Meta-analysis: the effects of smoking on the disposition of two commonly used antipsychotic agents, olanzapine and clozapine

Psychiatric pharmacist's role in overcoming barriers to clozapine use and improving management

Clozapine is an antipsychotic that exhibits superior efficacy and effectiveness for those with schizophrenia and other serious mental illness. However, its side-effect profile and administrative burdens present challenges to its use. In the United States, the medication is grossly underused even though it may improve outcomes and reduce costs. Current barriers to use include lack of prescriber knowledge and confidence, negative prescriber attitudes, special monitoring requirements, administrative factors, lack of clozapine on formularies, lack of support and infrastructure to use the medication within many health systems, and inadequate understanding or acknowledgement of clozapine prescribing and risks by policy makers and payers. Approaches using interprofessional models of care, which include pharmacists specializing in psychiatric care, can help meet the needs of patients receiving clozapine. This article lays out the big picture of barriers to clozapine and how psychiatric pharmacists could play a role in improving access.

Impact of CYP1A2 genetic polymorphisms on pharmacokinetics of antipsychotic drugs: a systematic review and meta-analysis

OBJECTIVE

To determine the impact of CYP1A2 genetic polymorphisms on the pharmacokinetics of CYP1A2-metabolized antipsychotic drugs in humans by means of systematic review and meta-analysis.

METHOD

A systematic search was conducted in PubMed and Scopus databases as of June 26, 2018. Studies reporting the pharmacokinetic parameters of CYP1A2-metabolized antipsychotic drugs in individuals who were genotyped for CYP1A2 genetic polymorphisms were retrieved. Pharmacokinetic parameters of individuals who have mutant alleles of a CYP1A2 genetic polymorphism were compared with the wild-type individuals. Pooled-effect estimates, presented as standardized mean difference, were calculated by means of the fixed-effect or random-effects model, as appropriate.

RESULTS

Ten studies involving 872 clozapine users, seven studies involving 712 olanzapine users, and two studies involving 141 haloperidol users were included. All but one study reported no associations between any CYP1A2 genetic polymorphisms and the pharmacokinetics of CYP1A2-metabolized antipsychotic drugs. The pooled-effect estimates through meta-analyses of seven studies demonstrated no significant associations between the -163C>A or -2467delT polymorphism and clozapine or olanzapine concentrations in the blood.

CONCLUSIONS

This study suggests that CYP1A2 genetic polymorphisms have no significant impact on the pharmacokinetics of CYP1A2-metabolized antipsychotic drugs. CYP1A2 genotyping may have no clinical implications for personalized dosing of CYP1A2-metabolized antipsychotic drugs.

Neurobiological Determinants of Tobacco Smoking in Schizophrenia

Purpose of review: To provide an overview of the underlying neurobiology of tobacco smoking in schizophrenia, and implications for treatment of this comorbidity. Recent findings: Explanations for heavy tobacco smoking in schizophrenia include pro-cognitive effects of nicotine, and remediation of the underlying pathophysiology of schizophrenia. Nicotine may ameliorate neurochemical deficits through nicotine acetylcholine receptors (nAChRs) located on the dopamine, glutamate, and GABA neurons. Neurophysiological indices including electroencephalography, electromyography, and smooth pursuit eye movement (SPEM) paradigms may be biomarkers for underlying neuronal imbalances that contribute to the specific risk of tobacco smoking initiation, maintenance, and difficulty quitting within schizophrenia. Moreover, several social factors including socioeconomic factors and permissive smoking culture in mental health facilities, may contribute to the smoking behaviors (initiation, maintenance, and inability to quit smoking) within this disorder. Summary: Tobacco smoking may alleviate specific symptoms associated with schizophrenia. Understanding the neurobiological underpinnings and psychosocial determinants of this comorbidity may better explain these potential beneficial effects, while also providing important insights into effective treatments for smoking cessation.

Age Impacts Olanzapine Exposure Differently During Use of Oral Versus Long-Acting Injectable Formulations: An Observational Study Including 8,288 Patients

PURPOSE

Olanzapine is a commonly prescribed antipsychotic available as oral and long-acting injectable (LAI) formulations. Data are lacking on the use and safety of olanzapine-LAI in older patients. The aim of this study was to investigate the effect of increasing age on olanzapine exposure during oral versus LAI administration in a real-life setting.

METHODS

This observational study was based on routine therapeutic drug monitoring data collected during 2005-2017. As a measure of exposure, absolute concentrations and concentration/dose ratios of olanzapine were defined as outcome variables. Linear mixed-model analyzes were used to allow for inclusion of multiple samples per patient and adjustment for covariate effects.

RESULTS

Olanzapine concentrations and doses from 8,288 patients (21,378 measurements) were included. The number of patients on oral treatment was 7,893 (42%, 50 years or older), while 395 were using olanzapine-LAI (27%, 50 years or older). In contrast to oral use, where the dose-adjusted concentration of olanzapine increased significantly for patients 50 years or older (P < 0.001), increasing age had no effect on olanzapine concentration following LAI administration (P = 0.550). The effects of smoking habits and gender were equal in oral and olanzapine-LAI users.

CONCLUSION

While the dose-adjusted systemic exposure of olanzapine increases by age after oral administration, these novel findings from a large patient population show that systemic exposure of olanzapine-LAI is unaffected by age, probably due to the lacking influence of age-related changes in gastrointestinal absorption and/or presystemic metabolism. From a pharmacokinetic point of view, it is therefore no reason to restrict the use of olanzapine-LAI in older patients requiring long-term treatment.

Haplotypic and Genotypic Association of Catechol-O-Methyltransferase rs4680 and rs4818 Polymorphisms and Treatment Resistance in Schizophrenia

Treatment-resistant schizophrenia (TRS) continues to be a challenge. It was related to different factors, including alterations in the activity of brain dopaminergic system, which could be influenced by the dopamine-degrading enzyme, catechol-O-methyltransferase (COMT). Variants of the COMT gene have been extensively studied as risk factors for schizophrenia; however, their association with TRS has been poorly investigated. The aim of the present study was to determine the haplotypic and genotypic association of COMT rs4680 and rs4818 polymorphisms with the presence of TRS. Overall, 931 Caucasian patients diagnosed with schizophrenia (386 females and 545 males) were included, while 270 participants met the criteria for TRS. In males, no significant haplotypic and genotypic associations between COMT rs4680 and rs4818 polymorphisms and TRS were detected. However, genotypic analyses demonstrated higher frequency of COMT rs4680 AA genotype carriers compared to G-allele carriers (p = 0.033) and higher frequency of COMT rs4818 CC genotype carriers than G-allele carriers (p = 0.014) in females with TRS. Haplotype analyses confirmed that the presence of the G allele in females was associated with lower risk of TRS. In women with TRS, the high activity G-G/G-G haplotype was rare, while carriers of other haplotypes were overrepresented (p = 0.009). Such associations of COMT rs4680 and rs4818 high-activity (G variants), as well as G-G/G-G haplotype, with the lower risk of TRS in females, but not in males, suggest significant, but sex-specific influence of COMT variants on the development of treatment-resistance in patients with schizophrenia. However, due to relatively low number of females, those findings require replication in a larger sample.

Gender differences and risk factors for smoking among patients with various psychiatric disorders in Saudi Arabia: a cross-sectional study

Background

The higher prevalence of smoking among psychiatric patients is well established. However, gender-specific associations have rarely been the focus of studies among patients with various psychiatric disorders. The aim of this study was to estimate the gender-specific prevalence of current smoking by psychiatric patients and its association with various psychiatric disorders and the use of psychotropic medications.

Methods

A cross-sectional observational study was performed between July 2012 and June 2014. Patients were recruited from six hospitals located in the five regions of Saudi Arabia.

Results

Of the 1193 patients, 402 (33.7%) were current smokers. The incidence of current smoking was much higher among males than females (58.3% versus 6.7%, p < 0.001). In one or both genders, current smoking was associated with marital status, education, family income, residence, obesity, physical activity, substance abuse, inpatient status, previous psychiatric hospitalization, and age at onset of psychiatric illness. In both gender, smoking was higher in patients who had a secondary psychiatric disorder (66.7% versus 37.5%, respectively), those who had a primary psychotic disorder (63.7% versus 12.3%), and those taking antipsychotic medication (64.1% versus 8.3%) but lower in patients who had a primary depressive disorder (40.3% versus 4.3%), those who had a primary anxiety disorder (45.8% versus 0.0%), and those taking antidepressant medications (53.7% versus 3.6%). In a multivariate analysis adjusted for demographic/clinical characteristics and psychiatric disorders, current smoking was independently associated with primary psychotic disorders in females (OR = 3.47, 1.45–8.27, p = 0.005) but not in males. In a multivariate analysis adjusted for demographic/clinical characteristics and psychotropic medications, current smoking was independently associated with antipsychotic medication use in males (OR = 1.79, 1.10–2.93, p = 0.020). Current smoking was strongly associated with substance abuse in both univariate and multivariate analyses.

Conclusion

The prevalence of current smoking is high with marked gender difference in a large sample of mixed psychiatric patients in Saudi Arabia. Smoking-cessation programs may be urgently needed for these vulnerable patients.

Treating schizophrenia during menopause

OBJECTIVE

The aim of this review is to examine three questions: What are the risks and benefits of treating women with schizophrenia with hormone therapy (HT) at menopause? Should the antipsychotic regimen be changed at menopause? Do early- and late-onset women with schizophrenia respond differently to HT at menopause?

METHODS

MEDLINE databases for the years 1990 to 2016 were searched using the following interactive terms: schizophrenia, gender, menopause, estrogen, and hormones. The selected articles (62 out of 800 abstracts) were chosen on the basis of their applicability to the objectives of this targeted narrative review.

RESULTS

HT during the perimenopause in women with schizophrenia ameliorates psychotic and cognitive symptoms, and may also help affective symptoms. Vasomotor, genitourinary, and sleep symptoms are also reduced. Depending on the woman's age and personal risk factors and antipsychotic side effects, the risk of breast cancer and cardiovascular disease may be increased. Antipsychotic types and doses may need to be adjusted at menopause, as may be the mode of administration.

CONCLUSIONS

Both HT and changes in antipsychotic management should be considered for women with schizophrenia at menopause. The question about differences in response between early- and late-onset women cannot yet be answered.

Nicotine dependence in Croatian male inpatients with schizophrenia

BACKGROUND

Patients with schizophrenia have the highest known rates of cigarette smoking, but less is known about their smoking behavior and the differences across geographical regions, including Croatia. The aim of this study was to compare patterns of nicotine dependence between patients with schizophrenia and healthy individuals, and to determine the relationship between clinical presentation and the severity of smoking.

METHODS

This cross-sectional study included 182 recently hospitalized male inpatients and 280 healthy males, who were daily smokers. All participants have fulfilled the Fagerstrom Test for Nicotine Dependence (FTND). Patients were also evaluated by the Positive and Negative Syndrome Scale (PANSS).

RESULTS

Patients had higher FTND total score (p = 0.010), smoked their first cigarette earlier in the morning (p = 0.000), consumed higher number of cigarettes (p = 0.000), while healthy subjects had more difficulties to refrain from smoking in places where it is forbidden (p = 0.000) and smoked more even when they were sick (p = 0.000). While severe dependence was more prevalent in the patient group, light dependence was more frequent in control subjects (p = 0.04). Smoking behavior was not associated with either PANSS total score or any of its subscales and items.

CONCLUSIONS

Smokers with schizophrenia differ from healthy smokers in both smoking behavior and level of dependence. Longitudinal studies are needed to shed more light on the complex relationship between smoking and psychopathology in schizophrenia.

Influence of dose, gender, and cigarette smoking on clozapine plasma concentrations

INTRODUCTION

Therapeutic drug monitoring (TDM) of clozapine is a very useful method for verifying both the correct intake and the interindividual variability of its metabolism, thereby avoiding the risk of toxicity. The purposes of this paper were to discover how many patients using clozapine in common clinical practice have clozapine plasma concentration (PC) levels in the proposed reference range and to identify factors that influence clozapine PC levels.

METHODS

Our study included 100 inpatients (diagnosed with schizophrenia or schizoaffective disorder) taking standard doses of clozapine (100-700 mg/day). Clozapine concentration was measured by high-performance liquid chromatography. Correlations between doses and PC levels and the influence of smoking and gender on clozapine PC levels were calculated.

RESULTS

A large number of the patients (67%) had PC levels outside the proposed reference range. The clozapine PC levels were influenced by dose, gender, and cigarette smoking.

CONCLUSION

The correlations between dose, gender, and cigarette smoking and clozapine PC levels highlighted by our study overlap other research. It was surprising to find such a large number of patients with clozapine PC levels outside the therapeutic range. This result suggests the importance of clozapine TDM due to misunderstood inter- and/or intraindividual variability or misestimated partial therapeutic compliance.

Effect of risperidone on serum homocysteine levels in first-episode, drug-naïve patients with schizophrenia

Some studies have shown that homocysteine (Hcy) levels are increased in patients with schizophrenia, and may be involved in its pathophysiology. The purpose of this study was to investigate the effect of the atypical antipsychotic drug risperidone on serum Hcy levels and to explore the relationship between the changes in Hcy levels and the therapeutic outcome, which, to our best knowledge have not been investigated. Fifty-six first-episode and drug-naïve inpatients with schizophrenia were assigned to a 12-week treatment regime with risperidone. Clinical efficacy was determined with the Positive And Negative Syndrome Scale (PANSS). Serum Hcy levels were measured by sandwich enzyme-linked immunosorbent assay in schizophrenia patients before and after the 12-week treatment, and the values were compared with those of fifty-six age- and gender- matched healthy controls. Serum Hcy levels were significantly higher in first-episode and drug-naïve patients than in control subjects (11.18±4.53 vs. 5.99±3.61μmol/L, F=37.195, df=1, p=1.73×10^-8). Moreover, a significant positive correlation between Hcy levels and PANSS negative sub-score was observed (r=0.515; p=4.81×10^-5). Serum Hcy levels were significantly decreased in patients after risperidone treatment (baseline: 11.18±4.53μmol/L vs. post-treatment: 8.98±4.07μmol/L, t=3.857, p=3.034×10^-4). At post-treatment, there was a significant negative relationship between serum Hcy levels and PANSS negative sub-scores (r=-0.288, p=0.032). High Hcy levels at the onset of psychosis suggests that it may contribute to the pathogenesis of schizophrenia and is related to clinical psychopathology. Serum Hcy levels were significantly decreased in schizophrenia patients after risperidone treatment.

A Reasonable Alternative to Clozapine in the Chronically Relapsing Smoking Patient? A Retrospective Analysis

Background: Clozapine levels are severely decreased by cigarette smoke hydrocarbons. A new agent that is unaffected by smoking is paliperidone palmitate. Objective: The purpose of this study is to retrospectively evaluate hospital readmission and time until readmission for patients prescribed paliperidone palmitate intramuscular injection (PP) as an alternative to oral clozapine for patients with severe schizophrenia who resume smoking following discharge. A secondary analysis was performed to determine whether smoking status alone affects hospital readmission rates in both smoking and nonsmoking clozapine-treated patients. Methods: This was a retrospective analysis of all patients who were positive for smoking at admission and readmission who were prescribed clozapine and PP. Smokers were identified by concurrent orders for nicotine replacement. Readmission rates and time until readmission were determined. Data were analyzed utilizing nonparametric statistical methods. Results: A total of 133 subjects were identified, including 108 smokers in PP group, 18 smokers in clozapine group, and 7 nonsmoking clozapine patients. Readmission rates were statistically significant between smokers in the clozapine and PP groups, with significantly lower readmission rates in the PP group (p = .004). In the sub-analysis, hospital readmissions between smokers and nonsmokers in the clozapine group were statistically significant (p = .027). Results may be influenced by use of a single hospital site, limits of a retrospective analysis, and variation in pharmaceutical preparation. Conclusion: PP may be a reasonable alternative to clozapine in severe schizophrenia for patients who continually resume smoking following discharge. Smoking may also be an important predictor of decompensation in smokers prescribed clozapine. A further prospective study is warranted.

Fusing Sensor Paradigms to Acquire Chemical Information: An Integrative Role for Smart Biopolymeric Hydrogels

The Information Age transformed our lives but it has had surprisingly little impact on the way chemical information (e.g., from our biological world) is acquired, analyzed and communicated. Sensor systems are poised to change this situation by providing rapid access to chemical information. This access will be enabled by technological advances from various fields: biology enables the synthesis, design and discovery of molecular recognition elements as well as the generation of cell-based signal processors; physics and chemistry are providing nano-components that facilitate the transmission and transduction of signals rich with chemical information; microfabrication is yielding sensors capable of receiving these signals through various modalities; and signal processing analysis enhances the extraction of chemical information. The authors contend that integral to the development of functional sensor systems will be materials that (i) enable the integrative and hierarchical assembly of various sensing components (for chemical recognition and signal transduction) and (ii) facilitate meaningful communication across modalities. It is suggested that stimuli-responsive self-assembling biopolymers can perform such integrative functions, and redox provides modality-spanning communication capabilities. Recent progress toward the development of electrochemical sensors to manage schizophrenia is used to illustrate the opportunities and challenges for enlisting sensors for chemical information processing.

Clozapine administration in clinical practice: once-daily versus divided dosing

OBJECTIVE

While it is recommended that clozapine be administered in a divided dosing regimen, it is unclear whether this recommendation is followed in real-world clinical practice. In two large datasets, we examined clozapine dosing frequency and patient characteristics across different dosing regimens.

METHOD

We conducted a cross-sectional survey, collecting data on patients receiving clozapine in August/September 2015 from the Centre for Addiction and Mental Health (CAMH) in Toronto, Canada, and The Zucker Hillside Hospital (ZHH) in New York, United States.

RESULTS

Of 676 and 308 patients included in CAMH and ZHH datasets, clozapine was prescribed once daily in 75.1% and 74.4%, even though doses exceeding 200 mg/day were administered in 88.6% and 84.4% of the respective samples. No significant difference was found in the rates of positive symptom remission between once-daily vs. divided dosing (79.7% vs. 80.5%, P = 1.00). Higher clozapine dose and use of anticholinergic medications were significantly associated with divided dosing in both datasets. Older age or male gender was related to divided dosing in CAMH or ZHH dataset respectively.

CONCLUSION

Despite the product monograph recommendation, clozapine is frequently prescribed once daily in North America. Further studies are needed to compare clinical outcomes between once-daily vs. divided clozapine dosing.

Smoking and mental illness. An update for psychiatrists

OBJECTIVE

We aimed to review research on smoking and mental illness and provide evidence-based guidelines for psychiatrists to help smoking patients quit.

METHOD

We undertook a narrative review of the literature with a special focus on the Australian context.

RESULTS

Although one in three people with mental illness smoke tobacco, smoking is often neglected in psychiatric practice. Smoking is a significant contributor to the health gap between people with mental illness and the general population. Smokers with mental illness are motivated to quit and are able to do so, albeit with lower quit rates. Quitting can lead to substantial improvements in mental wellbeing and physical health and does not exacerbate pre-existing mental illness. Psychiatrists should advise all smokers to quit and provide counselling, medication and support, based on the 5As framework. Approved pharmacotherapy - nicotine replacement therapy, varenicline and bupropion - is recommended for nicotine-dependent smokers. Smoking induces the metabolism of certain psychotropic drugs such as clozapine and olanzapine and dose reductions may be necessary after cessation.

CONCLUSIONS

Psychiatrists have a duty of care to identify the smoking status of their patients and to provide evidence-based support to quit.

A computer-based quantitative systems pharmacology model of negative symptoms in schizophrenia: exploring glycine modulation of excitation-inhibition balance

Although many antipsychotics can reasonably control positive symptoms in schizophrenia, patients' return to society is often hindered by negative symptoms and cognitive deficits. As an alternative to animal rodent models that are often not very predictive for the clinical situation, we developed a new computer-based mechanistic modeling approach. This Quantitative Systems Pharmacology approach combines preclinical basic neurophysiology of a biophysically realistic neuronal ventromedial cortical-ventral striatal network identified from human imaging studies that are associated with negative symptoms. Calibration of a few biological coupling parameters using a retrospective clinical database of 34 drug-dose combinations resulted in correlation coefficients greater than 0.60, while a robust quantitative prediction of a number of independent trials was observed. We then simulated the effect of glycine modulation on the anticipated clinical outcomes. The quantitative biochemistry of glycine interaction with the different NMDA-NR₂ subunits, neurodevelopmental trajectory of the NMDA-NR_2B in the human schizophrenia pathology, their specific localization on excitatory vs. inhibitory interneurons and the electrogenic nature of the glycine transporter resulted in an inverse U-shape dose-response with an optimum in the low micromolar glycine concentration. Quantitative systems pharmacology based computer modeling of complex humanized brain circuits is a powerful alternative approach to explain the non-monotonic dose-response observed in past clinical trial outcomes with sarcosine, D-cycloserine, glycine, or D-serine or with glycine transporter inhibitors. In general it can be helpful to better understand the human neurophysiology of negative symptoms, especially with targets that show non-monotonic dose-responses.

Drug safety evaluation of olanzapine/fluoxetine combination

INTRODUCTION

Bipolar disorder and treatment-resistant depression (TRD) are common and recurrent conditions associated with significant disability, morbidity and mortality. Despite the clear need for effective treatments, only a few medications have been approved in the US for these indications. The combined formulation of olanzapine-fluoxetine (OFC) has been available for a decade now, thus a review on its safety profile and comparative efficacy is timely and can help clinicians to determine the benefit/risk profile of OFC within the context of other treatment alternatives.

AREAS COVERED

This paper summarizes the rationale and evidence supporting the use of OFC for both bipolar I depressive episodes and TRD with a focus on safety and tolerability. Product labels and the search engine PubMed was used to obtain relevant information on this subject.

EXPERT OPINION

Although further comparative studies are needed, the literature confirms that the OFC is an effective treatment for bipolar I depressive episodes, as well as major depressive episodes that have not responded to several adequate courses of antidepressant therapy. Its use as a first-line treatment for bipolar I depressive episodes and at a higher rung of algorithms for patients with TRD is limited by its propensity to cause weight gain and associated metabolic symptoms.