevalent inhibitory CNS neurotransmitter. Activating GABA-A receptors hyperpolarizes cells via Cl- influx, which inhibits action potentials. Although the exact pathophysiologies of tremor are incompletely understood, proposed neuroanatomy extensively implicates GABA pathways. Pathological studies and imaging studies also show GABA abnormalities in patients with ET. Most importantly, medications that activate GABA-A receptors, such as primidone, often improve tremor. Ongoing clinical trials and physiology research should further refine potential future GABAergic targets and treatments, which are currently the most promising targets for pharmacological intervention.

Determination of barbiturates in hair samples by using a validated UHPLC-HRMS method: application in investigation of drug-facilitated sexual assault.

In recent years, benzodiazepines and benzodiazepine-like drugs are the most common substances associated with drug-facilitated sexual assaults (DFSA); however, barbiturates are also detected occasionally. Segmental hair analysis provides useful information on the historic pattern of drug use, enabling differentiation between single exposure in DFSA cases and chronic use. However, sensitive and specific methods for barbiturate analysis in hair samples are needed. Herein, we present an ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS) method for qualitative and quantitative determination of seven barbiturates in hair samples. Firstly, a hair strand was decontaminated and then freeze-milled in liquid nitrogen. Next, 50 mg of powdered hair was extracted with methanol in an ultrasonic bath for 10 min in the presence of 10 ng phenobarbital-d5. The supernatant was dried under nitrogen gas, and the pellet was dissolved in 100 µL mobile phase. Afterwards, 10 µL of the suspension was injected into the UHPLC-HRMS system. The present method involved two UHPLC conditions for determination of barbiturates (I) and identification of the structural isomers amobarbital and pentobarbital (II). This method showed satisfactory linearity in a range of 0.02-20.00 ng/mg for UHPLC conditions I and II, both with a high determination coefficient (0.9991-0.9999). The selectivity, intra- and interday precision, accuracy and matrix effect of the method were acceptable. Next, the validated method was applied to investigate an authentic DFSA case. Hair samples (black, approximate 25 cm long) were collected 3 months after the assault, and the proximal segments (0-5 cm from the root; each segment was 1 cm long) were analyzed. Amobarbital was detected at a concentration of < LOQ (limit of quantification) and 0.09 ng/mg in the second and third 1 cm hair segment but not in the other segments. Thus, our method was successful in determining barbiturate concentration in human hair after a single-dose exposure, showing its potential for application in the investigation of DFSA cases.

Evaluation of a human urine barbiturate test to screen for pentobarbital euthanasia of dogs and cats.

Pentobarbital is used commonly to euthanize animals. Occasionally during a death investigation, it is necessary to determine whether a cat or dog was euthanized via pentobarbital overdose. Screening for the detection of barbiturates including pentobarbital can be performed using commercial immunochromatographic tests. We used a commercial immunochromatographic test for barbiturates in humans to screen for barbiturates in urine collected postmortem from 20 dogs and 20 cats to determine whether they had been euthanized with pentobarbital. Additionally, we analyzed the urine for pentobarbital using liquid chromatography-mass spectrometry as a confirmatory test. Screening and confirmation testing revealed 100% agreement between the tests and with the euthanasia status of each animal. Our results support the use of the immunochromatographic test for the screening of urine collected postmortem to assess for the presence of barbiturates, specifically pentobarbital, used for euthanasia.

Evaluation of diazepam as a drug treatment for water hemlock (Cicuta species) poisoning in Spanish goats.

Water hemlocks (Cicuta spp.) are toxic members of the Apiaceae plant family. The best drug treatment for the convulsions associated with acute water hemlock poisoning in livestock and humans has not been determined experimentally. This work compared the therapeutic actions of benzodiazepines (diazepam) and barbiturates (phenobarbital) on water hemlock poisoning in a goat model. C. maculata tubers were orally dosed to goats. Experimental groups consisted of; control saline; 20 mg/kg phenobarbital; 1.0 mg/kg diazepam; 10 mg/kg diazepam; and 1.0 mg/kg diazepam administered as needed to moderate convulsions by intravenous (i.v.) infusion. Diazepam provided nearly instant control of convulsions. Clinical signs of poisoning were completely controlled for the duration of the experiment in the goats that received the 10 mg/kg diazepam dose. These results suggest that diazepam is effective at managing the clinical signs of water hemlock poisoning in goats. We speculate that diazepam can be used as a potential treatment for water hemlock poisoning in other livestock species and humans.

Towards Optimized Bioavailability of 99mTc-Labeled Barbiturates for Non-invasive Imaging of Matrix Metalloproteinase Activity.

INTRODUCTION: Dysregulated activity of matrix metalloproteinases (MMPs) drives a variety of pathophysiological conditions. Non-invasive imaging of MMP activity in vivo promises diagnostic and prognostic value. However, current targeting strategies by small molecules are typically limited with respect to the bioavailability of the labeled MMP binders in vivo. To this end, we here introduce and compare three chemical modifications of a recently developed barbiturate-based radiotracer with respect to bioavailability and potential to image MMP activity in vivo. METHODS: Barbiturate-based MMP inhibitors with an identical targeting unit but varying hydrophilicity were synthesized, labeled with technetium-99m, and evaluated in vitro and in vivo. Biodistribution and radiotracer elimination were determined in C57/BL6 mice by serial SPECT imaging. MMP activity was imaged in a MMP-positive subcutaneous xenograft model of human K1 papillary thyroid tumors. In vivo data were validated by scintillation counting, autoradiography, and MMP immunohistochemistry. RESULTS: We prepared three new 99mTc-labeled MMP inhibitors, bearing either a glycine ([99mTc]MEA39), lysine ([99mTc]MEA61), or the ligand HYNIC with the ionic co-ligand TPPTS ([99mTc]MEA223) yielding gradually increasing hydrophilicity. [99mTc]MEA39 and [99mTc]MEA61 were rapidly eliminated via hepatobiliary pathways. In contrast, [99mTc]MEA223 showed delayed in vivo clearance and primary renal elimination. In a thyroid tumor xenograft model, only [99mTc]MEA223 exhibited a high tumor-to-blood ratio that could easily be delineated in SPECT images. CONCLUSION: Introduction of HYNIC/TPPTS into the barbiturate lead structure ([99mTc]MEA223) results in delayed renal elimination and allows non-invasive MMP imaging with high signal-to-noise ratios in a papillary thyroid tumor xenograft model.