Diazepam versus fentanyl for premedication during percutaneous coronary intervention: results from the Myocardial Protection by Fentanyl during Coronary Intervention (PROFIT) Trial

BACKGROUND: Sedation is a cornerstone in the premedication for percutaneous coronary intervention (PCI). Benzodiazepines and opioids are frequently used. Previous results suggest that opioids mimic the adaptation to ischemia during repeated balloon inflations and may provide direct myocardial protection in addition to their sedative effect. However, no comparative data exist. METHODS: We conducted a prospective, randomized, controlled, single-blind trial comparing diazepam and fentanyl in 276 patients undergoing elective PCI. Patients were randomized to either diazepam 5 mg sublingually or fentanyl 0.05 mg or 0.1 mg intravenously at least 5 minutes prior to the first balloon inflation. The primary end-point was the postprocedural elevation of myocardial markers of necrosis defined as an elevation of cardiac troponin T > or = 0.01 ng/ml. RESULTS: The three groups had similar baseline clinical, angiographic, and procedural characteristics, with no significant differences in lesion morphology, procedural complexity, or adjunctive medical treatment. No significant variation in the hemodynamic response to the study drugs was observed in the three groups. The rate of postprocedural troponin T elevation was 28% in the diazepam group, 20% in the fentanyl 0.05 mg group, and 30% in the fentanyl 0.1 mg group (P = 0.26). Rates of postprocedural myocardial infarction were 3%, 2%, and 2%, respectively (P = 0.84), with one case of in-hospital death in the diazepam group and no urgent TVR in the whole study population. CONCLUSION: Although providing a well-tolerated alternative to diazepam for sedation during PCI, fentanyl did not provide additional cardioprotection assessed through the postinterventional elevation of cardiac troponin T during elective coronary intervention.

Covalent modification of GABAA receptor isoforms by a diazepam analogue provides evidence for a novel benzodiazepine binding site that prevents modulation by these drugs

Classical benzodiazepines, for example diazepam, interact with alpha(x)beta(2)gamma(2) GABA(A) receptors, x = 1, 2, 3, 5. Little is known about effects of alpha subunits on the structure of the binding pocket. We studied here the interaction of the covalently reacting diazepam analog 7-Isothiocyanato-5-phenyl-1,3-dihydro-2H-1,4-benzodiazepin-2-one (NCS compound) with alpha(1)H101Cbeta(2)gamma(2) and with receptors containing the homologous mutation, alpha(2)H101Cbeta(2)gamma(2), alpha(3)H126Cbeta(2)gamma(2) and alpha(5)H105Cbeta(2)gamma(2). This comparison was extended to alpha(6)R100Cbeta(2)gamma(2) receptors as this mutation conveys to these receptors high affinity towards classical benzodiazepines. The interaction was studied at the ligand binding level and at the functional level using electrophysiological techniques. Results indicate that the geometry of alpha(6)R100Cbeta(2)gamma(2) enables best interaction with NCS compound, followed by alpha(3)H126Cbeta(2)gamma(2), alpha(1)H101Cbeta(2)gamma(2) and alpha(2)H101Cbeta(2)gamma(2), while alpha(5)H105Cbeta(2)gamma(2) receptors show little interaction. Our results allow conclusions about the relative apposition of alpha(1)H101 and homologous positions in alpha(2), alpha(3), alpha(5) and alpha(6) with the position occupied by -Cl in diazepam. During this study we found evidence for the presence of a novel site for benzodiazepines that prevents modulation of GABA(A) receptors via the classical benzodiazepine site. The novel site potentially contributes to the high degree of safety to some of these drugs. Our results indicate that this site may be located at the alpha/beta subunit interface pseudo-symmetrically to the site for classical benzodiazepines located at the alpha/gamma interface.

Relative positioning of diazepam in the benzodiazepine-binding-pocket of GABA receptors

GABA(A) receptors are the major inhibitory neurotransmitter receptors in the brain. Some of them are targets of benzodiazepines that are widely used in clinical practice for their sedative/hypnotic, anxiolytic, muscle relaxant and anticonvulsant effects. In order to rationally separate these different drug actions, we need to understand the interaction of such compounds with the benzodiazepine-binding pocket. With this aim, we mutated residues located in the benzodiazepine-binding site individually to cysteine. These mutated receptors were combined with benzodiazepine site ligands carrying a cysteine reactive group in a defined position. Proximal apposition of reaction partners will lead to a covalent reaction. We describe here such proximity-accelerated chemical coupling reactions of alpha(1)S205C and alpha(1)T206C with a diazepam derivative modified at the C-3 position with a reactive isothiocyanate group (-NCS). We also provide new data that identify alpha(1)H101C and alpha(1)N102C as exclusive sites of the reaction of a diazepam derivative where the -Cl atom is replaced by a -NCS group. Based on these observations we propose a relative positioning of diazepam within the benzodiazepine-binding site of alpha(1)beta(2)gamma(2) receptors.

Frequency-domain source localization shows state-dependent diazepam effects in 47-channel EEG

The topic of this study was to evaluate state-dependent effects of diazepam on the frequency characteristics of 47-channel spontaneous EEG maps. A novel method, the FFT-Dipole-Approximation (Lehmann and Michel, 1990), was used to study effects on the strength and the topography of the maps in the different frequency bands. Map topography was characterized by the 3-dimensional location of the equivalent dipole source and map strength was defined as the spatial standard deviation (the Global Field Power) of the maps of each frequency point. The Global Field Power can be considered as a measure of the amount of energy produced by the system, while the source location gives an estimate of the center of gravity of all sources in the brain that were active at a certain frequency. State-dependency was studied by evaluating the drug effects before and after a continuous performance task of 25 min duration. Clear interactions between drug (diazepam vs. placebo) and time after drug intake (before and after the task) were found, especially in the inferior-superior location of the dipole sources. It supports the hypothesis that diazepam, like other drugs, has different effects on brain functions depending on the momentary functional state of the brain. In addition to the drug effects, clearly different source locations and Global Field Power were found for the different frequency bands, replicating earlier reports (Michel et al., 1992).

Influence of GABA(A) receptor α subunit isoforms on the benzodiazepine binding site

Classical benzodiazepines, such as diazepam, interact with α(x)β(2)γ(2) GABA(A) receptors, x = 1, 2, 3, 5 and modulate their function. Modulation of different receptor isoforms probably results in selective behavioural effects as sedation and anxiolysis. Knowledge of differences in the structure of the binding pocket in different receptor isoforms is of interest for the generation of isoform-specific ligands. We studied here the interaction of the covalently reacting diazepam analogue 3-NCS with α(1)S204Cβ(2)γ(2), α(1)S205Cβ(2)γ(2) and α(1)T206Cβ(2)γ(2) and with receptors containing the homologous mutations in α(2)β(2)γ(2), α(3)β(2)γ(2), α(5)β(1/2)γ(2) and α(6)β(2)γ(2). The interaction was studied using radioactive ligand binding and at the functional level using electrophysiological techniques. Both strategies gave overlapping results. Our data allow conclusions about the relative apposition of α(1)S204Cβ(2)γ(2), α(1)S205Cβ(2)γ(2) and α(1)T206Cβ(2)γ(2) and homologous positions in α(2), α(3), α(5) and α(6) with C-atom adjacent to the keto-group in diazepam. Together with similar data on the C-atom carrying Cl in diazepam, they indicate that the architecture of the binding site for benzodiazepines differs in each GABA(A) receptor isoform α(1)β(2)γ(2), α(2)β(2)γ(2), α(3)β(2)γ(2), α(5)β(1/2)γ(2) and α(6)β(2)γ(2).

Two neighboring residues of loop A of the alpha1 subunit point towards the benzodiazepine binding site of GABAA receptors

Benzodiazepines are widely used drugs exerting sedative, anxiolytic, muscle relaxant, and anticonvulsant effects by acting through specific high affinity binding sites on some GABA(A) receptors. It is important to understand how these ligands are positioned in this binding site. We are especially interested here in the conformation of loop A of the alpha(1)beta(2)gamma(2) GABA(A) receptor containing a key residue for the interaction of benzodiazepines: alpha(1)H101. We describe a direct interaction of alpha(1)N102 with a diazepam- and an imidazobenzodiazepine-derivative. Our observations help to better understand the conformation of this region of the benzodiazepine pocket in GABA(A) receptor.

Rapid tranquilization of severely agitated patients with schizophrenia spectrum disorders: a naturalistic, rater-blinded, randomized, controlled study with oral haloperidol, risperidone, and olanzapine

INTRODUCTION Agitation is a major problem in acute schizophrenia. Only a few studies have tested antipsychotic agents in severely agitated patients, mainly because of legal issues. Furthermore, most studies were limited to the first 24 hours. We aimed to investigate the efficacy of oral haloperidol, risperidone, and olanzapine in reducing psychotic agitation in severely agitated patients with schizophrenia or schizophreniform or schizoaffective disorder over 96 hours using a prospective, randomized, rater-blinded, controlled design within a naturalistic treatment regimen. METHODS In total, 43 severely agitated patients at acute care psychiatric units were enrolled. Participants were randomly assigned to receive either daily haloperidol 15 mg, olanzapine 20 mg, or risperidone 2 to 6 mg over 5 days. Positive and Negative Syndrome Scale psychotic agitation subscale score was the primary outcome variable. A mixed-model analysis was applied. RESULTS All drugs were effective for rapid tranquilization within 2 hours. Over 5 days, the course differed between agents (P < 0.001), but none was superior. Dropouts occurred only in the risperidone and olanzapine groups. Men responded better to treatment than did women during the initial 2 hours (P = 0.046) as well as over the 5-day course (P < 0.001). No difference between drug groups was observed regarding diazepam or biperiden use. CONCLUSIONS Oral haloperidol, risperidone, and olanzapine seem to be suitable for treating acute severe psychotic agitation in schizophrenia spectrum disorders. Response to oral antipsychotics demonstrated a gender effect with poorer outcome in women throughout the study.

Rapid tranquilization of severely agitated patients with schizophrenia spectrum disorders: a naturalistic, rater-blinded, randomized controlled study with oral haloperidol, risperidone, and olanzapine

Agitation is a major problem in acute schizophrenia. Still, only limited evidence exists on antipsychotic efficacy in severely agitated patients after the first 24 hours. We aimed to investigate the efficacy of oral haloperidol, risperidone, and olanzapine in reducing psychotic agitation in severely agitated patients with schizophrenia or schizophreniform or schizoaffective disorder over 96 hours using a prospective, randomized, rater-blinded, controlled design within a naturalistic treatment regimen. We enrolled 43 severely agitated patients at acute care psychiatric units. Participants were randomly assigned to receive either daily haloperidol 15 mg, olanzapine 20 mg, or risperidone 2 – 6 mg over 5 days. Positive and Negative Syndrome Scale psychotic agitation (PANSS-PAS) subscore was the primary outcome variable. A mixed model analyses was applied. All drugs were effective for rapid tranquillization within 2 hours. Over 5 days, the course differed between agents (p < 0.001) but none was superior. Dropouts occurred only in the risperidone and olanzapine groups. Men responded better to treatment than women during the initial 2 hours (p = 0.046) as well as over the 5 day course (p < 0.001). No difference between drug groups was observed regarding diazepam or biperiden use. Oral haloperidol, risperidone, and olanzapine seem to be suitable for treating acute severe psychotic agitation in schizophrenia spectrum disorders. We observed a gender effect with poorer outcome in women.

Doramectin-Intoxikation bei drei Katzenwelpen

Dieser Fallbericht beschreibt drei Katzenwelpen mit Verdacht auf Doramectin-Intoxikation. Ein Wurf von insgesamt 7 Katzenwelpen wurde mit Doramectin behandelt, woraufhin drei Welpen neurologische Symptome entwickeltena Ein Welpe zeigte leichte Apathie und Zittern, ein weiterer zusätzlich Verhaltensänderungen und epileptiforme Anfälle, die mit Diazepam behandelt werden mussten. Beide Welpen erholten sich vollständig. Ein dritter Welpe wurde 3 Tage nach Doramectin-Gabe stuporös vorgestellt und zeigte im weiteren Verlauf Verhaltensänderungen wie Aggressivität, Hyperästhesie, Tremor und epileptiforme Anfälle. Er verstarb 36 Stunden nach Vorstellung. Bei der histopathologischen Untersuchung des Gehirns konnten ein zytotoxisches Ödem und Polioenzephalomalazie festgestellt werden. Die Doramectin-Dosis beim verstorbenen Welpen betrug 380 μg/kg.

Relative positioning of classical benzodiazepines to the γ2-subunit of GABAA receptors.

GABAA receptors are the major inhibitory neurotransmitter receptors in the brain. Benzodiazepine exert their action via a high affinity-binding site at the α/γ subunit interface on some of these receptors. Diazepam has sedative, hypnotic, anxiolytic, muscle relaxant, and anticonvulsant effects. It acts by potentiating the current evoked by the agonist GABA. Understanding specific interaction of benzodiazepines in the binding pocket of different GABAA receptor isoforms might help to separate these divergent effects. As a first step, we characterized the interaction between diazepam and the major GABAA receptor isoform α1β2γ2. We mutated several amino acid residues on the γ2-subunit assumed to be located near or in the benzodiazepine binding pocket individually to cysteine and studied the interaction with three ligands that are modified with a cysteine-reactive isothiocyanate group (-NCS). When the reactive NCS group is in apposition to the cysteine residue this leads to a covalent reaction. In this way, three amino acid residues, γ2Tyr58, γ2Asn60, and γ2Val190 were located relative to classical benzodiazepines in their binding pocket on GABAA receptors.

International online survey to assess current practice in equine anaesthesia.

REASONS FOR PERFORMING STUDY Multicentre Confidential Enquiries into Perioperative Equine Fatalities (CEPEF) have not been conducted since the initial CEPEF Phases 1-3, 20 years ago. OBJECTIVES To collect data on current practice in equine anaesthesia and to recruit participants for CEPEF-4. STUDY DESIGN Online questionnaire survey. METHODS An online questionnaire was prepared and the link distributed internationally to veterinarians possibly performing equine anaesthesia, using emails, posters, flyers and an editorial. The questionnaire included 52 closed, semiclosed and open questions divided into 8 subgroups: demographic data, anaesthetist, anaesthesia management (preoperative, technical equipment, monitoring, drugs, recovery), areas of improvements and risks and motivation for participation in CEPEF-4. Descriptive statistics and Chi-squared tests for comparison of categorical variables were performed. RESULTS A total of 199 questionnaires were completed by veterinarians from 14 different countries. Of the respondents, 43% worked in private hospitals, 36% in private practices and 21% in university teaching hospitals. In 40 institutions (23%) there was at least one diplomate of the European or American colleges of veterinary anaesthesia and analgesia on staff. Individual respondents reported routinely employ the following anaesthesia monitoring modalities: electrocardiography (80%), invasive arterial blood pressures (70%), pulse oximetry (60%), capnography (55%), arterial blood gases (47%), composition of inspired and expired gases (45%) and body temperature (35%). Drugs administered frequently or routinely as part of a standard protocol were: acepromazine (44%), xylazine (68%), butorphanol (59%), ketamine (96%), diazepam (83%), isoflurane (76%), dobutamine (46%), and, as a nonsteroidal anti-inflammatory drug, phenylbutazone (73%) or flunixin meglumine (66%). Recovery was routinely assisted by 40%. The main factors perceived by the respondents to affect outcome of equine anaesthesia were the preoperative health status of the animal and training of the anaesthetist. CONCLUSIONS Current practice in equine anaesthesia varies widely, and the study has highlighted important topics relevant for designing a future prospective multicentre cohort study (CEPEF-4). The Summary is available in Chinese - see Supporting information.

Accelerated discovery of novel benzodiazepine ligands by experiment-guided virtual screening.

High throughput discovery of ligand scaffolds for target proteins can accelerate development of leads and drug candidates enormously. Here we describe an innovative workflow for the discovery of high affinity ligands for the benzodiazepine-binding site on the so far not crystallized mammalian GABAA receptors. The procedure includes chemical biology techniques that may be generally applied to other proteins. Prerequisites are a ligand that can be chemically modified with cysteine-reactive groups, knowledge of amino acid residues contributing to the drug-binding pocket, and crystal structures either of proteins homologous to the target protein or, better, of the target itself. Part of the protocol is virtual screening that without additional rounds of optimization in many cases results only in low affinity ligands, even when a target protein has been crystallized. Here we show how the integration of functional data into structure-based screening dramatically improves the performance of the virtual screening. Thus, lead compounds with 14 different scaffolds were identified on the basis of an updated structural model of the diazepam-bound state of the GABAA receptor. Some of these compounds show considerable preference for the α3β2γ2 GABAA receptor subtype.

Attitudes towards a maintenance (-agonist) treatment approach in high-dose benzodiazepine-dependent patients: a qualitative study

BACKGROUND High-dose benzodiazepine dependence constitutes a major clinical concern. Although withdrawal treatment is recommended, it is unsuccessful for a significant proportion of affected patients. More recently, a benzodiazepine maintenance approach has been suggested as an alternative for patients' failing discontinuation treatment. While there is some data supporting its effectiveness, patients' perceptions of such an intervention have not been investigated. METHODS An exploratory qualitative study was conducted among a sample of 41 high-dose benzodiazepine (BZD)-dependent patients, with long-term use defined as doses equivalent to more than 40 mg diazepam per day and/or otherwise problematic use, such as mixing substances, dose escalation, recreational use, or obtainment by illegal means. A qualitative content analysis approach was used to evaluate findings. RESULTS Participants generally favored a treatment discontinuation approach with abstinence from BZD as its ultimate aim, despite repeated failed attempts at withdrawal. A maintenance treatment approach with continued prescription of a slow-onset, long-acting agonist was viewed ambivalently, with responses ranging from positive and welcoming to rejection. Three overlapping themes of maintenance treatment were identified: "Only if I can try to discontinue…and please don't call it that," "More stability and less criminal activity…and that is why I would try it," and "No cure, no brain and no flash…and thus, just for everybody else!" CONCLUSIONS Some patients experienced slow-onset, long-acting BZDs as having stabilized their symptoms and viewed these BZDs as having helped avoid uncontrolled withdrawal and abstain from criminal activity. We therefore encourage clinicians to consider treatment alternatives if discontinuation strategies fail.

Clinical and pharmacokinetic evaluation of S-ketamine for intravenous general anaesthesia in horses undergoing field castration.

BACKGROUND Intravenous anaesthetic drugs are the primary means for producing general anaesthesia in equine practice. The ideal drug for intravenous anaesthesia has high reliability and pharmacokinetic properties indicating short elimination and lack of accumulation when administered for prolonged periods. Induction of general anaesthesia with racemic ketamine preceded by profound sedation has already an established place in the equine field anaesthesia. Due to potential advantages over racemic ketamine, S-ketamine has been employed in horses to induce general anaesthesia, but its optimal dose remains under investigation. The objective of this study was to evaluate whether 2.5 mg/kg S-ketamine could be used as a single intravenous bolus to provide short-term surgical anaesthesia in colts undergoing surgical castration, and to report its pharmacokinetic profile. RESULTS After premedication with romifidine and L-methadone, the combination of S-ketamine and diazepam allowed reaching surgical anaesthesia in the 28 colts. Induction of anaesthesia as well as recovery were good to excellent in the majority (n = 22 and 24, respectively) of the colts. Seven horses required additional administration of S-ketamine to prolong the duration of surgical anaesthesia. Redosing did not compromise recovery quality. Plasma concentration of S-ketamine decreased rapidly after administration, following a two-compartmental model, leading to the hypothesis of a consistent unchanged elimination of the parent compound into the urine beside its conversion to S-norketamine. The observed plasma concentrations of S-ketamine at the time of first movement were various and did not support the definition of a clear cut-off value to predict the termination of the drug effect. CONCLUSIONS The administration of 2.5 mg/kg IV S-ketamine after adequate premedication provided good quality of induction and recovery and a duration of action similar to what has been reported for racemic ketamine at the dose of 2.2 mg/kg. Until further investigations will be provided, close monitoring to adapt drug delivery is mandatory, particularly once the first 10 minutes after injection are elapsed. Taking into account rapid elimination of S-ketamine, significant inter-individual variability and rapid loss of effect over a narrow range of concentrations a sudden return of consciousness has to be foreseen.

Clinical evaluation of ketamine and lidocaine intravenous infusions to reduce isoflurane requirements in horses under general anaesthesia

OBJECTIVE To compare isoflurane alone or in combination with systemic ketamine and lidocaine for general anaesthesia in horses. STUDY DESIGN Prospective, randomized, blinded clinical trial. ANIMALS Forty horses (ASA I-III) undergoing elective surgery. METHODS Horses were assigned to receive isoflurane anaesthesia alone (ISO) or with ketamine and lidocaine (LKI). After receiving romifidine, diazepam, and ketamine, the isoflurane end-tidal concentration was set at 1.3% and subsequently adjusted by the anaesthetist (unaware of treatments) to maintain a light plane of surgical anaesthesia. Animals in the LKI group received lidocaine (1.5 mg kg(-1) over 10 minutes, followed by 40 microg kg(-1) minute(-1)) and ketamine (60 microg kg(-1) minute(-1)), both reduced to 65% of the initial dose after 50 minutes, and stopped 15 minutes before the end of anaesthesia. Standard clinical cardiovascular and respiratory parameters were monitored. Recovery quality was scored from one (very good) to five (very poor). Differences between ISO and LKI groups were analysed with a two-sample t-test for parametric data or a Fischer's exact test for proportions (p < 0.05 for significance). Results are mean +/- SD. RESULTS Heart rate was lower (p = 0.001) for LKI (29 +/- 4) than for ISO (34 +/- 6). End-tidal concentrations of isoflurane (ISO: 1.57% +/- 0.22; LKI: 0.97% +/- 0.33), the number of horses requiring thiopental (ISO: 10; LKI: 2) or dobutamine (ISO:8; LKI:3), and dobutamine infusion rates (ISO:0.26 +/- 0.09; LKI:0.18 +/- 0.06 microg kg(-1) minute(-1)) were significantly lower in LKI compared to the ISO group (p < 0.001). No other significant differences were found, including recovery scores. CONCLUSIONS AND CLINICAL RELEVANCE These results support the use of lidocaine and ketamine to improve anaesthetic and cardiovascular stability during isoflurane anaesthesia lasting up to 2 hours in mechanically ventilated horses, with comparable quality of recovery.