Clozapine: a novel antipsychotic agent

Consequences of Antipsychotic Medications on Mental Health

Individuals suffering from mental illnesses, unfortunately, have a shorter lifespan. The increase in mortality rates is primarily due to physical illness, unhealthy lifestyle, and associated comorbidities. Antipsychotic medications, previously known as tranquilizers, antipsychotics, or neuroleptics, can alleviate or attenuate symptoms related to psychosis, delusion, and/or hallucinations and are used in the treatment of psychosis, schizophrenia, bipolar disorder, depression, or Alzheimer's disease. Within hours to days, these medications cause calm and reduce confusion in individuals with psychosis however may take longer for full effect. Importantly, these drugs are not curing, but only treat the disease symptoms. The treatment is adjusted to reduce any psychotic symptoms while keeping the adverse effects to a minimum level. Antipsychotics may lead to increased risk of diseases, including but not limited to, diabetes, obesity, metabolic disorders, cardiovascular, renal, or respiratory disorders. Improved dosages, polypharmacy, and age-specific treatment play an important role in limiting the comorbidities as well as the side effects. Further research and clinical attention are required to understand the functioning of these medications. The review focuses on the use of antipsychotic medications in different diseases and their effect on mental health.

Selective Serotonin Reuptake Inhibitors and Clozapine: Clinically Relevant Interactions and Considerations

The monoamine hypothesis of depression attributes the symptoms of major depressive disorders to imbalances of serotonin, noradrenaline, and dopamine in the limbic areas of the brain. The preferential targeting of serotonin receptor (SERT) by selective serotonin reuptake inhibitors (SSRIs) has offered an opportunity to reduce the range of these side effects and improve patient adherence to pharmacotherapy. Clozapine remains an effective drug against treatment-resistant schizophrenia, defined as failing treatment with at least two different antipsychotic medications. Patients with schizophrenia who display a constellation of negative symptoms respond poorly to antipsychotic monotherapy. Negative symptoms include the diminution of motivation, interest, or expression. Conversely to the depressive symptomology of interest presently, supplementation of antipsychotics with SSRIs in schizophrenic patients with negative symptoms lead to synergistic improvements in the function of these patients. Fluvoxamine is one of the most potent inhibitors of CYP1A2 and can lead to an increase in clozapine levels. Similar increases in serum clozapine were detected in two patients taking sertraline. However, studies have been contradictory as well, showing no such increases, which are worrying. Clinicians should be aware that clozapine levels should be monitored with any coadministration with SSRIs.

Toward personalized medicine in schizophrenia: Genetics and epigenetics of antipsychotic treatment

Schizophrenia is a complex psychiatric disorder where genetic, epigenetic, and environmental factors play a role in disease onset, course of illness, and treatment outcome. Pharmaco(epi)genetic research presents an important opportunity to improve patient care through prediction of medication side effects and response. In this narrative review, we discuss the current state of research and important progress of both genetic and epigenetic factors involved in antipsychotic response, over the past five years. The review is largely focused on the following frequently prescribed antipsychotics: olanzapine, risperidone, aripiprazole, and clozapine. Several consistent pharmacogenetic findings have emerged, in particular pharmacokinetic genes (primarily cytochrome P450 enzymes) and pharmacodynamic genes involving dopamine, serotonin, and glutamate neurotransmission. In addition to studies analysing DNA sequence variants, there are also several pharmacoepigenetic studies of antipsychotic response that have focused on the measurement of DNA methylation. Although pharmacoepigenetics is still in its infancy, consideration of both genetic and epigenetic factors contributing to antipsychotic response and side effects no doubt will be increasingly important in personalized medicine. We provide recommendations for next steps in research and clinical evaluation.

Clozapine as a potential treatment for refractory impulsive, compulsive, and punding behaviors in Parkinson's disease

There have been emerging cases of medication refractory obsessions, impulsivity, compulsivity, and/or punding in Parkinson's disease. These cases have proven difficult to treat, even for the experienced clinician. We report several medication refractory cases with a positive response to treatment with clozapine.

New 3-benzisothiazolyl and 3-benzisoxazolylpiperazine derivatives with atypical antipsychotic binding profile

New 3-benzisothiazolyl and 3-benzisoxazolylpiperazine derivatives were synthesised and their 5-HT(1A), 5-HT(2A) and D(2) receptor binding affinities evaluated. The compounds displayed high affinity for the 5-HT(2A) receptor combined with moderate to low 5-HT(1A) and D(2) affinities. Two of them, 18 and 25, have been selected for further pharmacological studies to be evaluated as potential atypical antipsychotics.

Structure-activity relationships of a series of substituted benzamides: potent D2/5-HT2 antagonists and 5-HT1a agonists as neuroleptic agents

A series of substituted (4-(4-(1,2-benzisothiazol-3-yl)-1-piperazinyl)butyl)benzamide derivatives was prepared and evaluated as potential atypical antipsychotic agents. The target compounds were readily prepared from their benzoyl chloride, benzoic acid, or isatoic anhydride precursors, and they were evaluated in vitro for their ability to bind to dopamine D2, serotonin 5-HT2, and serotonin 5-HT1a receptors. To assess the potential antipsychotic activity of these compounds, we investigated their ability to inhibit the apomorphine-induced climbing response in mice. Selected compounds were evaluated further to determine their side-effect potentials. Structure-activity relationships of both mono- and polysubstituted benzamides are discussed herein. While several analogues had potent in vitro and in vivo activities indicative of potential atypical antipsychotic activity, anthranilamide 77 (1192U90) ddemonstrated a superior pharmacological profile. As a result of this investigation, 1192U90 (2-amino-N-(4-(4-(1,2-benzisothiazol-3-yl)-1-piperazinyl)butyl)ben zamide hydrochloride) was selected for further evaluation and is currently in phase I clinical trials as a potential atypical antipsychotic agent.

Effect of linking bridge modifications on the antipsychotic profile of some phthalimide and isoindolinone derivatives

A series of phthalimide and isoindolinone derivatives bridged to 4-(1,2-benzisothiazol-3-yl)-1-piperazinyl was prepared. The compounds were evaluated in vitro at dopamine D2 and serotonin 5-HT1a and 5-HT2 receptors and in vivo for their ability to antagonize the apomorphine-induced climbing response in mice. The effects of bridge length and conformation on the biological activity of these potential antipsychotic agents are discussed. A four-carbon spacer provided optimal activity within the two homologous series. Conformational investigations of the lead compound, isoindolinone 2, were conducted in an attempt to account for the superior activity observed for the butyl derivatives. On the basis of NMR and molecular modeling studies, two types of folded structures were proposed and several conformationally restrained analogues were synthesized. In general, restrictions incorporated within the linking bridge were detrimental to activity.

Thermal degradation of clozapine-N-oxide to clozapine during gas chromatographic analysis

Studies were undertaken to determine if clozapine-N-oxide, the principal urinary metabolite of the antipsychotic agent clozapine, may interfere with the gas chromatographic-mass spectrometric bioanalysis of clozapine. Following injection of clozapine-N-oxide onto a (5% phenyl)methylpolysiloxane capillary column operated at 250 degrees C, significant on-column reduction of clozapine-N-oxide to the parent drug occurred. Accordingly, preparation of biological samples for clozapine determination by gas chromatography should avoid conditions which reportedly co-extract the N-oxide to assure no artifactual contribution of this metabolite in the detection of clozapine.

Clinical features, pathogenesis and management of drug-induced seizures

Many classes of pharmacological agents have been implicated in cases of drug-induced seizures. The list includes antidepressant drugs, lithium salts, neuroleptics, antihistamines (H1-receptor antagonists), anticonvulsants, central nervous system stimulants, general and local anaesthetics, antiarrhythmic drugs, narcotic and non-narcotic analgesics, non-steroidal anti-inflammatory drugs, antimicrobial agents, antifungal agents, antimalarial drugs, antineoplastic drugs, immunosuppressive drugs, radiological contrast agents and vaccines. For each of these classes of drugs, this article offers a revision of the literature and emphasises in particular the frequency of the adverse reaction, its clinical presentation, its presumed epileptogenic mechanism and the therapeutic strategy for the management of drug-induced seizures. An attempt is also made to distinguish seizures induced by standard dosages from those provoked by accidental or self-induced intoxication. For some classes of drugs such as antidepressants, neuroleptics, central nervous system stimulants (e.g. theophylline, cocaine, amphetamines) and beta-lactam antibiotics, seizures are a well recognised adverse reaction, and a large body of literature has been published discussing exhaustively the major aspects of the issue; sufficient data are available also for the other classes of pharmacological agents mentioned above. In contrast, several other drugs [e.g. allopurinol, digoxin, cimetidine, protirelin (thyrotrophin releasing hormone), bromocriptine, domperidone, insulin, fenformin, penicillamine, probenecid, verapamil, methyldopa] have not been studied thoroughly under this aspect, and the only source of information is the occasional case report. This review does not address the issue of seizures induced by drug withdrawal.