[The stress-protective effect of fenazepam in rats with different capacities for escape in an acute aversive situation]

Stress-protective effect of phenazepam (1 mg/kg) was studied in rats with different ability to avoid acute aversive situation. Two types of extreme situations were created, immobilization and hyperkinesia (permanent running inside the wheel). It was found out that rats which easily avoided acute aversive situation (I group) were more resistant to extreme effects. In immobilization stress phenazepam produced protective effect mostly in rats with low ability to avoid acute stress situation (II group). In situation with hyperkinesia the drug did not essentially influence the state of rats of the II group and even aggravated the state of rats of the I group. It seems likely that stress resistance of animals and dissimilar protective effects of phenazepam are determined by distinctions in coping mechanisms.

Effect of chronic administration of hydrocortisone on the induction and evolution of acute pancreatitis induced by cerulein

The effects of chronic administration of hydrocortisone (10 mg/kg/day) on the development and evolution of acute pancreatitis induced by supramaximal stimulation with cerulein were examined in the rat. In these circumstances the potentially therapeutic effect of L-364,718, a CCK-receptor antagonist, was assayed. Administration of hydrocortisone over 7 days did not increase the severity of edematous acute pancreatitis induced by cerulein, since the reduction in pancreatic secretion, the hyperamylasemia and the increase in the levels of hematocrit and fluid in the pancreatic tissue were similar in rats with acute pancreatitis treated and untreated with hydrocortisone previously. When hydrocortisone was administered chronically, before administration of supramaximal doses of cerulein, a spontaneous regression of acute pancreatitis occurred. However, when hydrocortisone administration was continued after inducing pancreatitis, pancreatic recovery was prevented, observing a significantly depressed acinar secretion and elevated values of hematocrit and tissue fluid (edema). L-364,718 administration proved to be detrimental in the evolution of edematous acute pancreatitis when the rats had been treated chronically with hydrocortisone because the blockade exerted on secretion prevented the draining of enzymes stored in excess by hydrocortisone administration.

Clobazam in long-term epilepsy treatment: sustained responders versus those developing tolerance

Clobazam (CLB) is a structurally unique benzodiazepine (BZD) that has anticonvulsant activity in all types of refractory seizures. The main drawback to CLB, as to other BZDs, is the occurrence of tolerance. To date, there has been no way to predict which patients will develop tolerance. We compared clinical features and treatment variables between two groups of patients whose seizures were initially well controlled with CLB: patients with a sustained response and patients who developed tolerance. We retrospectively identified a group of 50 very good responders from among 173 consecutive patients with uncontrolled epilepsy treated with CLB. Very good responders were defined as patients with > 75% reduction in seizures after the addition of CLB who continued CLB treatment for at least 1 month. At a mean follow-up of 37.5 +/- 12.8 months, 25 patients continued to respond and 25 developed tolerance (mean follow-up 17.0 +/- 15.7 months). Tolerance was defined as a relapse to a level > or = 50% of pre-CLB seizure frequency after an initial very good response for a minimum period of 1 month, despite constant CLB dose and, when available, serum levels. There was no change in concomitant medication. Significant differences were noted between the two groups. The sustained response group had a shorter duration of epilepsy (mean 16.5 vs. 24.5 years, p = 0.015), a greater proportion of individuals with a known etiology for their epilepsy (48 vs. 16%, p = 0.006), and higher CLB levels (0.50 vs. 0.22 microM, p = 0.017), but no significant difference in N-desmethyl-CLB levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of the cholecystokinin receptor antagonist L-364,718 on pancreatitis induced by a deficient in choline and supplemented with ethionine (CDE) diet in the rat

The role of cholecystokinin (CCK) in the development of a necrotizing acute pancreatitis induced by a diet deficient in choline and supplemented with ethionine (CDE) has been evaluated in the rat by using a potent CCK receptor antagonist L-364,718. Acute pancreatitis was induced by administration of CDE diet for 14 days. L-364,718 administration was carried out by subcutaneous injections at dose of 0.1 mg/kg/day. Pancreatic exocrine secretion (flow, protein, amylase and trypsin outputs) in resting and under infusion of 1.25 microgram/kg/h of CCK-8 were used to evaluate the pancreatic functionality. Others parameters (serum amylase, percentage fluid in pancreas, haematocrit and mortality) evaluated the severity of pancreatitis. L-364,718 slightly reduced the mortality and the increases of percentage of fluid accumulated in pancreas in CDE diet acute pancreatitis. Basal and CCK stimulated pancreatic secretion was significantly depressed 36 hours after L-364,718 treatment. A slight response to CCK was observed. Nevertheless it was lower than usually observed in control rats. Our results demonstrate that in the rat, chronic L-364,718 treatment did not completely restore pancreatic activity in acute pancreatitis induced by CDE diet. Hence CCK cannot be considered as the main factor involved in the development of this pancreatitis model.

Characterization of the receptors and mechanisms involved in the cardiovascular actions of sCCK-8 in the pithed rat

1. The cardiovascular actions of cholecystokinin and related peptides were investigated in the pithed rat. The receptors and the mechanisms involved in these experiments were characterized. 2. Sulphated cholecystokinin octapeptide (sCCK-8, 0.1-100 nmol kg-1, i.v.) elicited a dose-dependent bradycardia and increase in mean arterial blood pressure. Neither gastrin-17 nor pentagastrin had any effect at concentrations up to 100 nmol kg-1. 3. Both the pressor response and bradycardia elicited by sCCK-8 were reduced by the selective CCKA receptor antagonists, devazepide (0.5-50 nmol kg-1) and lorglumide (1-7 mumol kg-1). The selective CCKB receptor antagonists, CI-988 (1 mumol kg-1) and L-365,260 (15 mumol kg-1) did not inhibit the effects of sCCK-8. 4. The pressor response induced with sCCK-8 was reduced by treatment with either phentolamine (3 mumol kg-1) or guanethidine (2 mumol kg-1) and was unaffected by treatment with propranolol, atropine or hexamethonium. The pressor response also persisted following bilateral adrenalectomy. 5. The bradycardia induced with sCCK-8 was unaffected by treatment with phentolamine, propranolol, guanethidine, atropine, hexamethonium or bilateral adrenalectomy. 6. The tetrapeptide of cholecystokinin (CCK-4) elicited a dose-dependent pressor response but did not induce bradycardia. The pressor response was unaffected by devazepide (50 nmol kg-1), L-365260 (15 mumol kg-1) or phentolamine (3 mumol kg-1). 7. In the pithed rat, sCCK-8 acted via CCKA receptors to increase arterial blood pressure indirectly, at least in part, through activation of alpha-adrenoceptors. The observed bradycardia was also mediated byCCKA receptors but possibly through a direct action on the heart.

The benzodiazepine receptor inverse agonist RO 15-3505 reverses recent memory deficits in aged mice

The benzodiazepine receptor partial inverse agonist RO 15-3505 was tested for its ability to improve impaired recent memory of aged mice. All mice successfully acquired a learning set for accurate identification of the correct arm of a T-maze and could perform with nearly 100% accuracy after 1-min delays. However, performance of the aged mice approached chance levels after 2-h delays. When injected just before testing on a series of 2-h retention tests, RO 15-3505 (from 2.5-3505 (from 2.5-10.0 mg/kg) resulted in a marked improvement of response accuracy. These results confirm the role of benzodiazepine receptor mechanisms in the modulation of memory processes, and suggest that the memory-facilitating effects RO 15-3505 or similar benzodiazepine receptor ligands may be generalized to aged rodents with impaired memory function.

Clobazam for intractable pediatric epilepsy

We report our experience with add-on clobazam therapy over a 5-year period in 63 children with refractory epilepsy. The mean duration of epilepsy was 6.7 years. Children were followed for 15 to 64 months. Of 63 children, 57 were developmentally delayed, and 54 had a symptomatic/cryptogenic epilepsy. Forty-one percent became either seizure free or had a greater than 90% reduction in seizure frequency. Seizure frequency was reduced 50% to 90% in another 24%. The average daily dose of clobazam was 0.8 mg/kg. Thirty-five percent had the medication withdrawn for persistent or unacceptable side effects or the development of tolerance (seven patients). Side effects included severe aggressive outbursts, hyperactivity, insomnia, and depression with suicidal ideation. Clobazam is a useful add-on medication for 65% of children with epilepsy. Clinical utility may be limited by behavioral side effects in some patients.

A placebo-controlled trial of L-365,260, a CCKB antagonist, in panic disorder

The functional role of cholecystokinin in the central nervous system is unknown. The tetra peptide CCK-4 was previously observed to induce panic attacks in a majority of normal volunteers and patients with panic disorder. Furthermore, it had been demonstrated that pretreatment with 10-50 mg of L-365,260, a selective CCKB antagonist, blocked CCK-4 induced panic in patients with panic disorder. Therefore, the present multicenter, placebo-controlled, double-blind trial was designed to investigate the efficacy of L-365,260, a CCKB antagonist, in patients with panic disorder with or without agoraphobia. Following a 1-week, single-blind placebo period, 88 patients were randomized to double-blind treatment in which they received either L-365,260, 30 mg qid, or placebo for 6 weeks. At the dose tested, there were no clinically significant differences between L-365,260 and placebo in global improvement ratings, Hamilton anxiety rating scale scores, panic attack frequency, panic attack intensity, or disability measures. The possible reasons for lack of effect with L-365,260 are discussed.

Hyperekplexia, a cause of neonatal apnea: a case report

We report a case of non-familial hyperekplexia which characteristically developed apnea and feeding difficulties in the neonatal period. The abnormal startle response was evident from the second week of life onwards. The infant showed a marked improvement of the startle response and muscle hypertonia with clonazepam. Clobazam was also tried with no apparent response. A prominent long latency C response was observed on EMG examination, suggesting a possible cortical neuronal hyperexcitability origin for the abnormal startle response observed in hyperekplexia.

Propranolol in startle induced epileptic seizures

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Adjunctive therapy in epilepsy: a cost-effectiveness comparison of alternative treatment options

A pharmaco-economic study of the administration of adjunctive therapy in patients with chronic epilepsy is described. A decision-analytic model has been used, which represents the consequences of treatment over a 1-year time period, when one of three drugs is used first. The cost-effectiveness ratio for clobazam, lamotrigine and vigabatrin have been calculated. The expected cost per patient of treatment over the 1-year period was up to 50% higher with vigabatrin and lamotrigine compared with clobazam, with a cost-effectiveness ratio around 40% higher.

Clobazam, oxcarbazepine, tiagabine, topiramate, and other new antiepileptic drugs

Clinical investigators recently have studied at least 21 new antiepileptic drugs (AEDs) in people with epilepsy. This review briefly examines 15 of these new AEDs: clobazam (CLB), dezinamide, flunarizine (FNR), loreclezole, milacemide (MLM), MK-801, nafimidone, ORG-6370, oxcarbazepine (OCBZ), progabide (PGB), ralitoline, stiripentol, tiagabine (TGB), topiramate (TPM), and zonisamide (ZNS). CLB, PGB, and TGB represent agents that act on the GABA system, and MLM acts on the glycine system. MK-801 and ZNS (in part) are excitatory amino acid antagonists, and FNR is a calcium-channel antagonist. OCBZ is a keto analogue of carbamazepine, which is not metabolized to the epoxide and may have fewer side effects. The remaining agents are novel compounds with a variety of suspected mechanisms. TPM appears especially effective for intractable partial seizures but has a high incidence of cognitive side effects. None of these new AEDs is useful for all patients with inadequate seizure control or ongoing toxicity. The role of each will require further clinical study and experience.

Treatment of "benign" partial epilepsies of childhood, including atypical forms

In a retrospective study the results of therapy in 60 children with so-called benign partial epilepsies are reported. It has been shown that the assessment of the therapeutic effect has to include the EEG, especially in epilepsies with atypical course. Carbamazepine has no effect on the EEG, in epilepsies with atypical course (atypical benign partial epilepsy, Landau-Kleffner syndrome, epilepsy with continuous spikes and waves during slow sleep [CSWS]) carbamazepine usually has no effect either on the seizures or on the EEG, on the contrary, in some cases both may even get worse. In our experience, the drug of choice in all types of benign childhood epilepsy is sulthiame, if necessary in combination with clobazam. Other drugs previously administered, including carbamazepine, should be dropped quickly. If the treatment with sulthiame or sulthiame/clobazam in children with atypical course is not effective, ACTH-therapy should be considered as soon as possible. These results should be confirmed in a prospective randomized study.

The CCKA receptor antagonist devazepide inhibits the effect of apomorphine on vasopressin release in pigs

1. A transient increase in plasma vasopressin concentrations represents a physiological correlate of nausea in animals that vomit. 2. The CCKA receptor antagonist devazepide has previously been shown to inhibit vasopressin release induced in pigs by intravenous (i.v.) CCK. 3. This study investigated whether devazepide (70 micrograms/kg i.v.) would affect vasopressin secretion induced in pigs (n = 6) by the emetic drug apomorphine (25 micrograms/kg i.v.). 4. Apomorphine stimulated vasopressin release in the 30 min period following injection; this effect was prevented by prior administration of devazepide. 5. The results suggest that CCKA receptor antagonists may have the ability to prevent nausea and/or emesis.

In vivo modulation of cisplatin cytotoxicity by the cholecystokinin antagonist MK-329 in human pancreatic cancer xenografts

We have previously reported that the cholecystokinin antagonist MK-329 (also known as L-364,718 or devazepide) synergistically enhances sensitivity to cisplatin (DDP) in MIA-PaCa2 human pancreatic cancer cells in tissue culture. In this study, we examined the ability of MK-329 to modulate DDP sensitivity in vivo using MIA-PaCa2 pancreatic cancer xenografts growing subcutaneously in athymic nude mice. Twenty-four hours after tumor inoculation, mice received either DDP intraperitoneally, MK-329 subcutaneously, both DDP and MK-329 or drug vehicles alone. Both DDP and MK-329 alone caused a reduction in the rate of tumor growth. The combination of DDP and MK-329 resulted in enhanced tumor growth delay compared to DDP or MK-329 treated mice. Although MK-329 alone was not nephrotoxic, the addition of MK-329 to DDP treatment resulted in a significant increase in weight loss and nephrotoxicity compared to mice treated with DDP alone; this was reflected by an increase in the plasma BUN levels. Although we believe that the enhanced anti-tumor effect of DDP/MK-329 combination therapy may be independent MK-329's capability to block CCK receptors, the role of CCK receptor blockade in potentiating DDP-induced nephrotoxicity less clear.

Effects of bretazenil vs. zolpidem and placebo on experimentally induced sleep disturbance in healthy volunteers

The effects of bretazenil 0.25 and 0.5 mg, a partial agonist at the benzodiazepine receptor, on sleep electroencephalogram (EEG), subjective sleep quality and morning psychomotor performance were compared to zolpidem 10 mg and placebo using noise as an experimental sleep disturbing factor in a single dose, double-blind, crossover study. Twelve healthy volunteers were subjected to prerecorded traffic noise with a mean sound level of 52 dB(A) during eight hours in bed. Significant effects of noise were found on sleep electroencephalogram (EEG) parameters (rapid eye movement [REM] sleep, stage 2 sleep and number of arousals), and subjective sleep quality assessments, but not on psychomotor performance (choice reaction time, digit span memory, and symbol digit substitution). Both drugs reduced the number of shifts between sleep stages and the number of arousals and increased REM sleep latency. Only after 0.5 mg bretazenil, stage 2 sleep increased and REM sleep decreased. Both doses of bretazenil significantly affected performance in the symbol digit substitution test. Sleep quality improved under drug treatments compared to placebo. The results suggest that experimental sleep disturbance can be a valuable tool in the investigation of potential sleep promoting compounds.

Clobazam in the treatment of epilepsy: a review of the literature

The literature was reviewed to define the role of clobazam (CLB) in the treatment of epilepsy. CLB is an effective antiepileptic drug (AED) in most varieties of seizures and epilepsies for both short-term and long-term treatment. Tolerability of CLB is satisfactory, better than for conventional benzodiazepines. CLB has no significant interaction with other drugs. Tolerance may develop, but this aspect may have been overemphasized: a long-term benefit figure of 28% can be expected without tolerance. When CLB maintains efficacy, patients continue to benefit for years without drug dependence or unwanted side effects. CLB appears to be a useful treatment for epilepsy as intermittent or short-term add-on therapy; but it should also be tried as long-term therapy in some situations, especially as add-on therapy for patients with refractory epilepsy, as add-on or monotherapy for patients with anxiety, or in some women in association with oral contraceptives.

Benign familial nocturnal alternating hemiplegia of childhood

In infancy, two brothers developed recurrent attacks of alternating or bilateral hemiplegia arising exclusively out of sleep. The episodes were terminated by even brief sleep. Neither child had hypotonia, dystonic attacks, paroxysmal eye movement abnormalities, or other features characteristic of the now-classic form of alternating hemiplegia of childhood (AHC). The development of the brothers has so far remained normal. Both parents have a history of migraine. In the older boy, magnetic resonance spectroscopy (MRS) of muscle showed increased inorganic phosphate similar to what is found in children with AHC. In the younger brother and parents, MRS of muscle was normal. Other investigations were unrevealing. Flunarizine greatly reduced the duration of attacks. This genetically determined disorder represents a specific entity that is probably migraine-related and is easily misdiagnosed as AHC. Because of its benign course, particularly as far as mental development is concerned, it must be distinguished from classic AHC, which has a terrible prognosis.

Clobazam for treatment of intractable epilepsy: a critical assessment

Clobazam (CLB), a 1,5-benzodiazepine, is a remarkably effective add-on drug for individual patients with refractory partial epilepsy. CLB has an excellent safety record. As with all benzodiazepines used for treating epilepsy, sedation and withdrawal effects, together with the development of tolerance, limit its usefulness. Recent efforts to prevent or reverse tolerance with intermittent administration of CLB or periodic injection of a benzodiazepine antagonist, flumazenil, are encouraging and justify further investigations.

Benzodiazepine receptor ligands modulate ethanol drinking in alcohol-preferring rats

The effects of benzodiazepine receptor ligands with different intrinsic activity profiles were studied on voluntary ethanol consumption in the selectively bred alcohol-preferring AA (Alko, Alcohol) rat line, and compared to those of an opiate antagonist, naloxone, and a serotonin uptake inhibitor, citalopram. The rats were first allowed to develop a strong preference for 10% (v/v) ethanol solution in tap water over plain water until their ethanol consumption stabilized. Thereafter, the period when ethanol solution was available for the rats was gradually reduced to 4 h, 3 times a week, every second working day. The acute effects of positive allosteric modulators (agonists) of the gamma-aminobutyric acid type A (GABAA)/benzodiazepine receptor [midazolam, abecarnil, ethyl 5-benzyloxy-4-methoxymethyl-beta-carboline-3-carboxylate (ZK 91296), bretazenil, and 2,5-dihydro-2-(4-methylphenyl)-3H-pyrazolo[4,3-C]quinolin-3(5H)-on e (CGS 9895)] and of negative allosteric modulators [inverse agonists, ethyl 8-azido-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5- a][1,4]benzodiazepine-3-carboxylate (Ro 15-4513) and t-butyl 5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a]thieno[2,3- f][1,4]diazepine-3-carboxylate (Ro 19-4603)] were tested after i.p. injections of three different drug doses using saline injections as a control treatment. The benzodiazepine agonists had rather modest effects on ethanol intake, measured 1 and 4 h after the injections, whereas the inverse agonists and naloxone strongly decreased ethanol consumption. Acute citalopram had no clear effect on ethanol drinking, but it slightly decreased the consumption of novel food during the 4-h session, as did all other benzodiazepine agonists except bretazenil. Neither the inverse agonists nor naloxone had any significant effect on food intake.(ABSTRACT TRUNCATED AT 250 WORDS)

Aggression in children treated with clobazam for epilepsy

Seven of 63 children (11%) treated with clobazam (CLB) for refractory epilepsy developed a severe behavior disorder. This disorder was characterized by aggressive agitation, self injurious behavior, insomnia, and incessant motor activity occurring between 10 and 55 days after initiation of drug therapy. The affected children were relatively young (mean age 6.4 years) and developmentally disabled (four were autistic and two had isolated mental retardation). The disorder occurred with a short latency after initiation of therapy and at a relatively low dosage of CLB. Serum levels of other coadministered antiepileptic drugs were unchanged by the administration of CLB. One child was taking CLB monotherapy. This behavioral deterioration required the discontinuation of CLB, after which patients returned to their previous behavior within 3 weeks. After > 3 years of follow-up all children continue to require multiple antiepileptic drugs but have not had a recurrence of this aggressive agitation. The mechanism of the behavioral change is unclear.

Therapeutic and protective effect of subcutaneous injections of L-364,718 on caerulein-induced acute pancreatitis

The prophylactic and therapeutic effects of a potent cholecystokinin (CCK) receptor antagonist, L-364,718, on acute pancreatitis induced by caerulein were evaluated, analyzing morphologic and functional pancreatic parameters jointly. Edematous pancreatitis was induced by four subcutaneous injections of caerulein (20 micrograms/kg) in rats at 1-h intervals. Prophylactic administration of L-364,718 (0.1 mg/kg) prevented rise in serum amylase levels, interstitial edema, vacuolization, and impairment of pancreatic enzyme secretion that accompany caerulein-induced acute pancreatitis. After 7 days, a spontaneous regression of the morphologic alterations caused by caerulein-induced acute pancreatitis occurs; however, recovery of the secretory function of the pancreas was only reached after this period of time when L-364,718 was administered therapeutically (0.1 mg/kg/day). Prophylactically or therapeutically administered, L-364,718 exerts a beneficial effect on caerulein-induced acute pancreatitis, indicating that CCK (exogenous or endogenous) plays an important role in the development of this pathology.

Investigational antiepileptic drugs for the treatment of childhood seizure disorders: a review of efficacy and safety

Pediatric epileptology is very different from adult epileptology. Although some epileptic disorders occur in both children and adults (e.g., localization-related epilepsy with complex partial seizures and primary generalized epilepsy with tonic-clonic seizures), other disorders can be called the catastrophic epilepsies of childhood (e.g., infantile spasms and the Lennox-Gastaut syndrome). They occur, or at least begin, exclusively in childhood and are often associated with mental retardation. Many of these pediatric disorders are notoriously unresponsive to currently available antiepileptic drugs (AEDs). Although there are undoubtedly many reasons for this, one possible explanation is that the methods used to screen potential AEDs use animal models of adult epilepsy. No screening program uses an animal model of seizures that begin during development and lead to functional decline.