Amnesic action of and skills related to driving after intravenous flunitrazepam

Mnestic disorders in long-term high-dose diazepam abuse: a pilot study

Cognitive impairment in long-term high-dose diazepam abusers (dose > 30 mg diazepam/day; duration of abuse > 12 months) was examined by administering four memory-related tests and comparing the outcomes with those of matched controls. Deficits were found in spatial and visual learning, spatial and visual short-term memory (STM) as well as for spatial and visual long-term memory (LTM). As for verbal aspects of memory, solely the acquisition of novel verbal material (verbal learning) was impaired, Furthermore, deficits in a concentration task were observed. In chronic abuse the established memory deficits are similar to cognitive impairment after single doses. Relaxing or anxiety-reducing effects of diazepam were no longer present. The results of this experimental study demonstrate the risks of diazepam use beyond therapeutic range.

Characterization of Escherichia coli nitroreductase NfsB in the metabolism of nitrobenzodiazepines

Nitrobenzodiazepine (NBDZ) is a sedative-hypnotic drug used in the treatment of anxiety and sleep problems. Overdose of NBDZ may cause severe neurological effects, especially for people in drug abuse or addiction. In the present study, we investigated NBDZ nitroreduction in rat enteric contents and characterized the role of enterobacterial nitroreductase in the reductive pathway. Nitroreduction of flunitrazepam (FZ) was studied in the microsomal membrane fractions of rat liver, jejunum and jejunal microflora using HPLC analysis. In the jejunal microflora, FZ was demonstrated to be significantly reduced to its amino derivative under anaerobic condition. Escherichia coli type I nitroreductase NfsB (EC 1.5.1.34) was found in rat jejunal microflora via PCR technique and Western blotting. The participation of NfsB in FZ nitroreduction was demonstrated from inhibition studies. Kinetic study of the purified recombinant NfsB indicated that nitroreduction of FZ, nitrazepam (NZ) and clonazepam (CZ) are mediated by NfsB, where CZ shows lower k(cat)/K(M) ratio than that of the other two. Finally, two other nitroreductases E. cloacae NR (EC 1.6.99.7) and S. typhimurium Cnr were also found to be responsible for FZ nitroreduction. These results provide that the reduction of NBDZ in normal flora is catalyzed by type I nitroreductase NfsB.

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-demethylflunitrazepam (DM FNTZ) and 3-hydroxyflunitrazepam (3-OH FNTZ) and reduced to 7-aminoflunitrazepam (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 alpha-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.

General anesthesia does not impair simulator driving skills in volunteers in the immediate recovery period - a pilot study

PURPOSE

The current recommendations to refrain from driving for 24 hr after general anesthesia (GA) lack evidence. Our objective was to measure impairment of driving performance at various time intervals after anesthesia using driving impairment at different blood alcohol concentrations (BAC) as a gold standard for comparison.

METHODS

Institutional Review Board approval was obtained. A cross-over design, within subject comparison was used. Twelve volunteers were randomized to three treatments: GA, alcohol, and no drug. Psychomotor recovery was assessed by Digit Symbol Substitution Test (DSST) and Trieger Dot Test (TDT). On the anesthetic day, GA was induced with propofol 2.5 mg x kg(-1) and fentanyl l micro g x kg(-1) and maintained with N(2)O-O(2) 50:50 and approximately one minimum alveolar concentration of desflurane by spontaneous ventilation for 30 min. Driving simulator test runs occurred at two, three, four, and 24 hr postanesthesia. On the alcohol treatment day, a vodka and orange juice beverage was administered to reach the legal limit for BAC in the province of Ontario, Canada (BAC 0.08%). On the control day, no drug was given. Driving simulator test runs corresponded to the same time of day as the postanesthetic test runs. Two-way analysis of variance for dependent samples (ANOVA) was performed using the SAS program. P values of less than 0.05 were considered significant.

RESULTS

There was no significant difference in postanesthetic driving skills at two, three, and four hours postanesthesia, and the corresponding control sessions. There was no significant difference among the three sessions with respect to pen and paper tests of psychomotor performance. Performance during the alcohol session differed significantly from that during the control and postanesthetic sessions.

CONCLUSION

Certain driving skills return by two hours after one half hour of GA of propofol, desflurane, and fentanyl in a group of young volunteers.

Abuse liability of flunitrazepam

Flunitrazepam is among the most frequently prescribed hypnotics in many countries. Although it was never marketed in the United States, flunitrazepam, in recent years, has been smuggled into the country, and reports of abuse--including alleged use of the drug to facilitate "date rape"--have attracted a great deal of scrutiny. It has been suggested that flunitrazepam may have greater liability for abuse than other benzodiazepines; such suggestions are supported by surveys of opioid abusers, many of whom report a distinct preference for flunitrazepam over other benzodiazepines. Experimental studies of animals and normal human subjects indicate that, although flunitrazepam has high efficacy and is very potent, it is pharmacologically similar to most other benzodiazepines. Although the studies are limited in number and scope, the data show no apparent differences between flunitrazepam and other benzodiazepines in ability to produce drug-taking or drug-seeking behavior, in capacity to produce physiologic dependence, nor in the characteristics of withdrawal after administration of an antagonist or discontinuation of treatment. Similar to other benzodiazepines, flunitrazepam produces dose-dependent effects on psychomotor performance and recall. Flunitrazepam does not seem to be involved in medical emergencies more often than other benzodiazepines, and there is no indication that flunitrazepam is more toxic than other benzodiazepines when taken in overdose by drug abusers or other individuals. Survey research among typical patient populations suggests that flunitrazepam is characteristic of benzodiazepines in that it is used appropriately and conservatively, with low liability for abuse. Thus the reported preference for flunitrazepam among opioid abusers seems to be the only way in which flunitrazepam is distinguished from other benzodiazepines; it is unclear what characteristics of the drug may be responsible for this reported preference. The evidence considered in this review indicates that abuse of flunitrazepam in this special population is not associated with any distinctive threats to the health of the general public.

Clinical relevance of effects of benzodiazepines on learning and memory

The effects of benzodiazepines on learning and memory are examined in the various clinical situations in which these drugs are used. Alterations in performance arising from the conditions for which benzodiazepines are prescribed are also considered. Current evidence indicates that, in anxious patients, as in normal volunteers, benzodiazepines impair the acquisition of new information (episodic memory). Although some tolerance may develop to these impairments, deficits are observed even after patients have been taking their medication chronically. Like amnesic patients, benzodiazepine-treated subjects may be unaware of their impaired ability to learn. The effects of the impairments on behavioral psychotherapies are considered.

Tranquillising memories: a review of the effects of benzodiazepines on human memory

Studies from 1973 to 1985 of the effects of benzodiazepines on memory are summarised and reviewed. Anterograde amnesia appears a common effect of all benzodiazepines although its onset and duration vary with the particular benzodiazepine, its dose and route of administration. Memory impairments increase with task difficulty. There is some evidence that partial tolerance to amnesic effects develops with repeated doses of diazepam, but research with other benzodiazepines is inconclusive. Amnesia is in part a by-product of the sedative action of benzodiazepines, although these drugs may also have a specific effect of disrupting the consolidation of information in long-term memory. State-dependent effects are partial and relatively small. Methodological problems are discussed and attention is drawn to the lack of repeated dose studies, of studies with patient populations and with anxious volunteers.

Intravenous benzodiazepines as anaesthetic agents: pharmacokinetics and clinical consequences

Despite extensive and numerous pharmacokinetic studies on benzodiazepines, the published pharmacokinetic data do not adequately explain the clinical differences found between different benzodiazepine derivatives after intravenous administration. Especially, correlations between initial drug responses and distributional changes of the benzodiazepines are limited. However, during the elimination phase some relationships exist between the kinetic and dynamic phenomena. Age, sex, diseases and concomitantly given drugs cause clinically important alterations in the pharmacokinetics of benzodiazepines. Generally these anxiolytics and sedatives should be considered as adjuvants to general anaesthesia, but not primarily as routine induction agents. The major reasons for this limitation are a high variability in drug response, a relatively slow onset of action and long-lasting residual effects. However, benzodiazepines have many important advantages (see Table 5) when used as intravenous inducing agents of general anaesthesia.

Efficacy and side effects of flunitrazepam and pentobarbital in severely insomniac patients

One hundred thirty-seven current or prospective recipients of hypnotics were screened to obtain a sample of 12 severely insomniac patients for a study concerning efficacy and side effects of 2 mg flunitrazepam and 100 mg pentobarbital as hypnotics. During the baseline period, these 12 subjects showed wide intraindividual variability of sleep and performance. This variability was not reduced by the hypnotics, which on the average did not adversely affect performance. Flunitrazepam, but not pentobarbital, slightly reduced sleep latency. Neither hypnotic prolonged sleep duration or reduced the number of wakings. The generalizability of the results to the population of recipients of hypnotics is discussed.

Effects of alcohol and flunitrazepam on mood and performance in healthy young men

Alcohol and flunitrazepam did not have any pharmacokinetic interactions when ingested 30 minutes apart at night. Flunitrazepam, 2.0 mg, but not 0.8 Gm/kg alcohol had a strong deleterious effect on performance shortly after ingestion. The combination of flunitrazepam and alcohol impaired tracking in a divided attention task the following morning.

Flunitrazepam: a review of its pharmacological properties and therapeutic use

Flunitrazepam is a benzodiazepine derivative whose hypnotic effect predominates over the sedative, anxiolytic, muscle-relaxing and anticonvulsant effects characteristic of benzodiazepines. Thus, it is used as a night-time hypnotic and in anaesthesiology: due to the pronounced hypnotic effect it is not appropriate as a daytime sedative. As a hypnotic for insomnia its effect is usually characterised by a very fast onset of action and quiet sleep without interruptions. On the morning after a hypnotic dose some residual psychomotor impairment does occur, which is comparable to that with usual doses of nitrazepam or flurazepam, but clinically apparent 'hangover' occurs infrequently. There is no pronounced cumulative effect with chronic use. In anaesthesiology it has proven to be useful as a hypnotic on the night before operation, as an oral, intramuscular or intravenous premedication, in induction and as a supplement to other anaesthetics. Its sedative and amnesic properties can also be beneficial in intensive care patients. Much of the usefulness of flunitrazepam in anaesthesia relates to its synergistic effect with other anaesthetics, to its effective amnesic action and its acceptable effects on circulation and respiration. Possible drawbacks include a somewhat unusual course of induction (when used for this purpose) and an often prolonged recovery. Although the safe dosage range is wide with flunitrazepam, its effective application both as a hypnotic for insomnia and in anaesthesiology is dependent upon use of the optimal dosage, and adequate knowledge of its pharmacokinetic properties.

Venous complications after intravenous injection of diazepam, flunitrazepam, thiopentone and etomidate

The occurrence of phlebitis, thrombosis, and thrombophlebitis after intravenous premedication with diazepam (0.15 mg/kg) dissolved in propylene glycol (Valium) or in polyethylene glycol (Diapam) or flunitrazepam (0.0125 mg/kg), and after intravenous induction of balanced general anaesthesia with thiopentone (4.0 mg/kg) or etomidate (0.3 mg/kg) was studied on the 7th and 14th postoperative days in 115 patients undergoing short-stay varicose vein surgery. Venous complications occurred most frequently after etomidate (43% at 14 days), thiopentone (23% at 14 days), and Valium (21% at 7 days). Diapam caused fewer venous sequelae (9% at 14 days) than Valium (18% at 14 days), but the smallest number of complications were noticed after flunitrazepam (8% at 7 days and none at 14 days). Venous sequelae were more severe and more extended after thiopentone and after etomidate than those after the diazepam preparations. It is concluded that venous complications after flunitrazepam premedication were mild and infrequent and that the incidence of such complications was unacceptably high after etomidate induction.

Flunitrazepam versus placebo premedication for minor surgery

The clinical effects of oral flunitrazepam (2 mg on the night before operation followed by 2 mg on the morning of operation) and placebo as premedicants were tested in a double-blind study in 81 gynaecological patients. The separate or total concentrations of flunitrazepam and its demethylated metabolite in plasma (measured by gas chromatography) were correlated with the clinical effects of flunitrapam premedication, assessed both sugjectively and objectively. In most parameters tested (sleep on the night before operation, sedation, apprehension, headache, pulse rate), there was a positive, significant difference between the flunitrazepam group (n = 44) and the placebo group (n = 37). No significant difference was found between the two groups in emetic effect, excitement, systolic blood pressure increase, and vene-puncture, but the patients receiving flunitrazepam felt significantly more dizziness. The temperature of the left forefinger before, during and after the anaesthesia did not vary significantly between the two groups. There was no correlation between the plasma concentration of flunitrazepam and its demethylated metabolite (separate or total concentrations) and any of the parameters tested before induction of anaesthesia. Flunitrazepam is a new oral premedicant with prominent sedative and anxiolytic actions. When the drug is given as a sedative on the night before operation, followed by a second dose on the morning of operation, the beneficial effects last for at least 8 hours after the second dose.

Lack of impairment in skills related to driving after intramuscular administration of prilocaine or mepivacaine

A saline placebo, 3 mg/kg of 2% plain prilocaine, and 3 mg/kg of 2% plain mepivacaine were injected into the deltoid muscles of 10 healthy subjects in a doubleblind, cross-over trial. Before and at 0.5, 1.5 and 3 h after injection, psychomotor skills related to driving were measured. When compared to the saline placebo, neither prilocaine nor mepivacaine impaired the parameters of psychomotor function measured. Blood concentrations of prilocaine were significantly (P less than 0.001) lower than those of mepivacaine during the whole observation period. It was concluded that in comparison to lidocaine, bupivacaine, or etidocaine, which have been tested previously and found to impair psychomotor performance, mepivacaine and, especially, prilocaine are the anaesthetic agents to be preferred when effects on central nervous system should be avoided, e.g. in outpatient practice.

Residual effects and skills related to driving after a single oral administration of diazepam, medazepam or lorazepam

Psychomotor skills and visual functions related to driving were measured double-blind cross-over in ten healthy volunteers before, and 1,3,5 and 7 h after a single oral administration of diazepam (10mg), medazepam (15 mg) or lorazepam (2.5 mg). The late effects of lorazepam were tested in seven other subjects 12 and 24 h after the administration. Lorazepam impaired almost all the measured skills more (P less than 0.05 to 0.001) than diazepam, medizepam or the placebo. The lorazepam impairment of reactive skills and flicker fusion discrimination remained statistically significant (P less than 0.05) for as long as 12 h. Medazepam impaired only reactive skills and flicker fusion, the latter remaining impaired (P less than 0.05) for as long a 5 h after the administration. The magnitude and duration of the effects of diazepam were intermediate between those of lorazepam and medazepam. Diazepam impaired perceptual speed and reactive and co-ordinative skills as well as flicker fusion discrimination and visual parameters related to driving. Slight impairments in performance were measurable for up to 5 h after administration but at 7 h the results resembled those measured after the placebo. The lack of alterations in adaptation to darkness, sensitivity to brightness or visual discrimination ability in bright counterlight at a time when flicker fusion discrimination was severely depressed suggests that an impaired ability to discriminate flickering light is of no or little clinical significance to driving ability. It is concluded that patients receiving a 2.5 mg dose of lorazepam should not drive or operate machinery for 24 h after the administration. After diazepam (10 mg) or medazepam (15 mg) patients should refrain from driving or participating inskilled performances for only 5 to 7 hours.