Effects of S-0509, a novel CCKB/gastrin receptor antagonist, on acid secretion and experimental duodenal ulcers in rats

BACKGROUND

S-0509, 2-[(tert-butoxycarbonylmethyl) [(m-(carboxy-phenyl)-ureidomethyl-carbonyl]] aminobenzo phenone, was developed as a potent and selective CCKB/gastrin receptor antagonist that does not affect the central nervous system.

METHODS

We evaluated the effects of S-0509 on gastric acid secretion and duodenal ulcerogenic and healing responses in rats comparing it with L-365,260, another CCKB/gastrin receptor antagonist.

RESULTS

S-0509 (0.1 approximately 10 mg/kg, i.d.) was able to dose-dependently decrease basal acid secretion and inhibit the acid secretory responses induced by both pentagastrin (60 microg/kg/h, i.v.) and peptone (10%, i.g.) but not histamine (4 mg/kg/hr, i.v.) or carbachol (60 microg/kg/h, i.v.). L-365,260 (10 and 30 mg/kg, i.d.) caused only partial a suppression of the acid secretory response to pentagastrin but not to other stimuli, including peptone treatment. On the other hand, a duodenal ulcerogen, mepirizole (200 mg/kg, s.c. ) caused an increase in acid secretion and resulted in penetrating ulcers in the proximal duodenum, and these ulcers gradually healed over 3 weeks. S-0509 significantly inhibited both the acid secretory (> 1.0 mg/kg, i.d.) and ulcerogenic (> 3 mg/kg, p.o.) responses induced by mepirizole when it was given as a pre-treatment. It also promoted significantly the healing of these ulcers (> 3 x 2 mg/kg, p. o.) when it was given twice daily for 14 days. In contrast, L-365, 260 (30 mg/kg) tended to reduce the severity of mepirizole-induced duodenal ulcers, with a slight inhibition of acid secretion, but it caused no influence on the healing response of these ulcers.

CONCLUSION

These results confirmed that S-0509 is a selective CCKB/gastrin receptor antagonist with potent antisecretory action in vivo conditions, and further demonstrated that this agent not only prevents the development of duodenal ulcers but also shows healing promoting action on duodenal ulcers, probably through the blockade of CCKB/gastrin receptors.

Carbamazepine intoxication with negative myoclonus after the addition of clobazam

We report a case a carbamazepine (CBZ) intoxication with negative myoclonus that occurred 4 weeks after clobazam (CLB) had been added to a stable regimen of CBZ and topiramate (TPM). Both CBZ and CBZ-epoxide (CBZ-E) blood levels were elevated, and the symptoms resolved quickly when CBZ dosage was reduced and CLB discontinued. CLB was reintroduced a year later with the patient's consent, and the time course of the interaction was studied: CBZ and CBZ-E levels increased slowly over 12 days. The interaction is thus probably related to the progressive increase in Nor-CLB.

Clobazam has equivalent efficacy to carbamazepine and phenytoin as monotherapy for childhood epilepsy. Canadian Study Group for Childhood Epilepsy

PURPOSE

To compare the effectiveness of monotherapy clobazam (CLB) to carbamazepine (CBZ) and phenytoin (PHT) in children with epilepsy.

METHODS

Children aged 2-16 years with newly diagnosed epilepsy or previous failure of one drug (for poor efficacy or side effects) were assigned to one of two study arms and then randomized--CLB versus CBZ or CLB versus PHT. Eligible children had partial epilepsies or only generalized tonic-clonic seizures. After a drug initiation protocol, monotherapy treatment mimicked the usual routines used by Canadian child neurologists. Blinding used a "double dummy" technique with blinded medication serum levels (6-point scale). Intention to treat analysis using survival curves assessed the primary endpoint--length of retention on the initial medication during the year after randomization.

RESULTS

Fifteen centers entered 235 patients: 159 randomized to CLB versus CBZ and 76 to CLB versus PHT. Altogether, in all study arms, 119 received CLB, 78 CBZ, and 38 PHT. Overall, 56% continued to receive the original medication for 1 year with no difference between CLB and standard therapy (CBZ and PHT). Seizure control was equivalent for all three medications, as were side effects. PHT and CBZ induced more biologic side effects, such as rash, while CLB induced slightly more behavioral effects. Tolerance developed in 7.5% of patients receiving CLB, 4.2% with CBZ and 6.7% with PHT.

CONCLUSIONS

CLB should be considered as "first line" monotherapy along with CBZ and PHT for all partial and selected generalized childhood epilepsies.

Antiepileptic drug treatment following temporal lobectomy

Antiepileptic drug use was documented before and after temporal lobectomy. Carbamazepine, phenytoin, and clobazam were the most commonly used drugs, both pre- and postoperatively. Preoperatively, polytherapy was used in 78% of patients; at 6 months follow-up, 47%; at 12 months, 18%; and at 24 months, 14%. Preoperatively, monotherapy was used in 20% of patients; at 6 months follow-up, 49%; at 12 months, 55%; and at 24 months, 42%. No medication was used preoperatively by 2% of patients; at 6 months follow-up, 2%; at 12 months, 27%; and at 24 months, 44% (p < 0.001). After 2 years, 53% of patients who were seizure free had stopped taking medication, as had 33% who had some seizures after surgery.

The selective cholecystokininB receptor antagonist L-365,260 diminishes the expression of naloxone-induced morphine withdrawal symptoms in normal and neuropathic rats

The ability of a pretreatment with the cholecystokininB-receptor (CCK[B]) antagonist L-365,260 to prevent the development of morphine dependence was studied in normal and neuropathic (unilateral peripheral neuropathy) rats. A 4-day pretreatment regimen with two daily s.c. injections of either saline+saline, saline+morphine (3.0 mg/kg) or L-365,260 (0.2 mg/kg)+morphine was used, and withdrawal was precipitated by an injection of naloxone (1.0 or 2.0 mg/kg i.v.) at 24 h after the last pretreatment injection. After pretreatment with morphine alone, physical dependence developed in both normal and neuropathic rats. However, the incidence of teeth chattering and ptosis was higher in neuropathic rats. Pretreatment with the combination of L-365,260 and morphine prevented the expression of teeth chattering, ptosis, diarrhea, writhing and piloerection, but was devoid of effects on the exploratory activity among both groups of rats. These results suggest that endogenous CCK acting on CCK(B)-receptors may be involved in the development of morphine dependence both in normal and neuropathic rats.

Treatment of febrile seizures with intermittent clobazam

Fifty children, 24 female and 26 male, with ages varying from 6 to 72 months (mean = 23.7 m.) that experienced at least one febrile seizure (FS) entered a prospective study of intermittent therapy with clobazam. Cases with severe neurological abnormalities, progressive neurological disease, afebrile seizures, symptomatic seizures of other nature, or seizures during a central nervous system infection were excluded. Seizures were of the simple type in 25 patients, complex in 20 and unclassified in 5. The mean follow-up period was 7.9 months (range = 1 to 23 m.), and the age at the first seizure varied from 5 to 42 months (mean = 16.8 m.). Clobazam was administered orally during the febrile episode according to the child's weight: up to 5 kg, 5 mg/day; from 5 to 10 kg, 10 mg/day; from 11 to 15 kg, 15 mg/day, and over 15 kg, 20 mg/day. There were 219 febrile episodes, with temperature above 37.8 degrees C, in 40 children during the study period. Twelve children never received clobazam and 28 received the drug at least once. Drug efficacy was measured by comparing FS recurrence in the febrile episodes that were treated with clobazam with those in which only antipyretic measures were taken. Ten children (20%) experienced a FS during the study period. Of the 171 febrile episodes treated with clobazam there were only 3 recurrences (1.7%), while of the 48 episodes treated only with antipyretic measures there were 11 recurrences (22.9%), a difference highly significant (p < 0.0001). Adverse effects occurred in 10/28 patients (35.7%), consisting mainly in vomiting, somnolence and hyperactivity. Only one patient had recurrent vomiting which lead to drug interruption. These effects did not necessarily occurred in every instance the drug was administered, being present in one febrile episode and not in the others. We conclude that clonazepam is safe and efficacious in preventing FS recurrence. It may be an alternative to diazepam in the intermittent treatment of FS recurrence.

[The therapeutic efficacy and the effect of gidazepam and fenazepam on the psychophysiological status and on the performance of operators with mental disorders at a neurotic level]

The effect of placebo and gidazepam on the state, psychophysiological predictors of the quality of the operator's performance and its results in individuals with neurotic reactions was studied (test dose 20 mg 7-day course, 40 mg daily, 24 individuals), as well as the effect of gidazepam and phenazepam (42 individuals with neurotic and neurosis-like states; gidazepam test doses 20 and 50 mg, 14-day course, 40 and 100 mg daily; phenazepam test doses 0.5 and 1 mg, 14-day course, daily dose 2 mg). The generally accepted methods of clinical and psychophysiological examination were applied. Gidazepam in the doses under study did not yield to phenazepam in therapeutic activity. A single and a course administration of gidazepam improved the parameters of the psychophysiological state and the efficacy of the operator performance in patients with neurotic reactions and in those with neurotic and neurosis-like states. This makes it possible, whenever necessary, to recommend this drug for the treatment of the indicated disorders in the working operators.

Neurosteroid coadministration prevents development of tolerance and augments recovery from benzodiazepine withdrawal anxiety and hyperactivity in mice

Neurosteroids are potent and specific modulators of the GABAA receptors which regulate the neuronal activity through diverse neurotransmitter mechanisms. In the present study we investigated the effects of concomitant treatment with various neurosteroids on the development of tolerance and recovery from withdrawal anxiety and hyperactivity to chronic benzodiazepines. Long-term treatment of mice with full allosteric modulator (triazolam 0.25 mg/kg/day for 8 days) or selective allosteric modulator (diazepam 20 mg/kg/day for 21 days) of GABAA receptor induced tolerance to behavioral sedation on actimeter and anxiolytic effects on plus-maze, and produced a marked withdrawal anxiety and hyperactivity syndrome upon abrupt cessation of treatment, respectively. Concomitant progesterone (10 mg/kg, s.c.), a neurosteroid precursor, of 4'-chlordiazepam (0.25 mg/kg, i.p.), a mitochondrial diazepam binding inhibitor (DBI) receptor (MDR) ligand, prevented the development of tolerance and significantly augmented the recovery from withdrawal-induced anxiety and hyperlocomotion to diazepam. When administered alone for 21 days, neither progesterone nor 4'-chlordiazepam produced any per se effects on actimeter or plus-maze when tested on post-withdrawal days. Coadministration of neurosteroid allopregnanolone (AP) (0.25 and 0.5 mg/kg), or pregnenolone sulfate (PS) (2 mg/kg), but not dehydroepiandrosterone sulfate (2 mg/kg), abolished the development of tolerance and attenuated withdrawal-induced anxiety and hyperlocomotion due to triazolam, without producing any per se behavioral effects when tested at 1 and 2 days after the last injection. Coadministration of flumazenil (5 mg/kg), progesterone (10 mg/kg), 4'-chlordiazepam (0.25 mg/kg), hydrocortisone (100 mg/kg) or nifedipine (2 mg/kg) also prevented the development of tolerance and suppressed the triazolam withdrawal syndrome. However, pretreatment with PK11195 (2 mg/kg), a MDR partial antagonist, reversed the effects of 4'-chlordiazepam on triazolam tolerance and recovery from chronic triazolam. When injected simultaneously, nifedipine, a Ca2+ channel antagonist, potentiated the progesterone- and 4'-chlordiazepam-induced attenuation of triazolam tolerance and withdrawal behavior. These findings suggest that coadministration of neurosteroids allopregnanolone, pregnenolone sulfate and progesterone, and MDR ligand 4'-chlordiazepam prevents the development of tolerance to benzodiazepines and augments the recovery from chronic benzodiazepines. These results indicate that coadministration of neurosteroids may facilitate discontinuation of benzodiazepines in long-term therapy.

[Newly-developing therapies of pancreatic cancer--immunotherapy, gene therapy, differentiation therapy, endocrine therapy and others]

Pancreatic cancer is extremely resistant to various cancer therapies, however, variety of new therapies for pancreatic cancer have been investigated: (1) immunotherapy including cytokines like TNF, adoptive immunotherapy with lymphokine-activated killer cells or cytotoxic T-lymphocytes, and tumor vaccines using mutated Ki-ras oncoprotein or irradiated tumor cells which were transfected by cytokine genes; (2) gene therapy including transfer of cytokine genes or antisense Ki-ras oncogene, and a combination of gene transfer of herpes simplex virus thymidine kinase and subsequent administration of ganciclovir; (3) differentiation therapy including a quinolinone derivative, vesnarinone; (4) endocrine therapy including cholecystokinin-receptor antagonist, CR1505 or L364,718; (5) heavy water, and etc. All of these therapies will be applied for the treatment of pancreatic cancer in the near future.

Interactions of clobazam with conventional antiepileptics in children

Clobazam is a 1,5-benzodiazepine effective in antiepileptic therapy of children and adults. Presently it is mainly used as adjuvant therapy for intractable seizures. Our objective was to evaluate the effect of clobazam on the apparent clearance of other antiepileptic drugs at steady state, and to determine the factors that determine the plasma levels of clobazam and its active metabolite N-desmethylclobazam. Patients were 74 children with intractable seizures who received treatment with clobazam at our institution as part of the Canadian Cooperative Clobazam Study Group during the years 1987 to 1991. Serum concentrations of clobazam, N-desmethylclobazam, and of concomitant antiepileptic drugs were monitored and prospectively collected. The effect of clobazam treatment on the apparent clearance steady state of the other antiepileptic drugs was determined by statistical comparison of the clearances of each drug before and after initiation of clobazam treatment using Wilcoxon's signed rank test. The effects of dosage, age, and concomitant antiepileptic therapy on the levels of clobazam and N-desmethylclobazam was assessed by multivariate analysis. Response to treatment and incidence of adverse effects were evaluated for each conventional antiepileptic drug to possibly identify favorable or unfavorable combinations with clobazam. Whereas the clearances of most conventional antiepileptics are not affected by cotherapy with clobazam, the apparent clearances of valproic acid and primidone are significantly reduced in the presence of clobazam. Serum concentrations of clobazam increased with dosage and age, and decreased with phenobarbital cotherapy. Serum concentrations of N-desmethylclobazam significantly correlated with clobazam serum levels, age, or clobazam dosage and were significantly increased by cotherapy with phenytoin or carbamazepine. None of the concomitantly used drugs were associated with increased or decreased rate of seizure control. Twelve patients experienced mild adverse drug effects that were not associated with particular cotherapy, clobazam dose, or plasma concentrations. When clobazam is added to a therapy regimen that includes valproic acid, the patient should be closely followed for possible adverse drug reactions caused by elevated valproic acid serum concentrations, and monitoring of valproate serum levels should be considered. When clobazam doses are gradually increased to achieve an optimal clinical effect, the interactions with phenobarbital, carbamazepine, and phenytoin do not necessitate therapeutic drug monitoring of clobazam or N-desmethylclobazam, because there is a large therapeutic window and a poor correlation between plasma concentrations and therapeutic efficacy.

[Differences in the effects of piracetam and fenazepam in emotional stress caused by the spatial reversal of a habit]

Emotional stress was caused in rats by changing the location of the gate in the shuttle chamber through which training had been accomplished in the previous experiments. The procedure led to disorder of the avoidance response (AR) and increase of intertrial responses (ITR). Phenazepam (0.1 mg/kg) prevented increase in the number of ITS. Piracetam (300 mg/kg) reduced the sharp growth of ISR but, in contrast to phenazepam, it provided a higher level of AR reproduction. The ISR were greater in piracetam than in phenazepam administration. The obtained results show that the suggested model allows the difference in the effects of piracetam and phenazepam to be disclosed.

[Treatment of the epilepsy: new drugs]

New advances in the knowledge on the physiopathogenesis of epilepsy and their relationship with sodium and calcium channels and with the excitatory and inhibitory neurotransmitters actions have recently been developed. These knowledges have produced the research on new antiepileptic drugs which action places have specially based on the known impaired mechanisms. As the conventional drugs, the new therapeutic tool have produced a great advance in the therapy of epileptic events, specially in the refractory seizures, which represent 25-30% of the whole group of epilepsies. In the present work, we review the new drugs, ones have been registered, in order to their pharmacological properties, their efficacy their safety and their clinical indications as first-election or adjuvant drugs. We also discuss their known side adverse effects.

Effects of clobazam and its active metabolite on GABA-activated currents in rat cerebral neurons in culture

PURPOSE

The antiepileptic effects of clobazam, a 1,5-benzodiazepine, have been well documented in animal experiments and clinical trials. However, the drug's mechanisms of antiepileptic actions are still undetermined. The purpose of this study was to learn how clobazam and its active metabolite modulate gamma-aminobutyric acid (GABA)-activated currents in rat cerebral neurons in culture.

METHODS

Whole-cell voltage-clamp recordings were performed on cultured cerebral neurons of the rat. Clobazam or its metabolite N-desmethylclobazam was dissolved in the extracellular solution and applied for 2 s by pressure ejection from a micropipette. To maintain GABA-activated currents, 2 mM Mg adenosine triphosphate (ATP) was added to the intracellular solution.

RESULTS

GABA elicited outward currents that were mediated by GABAA receptor-coupled Cl- channels. Applying clobazam with 10 microM GABA elicited enhanced outward currents. Flumazenil, an antagonist of the benzodiazepine receptor, inhibited the enhancing effect of clobazam. The enhancement ratio increased as much as 2.28-fold in a dose-dependent manner at a concentration of 3 microM clobazam. However, it started to decrease at a concentration of 10 microM clobazam. The metabolite N-desmethylclobazam was tested in the same manner, and exhibited an identical dose-dependent enhancement of GABA-activated currents.

CONCLUSIONS

The antiepileptic effects of the 1,5-benzodiazepines are attributed to the enhancement of GABAergic inhibitory neurotransmission. The antiepileptic effects of clobazam are thought to depend mainly on its active metabolite N-desmethylclobazam, which is present in high concentrations in patients who receive long-term clobazam. Clobazam's enhancement of GABA-activated currents was most marked on weaker GABA currents. We therefore infer that clobazam acts more efficiently on tissues in which the release of GABA is diminished.

[The effect of benzodiazepine derivatives on the formation of brain edema-swelling in the dynamics of the posttraumatic period]

In experiments on rats the influence of diazepam, cinazepam, and phenazepam (0.5 mg/kg, intraperitoneally) on the development of brain edema in the dynamics of acute craniocerebral injury was studied. The diazepam and phenazepam prevented the development of brain edema in the post-traumatic period. The antiedematous effect of benzodiazepines was connected with their influence on metabolism of the brain.

A new design of trial for hypnotics comparison: a double-blind cross-over trial with patient's preference assessment and continuation of the preferred treatment

1. This study compared two hypnotics administrated at comparable therapeutic dosages: triazolam (0.25 mg) and loprazolam (1 mg), were administered using an original scheme (cross-over on the first 2 nights, and continuation of the preferred treatment or new randomization). 2. Sixty-seven outpatients complaining of common insomnia participated in this study conducted by general practitioners. 3. Both drugs provided improvement in sleep quality (decreased sleep latency, increased total duration of sleep, decreased number of night awakenings), and are equally well tolerated. 4. For the first 2 nights, triazolam was evaluated to be more efficient than loprazolam (p < 0.001), and patients felt more rested the following day (p < 0.01) with the former drug. Moreover, triazolam is more frequently preferred than loprazolam by 47.7% and 29.2%, respectively, (p = 0.09). 5. No interaction was found between treatment and order of administration or specific effects and order of administration.

Effectiveness and tolerance of clobazam in temporal lobe epilepsy

INTRODUCTION

The main objective of this retrospective study was the further exploration of the loss of efficiency of the clobazam therapy (CLOB tolerance) in resistant temporal lobe epilepsy (TLE).

MATERIAL AND METHODS

For up to 42 months we closely followed the state of 55 TLE patients placed on CLOB as an add-on therapy. Also, we sought for a connection between CLOB tolerance and clinical characteristics.

RESULTS

By the end of the 1st month 71% of the patients were seizure-free; 20% improved; 3% relapsed totally and 6% did not respond at all. After 24 months 15% were seizure-free, 11% maintained the original improved state, 36% relapsed totally and 32% partially--which remained unchanged thereafter. Long-term efficiency was in inverse proportion to the pretreatment interictal spike activity. No significant cross-tolerance was noted between CLOB and clonazepam.

CONCLUSION

Although the problem of CLOB tolerance is hardly overestimated, the use of CLOB in the treatment of TLE deserves consideration--despite the possibilities new drugs offer.

Influence of acupuncture and pharmacotherapy on sensitivity of sensory systems to alcohol irritants in patients with alcoholism

The sensitivity of an alcoholic's sensory systems (SS) to alcohol therapy is a good indication of treatment efficacy in this disease. In this study, we compare pharmacotherapy (PHT) and acupuncture therapy (AP) on the sensitivity of visual (VL), acoustic (AC), olfactory (OL) and taste (TS) systems to alcohol irritants (AI). The results showed that PHT changed the threshold sensitivity of SS to AI but did not cause aversion of SS to AI. In acupuncture treatment, results can be divided into four groups: Group 1, no aversion of AC was produced to AI; Group 2, no aversion of TS and OL were produced to AI; Group 3, no aversion of VL to AI; and group 4, no aversion was recorded to AI. Supposedly, one of the sensory systems of the organism is genetically leading in organizing sensory-emotional operation of information, and other SS are subordinates. Therefore, before acupuncture treatment for alcoholism, it is necessary to cause excitation to the ethanol-dependent system (target-system) by means of irritation to the leading sensory system of the patient.

Regulation of morphine antiallodynic efficacy by cholecystokinin in a model of neuropathic pain in rats

Neuropathic pains have often been classified as opioid-resistant. Here, spinal (intrathecal) actions of morphine and nonmorphine opioids have been studied in a nerve ligation model of neuropathic pain in rats. Mechanical allodynia was evaluated using von Frey filaments. Nerve-injured animals exhibited allodynia that was stable for up to 6 weeks after the surgery. Morphine did not alter allodynia at doses up to 300 nmol (100 micrograms). In contrast, [D-Ala2, NMPhe4, Gly-ol]enkephalin (DAMGO), a high-efficacy mu opioid agonist, produced a significant, dose-related antiallodynic action. [D-Ala2, Glu4]deltorphin (delta agonist) produced a significant antiallodynic effect only at 300 nmol, reaching approximately 70% of the maximum. Coadministration of morphine with a dose of [D-Ala2, Glu4]deltorphin, which was inactive alone, produced a significant and long-lasting antiallodynic action that was antagonized by NTI (delta receptor antagonist); NTI alone had no effect. Although blockade of cholecystokinin-B (CCKB) receptors with L365,260 did not produce effects alone, a significant antiallodynic action was observed when coadministered with morphine; this elevation of nociceptive threshold was abolished by NTI. The finding that DAMGO, but not very large doses of morphine, produced antiallodynic actions suggests that the ability of mu opioids to alleviate the allodynia is related, in part, to efficacy at postsynaptic mu receptors. At an inactive dose, a delta agonist or a CCKB antagonist enhanced morphine antiallodynic efficacy in an NTI-sensitive fashion. CCKB receptor blockade may enhance endogenous enkephalin actions, resulting in enhancement of morphine efficacy through a mu-delta receptor interaction.