Midazolam selectively potentiates the A(2A) - but not A1- receptor--mediated effects of adenosine: role of nucleoside transport inhibition and clinical implications

Acute Cardiovascular Toxicity of Cocaine

Cocaine is one of the most commonly abused drugs and represents a major public health concern. Cocaine users frequently present to the emergency department, with chest pain being the most common presenting complaint. The incidence of acute myocardial infarction in patients with cocaine-associated chest pain is often quoted as 6%, but it is highly variable depending on the included population. Risk assessment can be challenging in these patients; serial assessment of electrocardiograms and troponins is often required. This review focuses on the assessment and management of patients presenting with cocaine-associated chest pain and cardiotoxicity. Specific treatments are discussed, including benzodiazepines, nitroglycerin, calcium channel blockers, and phentolamine, and how treatment priorities differ from patients with noncocaine presentations. The use of beta-blockers in this population remains controversial, and the literature around its use is reviewed. The most recent literature and recommendations for the use of percutaneous coronary intervention and fibrinolytics in cocaine-associated myocardial infarction is discussed as well. Cocaine-associated dysrhythmias are suggested to be the cause of sudden cardiac death in some users. The pathophysiology and evidence-based treatments for dysrhythmias are reviewed. This review provides evidence-based recommendations for the assessment and management of patients presenting with cocaine-associated cardiovascular toxicity.

Structure-Activity Relationship Studies of 4-((4-(2-fluorophenyl)piperazin-1-yl)methyl)-6-imino-N-(naphthalen-2-yl)-1,3,5-triazin-2-amine (FPMINT) Analogues as Inhibitors of Human Equilibrative Nucleoside Transporters

Equilibrative nucleoside transporters (ENTs) play a vital role in nucleotide synthesis, regulation of adenosine function and chemotherapy. Current inhibitors of ENTs are mostly ENT1-selective. Our previous study has demonstrated that 4-((4-(2-fluorophenyl)piperazin-1-yl)methyl)-6-imino-N-(naphthalen-2-yl)-1,3,5-triazin-2-amine (FPMINT) is a novel inhibitor of ENTs, which is more selective to ENT2 than to ENT1. The present study aimed to screen a series of FPMINT analogues and study their structure-activity relationship. Nucleoside transporter-deficient cells transfected with cloned human ENT1 and ENT2 were used as in vitro models. The results of the [³H]uridine uptake study showed that the replacement of the naphthalene moiety with the benzene moiety could abolish the inhibitory effects on ENT1 and ENT2. The addition of chloride to the meta position of this benzene moiety could restore only the inhibitory effect on ENT1 but had no effect on ENT2. However, the addition of the methyl group to the meta position or the ethyl or oxymethyl group to the para position of this benzene moiety could regain the inhibitory activity on both ENT1 and ENT2. The presence of a halogen substitute, regardless of the position, in the fluorophenyl moiety next to the piperazine ring was essential for the inhibitory effects on ENT1 and ENT2. Among the analogues tested, compound 3c was the most potent inhibitor. Compound 3c reduced V _max of [³H]uridine uptake in ENT1 and ENT2 without affecting K _m. The inhibitory effect of compound 3c could not be washed out. Compound 3c did not affect cell viability, protein expression and internalization of ENT1 and ENT2. Therefore, similar to FPMINT, compound 3c was an irreversible and non-competitive inhibitor. Molecular docking analysis also showed that the binding site of compound 3c in ENT1 may be different from that of other conventional inhibitors. It is expected that structural modification may further improve its potency and selectivity and lead to the development of useful pharmacological agents.

Cladribine as a Potential Object of Nucleoside Transporter-Based Drug Interactions

Cladribine is a nucleoside analog that is phosphorylated in its target cells (B and T-lymphocytes) to its active triphosphate form (2-chlorodeoxyadenosine triphosphate). Cladribine tablets 10 mg (Mavenclad®), administered for up to 10 days per year in 2 consecutive years (3.5-mg/kg cumulative dose over 2 years), are used to treat patients with relapsing multiple sclerosis. Cladribine has been shown to be a substrate of various nucleoside transporters (NTs). Intestinal absorption and distribution of cladribine throughout the body appear to be essentially mediated by equilibrative NTs (ENTs) and concentrative NTs (CNTs), specifically by ENT1, ENT2, ENT4, CNT2 (low affinity), and CNT3. Other efficient transporters of cladribine are the ABC efflux transporters, specifically breast cancer resistance protein, which likely modulates the oral absorption and renal excretion of cladribine. A key transporter for the intracellular uptake of cladribine into B and T-lymphocytes is ENT1 with ancillary contributions of ENT2 and CNT2. Transporter-based drug interactions affecting absorption and target cellular uptake of a prodrug such as cladribine are likely to reduce systemic bioavailability and target cell exposure, thereby possibly hampering clinical efficacy. In order to manage optimized therapy, i.e., to ensure uncompromised target cell uptake to preserve the full therapeutic potential of cladribine, it is important that clinicians are aware of the existence of NT-inhibiting medicinal products, various lifestyle drugs, and food components. This article reviews the existing knowledge on inhibitors of NT, which may alter cladribine absorption, distribution, and uptake into target cells, thereby summarizing the existing knowledge on optimized methods of administration and concomitant drugs that should be avoided during cladribine treatment.

Inhibition of human equilibrative nucleoside transporters by 4-((4-(2-fluorophenyl)piperazin-1-yl)methyl)-6-imino-N-(naphthalen-2-yl)-1,3,5-triazin-2-amine

Equilibrative nucleoside transporters (ENTs) play a crucial role in the transport of nucleoside and nucleoside analogues, which are important for nucleotide synthesis and chemotherapy. In addition, ENTs regulate extracellular adenosine levels in the vicinity of its receptors and hence influence adenosine-related functions. The clinical applications of ENT inhibitors in the treatment of cardiovascular diseases and cancer therapy have been explored in numerous studies. However, all ENT inhibitors to date are selective for ENT1 but not ENT2. In the present study, we investigated the novel compound 4-((4-(2-fluorophenyl)piperazin-1-yl)methyl)-6-imino-N-(naphthalen-2-yl)-1,3,5-triazin-2-amine (FPMINT) as an inhibitor of ENT1 and ENT2. Nucleoside transporter-deficient PK15NTD cells stably expressing ENT1 and ENT2 showed that FPMINT inhibited [³H]uridine and [³H]adenosine transport through both ENT1 and ENT2 in a concentration-dependent manner. The IC₅₀ value of FPMINT for ENT2 was 5-10-fold less than for ENT1, and FPMINT could not be displaced with excess washing. Kinetic studies revealed that FPMINT reduced V_max of [³H]uridine transport in ENT1 and ENT2 without affecting K_M. Therefore, we conclude that FPMINT inhibits ENTs in an irreversible and non-competitive manner. Although already selective for ENT2 over ENT1, further modification of the chemical structure of FPMINT may lead to even better ENT2-selective inhibitors of potential clinical, physiological and pharmacological importance.

Experimental treatments for cocaine toxicity: a difficult transition to the bedside

Cocaine is a commonly abused illicit drug that causes significant morbidity and mortality. Although there is no true antidote to cocaine toxicity, current management strategies address the life-threatening systemic effects, namely hyperthermia, vasospasm, and severe hypertension. Clinicians rely on rapid cooling, benzodiazepines, and α-adrenergic antagonists for management, with years of proven benefit. Experimental agents have been developed to more effectively treat acute toxicity. Pharmacodynamic approaches include antipsychotics that are thought to interfere with cocaine's actions at several neurotransmitter receptors. However, these medications may worsen the consequences of cocaine toxicity as they can interfere with heat dissipation, cause arrhythmias, and lower the seizure threshold. Pharmacokinetic approaches use cocaine-metabolizing enzymes, such as butyrylcholinesterase (BChE), cocaine hydrolase (CocH), and bacterial cocaine esterase (CocE). Experimental models with these therapies improve survival, primarily when administered before cocaine, although newer evidence demonstrates beneficial effects shortly after cocaine toxicity has manifested. CocE, a foreign protein, can induce an immune response with antibody formation. When enzyme administration was combined with vaccination against the cocaine molecule, improvement in cocaine-induced locomotor activity was observed. Finally, lipid emulsion rescue has been described in human case reports as an effective treatment in patients with hemodynamic compromise because of cocaine, which correlates well with its documented benefit in toxicity due to other local anesthetics. A pharmaceutical developed from these concepts will need to be expedient in onset and effective with minimal adverse effects while at the same time being economical.

Changes in biomechanical parameters during heart perfusion and after midazolam pre-medication--experimental pilot study

BACKGROUND

Midazolam is a frequently used benzodiazepine in anaesthesiology and intensive care.

AIM

The aim of pilot study was to monitor its effect during heart perfusion in the laboratory rat.

METHODS

The same groups of animals (n = 10). The 1(st) group was treated with midazolam in a dose of 0.5mg/kg i.p. The 2(nd) group was a placebo. After i.p. administration of heparine injection of 500 IU dose, the hearts were excised and perfused (modified Langendorf's method). Working schedule: stabilization/ischaemia/reperfusion proceed at intervals of 20/30/60 min. Monitored parameters in isolated heart: left ventricle pressure (LVP), end-diastolic pressure (LVEDP), contractility (+dP/dt(max)).

RESULTS

The treated hearts showed improved postischemic recovery, reaching LVP values of 92 +/- 6 % at the end of the reperfusion, placebo only 61 +/- 7 %. In placebo hearts LVEDP rose from 10.0 +/- 0.5 mmHg to 43 +/- 4 mmHg after, in treated animals only about 25 mmHg. The treated hearts improved +dP/dt(max) recovery during reperfusion to 91 +/- 8 %. These values were significantly greater than those obtained from the placebo hearts.

CONCLUSIONS

Positive changes in monitored parameters were found in this experimental pilot study. We conclude that the administration of midazolam in laboratory rats has a cardioprotective potential against ischemia-reperfusion induced injury.

Inhibition of human equilibrative nucleoside transporters by dihydropyridine-type calcium channel antagonists

Dihydropyridine-type calcium channel antagonists, in addition to having a vasodilatory effect, are known to inhibit cellular uptake of nucleosides such as adenosine. However, the nucleoside transporter subtypes involved and the mechanism by which this occurs are not known. Therefore, we have studied the inhibitory effects of dihydropyridines on both human equilibrative nucleoside transporters, hENT-1 and hENT-2, which are the major transporters mediating nucleoside transport in most tissues. Among the dihydropyridines tested, nimodipine proved to be the most potent inhibitor of hENT-1, with an IC(50) value of 60+/-31 muM, whereas nifedipine, nicardipine, nitrendipine, and felodipine exhibited 100-fold less effective inhibitory activity. Nifedipine, nitrendipine, and nimodipine inhibited hENT-2 with IC(50) values in the micromolar range; however, nicardipine and felodipine had no significant effect on hENT-2. Removal of the 4-aryl ring or changing the nitro group at the 4-aryl ring proved not to be detrimental to the inhibitory effects of dihydropyridines on hENT-1, but resulted in a drastic decrease in their inhibitory effects on hENT-2. Kinetic studies revealed that nimodipine and nifedipine reduced V(max) of [(3)H]uridine transport without affecting K(m). The inhibitory effects of nimodipine and nifedipine could be washed out. In addition, nimodipine and nifedipine inhibited the rate of NBTGR-induced dissociation of [(3)H]NBMPR from hENT-1 cell membrane. We conclude that dihydropyridines are non-competitive inhibitors of hENT-1 and hENT-2, probably working through reversible interactions with the allosteric sites. The inhibitory potencies of dihydropyridines may be associated with the structure of the 4-aryl ring, as well as the ester groups at the C-3 and C-5 positions.

The anti-schistosomal drug praziquantel is an adenosine antagonist

The mechanism of action of praziquantel (PZQ), the drug of choice against schistosomiasis, is still unclear. Since exposure of schistosomes to the drug is associated with calcium influx and muscular contraction, calcium channels have been suggested as the target, although direct combination of PZQ with their subunits was never demonstrated. We report a hitherto unknown effect of PZQ, namely the inhibition of nucleoside uptake, as observed in living worms using radio-isotope labelled adenosine and uridine. This effect is clearly seen in schistosomes but is absent in mammalian cells in culture. Moreover it is a specific pharmacological effect seen exclusively with the active levo-R(-)stereo isomer of the drug, and is shared by at least one benzodiazepine having antischistosomal activity. This novel effect acquires significance given that schistosomes cannot synthesize purine nucleosides de novo. A possible relationship between this novel effect and the known action of PZQ on calcium channels is discussed, since adenosine is known to bind to specific receptors and to behave as an indirect antagonist of calcium release in mammalian cells. If calcium channels were correlated with adenosine receptors also in schistosomes, as they are in mammals, this would support the hypothesis that PZQ-induced calcium influx may be correlated to adenosine receptor blockade.

Novel antiseizure drug mechanisms

The amount of new knowledge being generated regarding brain mechanisms in general, and epileptic mechanisms in particular, is enormous. Anticonvulsant drugs are ineffective in approximately a third of people with epilepsy. To our knowledge, strategies for preventing epilepsy after an initial insult are nonexistent. In this review, we briefly examine some recent novel concepts for preventing seizures, which might lead to enhanced anticonvulsant drug therapy. We start with some known seizure mechanisms that have yet to yield widely used anticonvulsant drugs, including potassium channels, chloride cotransporters, extracellular space constriction, gap junctions and magnesium. Pharmacoresistance is then discussed, focusing on the upregulation of drug-resistance proteins (a concept with significant therapeutic appeal) and the drug-target hypothesis. Two further areas that hold great promise for future therapeutics are sex hormones and inflammatory processes. The genetics of epilepsy are currently being elaborated, providing potential novel anticonvulsant targets. Prevention being better than a cure, we discuss epileptogenesis and its treatment. Given the astounding progress of neuroscience research, one hopes for many new therapeutics for our intractable epileptic patients.

Functional and pharmacological mechanisms of nucleoside transport across the basolateral membrane of rabbit tracheal epithelial cells

The role of basolateral membrane nucleoside transport in primary cultured rabbit tracheal epithelial cells (RTEC) was studied. Primary cultured RTEC were grown on permeable support at an air-interface. Transport studies were conducted in the uptake, efflux, and transepithelial transport configurations using (3)H-uridine as a model substrate. Time, temperature and concentration dependency of (3)H-uridine transport were evaluated in parallel to the metabolism of this substrate using scintillation counting and thin layer chromatography. Inhibition of (3)H-uridine uptake from basolateral fluid was estimated in presence of all unlabeled natural nucleosides as well as analogs and nucleobases. Functional modulation pathways of (3)H-uridine uptake were studied after treatment of RTEC with pharmacological levels of A23187, forskolin, tamoxifen, H89 and colchicine. The basolateral aspect has a low-affinity and high-capacity transport system that exhibits characteristics of bi-directionality, temperature/concentration dependency, and broad specificity towards purines and pyrimidines without requiring Na(+). Basolateral equilibrative-sensitive/insensitive (es/ei) type transport machinery manifested as a biphasic dose response to nitro-benzyl-mercapto-purine-ribose (NBMPR) inhibition. In addition, a number of therapeutically relevant nucleoside analogs appeared to compete with the uptake of uridine from basolateral fluid. Short-term pre-incubation of primary cultured RTEC with the calcium ionophore A23187 inhibited basolateral uridine uptake without affecting the J(max) and K(m). The inhibitory effect was not reversible with a protein kinase C (PKC) antagonist, tamoxifen. In contrast, basolateral uridine uptake was increased by adenylyl cyclase activator forskolin (reversible with protein kinase A (PKA) inhibitor H89), resulting in a decreased K(m), but a lower J(max). Uridine exit across the basolateral membrane of primary cultured RTEC occurs via a facilitative diffusion carrier, which can be modulated by intracellular Ca(2+) levels and PKA. Information about these carriers will help improve the transportability of antitumor and antiviral nucleoside analogs in the pulmonary setting.

Myocardial O2 consumption in porcine left ventricle is heterogeneously distributed in parallel to heterogeneous O2 delivery

Myocardial blood flow is unevenly distributed, but the cause of this heterogeneity is unknown. Heterogeneous blood flow may reflect heterogeneity of oxygen demand. The aim of the present study was to assess the relation between oxygen consumption and blood flow in small tissue regions in porcine left ventricle. In seven male, anesthetized, open-chest pigs, local oxygen consumption was quantitated by computational model analysis of the incorporation of 13C in glutamate via the tricarboxylic acid cycle during timed infusion of [13C]acetate into the left anterior descending coronary artery. Blood flow was measured with radioactive microspheres before and during acetate infusion. High-resolution nuclear magnetic resonance 13C spectra were obtained from extracts of tissue samples (159 mg mean dry wt) taken at the end of the acetate infusion. Mean regional myocardial blood flow was stable [5.0 ± 1.6 (SD) and 5.0 ± 1.4 ml·min−1·g dry wt−1 before and after 30 min of acetate infusion, respectively]. Mean left ventricular oxygen consumption measured with the NMR method was 18.6 ± 7.7 μmol·min−1·g dry wt−1 and correlated well ( r = 0.85, P = 0.02, n = 7) with oxygen consumption calculated from blood flow, hemoglobin, and blood gas measurements (mean 22.8 ± 4.7 μmol·min−1·g dry wt−1). Local blood flow and oxygen consumption were significantly correlated ( r = 0.63 for pooled normalized data, P < 0.0001, n = 60). We calculate that, in the heart at normal workload, the variance of left ventricular oxygen delivery at submilliliter resolution is explained for 43% by heterogeneity in oxygen demand.

The influence of diazepam and midazolam on adenosine-induced forearm vasodilation in humans

Adenosine is an endogenous purine with vasodilating and cardioprotective properties. Animal experiments have shown that some benzodiazepine-induced effects can be explained by potentiation of adenosine effects, via inhibition of the nucleoside transport system. The objective of this study was to determine whether the frequently used benzodiazepines diazepam and midazolam increase adenosine-induced vasodilation in the human forearm vascular bed, measured by venous occlusion plethysmography. Adenosine (0.6, 6, 20, and 60 nmol/min/dl ForeArm Volume) was infused into the brachial artery with and without concomitant separate infusion of diazepam (21 nmol/min/dl, n = 9) and midazolam (23 nmol/min/dl, n = 8). Plasma concentrations of diazepam resp. midazolam at the end of the infusion protocol averaged 0.5 +/- 0.2 microg/ml plasma (1.6 microM) for diazepam versus 1.2 +/- 0.4 microg/ml plasma (3 microM) for midazolam. Intra-arterial infusion of the benzodiazepines did not alter baseline vascular tone, and had no significant influence on the forearm vasodilator response to adenosine. The adenosine-induced relative change in Forearm Vascular Resistance (FVR) was -3 +/- 7, -48 +/- 8, -75 +/- 6, and -85 +/- 3% in the absence and 3.5 +/- 11, -54 +/- 5, -74 +/- 5, and -82 +/- 3% resp. in the presence of diazepam (P > 0.1, repeated measures ANOVA, n = 9). Likewise, in the absence resp. presence of midazolam, FVR fell by 1 +/- 6, 55 +/- 5, 74 +/- 3, and 84 +/- 2% resp. 11 +/- 11, 59 +/- 2, 80 +/- 3, and 87 +/- 2% (P > 0.1, n = 7). Intra-brachial infusion of diazepam and midazolam resulting in forearm concentrations in the high therapeutic range does not augment adenosine-induced forearm vasodilation. A possible interaction at supra-therapeutic levels of the benzodiazepines can not be excluded from the present study, but lacks clinical significance.

Adenosine uptake inhibitors

Adenosine is a purine nucleoside and modulates a variety of physiological functions by interacting with cell-surface adenosine receptors. Under several adverse conditions, including ischemia, trauma, stress, seizures and inflammation, extracellular levels of adenosine are increased due to increased energy demands and ATP metabolism. Increased adenosine could protect against excessive cellular damage and organ dysfunction. Indeed, several protective effects of adenosine have been widely reported (e.g., amelioration of ischemic heart and brain injury, seizures and inflammation). However, the effects of adenosine itself are insufficient because extracellular adenosine is rapidly taken up into adjacent cells and subsequently metabolized. Adenosine uptake inhibitors (nucleoside transport inhibitors) could retard the disappearance of adenosine from the extracellular space by blocking adenosine uptake into cells. Therefore, it is expected that adenosine uptake inhibitors will have protective effects in various diseases, by elevating extracellular adenosine levels. Protective or ameliorating effects of adenosine uptake inhibitors in ischemic cardiac and cerebral injury, organ transplantation, seizures, thrombosis, insomnia, pain, and inflammatory diseases have been reported. Preclinical and clinical results indicate the possibility of therapeutic application of adenosine uptake inhibitors.

Characterization of genomic organization of the adenosine A2A receptor gene by molecular and bioinformatics analyses

The adenosine A(2A) receptor (A(2A)R) is abundantly expressed in brain and emerging as an important therapeutic target for Parkinson's disease and potentially other neuropsychiatric disorders. To understand the molecular mechanisms of A(2A)R gene expression, we have characterized the genomic organization of the mouse and human A(2A)R genes by molecular and bioinformatic analyses. Three new exons (m1A, m1B and m1C) encoding the 5' untranslated regions (5'-UTRs) of mouse A(2A)R mRNA were identified by rapid amplification of 5' cDNA end (5' RACE), RT-PCR analysis and genome sequence analyses. Similar bioinformatics analysis also suggested six variants of the non-coding "exon 1" (h1A, h1B, h1C, h1D, h1E and h1F) in the human A(2A)R gene, which were confirmed by RT-PCR analysis, while three of the human exon 1 variants (h1D, h1E and h1F) were likewise verified by 5' oligonucleotide capping analysis suggesting multiple transcription start sites. Importantly, RT-PCR and quantitative PCR analysis demonstrated that the A(2A)R transcripts with different exon 1 variants displayed tissue-specific expression patterns. For instance, the mouse exon m1A mRNA was detected only in brain (specifically striatum) and the human exon h1D mRNA in lymphoreticular system. Furthermore, the determination of the three new transcription start sites of human A(2A)R gene by 5' oligonucleotide capping and bioinformatics analyses led to the identification of three corresponding promoter regions which contain several important cis elements, providing additional target for further molecular dissection of A(2A)R gene expression. Finally, our analysis indicates that A(2A)R mRNA and a novel transcript partially overlapping with the 3' exon h3, but in opposite orientation to the A(2A)R gene, could conceivably form duplexes to mutually regulate transcript expression. Thus, combined molecular and bioinformatics analyses revealed a new A(2A)R genomic structure, with conserved coding exons 2 and 3 and divergent, tissue-specific exon 1 variants encoding for 5'-UTR. This raises the possibility of generating multiple tissue-specific A(2A)R mRNA species by alternative promoters with varying regulatory susceptibility.

Aberrant A2A receptor function in peripheral blood cells in Huntington's disease

A2A adenosine receptors specifically found on striatal medium spiny neurons play a major role in sensory motor function and may also be involved in neuropsychiatric and neurodegenerative disorders. One hypothesis concerning Huntington's disease (HD) proposes that an imbalance of the cortico-striatal pathway, due to the mutation in the HD gene, leads to striatal vulnerability. An A2A receptor dysfunction has been previously demonstrated in striatal cells engineered to express mutant huntingtin. Here we tested whether a similar dysfunction (i.e., the binding and functional parameters of A2A adenosine receptors) is present in peripheral blood cells (platelets, lymphocytes, and neutrophils) of subjects carrying the mutant gene. This study involved 48 heterozygous and three homozygous patients compared with 58 healthy subjects. Moreover, we selected seven at-risk mutation carriers. A2A receptor density and function are substantially increased in peripheral blood cells from both patients and subjects at the presymptomatic stage. In the neutrophils of the three homozygous HD subjects receptor dysfunction was higher than in heterozygotes. These data indicate the existence of an aberrant A2A receptor phenotype in the peripheral blood cells of subjects carrying the HD mutation. Future studies will assess whether this parameter can be exploited as a peripheral biomarker of Huntington's disease.

Heat loss, sleepiness, and impaired performance after diazepam administration in humans

In spite of the accumulation of knowledge regarding the neuropharmacological action of benzodiazepines (Bz), the physiological process by which their sedative/hypnotic effects are induced remains poorly understood. We conducted a single-blind, crossover trial to evaluate the role of the thermoregulatory process in sleepiness and impaired psychomotor performance induced by a standard Bz, diazepam (DZP). Each of the eight healthy young male volunteers (mean age, 19.75 years; range, 18-23 years) was given a single oral dose of either 5 or 10 mg of DZP or placebo 12 h after his average sleep onset time. Changes in plasma DZP concentration, proximal body temperature (p-BT), distal body temperature (d-BT), subjective sleepiness measured by the Visual Analog Scale and Stanford Sleepiness Scale, and psychomotor performance measured by Choice Reaction Time were monitored under a modified constant routine condition in which various factors affecting thermoregulation, alertness, and psychomotor performances were strictly controlled. Orally administered DZP induced a significant transient decrease in p-BT and psychomotor performance as well as an increase in d-BT and subjective sleepiness. Distal-p-BT gradient (DPG; difference between d-BT and p-BT), which is an indicator of blood flow in distal skin regions, showed a strong positive correlation with the plasma DZP concentration, indicating that DZP in clinical doses promotes heat loss in a dose-dependent manner. The DPG also correlated positively with the magnitude of subjective sleepiness and impaired psychomotor performance. These findings indicate that the sedative/hypnotic effects of Bz could be due, at least in part, to changes in thermoregulation, especially in the process of heat loss, in humans.

A prospective, randomized, controlled trial of benzodiazepines and nitroglycerine or nitroglycerine alone in the treatment of cocaine-associated acute coronary syndromes

The purpose of the present study was to compare the use of lorazepam plus nitroglycerine (NTG) versus NTG alone in the reduction of cocaine induced chest pain in the emergency department. The secondary objective of the study was to help determine the safety of lorazepam in the treatment of cocaine- associated chest pain. The study was a prospective, randomized, single-blinded, controlled trial conducted at an university-affiliated urban emergency department (ED). All patients who presented with cocaine-associated chest pain were enrolled. Exclusion criteria included age greater than 45 years, documented coronary artery disease, chest pain of more than 72 hours duration, or pretreatment with nitroglycerin. Patients were given either sublingual nitroglycerine (SL NTG) (Group 1) or SL NTG plus 1 mg of lorazepam intravenously (Group 2) every 5 minutes for a total of 2 doses. Chest pain was recorded on an ordinal scale of 0 to 10 at baseline, and then at 5 minutes after each dose. Adverse reactions to medication were also recorded. Twenty-seven patients met the inclusion criteria and were enrolled in the study. The average age of these subjects was 34.1 years, and 67% were men. The NTG-only group consisted of 15 patients and the NTG-plus-lorazepam group consisted of 12 patients. Baseline mean chest-pain scores were 6.87 in Group 1 and 6.54 in Group 2, with no differences between groups. Five minutes after initial treatment, mean scores for the two groups were 5.2 and 3.9, respectively, with a difference in means of 1.24 (95% confidence interval [CI] -0.8-3.8). Five minutes after the second treatment, the mean scores were 4.6 and 1.5, respectively, with a difference in means of 3.1 (95% CI 1.2-5). Kruskal-Wallis testing showed a significant difference in pain relief between the two study groups (P =.003), with greater pain relief noted at 5 and 10 minutes in the NTG-plus-lorazepam group (P =.02 and P =.005, respectively). All patients in the study were admitted to the hospital, but no patient in either group had an acute myocardial infarction or cardiac complications in the ED. No adverse side effects were noted for either group. The early use of lorazepam with NTG was more efficacious than NTG alone, and appears to be safe in relieving cocaine-associated chest pain.