Anticonvulsant Benzodiazepine Research Articles

Épidémiologie et facteurs associés au syndrome dépressif chez les patients suivis au centre hospitalo-universitaire de Rennes pour une épilepsie

ObjectivesThe occurrence of depression in people with epilepsy is almost twice as common as in the general population. Furthermore, depression is the first cause of lower quality of life among those patients. Which is why the main goal of this study was to assess the epidemiology of depression and its associated factors among the patients from the tertiary department of epileptology in Rennes. Methods/resultsThe subjects were included prospectively and consecutively at the moment of their consultation or hospitalisation in the department. Personal data about the socio-economic status and the type of epilepsy was collected. The subjects filled validated self-assessment of depression (NDDIE), anxiety (GAD-7) and quality of life (QOLIE-10). Thanks to the NDDIE, the patients were divided into: “depressed” and “not depressed”; and the two groups were compared with univariate and multivariate models. Of the 322 patients followed-up in the department between the 17th of June and the 9th of September 2016 223 of them were included in the study. According to the NDDIE, 22.6% suffered from depression; according to the GAD-7, 46.4% suffered from anxiety. In the “depressed” group, 82% were not under anti-depressant medication. In the univariate model, depression was associated with: anxiety, suicidal ideations, lower quality of life, vague nervus stimulation treatment, anticonvulsant benzodiazepine medication or psychiatric medication, and last of all bitherapy or polytherapy antiepileptic medication compared to monotherapy. In the multivariate model, depression was significantly related to anxiety (OR: 8.86 [3.00; 26.19] p=0.0001), suicidal ideas (OR: 7.43 [2.93; 18.81] p<0.0001), anticonvulsant benzodiazepine medication (OR: 3.31 [1.16; 9.49] p=0.0255), and lower quality of life (OR: 1.09 [1.02; 1.17] p=0.0087). Generalised epilepsy was a protective factor with uni and multivariate models (OR: 0.34 [0.11; 1.00] p=0.0492). ConclusionsIn the tertiary epileptic department of Rennes, more than 20% of patients with epilepsy suffered from depression during the inclusion period according to the NDDIE. Among those “depressed” subjects, fewer than one out of five seemed to receive proper psychiatric care. Which is why this study highlights the importance of interdisciplinary cooperation between neurologists and psychiatrists in order to aim at better management of epileptic patients as a whole.

Seizure protection by intrapulmonary delivery of midazolam in mice

The lung provides a portal of entry that could be used to rapidly deliver anticonvulsant substances to the brain to treat seizures. In the present study, we demonstrate that midazolam, a water-soluble anticonvulsant benzodiazepine, confers potent seizure protection when administered via the intrapulmonary route. High dose (100 mg/kg) intraperitoneal midazolam induced loss-of-righting reflex in mice. Lower doses of midazolam (100–1000 μg/kg) when administered intraperitoneally did not induce loss-of-righting reflex but protected animals against pentylenetetrazol (PTZ)-induced seizures. Intrapulmonary administration of midazolam via a tracheal cannula protected against intraperitoneal PTZ seizures at lower doses. The minimal intraperitoneal and intravenous doses of midazolam required to elevate the threshold for seizure signs induced by intravenous PTZ were 500 and 100 μg/kg, respectively, whereas the minimal intrapulmonary midazolam dose was 12.5 μg/kg. Intratracheal midazolam caused a large increase in intravenous PTZ threshold 5 min after administration but the effect declined rapidly over 60 min and no antiseizure activity was evident at 120 min. The minimal intraperitoneal doses of midazolam required to elevate the threshold for seizure signs induced by intravenous picrotoxin and kainic acid were 100 and 2000 μg/kg, respectively; the corresponding values for intratracheal midazolam were 25 and 100 μg/kg, respectively. We conclude that midazolam is a highly effective anticonvulsant when administered by the intrapulmonary route. Midazolam is substantially more potent when delivered into the lung than when administered intraperitoneally or intravenously. Inhalation could be an alternative to other routes of administration for the delivery of midazolam to rapidly abort acute seizures.

Enhancing the function of alpha5-subunit-containing GABAA receptors promotes action potential firing of neocortical neurons during up-states

Neocortical neurons mediate the sedative and anticonvulsant properties of benzodiazepines. These agents enhance synaptic inhibition via positive modulation of γ-aminobutyric acid (GABAA) receptors harboring α1-, α2-, α3- or α5-protein subunits. Benzodiazepine-sensitive GABAA receptors containing the α5-subunit are abundant in the neocortex, but their impact in controlling neuronal firing patterns is unknown. Here we studied how the discharge rates of cortical neurons are modified by a positive (SH-053-2′F-R-CH3) and a negative (L 655,708) α5-subunit-preferring allosteric modulator in comparison to diazepam, the classical non-selective benzodiazepine. Drug actions were characterized in slice cultures from wild-type and α5(H105R) knock-in mice by performing extracellular multi-unit-recordings. In knock-in mice, receptors containing the α5 subunit are insensitive to benzodiazepines. The non-selective positive allosteric modulator diazepam decreased the discharge rates of neocortical neurons during episodes of ongoing neuronal activity (up states). In contrast to diazepam, the α5-preferring positive modulator SH-053-2′F-R-CH3 accelerated action potential firing during up states. This promoting action was absent in slices from α5(H105R) mice, confirming that it is mediated by the α5-subunit. Consistent with these observations, the negative α5-selective modulator L 655,708 inhibited up state action potential activity in slices from wild-type mice. The opposing actions of diazepam and SH-053-2′F-R-CH3, which both enhance GABAA receptor function but differ in subtype-selectivity, uncovers contrasting roles of GABAA receptor subtypes in controlling the firing rates of cortical neurons. These findings may have important implications for the design of novel anaesthetic and anticonvulsant benzodiazepines displaying an improved efficacy and fewer side effects.

Acute Imidazenil Treatment after the Onset of DFP-Induced Seizure Is More Effective and Longer Lasting than Midazolam at Preventing Seizure Activity and Brain Neuropathology

Diazepam (DZ), the preferred anticonvulsant benzodiazepine (BZ) for the treatment of organophosphate (OP) nerve agent-induced seizures and neuronal damage, has been associated with unwanted effects such as sedation, amnesia, cardiorespiratory depression, anticonvulsant tolerance, and dependence liability. In a search for safer and more effective anticonvulsant BZs against OP-induced seizure and neuronal damage, we have previously shown that imidazenil (IMD), a low-intrinsic efficacy positive allosteric modulator of gamma-aminobutyric acid (GABA) action at α1-containing GABA(A) receptors, which has high intrinsic efficacy at α2-, α3-, and α5-containing GABA(A) receptors, is more potent and longer lasting than DZ pretreatment at protecting rats from diisopropyl fluorophosphate (DFP)-induced electrocorticographic (ECoG) seizures and neuronal damage. The effects of IMD were observed at doses that are devoid of sedative, amnestic, and anticonvulsant tolerance actions. In the present study, we compared the anticonvulsant and neuroprotective effects of a combination of atropine (2 mg/kg, ip) and pyridine-2-aldoxime methochloride (2-PAM, 20 mg/kg, ip) with IMD (0.5 mg/kg, ip) or midazolam (MDZ, 0.5-2 mg/kg, ip) administered after the onset of DFP (1.5 mg/kg, sc)-induced seizure activity. The severity of DFP-induced ECoG seizures was assessed by continuous radio telemetry recordings in unrestrained and freely moving rats. Furthermore, the extent of neuronal damage was evaluated using a neuron-specific nuclear protein immunolabeling and fluoro-jade B staining procedure. We report here that IMD is more efficacious and longer lasting than sedating doses of MDZ in protecting rats from DFP-induced ECoG seizures and neuronal damage.

Neuronal plasticity in animal models and the epileptic human hippocampus

Prolonged status epilepticus in humans as in experimental animals can initiate the development of temporal lobe epilepsy (TLE) (Kapur, 1999). Therefore, application of potent convulsant substances such as kainic acid or pilocarpine in rats induces acute status epilepticus that, after a silent period of 1–2 weeks, is followed by spontaneous convulsions. The status epilepticus is characterized by severe limbic seizures and sequelae of neuropathologic signs including opening of the blood–brain barrier, local brain edema, bleeding into the brain, and activation of microglia and astrocytes followed by neurodegeneration in the hippocampus, amygdala, entorhinal cortex, and other brain areas (Sperk et al., 1983; Du et al., 1993; Rizzi et al., 2003). Induced by the seizure activity, neurotransmitters such as γ-aminobutyric acid (GABA), glutamate, or amine transmitters are released from their stores and mechanisms of their resynthesis are strongly activated (Sperk et al., 1983). In addition, pronounced changes in the expression of multiple functionally important proteins have been found in brains of experimental animals and humans (Herdegen et al., 1993; Sperk, 1994; McNamara, 1999; Morimoto et al., 2004).

Imidazenil, a non-sedating anticonvulsant benzodiazepine, is more potent than diazepam in protecting against DFP-induced seizures and neuronal damage

Organophosphate (OP)-nerve agent poisoning may lead to prolonged epileptiform seizure activity, which can result in irreversible neuronal brain damage. A timely and effective control of seizures with pharmacological agents can minimize the secondary and long-term neuropathology that may result from this damage. Diazepam, the current anticonvulsant of choice in the management of OP poisoning, is associated with unwanted effects such as sedation, amnesia, cardio-respiratory depression, anticonvulsant tolerance, and dependence liabilities. In search for an efficacious and safer anticonvulsant benzodiazepine, we studied imidazenil, a potent anticonvulsant that is devoid of sedative action and has a low intrinsic efficacy at α1- but is a high efficacy positive allosteric modulator at α5-containing GABA A receptors. We compared the potency of a combination of 2 mg/kg, i.p. atropine with: (a) imidazenil 0.05–0.5 mg/kg i.p. or (b) equipotent anti-bicuculline doses of diazepam (0.5–5 mg/kg, i.p.), against diisopropyl fluorophosphate (DFP; 1.5 mg/kg, s.c.)-induced status epilepticus and its associated neuronal damage. The severity and frequency of seizure activities were determined by continuous radio telemetry recordings while the extent of neuronal damage and neuronal degeneration were assessed using the TUNEL-based cleaved DNA end-labeling technique or neuron-specific nuclear protein (NeuN)-immunolabeling and Fluoro-Jade B (FJB) staining, respectively. We report here that the combination of atropine and imidazenil is at least 10-fold more potent and longer lasting than the combination with diazepam at protecting rats from DFP-induced seizures and the associated neuronal damage or ongoing degeneration in the anterior cingulate cortex, CA1 hippocampus, and dentate gyrus. While 0.5 mg/kg imidazenil effectively attenuated DFP-induced neuronal damage and the ongoing neuronal degeneration in the anterior cingulate cortex, dentate gyrus, and CA1 hippocampus, 5 mg/kg or a higher dose of diazepam is required to produce similar protective effects. These finding suggests that imidazenil, a non-sedating anticonvulsant BZ ligand, is a more potent, effective, and safer drug than diazepam in protecting rats from DFP-induced seizures and the associated neuronal damage and/or ongoing neuronal degeneration.

Methcathinone: A new postindustrial drug

Methcathinone, a methyl derivative of cathinone, is an illicit drug also known as ephedrone. It is a stimulant found in the “khat” plant, Catha edulis, which can easily be synthesized from pseudoephedrine. Its intoxication is difficult to diagnose and cure properly for two reasons: (i) target consumers are usually “well-educated people” aware of the risks and precautionary measures and (ii) intoxication by cathinone derivatives of synthetic or natural (derived from the khat) origin induce misleading symptoms. As a result, documented reports of methcathinone intoxication that are based on reliable analyses are rare. This paper describes a case of reiterated coma due to an overdose of methcathinone dissolved in alcohol that was taken with bromazepam. A 29-year-old woman was admitted to an emergency department for a coma of toxic origin. Medical files showed that it was her second such episode to occur that month. Moreover, the family indicated signs of depression, incoherent behaviour and intake of “amphetamine-like” drugs. Clinical examination revealed a Glasgow coma score of 9, symmetrical reactive pupils with mydriasis and no convulsions. The patient presented with rapid respirations and her blood pressure was 93/53 mmHg. The ionogram and the blood gas analyses were normal, while the blood alcohol level was 0.167 g/dL. Urinalysis revealed the presence of benzodiazepines and a high concentration of amphetamines (methcathinone: 17.24 mg/L, ephedrine: 11.60 mg/L and methylephedrine: 11.10 mg/L). In addition, serum analysis revealed bromazepam (8.89 mg/L), methcathinone (0.50 mg/L) and methylephedrine (0.19 mg/L). This case showed that the consumption of bromazepam and alcohol altered the typical clinical symptoms of cathinone derivative intoxication, namely hypertension and convulsions. Methylephedrine, an impurity resulting from the alkylation of a primary amine, can be considered a chemical tag indicating fraudulent synthetic origin of the drug. This case describes a documented example of new addictive behaviour of “well-educated” people involving the intake of methcathinone, a postindustrial psychostimulant intentionally combined with an anticonvulsant benzodiazepine. However, this specific case suggests that in spite of a very high bromazepam concentration in presence of the potentiator alcohol, the vital respiratory function would be probably maintained, thanks to the association with methcathinone.

Differences between the tolerance characteristics of two anticonvulsant benzodiazepines in the amygdaloid-kindled rat

The characteristics of the development of tolerance to the anticonvulsant effects of chronic treatment by dipotassium clorazepate and diazepam using amygdaloid-kindled rats were investigated. Dipotassium clorazepate (5 mg/kg) or diazepam (5 mg/kg) were intraperitoneally administered for 10 consecutive days. Tolerance to the anticonvulsant effect of dipotassium clorazepate developed in seizure stage on day 6, after-discharge duration on day 7 and seizure latency on day 4. In contrast, tolerance to the effects of diazepam developed more rapidly in seizure stage on day 4, after-discharge duration on day 4 and seizure latency on day 3. Thus tolerance to the anticonvulsive effect of dipotassium clorazepate developed relatively slower than that to diazepam. All rats had stage 5 convulsions 24 hr after cessation of the administration of dipotassium clorazepate and diazepam. Concomitant determinations of plasma concentrations of the main metabolite of dipotassium clorazepate and diazepam, desmethyldiazepam, showed no statistical difference during treatment, suggesting that the developed tolerance was not metabolic but functional.

Evaluation of motor toxicity and anticonvulsant efficacy of barbiturates and benzodiazepines in a bicyclophosphate seizure model in mice

1. 4-Alkyl derivatives of 2,6,7-trioxa-l-phosphabicyclo [2.2.2] octane-I-oxide [Bicyclophosphates (BP)] are highly toxic convulsants and potent GABAA receptor antagonists. 2. The effects of various clinical used anticonvulsant drugs, barbiturates and benzodiazepines, on motor performance and 4-isopropylbicyclophosphate (IPBP), a homologue of BP, induced myoclonic and generalized tonic-clonic seizures were investigated in mice. 3. The anticonvulsant drugs were IP administered 30 min. prior to the inverted screen test, a measure of minimal neurological deficit, and were then challenged with a 97% convulsant dose of IPBP (0.15 mg/kg, SC). 4. The results show that: 1) benzodiazepines are more likely to have favorable motor toxicity and anticonvulsant profiles than barbiturates. 2) Various doses of these drugs that did not significantly cause motor impairment increase the mean latencies to myoclonic and generalized tonic-clonic seizures. 3) The increase in anticonvulsant activity is associated with a comparable increase in motor impairment. 4) Only 45-0088-S, an open-ring derivative of 1,4-benzodiazepines, and clonazepam have protective indices of more than 5, a satisfactory margin of safety. 5. The potential use of 45-0088-S and clonazepam in the treatment of BP-induced seizures should be explored further.

Quantitation of clonazepam and its major metabolite 7-aminoclonazepam in hair.

Clonazepam (CLO) is an anticonvulsant benzodiazepine approved by the Food and Drug Administration for use in the treatment of seizures. It produces pharmacological effects (depression, amnesia) similar to other compounds from the same therapeutic class, and in combination with alcohol, its CNS-depressant action can be significantly potentiated. As with some other benzodiazepines, CLO is a drug possibly used in "date-rape" situations. A method using solid-phase extraction followed by a highly sensitive negative chemical ionization gas chromatography-mass spectrometry for the simultaneous quantitation of CLO and its major metabolite 7-aminoclonazepam (7-ACLO) in hair was developed and validated. The method has potential application to alleged drug-facilitated rape cases. To determine the feasibility of detecting 7-ACLO and CLO in hair, specimens were collected from 10 psychiatric patients treated with CLO, divided into 2-cm segments, and analyzed. Standard curves for 7-ACLO (1-1000 pg/mg) and CLO (10-400 pg/mg) had correlation coefficients of 0.998. All precision and accuracy values were within acceptable limits. 7-ACLO was present in measurable quantities (1.37-1267 pg/mg) in 9 out of 10 patient samples. CLO concentrations in hair were much lower (10.7-180 pg/mg). In 4 out of 10 cases, CLO was not detected in hair. Two patients who had never been treated with CLO before received a single 2-mg dose of the drug. Approximately three weeks later, hair samples were collected, and measurable quantities of 7-ACLO (4.8 pg/mg) were detected in the first segment (proximal) of one of those samples, and traces of the drug were present in the other sample. We concluded that the 7-ACLO is being deposited in hair in much higher quantities than the parent drug and remains there for extended periods of time. Our study also indicates that it is possible to detect 7-ACLO after a single dose of CLO as in the typical date-rape scenarios.

Benzodiazepine Concentrations in Sera Determined by Radioreceptor Assay for Therapeutic-dose Recipients

Using a radioreceptor assay, the authors determined benzodiazepine concentrations in sera of the 168 subjects who had been taking one or more benzodiazepines daily without showing excessive or adverse effects. In most of the recipients (150 of 168, 89.3%) of the sleep-inducing, anxiolytic, sedative, or anticonvulsant benzodiazepines, the concentrations were below 500 ng/mL in diazepam equivalents. Only two recipients (1.2%) showed concentrations above 1,000 ng/mL. These data will be useful in managing benzodiazepine therapy and in determining a diagnosis of benzodiazepine overdose.

Effects of the anticonvulsant benzodiazepine clonazepam on event-related brain potentials in humans

The effects of the benzodiazepine clonazepam (a drug used as anticonvulsant) on event-related brain potentials ewere investigated in healthy human subjects. Thirty-six male student volunteers (mean age 30 years) received clonazepam or a placebo in a double-blind setting. VEPs (visual evoked potentials) were obtained from the standard checkerboard reversal procedure; AEPs (auditory evoked potentials) and slow cortical potentials (CNV) were measured during a 2-stimulus reaction time paradigm, in which the quality of the acoustic S1 signalled whether the acoustic S2 would follow after 2 sec or afer 6 sec. Each S2 requested a speeded button press. Compared to placebo, clonazepam significantly reduced P100 amplitude of the VEP and the amplitudes of the AEP components N1 and P3. On the other hand, clonazepam boosted the development of a distinct N2 which was not apparent in placebo subjects. The CNV was significantly reduced and reaction time increased under clonazepam compared to placebo. Specific versus non-specific damping effects of the benzodiazepine are discussed, comparing the present result with the pattern of ERP effects of the anticonvulsant carbamazepine that had been obtained using the same experimental paradigms.

The effect of the NMDA receptor antagonist, MK-801, on the course and outcome of kindling

A rapid kindling procedure was used to distinguish between the anticonvulsant activity of drugs and their ability to retard the kindling process. MK-801 is a specific ligand at the phenycyclidine (PCP) recognition site, and acts as a noncompetitive antagonist of NMDA-type glutamate/aspartate receptors. Intraperitoneal injections of MK-801 (0.5–4.0 mg/kg IP) significantly reduced the cumulated effect 12 2-hr kindling stimulations, as determined from behavioral measures of seizure activity in immediately ensuing 24-hr drug-free kindling sessions; however, the corresponding electrographic effects did not reach significance. MK-801 also showed significant anticonvulsant activity when injected in fully kindled rats. Higher doses tested were accompanied by locomotor and postural effects. The anticonvulsant benzodiazepine, clonazepam, formulated with a proprietary diluent (as Rivotril, Roche), injected in anticonvulsant doses during the first 12 kindling sessions (0.64 mg/kg IP, repeated after 9 hr) did not significantly affect the course of subsequent sessions of drug-free kindling. Systematic injections of kynurenic acid (300–600 mg/kg IP 4 hours), a nonspecific antagonist of glutamate receptors in vitro, were without significant anticonvulsant or antikindling activity. Activity of NMDA-sensitive glutamate/aspartate receptors associated with the PCP recognition site may induce lasting facilitation of neural transmission; this facilitation may be responsible for the remote propagation and progressive enhancement of seizure activity kindled in the amygdala. The facilitatory process appears to be antagonised by MK-801.

Tolerance to anticonvulsant effects of diazepam, clonazepam, and clobazam in amygdala-kindled rats.

Benzodiazepines are effective anticonvulsants, but long-term clinical usefulness is limited by development of tolerance. Tolerance to the actions of three prototype anticonvulsant benzodiazepines (BZDs)--diazepam (DZP), clonazepam (CZP), and clobazam (CLB)--was studied in amygdala-kindled rats. Fully kindled rats were dosed three times daily for 2 or 4 weeks. Amygdala stimulation was given 30 min after drug administration on days 1, 2, 3, 5, and 7 of chronic treatment and then three times weekly. During treatment, tolerance was observed as a loss of drug effect to suppress behavioral and EEG manifestations of seizure activity. Seizure activity remained stable in rats treated with vehicle. Tolerance to the anticonvulsant effects developed most rapidly during CLB treatment and most slowly during CZP treatment. Tolerance to the motor impairment caused by the drugs developed more rapidly. Assay of the amount of drug in brain extracts, using a BZD receptor assay, showed that tolerance was functional, not metabolic. Doubling the dose did not readily restore full anticonvulsant activity. The response to amygdala stimulation 24 h after treatment was stopped showed no residual BZD effect, but there was a rebound in duration of some seizure measures in rats that had been treated with CLB or DZP. Retesting 48 h after treatment was stopped showed that rats were still tolerant. The amygdala-kindled rat is a reliable and sensitive model for studying long-term actions of anticonvulsant BZDs.

Differences in the development of tolerance to two anticonvulsant benzodiazepines in the amygdaloid kindled rat.

The effects of chronic treatment with two benzodiazepines were studied on kindled amygdaloid seizures in rats. Clobazam (4 mg kg-1), clonazepam (0.3 mg kg-1) or vehicle (1 mL kg-1) was administered, by intraperitoneal injection, to fully kindled rats twice daily for nineteen days. Each rat was electrically stimulated 30 min after the morning dose on alternate days of treatment. Tolerance developed rapidly to the anticonvulsant effects of clobazam after only three days of treatment, following which only a small residual protection was maintained. Tolerance to clonazepam developed gradually over the course of the experiment, although this effect was relatively minor.

Microinjection of a benzodiazepine into substantia nigra elevates kindled seizure threshold

The purpose of these experiments was to initiate investigations of the brain site(s) at which the benzodiazepines exert their anticonvulsant effect. We examined the effects of microinjections of clonazepam into substantia nigra (SN) on seizure threshold in the kindling model. We also examined the distribution of microinjected [ 3H]methylclonazepam with autoradiographic methods. Microinjection of clonazepam bilaterally into substantia nigra pars reticulata (SNR), but not nearby, produced a 75% elevation of generalized seizure threshold. Quantitative analysis of autodiographic studies indicated that the vast majority of [ 3H]methylclonazepam was distributed within 400 μm of the injection cannula tip; even optimally placed injections did not result in drug access throughout the entire SN. The data demonstrate that local application of an anticonvulsant benzodiazepine to the substantia nigra alone is sufficient to suppress seizures. We suggest that the substantia nigra is one site at which systematically administered benzodiazepines act to suppress seizures.

Non-convulsive Status Epilepticus: A Prospective Study in an Adult General Hospital

A prospective study of non-convulsive status epilepticus was undertaken in order to evaluate the occurrence and characteristics of this condition in adults. The diagnosis was established in 22 of 113 patients (19 per cent) presenting with status epilepticus over a 23-month period. Non-convulsive status was most prevalent in the over 60 age group. Its two subgroups, absence status (18 cases) and complex partial status (four cases) were both manifest clinically by a prolonged alteration of consciousness of variable extent. Absence status presented de novo (six cases) or against a background of epilepsy (12 cases), often with a long seizure-free interval before presentation. Precipitating factors included infection, inadequate anticonvulsant medication and benzodiazepine withdrawal. The clouding of consciousness was usually characterised by confusion, disorientation and partial responsiveness. Myoclonic or clonic movements of the eyes, face or jaw were evident in all but two patients. Automatisms, including ambulatory behaviour (three cases) were less common. Serious psychiatric disorders preceded the status in seven cases, and contributed to the difficulty in diagnosis. Complex partial status was associated with underlying cerebrovascular disease in three of four cases, and is characterised by a more severe and variable clouding of consciousness, less frequent facial clonic movements, episodic adversive head and eye movements, and a more gradual recovery after treatment.

Seizures produced by pilocarpine: Neuropathological sequelae and activity of glutamate decarboxylase in the rat forebrain

Morphological analysis of brains from rats receiving a convulsant dose of the muscarinic cholinergic agonist, pilocarpine hydrochloride (380 mg/kg), revealed a widespread damage to the forebrain as assessed by light microscopy 5–7 days after seizures. The substantia nigra, olfactory cortex, amygdala, hippocampus, septum, temporal cortex and thalamus underwent prominent morphological injury and cell loss. A concurrent assessment of the activity of l-glutamate decarboxylase (GAD), the γ-aminobutryrate (GABA) synthesizing enzyme, demonstrated marked deficits in GAD activity in the brain regions undergoing morphological insult. Diazepam, 10 mg/kg, and scopolamine hydrochloride, 10 mg/kg, administered 30 min prior to the injection of pilocarpine, 380 mg/kg, prevented acute behavioral and electrographic, and long-term morphological and biochemical sequelae of seizures. These findings suggest that the muscarinic antagonist, scopolamine, and the anticonvulsant benzodiazepine, diazepam, may aid in preventing extensive brain damage related to pathological muscarinic cholinergic overactivity. The similarity of the topography of the damage and deficits in the GAD activity in brains of rats treated with pilocarpine indicates that GABAergic neurons are lost in the subregions of the brain preferentially sensitive to the convulsant action of pilocarpine.

Effect of Saikosaponin derivatives upon the immune response against T-dependent and T-independent antigens in mice

Methcathinone, a methyl derivative of cathinone, is an illicit drug also known as ephedrone. It is a stimulant found in the “khat” plant, Catha edulis, which can easily be synthesized from pseudoephedrine. Its intoxication is difficult to diagnose and cure properly for two reasons: (i) target consumers are usually “well-educated people” aware of the risks and precautionary measures and (ii) intoxication by cathinone derivatives of synthetic or natural (derived from the khat) origin induce misleading symptoms. As a result, documented reports of methcathinone intoxication that are based on reliable analyses are rare. This paper describes a case of reiterated coma due to an overdose of methcathinone dissolved in alcohol that was taken with bromazepam. A 29-year-old woman was admitted to an emergency department for a coma of toxic origin. Medical files showed that it was her second such episode to occur that month. Moreover, the family indicated signs of depression, incoherent behaviour and intake of “amphetamine-like” drugs. Clinical examination revealed a Glasgow coma score of 9, symmetrical reactive pupils with mydriasis and no convulsions. The patient presented with rapid respirations and her blood pressure was 93/53 mmHg. The ionogram and the blood gas analyses were normal, while the blood alcohol level was 0.167 g/dL. Urinalysis revealed the presence of benzodiazepines and a high concentration of amphetamines (methcathinone: 17.24 mg/L, ephedrine: 11.60 mg/L and methylephedrine: 11.10 mg/L). In addition, serum analysis revealed bromazepam (8.89 mg/L), methcathinone (0.50 mg/L) and methylephedrine (0.19 mg/L). This case showed that the consumption of bromazepam and alcohol altered the typical clinical symptoms of cathinone derivative intoxication, namely hypertension and convulsions. Methylephedrine, an impurity resulting from the alkylation of a primary amine, can be considered a chemical tag indicating fraudulent synthetic origin of the drug. This case describes a documented example of new addictive behaviour of “well-educated” people involving the intake of methcathinone, a postindustrial psychostimulant intentionally combined with an anticonvulsant benzodiazepine. However, this specific case suggests that in spite of a very high bromazepam concentration in presence of the potentiator alcohol, the vital respiratory function would be probably maintained, thanks to the association with methcathinone.

Benzodiazepine anticonvulsants accelerate and β-carboline convulsants decelerate the kinetics of [ 35S]TBPS binding at the chloride ionophore

The effect of flunitrazepam and DMCM was examined on the kinetics of [ 35S]t-butylbicyclophosphorothionate (TBPS) binding. The enhancing effect of flunitrazepam and the decreasing effect of DMCM on TBPS binding was due o non-equilibrium conditions. The anticonvulsant benzodiazepine increased both the association and dissociation rate constants. The convulsant β-carboline had the opposite effect. Benzodiazepine receptor ligands might affect the convulsant TBPS sites parallel with opening/closing of the chloride ionophores.