Flunitrazepam Research Articles

Effects of single and repeated phencyclidine administration on [ 3H]flunitrazepam binding in rat brain

Repeated administration of phencyclidine (PCP) induces behavioral sensitization to dopaminergic neural transmission. This phenomenon has been implicated in the pathophysiology of schizophrenia. Recently, GABAergic agonists have been shown to reduce behavioral activity induced by enhanced dopaminergic neural transmission, which is mediated by the GABA A/benzodiazepine (BZD) receptor complex. Thus, to investigate the role of BZD receptors during induction and expression of behavioral sensitization in PCP-sensitized animals, the effects of both single and repeated PCP administration on BZD receptors in rat brain were examined using in vitro quantitative autoradiography. Repeated PCP administration failed to significantly alter levels of [ 3H]flunitrazepam (FNZ) binding in any of the regions examined. However, significant increases in levels of [ 3H]FNZ binding were found in the nucleus accumbens and ventral pallidum 1 h after single administration of PCP. These results suggest that BZD binding sites may not play important roles in the development of PCP-induced sensitization at several sites of GABA A/BZD receptor complex, while changes in GABA function in the nucleus accumbens differ from other areas following single administration of N-methyl- d-aspartate (NMDA) antagonist.

Development and validation of a gas chromatography–mass spectrometry method for the simultaneous determination of buprenorphine, flunitrazepam and their metabolites in rat plasma: application to the pharmacokinetic study

Buprenorphine (BUP), a synthetic opioid analgesic, is frequently abused alone, and in association with benzodiazepines. Fatalities involving buprenorphine alone seem very unusual while its association with benzodiazepines, such as flunitrazepam (FNZ), has been reported to result in severe respiratory depression and death. The quantitative relationship between these drugs remain, however, uncertain. Our objective was to develop an analytical method that could be used as a means to study and explore, in animals, the toxicity and pharmacological interaction mechanisms between buprenorphine, flunitrazepam and their active metabolites. A procedure based on gas chromatography–mass spectrometry (GC–MS) is described for the simultaneous analysis of buprenorphine, norbuprenorphine (NBUP), flunitrazepam, N-desmethylflunitrazepam ( N-DMFNZ) and 7-aminoflunitrazepam (7-AFNZ) in rat plasma. The method was set up and adapted for the analysis of small plasma samples taken from rats. Plasma samples were extracted by liquid–liquid extraction using Toxi-tubes A. Extracted compounds were derivatized with N, O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA), using trimethylchlorosilane (TMCS) as a catalyst. They were then separated by GC on a crosslinked 5% phenyl-methylpolysiloxane analytical column and determined by a quadrupole mass spectrometer detector operated under selected ion monitoring mode. Excellent linearity was found between 0.125 and 25 ng/μl plasma for BUP, 0.125 and 12.5 ng/μl for NBUP and N-DMFNZ, 0.125 and 5 ng/μl for FNZ, and between 0.025 and 50 ng/μl for 7-AFNZ. The limit of quantification was 0.025 ng/μl plasma for 7-AFNZ and 0.125 ng/μl for the four other compounds. A good reproducibility (intra-assay CV=0.32–11.69%; inter-assay CV=0.63–9.55%) and accuracy (intra-assay error=2.58–12.73%; inter-assay error=0.83–11.07%) were attained. Recoveries were 71, 67 and 81%, for BUP, FNZ and N-DMFNZ, respectively, and 51% for NBUP and 7-AFNZ, with CV ranging from 5.4 to 13.9%, and were concentration-independent. The GC–MS method was successfully applied to the pharmacokinetic study of BUP, NBUP, FNZ, DMFNZ and 7-AFNZ in rats, after administration of BUP and FNZ.

Development and validation of a gas chromatography?mass spectrometry method for the simultaneous determination of buprenorphine, flunitrazepam and their metabolites in rat plasma: application to the pharmacokinetic study

Buprenorphine (BUP), a synthetic opioid analgesic, is frequently abused alone, and in association with benzodiazepines. Fatalities involving buprenorphine alone seem very unusual while its association with benzodiazepines, such as flunitrazepam (FNZ), has been reported to result in severe respiratory depression and death. The quantitative relationship between these drugs remain, however, uncertain. Our objective was to develop an analytical method that could be used as a means to study and explore, in animals, the toxicity and pharmacological interaction mechanisms between buprenorphine, flunitrazepam and their active metabolites. A procedure based on gas chromatography–mass spectrometry (GC–MS) is described for the simultaneous analysis of buprenorphine, norbuprenorphine (NBUP), flunitrazepam, N-desmethylflunitrazepam (N-DMFNZ) and 7-aminoflunitrazepam (7-AFNZ) in rat plasma. The method was set up and adapted for the analysis of small plasma samples taken from rats. Plasma samples were extracted by liquid–liquid extraction using Toxi-tubes A. Extracted compounds were derivatized with N,O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA), using trimethylchlorosilane (TMCS) as a catalyst. They were then separated by GC on a crosslinked 5% phenyl-methylpolysiloxane analytical column and determined by a quadrupole mass spectrometer detector operated under selected ion monitoring mode. Excellent linearity was found between 0.125 and 25 ng/μl plasma for BUP, 0.125 and 12.5 ng/μl for NBUP and N-DMFNZ, 0.125 and 5 ng/μl for FNZ, and between 0.025 and 50 ng/μl for 7-AFNZ. The limit of quantification was 0.025 ng/μl plasma for 7-AFNZ and 0.125 ng/μl for the four other compounds. A good reproducibility (intra-assay CV=0.32–11.69%; inter-assay CV=0.63–9.55%) and accuracy (intra-assay error=2.58–12.73%; inter-assay error=0.83–11.07%) were attained. Recoveries were 71, 67 and 81%, for BUP, FNZ and N-DMFNZ, respectively, and 51% for NBUP and 7-AFNZ, with CV ranging from 5.4 to 13.9%, and were concentration-independent. The GC–MS method was successfully applied to the pharmacokinetic study of BUP, NBUP, FNZ, DMFNZ and 7-AFNZ in rats, after administration of BUP and FNZ.

Nadph-Cytochrome P-450 Reductase is Involved in Flunitrazepam Reductive Metabolism in Hep G2 and Hep 3b Cells

Flunitrazepam (FNTZ), like other benzodiazepines, has a high affinity for the benzodiazepine receptor within the gama-aminobutyric acid (GABA) complex. These affinities correlate with the pharmacological and therapeutic potencies of the drug. FNTZ is a drug commonly abused by young adults. In humans, FNTZ is oxidized to the major metabolites N-demethylfluni-trazepam (DM FNTZ) and 3-hydroxyflunitrazepam (3-OH FNTZ) and reduced to 7-aminofluni-trazepam (7A FNTZ). Human CYP2C19 and CYP3A4 are the principal P-450 cytochromes involved in DM FNTZ and 3-OH FNTZ formation. However, it is not clear which enzyme is responsible for the reduction of FNTZ to 7-aminoflunitrazepam (7A FNTZ). In this study, the involvement of NADPH-cytochrome P-450 reductase in the conversion of FNTZ to 7A FNTZ was investigated in two human hepatoma cell lines, human lymphoblast microsomes specifically expressing human NADPH-cytochrome P-450 reductase and purified recombinant human HADPH-cytochrome P-450 reductase. Significantly more FNTZ was converted to 7A FNTZ in Hep G2 than in Hep 3B cells, and this difference was associated with the catalytic activity and protein levels of NADPH-cytochrome P-450 reductase in these cells. In Hep G2 cells, conversion of FNTZ to 7A FNTZ was effectively inhibited by α-lipoic acid, an NADPH-cytochrome P-450 reductase inhibitor. In addition, formation of 7A FNTZ by the microsomal fraction of Hep G2 cells was specifically inhibited by antibody against NADPH-cytochrome P-450 reductase. Under hypoxia (N2 85%; CO2 5%; H2 10%), human lymphoblast microsomes specifically expressing human NADPH-cytochrome P-450 reductase and purified recombinant human NADPH-P-450 reductase catabolized FNTZ to 7A FNTZ in a concentration-dependent manner. These results suggest that NADPH-cytochrome P-450 reductase is involved in the reductive metabolism of FNTZ to 7A FNTZ under hypoxic conditions.

Modafinil prevents the MPTP-induced increase in GABA A receptor binding in the internal globus pallidus of MPTP-treated common marmosets

The psychostimulant drug modafinil induces a reversal of motor deficits in MPTP treated primates and prevents MPTP toxicity to substantia nigra but its mechanism of action is not clear. In common marmosets acutely treated with MPTP in the presence or absence of modafinil, we have studied changes in GABA A receptor binding in the basal ganglia. MPTP treatment had no effect on [ 3H]-flunitrazepam (FNZ) binding density in the striatum or external globus pallidus (GPe) but increased [ 3H]-FNZ binding density in the internal globus pallidus (GPi). Administration of modafinil (10–100 mg/kg) with MPTP did not alter [ 3H]-FNZ binding density in the striatum or GPe. Low doses of modafinil (10 and 30 mg/kg) had no effect on the increased [ 3H]-FNZ binding density in the GPi but high dose modafinil (100 mg/kg) significantly decreased [ 3H]-FNZ binding density in GPi. These findings suggest that modafinil can selectively alter GABA binding density in the GPi either by preventing MPTP-induced toxicity or through an action on striatal output pathway related to its antiparkinsonian activity and its ability to inhibit MPTP toxicity.

The importance of a urine sample in persons intoxicated with flunitrazepam-legal issues in a forensic psychiatric case study of a serial murderer

The sedative–hypnotic benzodiazepine flunitrazepam (FZ) is abused worldwide. The purpose of our study was to investigate violence and anterograde amnesia following intoxication with FZ, and how this was legally evaluated in forensic psychiatric investigations with the objective of drawing some conclusions about the importance of urine sample in a case of a suspected intoxication with FZ. The case was a 23-year-old male university student who, intoxicated with FZ (and possibly with other substances such as diazepam, amphetamines or cannabis), first stabbed an acquaintance and, 2 years later, two friends to death. The police investigation files, including video-typed interviews, the forensic psychiatric files, and also results from the forensic autopsy of the victims, were compared with the information obtained from the case. Only partial recovery from anterograde amnesia was shown during a period of several months. Some important new information is contained in this case report: a forensic analysis of blood sample instead of a urine sample, might lead to confusion during police investigation and forensic psychiatric assessment (FPA) of an FZ abuser, and in consequence wrong legal decisions. FZ, alone or combined with other substances, induces severe violence and is followed by anterograde amnesia. All cases of bizarre, unexpected aggression followed by anterograde amnesia should be assessed for abuse of FZ. A urine sample is needed in case of suspected FZ intoxication. The police need to be more aware of these issues, and they must recognise that they play a crucial role in an assessment procedure. Declaring FZ an illegal drug is strongly recommended.

Flunitrazepam-induced changes in neurophysiological, behavioural, and subjective measures used to assess sedation

Introduction: Certain features of event-related potentials (ERPs), electroencephalographic (EEG), and behavioural measures vary with differing states of alertness and/or sedation. Purpose: This study was conducted to investigate changes in several measures usually viewed as reflecting states of sedation/sleepiness associated with the use of a range of doses of the hypnotic benzodiazepine (BZD) flunitrazepam (FNZ). Methods: This was a double blind, independent group design study of the effects of acute oral doses of FNZ in young healthy volunteers. Forty-eight subjects were randomly allocated to one of four groups—FNZ (0.6, 0.8, and 1.0 mg) and placebo (PLAC)—and tested prior to treatment and then in a posttreatment session close to the theoretical peak plasma concentration. ERP latencies and amplitudes were measured at midfrontal (Fz), midcentral (Cz), and midparietal (Pz) using a standard auditory oddball paradigm. EEG changes were assessed at Pz. Behavioural measures included the digit–symbol substitution test (DSST), a cancellation task (CT), and subjective ratings of alertness and attentiveness by the subjects (SUB) and the experimenter (EXP). Results: FNZ led to psychomotor impairments and decreased alertness and attention; these effects were consistent with previous findings. A progressive, dose-related increase in P3 latency occurred in Fz, Cz, and Pz, and there was an increase in N1 (Fz, Cz) and N2 (Fz). N2–P3 amplitude decreased in Fz. EEG power bands beta 1 increased for the two highest doses, but no significant differences were noted in theta, delta, and alpha bands. P3 latencies, experimenter-rated levels of alertness, and DSST scores differentiated all three doses of FNZ from PLAC. Conclusion: The most sensitive measures used were P3 latencies of the ERPs (which varied with FNZ dose), DSST, and the experimenter-rated levels of alertness. However, we found no evidence for the assumption that one single phenomenon was reflected in all measures and different mechanisms were probably involved. Further experiments will be needed for more in-depth probing of the finer mechanisms underlying sedation/sleepiness and how they affect behavioural and eletrophysiological measures of the central nervous system (CNS) function.

Simultaneous determination of flunitrazepam and 7-aminoflunitrazepam in human serum by ion trap gas chromatography–tandem mass spectrometry

A method for the determination of flunitrazepam (FNZ) and 7-aminoflunitrazepam (7-AFNZ) in human serum was developed with ion trap gas chromatography (GC)–tandem mass spectrometry. The 7-AFNZ was derivatizated with 50 μl trifluoroacetic anhydride (TFAA), 60°C-20 min. EI mass spectra and tandem mass spectra of FNZ and 7-AFNZ-TFA were m/z 238, 239, 266, 286, 294, 312, 313(M +), m/z 350, 351, 360, 378, 379(M +), m/z 238, 239, 240 (precursor ion m/z 286, collision energy 1.5 V), and m/z 239, 254, 264, 336 (precursor ion m/z 351, collision energy 1.8 V), respectively. The detection limits of full scan EI mass spectrometry and tandem mass spectrometry for FNZ and 7-AFNZ in human serum were ca. 200 ng/ml, 60 ng/ml, 15 ng/ml and 1 ng/ml, respectively.

19F NMR spectrometric determination of the partition coefficients of some fluorinated psychotropic drugs between phosphatidylcholine bilayer vesicles and water

A simple 19F NMR spectrometric method was proposed for the determination of the partition coefficients of fluorinated psychotropic drugs, trifluoperazine (TFPZ), flunitrazepam (FNZ) and flurazepam (FZ) between phosphatidylcholine (PC) bilayer of small unilamellar vesicles (SUVs) and water (buffer). Each 19F NMR spectrum of these drugs in the presence of PC SUV showed a single signal accompanying a PC concentration-depending shift change and broadening, which indicated a fast exchange of these drugs between the water phase and the PC bilayer of SUV. From the relationship between the 19F chemical shift change (Δ δ) of each drug and the PC concentration, the molar partition coefficients ( K p's) were calculated and obtained with a good precision of RSD below 6%. The fractions of the partitioned drugs calculated by using the obtained K p-values were in a good agreement with the experimental values. The results demonstrate that the 19F NMR method can be usefully applied to the determination of partition coefficients of many drugs having fluorine atom(s) without any separation procedure, especially for drugs which do not have absorption in the ultraviolet or visible region, or those having absorption but show insignificant spectral changes according to their incorporation to PC bilayers (e.g. FNZ).

The Behavioral and Cognitive Effects of Two Benzodiazepines Associated with Drug-Facilitated Sexual Assault

Recently, sexual assaults have included the use of benzodiazepines to impair the victim. Our aim was to examine the physiological, cognitive, and behavioral effects of flunitrazepam (FN) and clonazepam (CLO). In the first study, ten healthy volunteers received a single oral dose of 2 mg of FN. Mini Mental State Examination (MMSE), behavioral reports and staff observations were then collected. In the second study, ten healthy volunteers received a single oral dose of 3 mg of CLO. Vital signs, performance on the MMSE and Digit Symbol Substitution Test, and behavioral changes were examined. FN significantly decreased systolic and diastolic blood pressure 4 h post drug ingestion with diastolic remaining low at 6 h. CLO was associated with changes in temperature and decreased systolic pressure. FN affected memory and attention 4 h following ingestion. CLO affected memory and attention throughout the study (6 h), and psychomotor performance was decreased 2 h post ingestion. In both studies, subjects were disinhibited and did not perceive their own impairment.

The Contribution of Imperfections in Nursery Stock to the Decline of Young Vines in California

‘Petri disease’, as defined at the 2nd International Workshop on Grapevine Trunk Diseases (Esca and Grapevine Declines, September 14–15 2001, Lisbon, Portugal), is a condition associated worldwide with the decline of young vines contaminated by Phaeoacremonium and/or Phaeomoniella pathogens. Vines exhibit stunted development with vascular tissues characteristically exuding darkened gums when sectioned transversally. ‘Young Vine Decline’ (YVD), historically including the condition now known as Petri disease, is a term still used widely in California to describe unexpectedly poor performance of young vines exhibiting symptoms that include those associated with Petri disease. Examination of more than eight hundred thousand dormant nursery vines as well as new and established declining vineyards demonstrated that nursery stock defects and mechanical and biotic vineyard stresses were frequently associated with YVD in California. Rootstock shaft lesions and weak roots were most commonly associated with YVD in very young vineyards, while root system contamination by nematodes and fungal pathogens was frequently associated with YVD in older vineyards.

Flunitrazepam abuse and personality characteristics in male forensic psychiatric patients

Sixty male non-psychotic forensic psychiatric patients (aged 16–35 years) were studied after they completed their ordinary forensic psychiatric assessment (FPA). The prevalence of flunitrazepam (FZ) abuse was investigated by using both structured and in-depth interviews with the objective of studying the relationship between the abuse and personality traits. The patient's characteristics, DSM-IV disorders, and actual sentences were obtained by studying their files. In order to obtain measures on their personality traits, self-report inventories were administered to the patients. Eighteen out of 60 patients were FZ abusers, but only 4 of them received a diagnosis related to the FZ abuse during the ordinary FPA. In almost all cases, however, indications of the FZ abuse were found in the files. No differences in personality traits were found between the groups. The frequency of previous admissions to an FPA and actual sentences of robbery, weapons offenses, narcotic-related offenses, and other crimes (such as theft) among the FZ abusers deviated significantly from forensic non-FZ abusers. Therefore, the FZ abuse per se might be more responsible for their tendency to commit crimes characterized by danger and thrill-seeking (such as robbery, weapons offences, and theft) than personality. The most important conclusion is that assessment of FZ abuse is needed in forensic psychiatry.

The association between intravenous haloperidol and prolonged QT interval.

Although intravenous haloperidol (HAL) is an effective medication that is often prescribed to treat agitation, several instances of torsade de pointes or prolonged QT interval have been reported. To investigate the association between intravenous HAL and QT prolongation and between intravenous HAL and ventricular tachyarrhythmia, a cross-sectional cohort study was performed that included measuring corrected QT intervals (QTc) on an emergency basis before intravenous HAL and continuously monitoring electrocardiographic (ECG) findings after intravenous HAL. During a 2-month period, 47 patients received intravenous injections to control psychotic disruptive behavior. According to clinical practice, patients were divided as follows. The FZ-alone group was treated with intravenous flunitrazepam (FZ), and the FZ-plus-HAL group received intravenous FZ followed by intravenous HAL. Although the difference in the mean QTc immediately after intravenous FZ between the two groups was not significant, the mean QTc after 8 hours in the FZ-plus-HAL group was longer than that in the FZ-alone group (p < 0.001). Four patients in the FZ-plus-HAL group had a QTc of more than 500 msec after 8 hours. The change in QTc during 8 hours significantly differed between the two groups (t = 2.64, p > 0.05). Furthermore, the change in QTc was moderately correlated with the dose of intravenous HAL, as evidenced by a coefficient of correlation of 0.48 (p < 0.001). However, ventricular tachyarrhythmia was not detected among 307 patients within a 1-year period, although the ECG was continuously monitored for at least 8 hours after intravenous HAL. The modest nature of QTc prolongation and the apparent absence of ventricular tachyarrhythmia under continuous ECG monitoring indicate that QTc prolongation associated with intravenous HAL is not necessarily dangerous. However, in an emergency situation, clinicians cannot exclude patients predisposed to torsade de pointes, such as those with inherited ion channel disorders. Therefore, clinicians should be aware of the association between intravenous HAL and QT prolongation.

Differential sensitivity to the anxiolytic effects of ethanol and flunitrazepam in PKCγ null mutant mice

Tests of ethanol effects in PKCγ null mutant mice have indicated that PKCγ plays a role in initial sensitivity to ethanol-induced sedation, hypothermia, and GABA A receptor function and impacts neurochemical pathways mediating anxiety. The present study was undertaken to evaluate whether the decreased sensitivity to ethanol previously observed in these mice generalized to the anxiolytic effects of ethanol. PKCγ null mutant mice and wild-type controls were tested in the elevated-plus maze, the black/white box, and the mirrored chamber after ethanol (0, 1.0, 1.25, 1.5 g/kg) or flunitrazepam (FNZ) (0, 0.015, 0.03, 0.06 mg/kg). Results indicated that although both genotypes exhibited anxiolytic responses to ethanol in the elevated plus-maze, null mutant mice were less sensitive than wild-type control mice; however, in the black/white box, PKCγ null mutants were more sensitive than controls to the anxiolytic effects of FNZ. Neither ethanol nor FNZ produced anxiolytic responses in the mirrored chamber for either genotype. These results suggest that PKCγ differentially mediates anxiolytic responses to ethanol and FNZ and that this relationship interacts with each drug's efficacy in reducing anxiety-related behaviors specific to each of the three mazes.

Flunitrazepam, a 7-nitro-1,4-benzodiazepine that is unable to bind to the indole-benzodiazepine site of human serum albumin

Benzodiazepine (BDZ) is generally thought to bind to site II of human serum albumin (HSA), also known as the indole-BDZ site, which is located at subdomain III A of the molecule. However, differences in the binding characteristics of BDZ drugs with HSA have been reported. The photolabeling profiles of HSA with [ 3H]flunitrazepam (FNZP) in the presence and absence of diazepam (DZP) were shown to be identical, suggesting that each drug primarily binds to different regions. The results of fluorescent probe displacement experiments showed that FNZP failed to decrease the fluorescence of dansylsarcosine to an extent similar to that of DZP. In the photoinhibition experiment, site I and site II ligands failed to inhibit the photoincorporation of [ 3H]FNZP to HSA. In order to evaluate the photolabeling specificity of FNZP, an attempt was made to photolabel α 1-acid glycoprotein (AGP) which also binds BDZ with similar affinity as HSA. The effect of myristate (MYR) and DZP on the FNZP photolabeling of these two major drug binding plasma proteins was examined. Photoincorporation was inhibited when HSA was photolabeled with [ 3H]FNZP in the presence of MYR but not in the presence of DZP. Conversely, DZP inhibited the photolabeling of [ 3H]FNZP to AGP. These results suggest that FNZP interacts with HSA at regions which are not located in the preformed binding pocket of subdomain III A.

Flunitrazepam partitioning into natural membranes increases surface curvature and alters cellular morphology

In recent studies, we showed that flunitrazepam (FNTZ) and other benzodiazepines interact with artificial phospholipid membranes locating at the polar head group region, inducing a membrane expansion, reducing the molecular packing and reorganising molecular dipoles. In the present paper we investigated the possibility that those phenomena could be transduced into changes in the curvature of membranes from natural origin. Hence we studied the effect of FNTZ on cellular morphology using human erythrocyte as a natural assay system. Shape changes of erythrocytes were evaluated by light microscopy and expressed as a morphological index (MI). FNTZ induced echinocytosis in a time-dependent manner with MI values significantly higher than those of control (without drug) or DMSO (vehicle) samples. Lidocaine, a local anesthetic known to induce stomatocytosis by incorporating in the inner monolayer, counterbalanced the concentration-dependent FNTZ crenating effects. FNTZ induced protective effects, compared with control and DMSO, against time-dependent hemolysis. Hypotonic-induced hemolysis, was also lowered by FNTZ in a concentration-dependent manner. Both antihemolytic effects suggested a drug-induced membrane expansion allowing a greater increase in cell volume before lysis. In such a complex system like a cell, curvature changes triggered by drug partitioning towards the plasma membrane, might be an indirect effect exerted through modifications of ionic-gradients or by affecting cytoskeleton–membrane linkage. In spite of that, the curvature changes can be interpreted as a mechanism suitable to relieve the tension generated initially by drug incorporation into the bilayer and may be the resultant of the dynamic interactions of many molecular fluxes leading to satisfy the spontaneous membrane curvature.

Flunitrazepam induces geometrical changes at the lipid–water interface

Flunitrazepam (FNTZ) effects on molecular packing and surface curvature in artificial model membranes were investigated. FNTZ, from the subphase under dipalmitoylphosphatidylcholine (dpPC) monolayers at the air–water interface, expanded the surface pressure-area isotherm and induced an increment in the limiting area; in this conditions, the collapse pressure of dpPC decreased, indicating a lowering in the stability of the monolayer. Thermodynamic–geometric correlations based on molecular parameters predicted a decrement in the aggregation number and stability, and an increase in the curvature of the self-aggregated structure of dpPC in aqueous medium in the presence of FNTZ. Accordingly, negative-staining electron microscopy of dpPC aqueous dispersions showed that the mean diameter of dpPC vesicles decreased 2 and 2.87 times in the presence of 10 nM and 50 μM FNTZ, respectively, compared with control samples. The release of a soluble marker entrapped in dpPC liposomes increased slightly respect to the control in the presence of FNTZ. In dpPC–dpPE mixed liposomes 50 μM FNTZ induced a decrement in the amount of the aminophospholipid exposed to the outer monolayer. Concluding, an FNTZ-induced expansion of dpPC–water interface region affected the constraints imposed on the lipid–water system by the molecular geometry, interacting free energies and entropy that determine the shape of a multimolecular structure. In liposomes composed of a pure phospholipid, the bilayer expansion leaded, through a structure instability, to reduce the liposome size; in mixed liposomes, phospholipid molecules translocation could be observed as another compensating mechanism of the initial perturbation. These results may be relevant for understanding benzodiazepines’ effects non-mediated by membrane receptors.

GABA-A Function and Receptor Binding in the Paraventricular Nucleus in Chronic Renal Wrap Hypertension

P48 The onset of renal wrap hypertension is associated with a reduced tonic GABA inhibition in the paraventricular nucleus (PVN) on the sympathetic nervous system. This reduced functional inhibition occurs without a change in GABA-A receptor binding in the PVN. The goal of the present study was to determine if GABAergic transmission and GABA binding is altered in chronic renal wrap hypertensive rats. Sprague-Dawley rats were made hypertensive or sham-operated. Four weeks later, animals were prepared with femoral artery catheters for the measurement of arterial pressure. Subgroups were also prepared with bilateral cannulae directed at the PVN. The renal wrap rats had higher mean arterial pressure (MAP): 139±4 mmHg vs.113±2 mmHg, but heart rate (HR) was not different (354±12 bpm vs. 369±6 bpm) as compared to control animals. Administration of the GABA-A antagonist, bicuculline, into the PVN caused a greater increase in MAP and HR in wrap animals (25±2 mmHg and 150±30 bpm) compared to sham operated rats (16±2 mmHg and 89±12 bpm). GABA-A binding sites in the PVN were estimated using in vivo autoradiography. [3H]-Flunitrazepam was used as the receptor ligand. Magnocellular neurons of the PVN showed a higher density of receptors than other areas of the nucleus. However, the number of binding sites was not different between normotensive and hypertensive rats in either the high density (1825±56 vs. 1756±41 fmol/mg protein) or low density (1454±26 vs. 1433±57 fmol/mg protein) regions of PVN. These data indicate that the inhibition by GABA in the PVN is augmented in the chronic stage of hypertension, and appears to be unrelated to a change in the number of GABA binding sites. The increased GABAergic inhibition is in contrast to the reduced inhibition that has been observed during the onset of hypertension.

Flunitrazepam compared to Nitrazepam and placebo at alcoholics

Flunitrazepam compared to Nitrazepam and placebo at alcoholics

The Influence of Valerian Treatment on 'Reaction Time, Alertness and Concentration' in Volunteers

A randomised, controlled, double-blind trial was performed on 102 male and female volunteers to determine whether reaction time, alertness and concentration might be impaired by treatment with a native valerian root extract (VRE). The effect was first examined the morning after a single evening dose of VRE (600 mg LI 156) vs. flunitrazepam (FNZ) (1 mg) and placebo (PL) (trial section A), and then after two weeks of evening administration of VRE (600 mg LI 156) vs. PL (trial section B). 99 volunteers were analysed in section A and 91 in section B. The primary criterion was the median of reaction time (MRT) measured with the Vienna Determination Test. Secondary criteria were cognitrones (alertness test), tracking test (two-handed co-ordination), sleep quality (VIS-A, Vis-M), further VDT parameters, and safety criteria. The single administration of LI 156 did not impair the reaction abilities, concentration and co-ordination. After 14 days of treatment, the equivalence of VRE and PL was proven by confirmative analysis concerning the improvement of MRT (p = 0.4481). Evaluation of the secondary criteria were consistent with the results of the primary criterion. It is concluded that neither single nor repeated evening administrations of 600 mg of VRE have a relevant negative impact on reaction time, alertness and concentration the morning after intake.