Selective antagonism of the ataxic effects of zolpidem and triazolam by the GABAA/alpha1-preferring antagonist beta-CCt in squirrel monkeys

RATIONALE

Delineation of the receptor mechanisms underlying the behavioral effects of benzodiazepines should allow for the development of drugs with improved clinical utility and reduced side effects. OBJECTIVES. The purpose of the present study was to investigate the role of GABAA/alpha1 receptors in the sedative and motor-impairing effects of benzodiazepines.

METHODS

Squirrel monkeys were tested with the GABAA/alpha1-preferring agonist zolpidem and the nonselective benzodiazepine agonist triazolam alone and in combination with the GABAA/alpha1-preferring antagonist beta-CCt and the nonselective benzodiazepine antagonist flumazenil. During 30-min experimental sessions, all occurrences of normal behaviors like locomotion, environment- and self-directed behaviors, as well as side effects such as ataxia, rest and procumbent postures were scored.

RESULTS

Zolpidem and triazolam produced dose-dependent reductions in locomotion and environment-directed behavior and increased ataxia and procumbent posture. Triazolam, but not zolpidem, also engendered species-typical rest posture at some doses. Flumazenil antagonized all of the behavioral effects of zolpidem and triazolam, whereas beta-CCt antagonized only zolpidem- and triazolam-induced ataxia.

CONCLUSIONS

GABAA/alpha1 receptor mechanisms appear to play a key role in the ataxic effects of benzodiazepine agonists in squirrel monkeys, similar to recent results with transgenic mice. In contrast to the findings of these recent studies, GABAA mechanisms other than or in addition to those mediated at the alpha1 subunit may play a more important role in the sedative/hypnotic effects of benzodiazepines in squirrel monkeys.

Mechanisms influencing acquisition and recall of motor memories

An internal model of the dynamics of a tool or an object is part of the motor memory acquired when learning to use the tool or to manipulate the object. Changes in synaptic efficacy may underlie acquisition and storage of memories. Here we studied the effect of pharmacological agents that interfere with synaptic plasticity on acquisition of new motor memories and on recall of a previously learned internal model. Forty-nine subjects, divided into six groups, made reaching movements while holding a robotic arm that applied forces to the hand. On day 1, all subjects learned to move in force field A. On day 2, each group of subjects was tested on their ability to recall field A and their ability to learn a new internal model in field B. Four groups participated in the experiments of day 2 under the effects of lorazepam (LZ; a GABA type A receptor-positive allosteric modulator), dextromethorphan [DM; an N-methyl-D-aspartate (NMDA) receptor blocker], lamotrigine (LG, a drug that blocks voltage-gated Na(+) and Ca(2+) channel), or scopolamine (SP; muscarinic receptor antagonist). Two control groups were tested in a drug-free condition: one group that was not exposed to additional experimental protocols (NP) and another group was tested under ~24 h of sleep deprivation between completion of learning on day 1 and start of testing on day 2 (SD). Recall of field A was normal in all groups. Learning of field B was reduced by LZ and DM but not by SP, LG, SD or in the NP condition. These results suggest that a 24-h sleep-deprivation period may have little or no effect on consolidation of this motor memory and that NMDA receptor activation and GABAergic inhibition are mechanisms operating in the acquisition but not recall of new motor memories in humans.

Continuous infusion of midazolam in the treatment of refractory generalized convulsive status epilepticus

We studied the efficacy and safety of midazolam given as a continuous infusion in the treatment of refractory generalized convulsive status epilepticus (RGCSE). We carried out a prospective, open study, in 19 patients (11 men) with RGCSE in the intensive care unit at Firat Medical Center in Elazig. When intravenous administration of 0.3 mg/kg diazepam (three times at 5-min intervals), 20 mg/kg phenytoin, and 20 mg/kg phenobarbital failed to bring the episode under control, patients were administered an intravenous bolus of midazolam (200 microg/kg) followed by a continuous infusion at 1 microg/kg min. The dose was increased by 1 microg/kg min every 15 min until the episode of seizure was brought under control. The time from beginning of treatment to control of seizures, infusion rate, and side-effects were monitored. The mean age of the patients was 40.4 years (range 16-87 years). The clinical etiology of RGCSE was idiopathic epilepsy (6 cases), anoxicischemic cerebral insult due to cardiac arrest (3), viral encephalitis (2), intrahemispheric hematoma due to hemorrhagic stroke (1), cerebral infarct due to ischemic stroke (1), pituitary adenoma (1), post-traumatic epilepsy (1), renal failure (1), tuberculous meningitis (1), and unknown (2). In eighteen (94.7%) patients, seizures were completely controlled in a mean time of 45 min (range, 5-120 min) at a mean infusion rate of 8 microg/kg min (range, 3-21 microg/kg min). In one patient seizures did not stop. Midazolam administration did not cause any significant change in blood pressure, heart rate, oxygen saturation, or respiratory status. The mean time to full consciousness for patients after stopping the infusion was 1.6 hours (range, 2.0-8.5 hours). The mean infusion duration of midazolam was 14.5 hours (range, 12-25 hours). Midazolam is an effective and safe drug to control RGCSE, and may represent a substantial improvement over current therapeutic approaches such as pentobarbital anesthesia.

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.

Propylene glycol toxicity associated with lorazepam infusion in a patient receiving continuous veno-venous hemofiltration with dialysis

IMPLICATIONS

We report a case of toxicity from the drug solvent propylene glycol resulting from prolonged, large-dose lorazepam infusion. The case is unusual in that toxicity developed during continuous veno-venous hemofiltration with dialysis, a renal replacement therapy that should been have been effective at eliminating the chemical and its metabolites.

Alprazolam, a benzodiazepine, does not modify the ACTH and cortisol response to hCRH and AVP, but blunts the cortisol response to ACTH in humans

Alprazolam (AL), a benzodiazepine which activates gamma-amino butyrric acid (GABA)-ergic receptors, exerts a clear inhibitory effect on the activity of the hypothalamo-pituitary-adrenal (HPA) axis and is able to markedly reduce the ACTH response to metyrapone-induced inhibition of glucocorticoid feedback. It has been suggested that its inhibitory action could be regulated by CRH or AVP mediated mechanisms. However, the effect of benzodiazepines on the HPA response to CRH or AVP is contradictory. It has been shown that benzodiazepines have specific receptors on the adrenal gland but it is unclear if they mediate biological effects in humans. In order to further clarify the mechanisms underlying the inhibitory effect of benzodiazepine on HPA axis in humans, we studied the effect of AL (0.02 mg/kg po at -90 min) or placebo in 7 healthy young volunteers (7 female, age: 26-34 yr; wt: 50-58 kg, BMI 20-22 kg/m2) on: 1) the ACTH and cortisol responses to hCRH (2.0 microg/kg iv at 0 min) or AVP (0.17 U/kg im at 0 min); 2) the cortisol, aldosterone and DHEA responses to ACTH 1-24 (0.06 and 250 microg iv at 0 and 60 min, respectively). After placebo, the ACTH and cortisol responses to hCRH (peaks, mean+/-SE: 29.8+/-4.4 pg/ml and 199.3+/-19.6 microg/l) were similar to those recorded after AVP (31.7+/-6.5 pg/ml and 164.8+/-18.0 microg/l); the cortisol response to 0.06 microg ACTH (190.4+/-11.8 microg/l) was similar to that recorded after hCRH and AVP but lower (p<0.01) than that after 250 microg ACTH (260.6+/-17.4 microg/l). AL did not modify the ACTH response to both hCRH (42.5+/-7.1 pg/ml) and AVP (33.3+/-2.7 pg/ml), which even showed a trend toward increase. AL also failed to significantly modify the cortisol response to both hCRH (156.3+/-12.7 microg/l) and AVP (119.4+/-14.5 microg/l), which, on the other hand, showed a trend toward decrease. The cortisol peaks after 0.06 microg ACTH were significantly reduced (p<0.02) by AL pre-treatment (115.0+/-7.7 microg/l) which, in turn, did not modify the cortisol response to the subsequent ACTH bolus (214.7+/-16.6 microg/l). The DHEA and aldosterone responses to all the ACTH doses were not significantly modified by AL. In conclusion, these data show that the HPA response to AVP as well as to hCRH is refractory to the inhibitory effect of AL which, in turn, blunts the cortisol response to low ACTH dose. These findings suggest that both CRH- and AVP-mediated mechanisms could underlie the CNS-mediated inhibitory effect of AL on HPA axis; in the meantime, these results suggest that benzodiazepines could also act on adrenal gland by blunting the sensitivity of the fasciculata zone to ACTH.

Clomethiazole Acute Stroke Study in ischemic stroke (CLASS-I): final results

BACKGROUND AND PURPOSE

A previous trial (the Clomethiazole Acute Stroke Study) generated the hypothesis that clomethiazole is effective in patients with a major ischemic stroke (total anterior circulation syndrome), and this was tested in the present study.

METHODS

A total of 1198 patients with major ischemic stroke and a combination of limb weakness, higher cortical dysfunction, and visual field deficits were randomly assigned to clomethiazole (68 mg/kg IV over 24 hours) or placebo. The study drug was initiated within 12 hours of symptom onset. Functional outcome and neurological recovery were assessed at days 7, 30, and 90, with the proportion of patients with a Barthel Index > or =60 at last follow-up as the primary outcome measure.

RESULTS

The patients were randomly assigned equally, and the two treatment groups were well matched for baseline characteristics, including stroke severity (mean National Institutes of Health Stroke Scale score 16.9+/-5.2). Ninety-six percent were classified as total anterior circulation syndrome. The proportion of patients reaching a Barthel Index score of > or =60 was 42% in the clomethiazole-treated group and 46% in the placebo-treated group (odds ratio, 0.81; 95% CI, 0.62 to 1.05; P=0.11). There was no evidence of efficacy on any secondary outcome variables (modified Rankin Score, National Institutes of Health Stroke Scale, Scandinavian Stroke Scale, and 30-day CT infarct volumes) compared with placebo. Subgroup analysis showed a similar lack of treatment effect in patients treated early (<6 hours) and in those treated later (6 to 12 hours). Somnolence was an expected pharmacological effect of clomethiazole, and this occurred during treatment as an adverse event in half of the patients randomly assigned to study drug.

CONCLUSIONS

The target population was selected, and sufficient drug was given to produce the expected pharmacological effect in the brain. Clomethiazole does not improve outcome in patients with major ischemic stroke.

GABA agonist: clomethiazole

Neuroprotective agents inhibit reactions in the brain ischaemic injury cascade which lead to neuronal death. Gamma-aminobutyric acid (GABA) is a naturally occurring inhibitory neurotransmitter that increases chloride influx into the neuron and counteracts the toxic effects of glutamate. Clomethiazole is a GABA(A) agonist, which causes membrane hyperpolarization, counteracting depolarization and the subsequent cascade of biochemical events that result in neuronal death. Promising results in animal models resulted in clinical trials conducted in humans. However, large randomized placebo controlled trials in Europe, Canada and North America did not show the superiority of clomethiazole over placebo that was seen in animal models.

Paradoxical reactions to benzodiazepines in intravenous sedation: a report of 2 cases and review of the literature

Paradoxical reactions to benzodiazepines have been thoroughly reported since the introduction of this type of drug. The mechanism of benzodiazepine action is through the gamma-aminobutyric acid receptors. Properties of benzodiazepine include sedation, anxiolysis, amnesia, anticonvulsion, and muscle relaxation. Unfortunately, adverse paradoxical reactions can be stimulated by benzodiazepines and are difficult to predict and diagnose. Two cases of paradoxical reactions associated with the use of intravenous midazolam are presented, and the management of this complication and its different etiologies are reviewed. The relationship of the paradoxical reaction to alteration of the cholinergic homeostasis, serotonin levels, the role of genetics, and gamma-aminobutyric acid receptor configuration is discussed.

Clonazepam in the pharmacological treatment of vertigo and tinnitus

We carried out a retrospective survey of 25 years of clinical experience with the use of clonazepam as a vestibular and tinnitus suppressant in the pharmacological treatment of vestibular or cochleovestibular disorders due to different causes. We reviewed the medical records of 3,357 outpatients treated with a 0.5 or 1.0-mg daily dosage of oral clonazepam during 60-180 days. Complete or substantial control of vertigo or nonvertiginous dizziness was achieved in 77.4% of the vertigo patients. Tinnitus was improved in 32.0% of the tinnitus patients. Light or mild drowsiness, depression, nightmares, or lowering of libido, reported by 16.9% of the patients as adverse side effects, tended to subside with continued therapy. We concluded that clonazepam is a very useful and safe drug for the symptomatic treatment of patients suffering from cochleovestibular disorders.

Reemergence of stroke deficits with midazolam challenge

BACKGROUND AND PURPOSE

Patients who have sustained a neurological injury and then improved may experience transient reemergence of their syndromes when given benzodiazepines. As a step toward assessing whether neurotransmitter systems underlie poststroke clinical improvement, we selected midazolam, a gamma-aminobutyric acid(A) (GABA(A)) agonist, for systemic administration to measure general or stroke-specific effects in patients.

METHODS

Eight patients with image-verified stroke (5 with left-sided and 3 with right-sided cerebral lesions) participated. The strokes had occurred from 7 days to 6 years earlier, with patients showing clinical improvement from their initial syndromes. Each patient underwent baseline testing for motor function, aphasia, and left hemispatial neglect, after which intravenous midazolam was delivered until mild drowsiness was detected. Patients were tested during this period and again after 2 hours when sedation had dissipated.

RESULTS

After the administration of midazolam, the 5 patients with left hemisphere stroke demonstrated reemergence or worsening of their initial right hemiparesis and aphasia but showed no left neglect. The 3 patients with right cerebral stroke showed reemergence of left hemiparesis and left visual field neglect but no aphasia. All patients returned to baseline after 2 hours.

CONCLUSIONS

Under conditions of light sedation, patients whose initial stroke syndrome had substantially improved clinically showed transient reemergence of their initial focal syndrome. These data suggest a possible role for GABA(A)-mediated neurochemical mechanisms in poststroke improvement and sensitivity to medication effects.

Burning mouth syndrome after taking clonazepam

OBJECTIVE

To report the first published case of clonazepam-induced burning mouth syndrome (BMS).

CASE SUMMARY

A 52-year-old white woman presented to the clinic with burning mouth symptoms. The patient was previously maintained on alprazolam therapy for anxiety, but was switched to clonazepam because of increased anxiety and panic. Clonazepam significantly relieved her symptoms, but after four weeks of therapy, she reported a constant, mild, oral burning sensation. An oral examination was negative for mucosal abnormalities, and laboratory tests were unremarkable. The clonazepam dose was reduced, and the symptoms decreased, but remained intolerable. Clonazepam was discontinued, and the burning mouth symptoms completely resolved. Since no other medications relieved the anxiety and panic symptoms, the patient requested clonazepam to be reinitiated, but she again developed intolerable burning mouth symptoms. As clonazepam was discontinued, the symptoms resolved.

DISCUSSION

The clinical presentation of BMS includes burning and painful sensations of the mouth in the absence of mucosal abnormalities. Candidiasis, anemia, menopause, diabetes mellitus, medications, anxiety, and depression are some causes of this syndrome. Paradoxically, clonazepam has been studied for the treatment of BMS and has demonstrated mild to moderate improvement. In this patient, underlying causes of BMS were eliminated when possible. The association between clonazepam and BMS was highly probable according to the Naranjo probability scale.

CONCLUSIONS

This is the first published report describing BMS with a benzodiazepine. Although uncommon, clinicians should be aware of this potential adverse effect due to the widespread use of benzodiazepines.

Are lorazepam-induced deficits in attention similar to those resulting from aging?

The purpose of this experiment was to compare, in three tasks of attention, the impairment caused by lorazepam (1 and 2.5 mg) administered to young volunteers with the impairment that results from aging. Performance on digit cancellation (DC), digit-symbol substitution (DSS), and Paced Auditory Serial Addition Task (PASAT) was significantly impaired by lorazepam (2.5 mg) and was significantly worse in the middle-aged group (mean +/- SEM, aged 58.9+/-0.8 years) compared with the younger, IQ-matched group (20.7+/-0.2 years). However, there were interesting differences in the extent of impairments among the three tests. In the DC test, lorazepam (2.5 mg) produced a significantly greater impairment than was seen in either the middle-aged men or middle-aged women. However, in the DSS test, the middle-aged women were significantly more impaired than either the middle-aged men or the young volunteers tested after lorazepam (2.5 mg). In the PASAT, both the lorazepam (2.5 mg) group and the middle-aged women were more impaired than the middle-aged men. These results raise the important possibility of gender differences in age-related decline of attentional processes.

[Benzodiazepines and benzodiazepine receptor agonists in the treatment of sleep disorders--importance and dangers. Evaluation from the clinical medical view]

After first giving an overview about the epidemiological situation, the indications and contraindications of benzodiazepines as well as those of the newer short-time hypnotics zolpidem and zopiclone are reviewed. Premises for their use and alternatives to their application are discussed and the different substances are discussed for their clinical use. Problems of drug abuse and addiction are accounted in detail for these effective and little toxic agents. Finally recommendations for treatment are given to contribute to a more critical and scientific way of prescribing these valuable, though problematic, drugs.

New alternative agents in essential tremor therapy: double-blind placebo-controlled study of alprazolam and acetazolamide

Propranolol and primidone are widely used, effective agents in essential tremor although they are not tolerated by all patients. In the present study, the effectiveness of alprazolam, a triazole analog of benzodiazapine class, and acetazolamide, a carbonic anhydrase inhibitor, were investigated as symptomatic treatments for essential tremor. We studied 22 patients with essential tremor in a double-blind, cross-over, placebo-controlled design. The patients received in random order alprazolam, acetazolamide, primidone and placebo for four weeks, each separated by a two-week washout period. The study demonstrated that alprazolam was superior to placebo and equipotent to primidone, whereas there was no statistically significant difference between acetazolamide and placebo. The mean effective daily dose of alprazolam was 0.75 mg and there was not any troublesome side effect reported by the patients on alprazolam. Alprazolam can be used as an alternative agent in elderly essential tremor patients who can not tolerate primidone or propranolol.

Prenatally protein-malnourished rats are less sensitive to the amnestic effects of medial septal infusions of chlordiazepoxide

Evidence is mounting that prenatal protein malnutrition affects the physiological properties of the GABAergic neurotransmitter system in rats. To investigate the functional behavioral consequences of these changes, chlordiazepoxide (CDP, a positive modulator of the GABA(A) receptor) was applied directly to the medial septum and the amnestic response appraised. In adulthood, male offspring of rats provided with a protein-deficient diet (6% casein) for 5 weeks prior to mating and throughout pregnancy underwent stereotaxic surgery to implant steel cannulae aimed at the medial septum. After recovery, spatial learning performance in the submerged platform version of the Morris water maze task was assessed immediately following a 1 microl infusion of either artificial cerebrospinal fluid (aCSF), or one of three doses of CDP (15, 30 and 60 nmol). Well-nourished control rats demonstrated a robust amnestic response to intraseptal CDP. During task acquisition, well-nourished rats administered each of the doses exhibited significantly longer escape latencies than those given aCSF. On the probe trial (platform removed) a lower proportion of time was spent in the target quadrant (all three doses) at a greater average distance from the former platform location (30 and 60 nmol doses). In contrast, prenatally malnourished rats exhibited a muted sensitivity to CDP, most notable at the 30 nmol dose. These findings provide further support for functional changes within the GABAergic system consequent to malnutrition.

Flumazenil potentiation of postoperative morphine analgesia

OBJECTIVE

The goal of this study was to test the effect of concomitant administration of flumazenil (FL) and morphine (MO) on immediate postoperative analgesia and the MO requirement to control pain in human beings.

DESIGN AND INTERVENTIONS

Thirty-six patients undergoing inguinal hernioplasty under lidocaine epidural anesthesia were enrolled in this double-blind, randomized, controlled study. On the first complaint of pain, either MO (2 mg) only or MO (2 mg) plus FL (0.2 mg) was administered. Additional doses of the same medications administered via a patient-controlled analgesia device with a 10-minute lockout period were available thereafter. The study continued for 2 hours after the loading doses of the medications were administered, with an additional 2-hour period of observation.

RESULTS

Thirty-two patients completed the study. Both groups reached a similar satisfactory equianalgesic state (2 in a 0-10 visual analogue scale). The MO plus FL group consumed 9.5 +/- 1.1 mg of MO versus 14.1 +/- 1.1 mg of MO (p < 0.001) in the MO only group. The MO plus FL patients were subjectively (visual analogue scale) more comfortable and less sedated than the MO patients. "Fine" coordination (using an electronic maze) and "coarse" coordination (measured by transferring a pen from one hand to another as rapidly as possible with both arms placed inside an 80-cm metal frame) in the MO group were worse than in the MO plus FL group. End-tidal CO2 increased and blood pressure decreased in the MO group. There were few and insignificant side effects in the MO group. None of these patients required an MO antagonist, and recovery was prolonged in none.

CONCLUSIONS

Flumazenil afforded lower MO consumption during the immediate postoperative period. Cognitive, hemodynamic, and respiratory functions were better after MO plus FL than after MO alone.

[Delayed postanoxic encephalopathy]

We report the case of a 9-year-old boy with delayed postanoxic encephalopathy. The patient improved after a period of coma and adult respiratory distress syndrome caused by benzodiazepine intoxication. Initial improvement appeared to be complete, but 9 days after discharge from the pediatric intensive care unit, extrapyramidal rigidity of the left arm became manifest. This event was followed by progressive neurologic impairment with involuntary, non-repetitive, but occasionally stereotyped movements, affecting distal, proximal and axial musculature in various combinations. On physical examination, passive movement of the left arm showed a plastic, lead-pipe rigidity with a ratchet-like cogwheel quality. Magnetic resonance imaging (MRI) was performed. Axial T 2 -weighted images of the brain showed characteristic signs of an ischemic area in the basal ganglia which were more evident in the right region, a finding consistent with anoxic-ischemic encephalopathy. Delayed postanoxic encephalopathy is a relatively uncommon and unexplained phenomenon which becomes manifest after an initial hypoxic-ischemic event that causes stupor or coma. The pathogenesis is unknown. Exceptionally, this syndrome can affect the basal ganglia more than the cerebral cortex and white matter. Initial improvement is followed after a variable period of time by relapse, progressing for weeks to months until the patient is left with permanent sequelae.

Precipitated and spontaneous withdrawal following administration of lorazepam but not zolpidem

Radiotelemetry was utilized to compare zolpidem and lorazepam tolerance and withdrawal in rats. Locomotor activity, electromyographic activity (EMG), and body temperatures were used to assess the acute drug effects, and as measures of tolerance and withdrawal. Lorazepam, zolpidem, or vehicle was administered for 12 days, and data were recorded daily, immediately, after treatment. Data were also recorded immediately after flumazenil (25 mg/kg, IP) precipitated withdrawal and during 4 days of spontaneous withdrawal. Complete tolerance to the acute effects of lorazepam administration developed within 7 days of treatment and both flumazenil-precipitated and spontaneous withdrawal were observed. In contrast, there was no tolerance to the sedative actions of zolpidem administration after 12 days, but complete tolerance to the hypothermic and muscle relaxant effects was apparent after 8 days of treatment. Despite the presence of tolerance, no evidence of either spontaneous or flumazenil-induced withdrawal was recorded in these rats. In conclusion, this model suggests that as a sedative zolpidem has significant advantages over the classic benzodiazepines.

[Alcohol withdrawal syndrome and its treatment]

When alcoholics decrease or interrupt alcohol intake abruptly, they will in general experience alcohol withdrawal symptoms. Clinically in most cases it develops a vegetative syndrome with gastroenteropathy, cardiovascular diseases, neurological and psychopathological symptom. Usually alcohol withdrawal symptoms abate after four to seven days, longer courses are rare. Application of drugs is required in approximately one third to one half of the patients. A variety of drugs was suggested for the treatment of alcohol withdrawal. In the first hours of alcohol detoxification, the sensitivity of epinephrine receptors is reduced, but rises afterwards substantially. The number of NMDA-receptors increases during chronic intoxication with ethanol. The standard therapy in Europe (except of Great Britain) is an oral mono therapy with clomethiazole in a dose which depends on the severity of the symptoms. Severe withdrawal symptoms may require treatment on an intensive care unit with infusion therapy, e.g. in the context of a delirium tremens, which represents a life-threatening status. In this case, benzodiazepines have been used successfully as an alternative to clomethiazole.

Gastric decontamination performed 5 min after the ingestion of temazepam, verapamil and moclobemide: charcoal is superior to lavage

AIMS

The aim was to study the efficacy of gastric lavage and activated charcoal in preventing the absorption of temazepam, verapamil and moclobemide when gastric decontamination was performed immediately after ingestion of the drugs.

METHODS

Nine healthy volunteers took part in a randomized cross-over study with three phases. The subjects were administered single oral doses of 10 mg temazepam, 80 mg verapamil and 150 mg moclobemide. Five minutes later, they were assigned to one of the following treatments: 200 ml water (control), 25 g activated charcoal as a suspension in 200 ml water or gastric lavage. Plasma concentrations and the cumulative excretion into urine of the three drugs were determined up to 24 h.

RESULTS

The mean AUC(0,24 h) of temazepam, verapamil and moclobemide was reduced by 95.2% (P < 0.01), 92.8% (P < 0.01) and 99. 7% (P < 0.01), respectively, by activated charcoal compared with control. Gastric lavage did not reduce significantly the AUC(0,24 h) of these drugs. The 24 h cumulative excretion of temazepam, verapamil and moclobemide into urine was reduced significantly (P < 0.05) by charcoal but not by gastric lavage. Charcoal reduced the AUC(0,24 h), Cmax and urinary excretion of all three drugs significantly more than lavage.

CONCLUSIONS

Activated charcoal is very effective and gastric lavage can be rather ineffective in preventing the absorption of temazepam, verapamil and moclobemide when the treatment is given very rapidly after ingestion of the drugs, before tablet disintegration has occurred.

Neocortical hyperexcitability after GABA withdrawal in vitro

The sharp interruption of the intracortical instillation of exogenous gamma-aminobutyric acid (GABA), generates an epileptic focus in mammals. Seizures elicited by GABA withdrawal last several days or weeks. The present work reports that GABA withdrawal-induced hyperexcitability can be produced in vitro: a sudden withdrawal of GABA (5 mM; 120 min) or benzodiazepine (60 microM flunitrazepam) from the superfusion, induced a gradual increase in the amplitude of the evoked population spike (PS) recorded on neocortical slices. PS enhancement reached 150% above the control value 2.5 h after GABA withdrawal. GABA withdrawal-induced hyperexcitability was facilitated by progesterone. PS enhancement induced by GABA withdrawal was associated with an impairment of GABA transmission occurring before epileptiform discharges were fully established. Paired pulse inhibition and evoked [3H]-GABA release appear decreased; suggesting that cortical hyperexcitability as a result of GABA withdrawal involves pre-synaptic changes. Specific muscimol binding decreased during GABA superfusion but recovered after GABA withdrawal. However, the sensitivity of the post-synaptic response to 3alpha-OH-5alpha-pregnan-20-one or allopregnanolone (alloP) was enhanced after GABA withdrawal, suggesting a functional change in the GABA(A) receptors. The changes described may be the cellular correlates of the withdrawal syndromes appearing after interruption of the administration of GABA(A) receptor agonists.

Cardiovascular response and stress reaction to flumazenil injection in patients under infusion with midazolam

OBJECTIVES

To evaluate the cardiovascular response and acute stress reaction after arousal induced by a benzodiazepine antagonist, flumazenil, in patients sedated with midazolam.

DESIGN

Prospective study.

SETTING

Emergency center in a university hospital.

PATIENTS

A total of 12 patients were ventilated mechanically under sedation with midazolam.

INTERVENTIONS

We monitored the consciousness level, heart rate, systemic blood pressure, pulmonary artery pressure, and pulmonary artery occlusion pressure before and after a bolus injection of 0.5 mg of flumazenil. The score for the consciousness level represents the sum of the scores for eye opening and best motor response, as determined by the Glasgow Coma Scale. We measured the cardiac output, concentrations of norepinephrine, epinephrine, and 3-methoxy-4-hydroxyphenylethyleneglycol in plasma, and concentration of cortisol in serum. We calculated the left ventricular ejection fraction, cardiac index, systemic vascular resistance index, pressure-rate product, systemic oxygen delivery, and systemic oxygen consumption at 0, 10, 30, and 60 mins after injection of flumazenil.

MEASUREMENTS AND MAIN RESULTS

The serum benzodiazepine's receptor binding activity in serum was in the range from 50 to 1000 ng/mL before injection of flumazenil. Flumazenil improved the consciousness level from 6.7+/-2.0 to 8.9+/-1.6 and induced transient elevations in heart rate, blood pressure, systolic pulmonary artery pressure, and pulmonary artery occlusion pressure. Left ventricular ejection fraction, oxygen delivery index, and pressure-rate product increased significantly, from 61%+/-8%, 640+/-170 mL/min/m2, and 13,300+/-2600 mm Hg/min at 0 mins to 67% +/-5%, 710+/-220 mL/min/m2, and 16,500+/-4400 mm Hg/min at 10 mins, respectively. Concentrations of norepinephrine and epinephrine in plasma increased significantly, from 890+/-840 pg/mL and 220+/-360 pg/mL, respectively, at 0 mins to 990+/-850 pg/mL and 270+/-300 pg/mL, respectively, at 10 mins. There were no significant changes in the plasma concentration of 3-methoxy-4-hydroxyphenylethyleneglycol, the serum concentration of cortisol after the administration of flumazenil.

CONCLUSIONS

Flumazenil did not result in a significant acute stress reaction in midazolam-sedated patients, but it increased myocardial oxygen consumption by enhancing sympathetic nervous activity or antagonizing cardiovascular depression induced by midazolam.

Posthallucinogen-like visual illusions (palinopsia) with risperidone in a patient without previous hallucinogen exposure: possible relation to serotonin 5HT2a receptor blockade

BACKGROUND

Previous reports document visual illusions resembling hallucinogen persisting perception disorder (HPPD) after risperidone treatment in patients with histories of previous LSD exposure.

METHODS

We report a case with visual disturbances resembling HPPD after each of three consecutive risperidone dose increases.

RESULTS

Contrasting with previous reports, our patient lacked any history of substance abuse, particularly hallucinogen exposure. She lacked neurologic or other contributory illnesses. Illusions generally remitted within 48 hours each time. Coadministration of trazodone and clonazepam may have contributed to these phenomena, although clonazepam has been used to treat this condition. She had been unusually sensitive to the side-effects of many psychotropics.

CONCLUSIONS

This case is unique due to the absence of substance abuse. This and another report note heightened sensitivity to medication side-effects. Visual phenomena resembling HPPD evidently can occur with risperidone and, possibly, other atypical antipsychotics and certain antidepressants regardless of previous hallucinogen use. Several lines of evidence implicate reduced 5HT2a serotonin receptor stimulation rather than increased 5HT2c stimulation.