Zotepine

Zotepine-induced convulsive seizures in a chronic case of treatment resistant paranoid schizophrenia.[Pubmed:23543675]

Indian J Pharmacol. 2013 Jan-Feb;45(1):95-7.

Adverse effects to antipsychotics are varied, frequently intolerable, often serious and sometimes fatal in clinical practice. Seizures are one of these adverse effects. Almost all first and second generation antipsychotics elicit dose-dependent lowering of seizure threshold, indicating increased seizure risk at higher drug dosages. The adverse event of Zotepine induced seizure is published in few case reports. We report the occurrence of myoclonic seizure progressing to generalized tonic-clonic seizures with Zotepine along with clear temporal association of dose dependent modulation evident in this case.

An open-label, randomized, controlled trial of zotepine and risperidone for acutely ill, hospitalized, schizophrenic patients with symptoms of agitation.[Pubmed:24100785]

J Clin Psychopharmacol. 2013 Dec;33(6):747-52.

Acutely ill, schizophrenic patients frequently require management of agitation. This study was conducted to compare the efficacy of oral Zotepine and risperidone in hospitalized, acutely ill schizophrenic patients with symptoms of agitation.This was a 6-week, multicenter, randomized, open-label, parallel-group, flexible dosing study. Thirty-nine patients with schizophrenia (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) who met the criteria of a Positive and Negative Syndrome Scale (PANSS) total score of greater than or equal to 60 points, PANSS-excitement component (EC) score of greater than or equal to 14 points, and at least 1 PANSS-EC score of greater than or equal to 4 were randomly assigned to either the Zotepine or risperidone group. The primary outcome was a comparison of the change in the PANSS-EC total score from baseline to the end of the study between groups.There was no significant between-group difference in dropout rates (Zotepine, 15.8% [3/19]; risperidone, 20.0% [4/20]). The mean (SD) daily dose of Zotepine from baseline to study end point ranged from 127.6 (62.3) to 236.8 (74.2) mg/d; the corresponding values for risperidone ranged from 3.3 (1.6) to 4.8 (1.7) mg/d. There were no statistically significant differences in patient characteristics, PANSS total score, and PANSS-EC total score between the Zotepine and risperidone groups at baseline. Both groups showed significant reductions in the PANSS-EC total scores (Zotepine, -10.1 [4.7], P < 0.001; risperidone, -8.0 [5.3], P < 0.001) and PANSS total scores (Zotepine, -34.7 [15.8], P < 0.001; risperidone, -28.6 [14.3], P < 0.001). However, there were no significant differences in PANSS-EC total score (P = 0.265) and PANSS total score (P = 0.125) changes from baseline to study end point between the 2 treatment groups. Serum uric acid and prolactin decreased more in the Zotepine group than the risperidone group (P < 0.001 and P = 0.018, respectively).Zotepine seemed to be as effective as risperidone in treating hospitalized, acutely ill, schizophrenic patients with agitation, and had the advantages of lowering hyperuricemia and hyperprolactinemia. Double-blind, fixed dose studies with a larger sample size of acutely ill, schizophrenic patients with agitation are needed to confirm the study results.

Norzotepine, a major metabolite of zotepine, exerts atypical antipsychotic-like and antidepressant-like actions through its potent inhibition of norepinephrine reuptake.[Pubmed:20223878]

J Pharmacol Exp Ther. 2010 Jun;333(3):772-81.

The antipsychotic drug Zotepine [ZTP; 2-[(8-chlorodibenzo[b,f]thiepin-10-yl)oxy]-N,N-dimethylethan-1-amine] is known to have not only atypical antipsychotic effects but also antidepressive effects in schizophrenia patients. NorZotepine [norZTP; N-desmethylZotepine, 2-[(8-chlorodibenzo[b,f]thiepin-10-yl)oxy]-N-methylethan-1-amine] has been postulated to be a major metabolite of ZTP in humans. Here, we characterized norZTP through several in vitro studies and in animal models of psychosis, depression, and extrapyramidal symptoms (EPS) and compared the pharmacological profiles with those of ZTP. Although both compounds showed similar overall neurotransmitter receptor binding profiles, norZTP showed 7- to 16-fold more potent norepinephrine reuptake inhibition than ZTP. In a pharmacokinetic study, both ZTP and norZTP showed good brain permeability when administered individually in mice, although norZTP was not detected in either plasma or brain after intraperitoneal injection of ZTP. In the methamphetamine-induced hyperlocomotion test in mice, norZTP and ZTP showed similar antipsychotic-like effects at doses above 1 mg/kg i.p. In contrast, unlike ZTP, norZTP did not induce catalepsy up to 10 mg/kg i.p. norZTP significantly antagonized the hypothermia induced by reserpine [(3beta,16beta,17alpha,18beta,20alpha)-11,17-dimethoxy-18-[(3,4,5-trimethoxybenzo yl)oxy]yohimban-16-carboxylic acid methyl ester], suggesting in vivo inhibition of the norepinephrine transporter. In the forced-swim test, norZTP exerted an antidepressant-like effect at the effective doses for its antipsychotic action, whereas ZTP neither antagonized reserpine-induced hypothermia nor showed antidepressant-like effect. These results collectively demonstrate that norZTP exerts more potent inhibitory action than ZTP on norepinephrine transporters both in vitro and in vivo, presumably accounting for its antidepressant-like effect and low EPS propensity. Given that norZTP is the major metabolite observed in humans, norZTP may contribute to the unique clinical profiles of its mother compound, ZTP.

Effects of zotepine on extracellular levels of monoamine, GABA and glutamate in rat prefrontal cortex.[Pubmed:19371334]

Br J Pharmacol. 2009 Jun;157(4):656-65.

BACKGROUND AND PURPOSE: The atypical antipsychotic drug, Zotepine, is effective in treatment of schizophrenia and acute mania, but the incidence of seizures during treatment is higher than with other antipsychotics. In addition, the mechanisms underlying the clinical actions of Zotepine remain uncharacterized. EXPERIMENTAL APPROACH: The effects of intraperitoneal administration of Zotepine and haloperidol on the extracellular levels of noradrenaline, dopamine, 5-HT, GABA, and glutamate in the medial prefrontal cortex (mPFC) were compared. Neuronal activities induced by each drug in the ventral tegmental area (VTA), locus coeruleus (LC), dorsal raphe nucleus (DRN) and mediodorsal thalamic nucleus (MTN) were also analysed. KEY RESULTS: Haloperidol did not affect extracellular neurotransmitter levels in the mPFC. In contrast, Zotepine activated neuronal activities in all nuclei and increased the extracellular levels of noradrenaline, dopamine, GABA, and glutamate in the mPFC, but not 5-HT levels. The Zotepine-stimulated neuronal activity in the VTA, LC, DRN and MTN enhanced the release of dopamine, noradrenaline, 5-HT, glutamate and GABA in the mPFC, although the enhanced GABAergic transmission possibly inhibited noradrenaline, dopamine and 5-HT release. The other afferent to mPFC, which releases dopamine and noradrenaline, was partially insensitive to GABAergic inhibition, but possibly received stimulatory AMPA/glutamatergic regulation from the MTN. CONCLUSIONS AND IMPLICATIONS: Our results indicated that the positive interaction between prefrontal catecholaminergic transmission and AMPA/glutamatergic transmission from MTN might explain the regulatory effects of Zotepine on neurotransmitter release. A mechanism is suggested to account for the pharmacological profile of this atypical antipsychotic and for its pro-convulsive action.

Inverse agonist activity of atypical antipsychotic drugs at human 5-hydroxytryptamine2C receptors.[Pubmed:10991983]

J Pharmacol Exp Ther. 2000 Oct;295(1):226-32.

Clozapine is the prototype atypical antipsychotic drug, producing little or no extrapyramidal side effects, while improving negative symptoms of psychosis. Clozapine's high affinity for serotonin receptors has been hypothesized to confer the unique antipsychotic properties of this drug. Recently, we demonstrated that both typical and atypical antipsychotic drugs are inverse agonists at constitutively active 5-hydroxytryptamine2A (5-HT(2A)) receptors. To determine whether inverse agonist activity at 5-HT(2C) receptors plays a role in antipsychotic efficacy, typical and atypical antipsychotic drugs were tested for inhibition of basal inositol phosphate production in mammalian cells expressing rat or human 5-HT(2C) receptors. Atypical antipsychotic drugs (sertindole, clozapine, olanzapine, ziprasidone, risperidone, Zotepine, tiospirone, fluperlapine, tenilapine) displayed potent inverse agonist activity at rat and human 5-HT(2C) receptors. Typical antipsychotic drugs (chlorpromazine, loxapine, thioridazine, prochlorperazine, perphenazine, mesoridazine, trifluperidol, fluphenazine, spiperone, haloperidol, pimozide, penfluridol, thiothixene) were devoid of inverse agonist activity, with the exception of loxapine. We review the evidence that loxapine has unique properties characteristic of both atypical and typical antipsychotic drugs. Several typical antipsychotic drugs (chlorpromazine, thioridazine, spiperone, thiothixene) displayed neutral antagonist activity by reversing clozapine inverse agonism. These data suggest that 5-HT(2C) inverse agonist activity is associated with atypical antipsychotic drugs with moderate to high affinity for 5-HT(2C) receptors, and imply that effects of atypical antipsychotic drugs on the 5-HT(2C) receptor may play a role in their unique clinical properties. These data also imply that dysfunction of brain 5-HT(2C) receptor systems may be one of the factors involved in the etiology of psychosis.