Smoking impact on CYP1A2 activity in a group of patients with schizophrenia

Population pharmacokinetics of olanzapine in pediatric patients with psychiatric disorders

OBJECTIVE

To develop and validate a population pharmacokinetic (PPK) model of oral olanzapine in pediatric Chinese patients in order to individualize therapy in this population.

METHODS

A total of 897 serum concentrations from 269 pediatric patients taking oral olanzapine (ages 8-17 years) were collected. Demographic parameters, biological characteristics and concomitant medications were investigated as covariates. The data were analyzed using a nonlinear mixed-effects modeling approach. Bootstrapping (1000 runs), normalized prediction distribution error (NPDE), and external validation of 62 patients were employed. Simulations were performed to explore the individualized dosing regimens in various situations.

RESULTS

The one-compartment model with first-order absorption and elimination had an apparent clearance (CL/F) of 10.38 L/h, a distribution volume (V/F) of 9.41 L/kg and an absorption rate constant (Ka) fixed at 0.3 h-1. The equation was CL∕F (L∕h) = 10.38 × (body weight∕60)0.25 ×1.33 (if male) × 0.71 (if co-occurrence of infection) × 0.51 (if co-therapy with fluvoxamine) × 1.27 (if co-therapy with sertraline) × 1.43 (if co-therapy with valproate). The final model had satisfactory stability, robustness, and predictive ability. The results from a simulation suggested the oral olanzapine doses required for male and female pediatric patients weighing between 40 and 60 kg without co-medication were 10-15 mg/day and 7.5-10 mg/day, respectively, and dosage adjustments should be based on sex and body weight; and co-administrated with valproate, sertraline, or fluvoxamine.

CONCLUSION

This model may help individualize optimum dosing of oral olanzapine for pediatric patients.

Second to none: rationale, timing, and clinical management of clozapine use in schizophrenia

Despite its enduring relevance as the single most effective and important evidence-based treatment for schizophrenia, underutilization of clozapine remains considerable. To a substantial degree, this is attributable to a reluctance of psychiatrists to offer clozapine due to its relatively large side-effect burden and the complexity of its use. This underscores the necessity for continued education regarding both the vital nature and the intricacies of clozapine treatment. This narrative review summarizes all clinically relevant areas of evidence, which support clozapine's wide-ranging superior efficacy - for treatment-resistant schizophrenia (TRS) and beyond - and make its safe use eminently feasible. Converging evidence indicates that TRS constitutes a distinct albeit heterogeneous subgroup of schizophrenias primarily responsive to clozapine. Most importantly, the predominantly early onset of treatment resistance and the considerable decline in response rates associated with its delayed initiation make clozapine an essential treatment option throughout the course of illness, beginning with the first psychotic episode. To maximize patients' benefits, systematic early recognition efforts based on stringent use of TRS criteria, a timely offer of clozapine, thorough side-effect screening and management as well as consistent use of therapeutic drug monitoring and established augmentation strategies for suboptimal responders are crucial. To minimize permanent all-cause discontinuation, re-challenges after neutropenia or myocarditis should be considered. Owing to clozapine's unique efficacy, comorbid conditions including substance use and most somatic disorders should not dissuade but rather encourage clinicians to consider clozapine. Moreover, treatment decisions need to be informed by the late onset of clozapine's full effects, which for reduced suicidality and mortality rates may not even be readily apparent. Overall, the singular extent of its efficacy combined with the high level of patient satisfaction continues to distinguish clozapine from all other available antipsychotics.

Pharmacokinetics of Caffeine: A Systematic Analysis of Reported Data for Application in Metabolic Phenotyping and Liver Function Testing

Caffeine is by far the most ubiquitous psychostimulant worldwide found in tea, coffee, cocoa, energy drinks, and many other beverages and food. Caffeine is almost exclusively metabolized in the liver by the cytochrome P-450 enzyme system to the main product paraxanthine and the additional products theobromine and theophylline. Besides its stimulating properties, two important applications of caffeine are metabolic phenotyping of cytochrome P450 1A2 (CYP1A2) and liver function testing. An open challenge in this context is to identify underlying causes of the large inter-individual variability in caffeine pharmacokinetics. Data is urgently needed to understand and quantify confounding factors such as lifestyle (e.g., smoking), the effects of drug-caffeine interactions (e.g., medication metabolized via CYP1A2), and the effect of disease. Here we report the first integrative and systematic analysis of data on caffeine pharmacokinetics from 141 publications and provide a comprehensive high-quality data set on the pharmacokinetics of caffeine, caffeine metabolites, and their metabolic ratios in human adults. The data set is enriched by meta-data on the characteristics of studied patient cohorts and subjects (e.g., age, body weight, smoking status, health status), the applied interventions (e.g., dosing, substance, route of application), measured pharmacokinetic time-courses, and pharmacokinetic parameters (e.g., clearance, half-life, area under the curve). We demonstrate via multiple applications how the data set can be used to solidify existing knowledge and gain new insights relevant for metabolic phenotyping and liver function testing based on caffeine. Specifically, we analyzed 1) the alteration of caffeine pharmacokinetics with smoking and use of oral contraceptives; 2) drug-drug interactions with caffeine as possible confounding factors of caffeine pharmacokinetics or source of adverse effects; 3) alteration of caffeine pharmacokinetics in disease; and 4) the applicability of caffeine as a salivary test substance by comparison of plasma and saliva data. In conclusion, our data set and analyses provide important resources which could enable more accurate caffeine-based metabolic phenotyping and liver function testing.

The Impact of Smoking, Sex, Infection, and Comedication Administration on Oral Olanzapine: A Population Pharmacokinetic Model in Chinese Psychiatric Patients

BACKGROUND AND OBJECTIVE: Prior olanzapine population pharmacokinetic (PPK) models have focused on the effects of sex and smoking on olanzapine clearance. This PPK model in Chinese adult psychiatric patients also investigated the influence of comedications and co-occurrence of infections on olanzapine clearance, and explored how to personalize oral olanzapine dosage in the clinical setting.

METHODS

A total of 1546 serum concentrations from 354 patients were collected in this study. A one-compartment model with first-order absorption was employed to develop the PPK model using a nonlinear mixed-effects modeling approach. Covariates included demographic parameters, co-occurrence of infection and concomitant medications (including dangguilonghui tablets, a Chinese herbal medicine for constipation). Bootstrap validation (1000 runs) and external validation of 50 patients were employed to evaluate the final model. Simulations were performed to explore the personalization of olanzapine dosing after stratification by sex, smoking, and comedication with valproate.

RESULTS

Typical estimates for the absorption rate constant (K_a), apparent clearance (CL/F), and apparent distribution volume (V/F) were 0.30 h^-1, 12.88 L/h, and 754.41 L, respectively. Olanzapine clearance was increased by the following variables: 1.23-fold by male sex, 1.23-fold by smoking, 1.23-fold by comedication with valproate, 1.16-fold by sertraline, and 2.01-fold by dangguilonghui tablets. Olanzapine clearance was decreased by the following variables: 0.75-fold by co-occurrence of infection, 0.70-fold by fluvoxamine, and 0.78-fold by perphenazine. The model evaluation indicated that the final model's performance was good, stable, and precise.

CONCLUSION

This study contributes to the personalization of oral olanzapine dosing, but further studies should be performed to verify the effects of infection and comedications, including valproate and dangguilonghui.

Psychopathology and extrapyramidal side effects in smoking and non-smoking patients with schizophrenia: Systematic review and meta-analysis of comparative studies

The association between smoking and psychopathology and extrapyramidal side effects (EPSE) in schizophrenia has been controversial. This systematic review and meta-analysis compared psychopathology and EPSE between smoking and non-smoking schizophrenia patients. The PubMed, EMBASE, PsycINFO, Cochrane Library, and Web of Science databases were independently and systematically searched by two researchers to identify relevant articles. Standardized mean differences (SMDs) and their 95% confidence intervals (CI) were calculated with random effect models. Subgroup and meta-regression analyses were performed to explore sources of heterogeneity. The systematic review and meta-analysis included 29 studies that compared psychotic, depressive and anxiety symptoms and EPSE between smoking (n = 3591) and non-smoking schizophrenia patients (n = 2980). Smoking patients had significantly more severe positive symptoms (24 studies; SMD = 0.33, 95% CI: 0.16 to 0.50, P < 0.001), but less severe EPSE (7 studies; SMD = -0.20, 95% CI: -0.38 to -0.02, P = 0. 03). No significant group differences in negative, depressive and anxiety symptoms were found. In conclusion, this systematic review and meta-analysis found that smoking schizophrenia patients had more severe positive symptoms but less severe EPSE than non-smoking patients.

Caffeine Consumption through Coffee: Content in the Beverage, Metabolism, Health Benefits and Risks

Caffeine (1,3,7-trimethylxanthine) is the most consumed psychoactive substance in the world, acting by means of antagonism to adenosine receptors, mainly A1 and A2A. Coffee is the main natural source of the alkaloid which is quite soluble and well extracted during the brew’s preparation. After consumption, caffeine is almost completely absorbed and extensively metabolized in the liver by phase I (cytochrome P450) enzymes, mainly CYP1A2, which appears to be polymorphically distributed in human populations. Paraxanthine is the major caffeine metabolite in plasma, while methylated xanthines and methyluric acids are the main metabolites excreted in urine. In addition to stimulating the central nervous system, caffeine exerts positive effects in the body, often in association with other substances, contributing to prevention of several chronic diseases. The potential adverse effects of caffeine have also been extensively studied in animal species and in humans. These aspects will be approached in the present review.

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.

The influence of tobacco smoke and nicotine on antidepressant and memory-improving effects of venlafaxine

In experimental and clinical studies, central nicotinic systems have been shown to play an important role in cognitive function. Nicotinic acetylcholine receptors also mediate the reinforcing properties of nicotine (NIC) in tobacco products. A variety of studies have shown that acute treatment with NIC or nicotinic agonists can improve working memory function. Moreover, it is known that the monoaminergic system plays an important role in memory function. And there is evidence suggesting that prolonged use of NIC may exert antidepressant action via nicotinic receptors. The purpose of this study was to investigate the interactions between a novel antidepressant, venlafaxine (VEN), a blocker of noradrenaline and 5–hydroxytryptamine reuptake sites, and pure NIC in the context of antidepressant and memory function in tobacco smoke exposed and nonexposed rats. The animals were subjected to Porsolt's test for testing antidepressant activity and their memory function (spatial memory) was evaluated in the Morris Water Maze Test. In tobacco smoke non–exposed and exposed rats both single and chronic administration of VEN (20 mg/kg po) shortened immobility time. NIC (0.2 mg/kg sc) significantly reduced immobility time on the 1st, 7th and 14th test days in both non–exposed and exposed rats. Combined VEN–NIC treatment in tobacco smoke non–exposed rats reduced immobility too. This effect of the combination of drugs was significantly stronger as compared to the effects obtained after individual administration of VEN or NIC. In the group exposed to tobacco smoke, joint administration of VEN–NIC induced a significant reduction of immobility as compared to the control and NIC groups. In the Morris Water Maze Test single and chronic administration of VEN, lower values of escape latencies and lower numbers of crossed quadrants were noted in both exposed and non–exposed rats, which indicates improved performance. After administering NIC we could observe improvement of spatial memory in both the exposed and non–exposed group. A similar effect of improvement of spatial memory was observed after joint administration of VEN and NIC. The study results support the involvement of nicotinic systems in memory processes in rats. Memory improvement and antidepressant effects following joint administration of VEN and NIC may depend on nicotinic interactions with monoaminergic systems and VEN may represent a new therapeutic approach to smoking cessation.

Frequency of CYP450 enzyme gene polymorphisms in the Greek population: review of the literature, original findings and clinical significance

The cytochrome P450 (CYP450) enzyme family is involved in the oxidative metabolism of many therapeutic drugs and various endogenous substrates. These enzymes are highly polymorphic. Prevalence of CYP450 enzyme gene polymorphisms vary among different populations and substantial inter- and intra-ethnic variability in frequency of CYP450 enzyme gene polymorphisms has been reported. This paper provides an overview and investigation of CYP450 genotypic and phenotypic reports published in the Greek population.

Considering CYP1A2 phenotype and genotype for optimizing the dose of olanzapine in the management of schizophrenia

INTRODUCTION

Schizophrenia, a mental disorder, is a debilitating condition which typically strikes young people in their early 20's. Antipsychotic medications are widely prescribed for the treatment of schizophrenia however a balancing act is necessary to provide the correct dose to each patient. It is suggested that a large number of patients discontinue antipsychotic pharmacotherapy because the treatments provided do not always reduce the positive symptoms of the disease, while many have adverse effects on the patients. This implies that neither the incorrect drug nor the optimal dosage for that patient is achieved.

AREAS COVERED

The current review investigates variability in response to olanzapine with a specific focus on the common intrinsic and extrinsic factors that influence both olanzapine and CYP1A2 activity. Furthermore, the authors discuss the utilization of phenotyping and genotyping of CYP1A2 and their potential utility in clinical practice for olanzapine dosing regimens. The authors also consider the potential of pharmacometrics compared to pharmacogenomics as a tool to personalize medicine.

EXPERT OPINION

Careful consideration must be given to the impact of a genetic variant on the disposition of a drug prior to implementing genetic 'tests' to determine response. CYP1A2 phenotypic assessment can yield important information regarding the disposition of olanzapine; however, it relies on the accuracy of the metric and the minimal impact of other metabolic pathways. The application of pharmacometrics provides an effective method to establish covariates that significantly influence olanzapine disposition which can incorporate phenotype and/or genotype.

Pharmacogenomics can improve antipsychotic treatment in schizophrenia

Schizophrenia is a widespread mental disease with a prevalence of about 1% in the world population, and heritability of up to 80%. Drug therapy is an important approach to treating the disease. However, the curative effect of antipsychotic is far from satisfactory in terms of tolerability and side effects. Many studies have indicated that about 30% of the patients exhibit little or no improvements associated with antipsychotics. The response of individual patients who are given the same dose of the same drug varies considerably. In addition, antipsychotic drugs are often accompanied by adverse drug reactions (ADRs), which can cause considerable financial loss in addition to the obvious societal harm. So, it is strongly recommended that personalized medicine should be implemented both to improve drug efficacy and to minimize adverse events and toxicity. There is therefore a need for pharmacogenomic studies into the factors affecting response of schizophrenia patients to antipsychotic drugs to provide informed guidance for clinicians. Individual differences in drug response is due to a combination of many complex factors including ADEM (absorption, distribution, metabolism, excretion) process, transporting, binding with receptor and intracellular signal transduction. Pharmacogenetic and pharmacogenomic studies have successfully identified genetic variants that contribute to this interindividual variability in antipsychotics response. In addition, epigenetic factors such as methylation of DNA and regulation by miRNA have also been reported to play an important role in the complex interactions between the multiple genes and environmental factors which influence individual drug response phenotypes in patients. In this review, we will focus on the latest research on polymorphisms of candidate genes that code for drug metabolic enzymes (CYP2D6, CYP1A2, CYP3A4, etc.), drug transporters (mainly ABCB1) and neurotransmitter receptors (dopamine receptors and serotonin receptors, etc.). We also discuss the genome-wide pharmacogenomic study of schizophrenia and review the current state of knowledge on epigenetics and potential clinical applications.

Pharmacokinetics of caffeine in plasma and saliva, and the influence of caffeine abstinence on CYP1A2 metrics

OBJECTIVES

To investigate the utility of metrics of CYP1A2 activity using caffeine as a probe, and saliva and plasma sampling with or without a 24-h caffeine abstinence.

METHODS

This was a cross-over pharmacokinetic study in 30 healthy male subjects who received a single oral 100mg caffeine dose after 24-h caffeine abstinence or after maintaining their regular caffeine intake (no caffeine abstinence). Serial blood and saliva samples were collected simultaneously over 24h. Caffeine and paraxanthine concentrations were measured using a validated HPLC assay.

KEY FINDINGS

There was a strong correlation between the paraxanthine/caffeine AUC(0-24) ratio (reference metric) and the paraxanthine/caffeine concentration (C(t) ) ratio at 4h (C(4) ) in both saliva and plasma (r≥0.75). The paraxanthine/caffeine AUC(0-24) ratio in plasma and saliva did not differ between the 24-h caffeine abstinence and the no abstinence period (P>0.05). The optimal paraxanthine/caffeine C(t) that correlated with the plasma paraxanthine/caffeine AUC(0-24) ratio in the 24-h abstinence period was 2 and 4h (r=0.88) in plasma, and 4 and 6h in saliva (r=0.70), while it was the saliva 4h time-point in the no abstinence period (r=0.78).

CONCLUSIONS

The saliva paraxanthine/caffeine concentration ratio at 4h was a suitable metric to assess CYP1A2 activity after oral administration of caffeine without the need for 24-h caffeine abstinence.

Caffeine and paraxanthine HPLC assay for CYP1A2 phenotype assessment using saliva and plasma

Caffeine has been extensively used as a probe to measure CYP1A2 activity in humans with caffeine clearance or the paraxanthine (major metabolite of caffeine) to caffeine concentration ratio being regarded as the preferred metric. A simple reverse-phased C(18) HPLC assay using ethyl acetate liquid-liquid extraction was developed to quantitate caffeine and paraxanthine concentrations in saliva and plasma. The mobile phase consisted of acetonitrile-acetic acid-H(2)O (100:1:899) and analytes were quantitated with UV detection at 280 nm. The extraction recovery for paraxanthine and caffeine was approximately 70% in both saliva and plasma. The assay was linear over the concentration ranges 0.05-2.50 and 0.05-5.00 µg/mL, for paraxanthine and caffeine, respectively, in saliva. In plasma the assay was linear over the ranges 0.025-2.50 and 0.025-5.00 µg/mL for paraxanthine and caffeine, respectively. Intra- and inter-assay precision and accuracy were less than 15%. Detection limits were 0.015 µg/mL for paraxanthine and caffeine in saliva, while it was 0.005 µg/mL for paraxanthine and caffeine in plasma. Utility was established in samples collected from two healthy volunteers who abstained from caffeine for 24 h and received a single 100 mg oral dose of caffeine. The assay developed is a robust, simple and precise technique to measure caffeine and paraxanthine in saliva and plasma of healthy volunteers after a single oral dose of caffeine.

Higher serum caffeine in smokers with schizophrenia compared to smoking controls

Previous studies of high dietary caffeine intake in individuals with schizophrenia have not demonstrated biological evidence of higher intake or controlled smoking behavior. This study aimed to examine differences in serum caffeine levels in 104 smokers with schizophrenia/schizoaffective disorder (SCZ/SA) and compare them to 63 smokers without any mental illness (CON). Since we were interested in measuring caffeine levels, we excluded all non-caffeine users from the study. Blood draws were standardized to occur at mid-day on a usual smoking day. The mean serum caffeine level was significantly higher for SCZ/SA group compared to CON (2722 ng/mL vs. 1122 ng/mL; p<0.001). This trend persisted in subsets of smokers who smoked less than 20 cigarettes per day (CPD; 2052 ng/mL vs. 587 ng/mL; p<0.05), 20-30 CPD (2743 ng/mL vs. 1170 ng/mL; p<0.001) or more than 30 CPD (3430 ng/mL vs. 1834 ng/mL; NSS). Linear backward stepwise regression analyses including demographic and smoking variables revealed that having a diagnosis of SCZ/SA (compared to CON) significantly predicted serum caffeine level (B=1528.2; p<0.001). In addition, SCZ/SA group had two times greater serum caffeine levels as compared to CON with similar smoking behavior. Clinical effects of smoking and caffeine intake are important and may complicate the interpretation of schizophrenia symptoms and antipsychotic medication side effects, thus warranting further research.

Clozapine exposure and the impact of smoking and gender: a population pharmacokinetic study

The primary objective of this study was to evaluate the magnitude and variability of concentration exposure to clozapine and norclozapine in a real-world clinical setting, with a focus on smoking status, using population pharmacokinetic methodologies. A retrospective review of plasma clozapine and norclozapine concentrations taken from inpatients at the Centre for Addiction and Mental Health, Toronto, from 2001 to 2007 was conducted. A nonlinear mixed-effects model was developed using NONMEM, including age, gender, weight, smoking status, and dosage formulation as covariates. Pharmacokinetic parameters and interindividual and residual variabilities were estimated with 1- and 2-compartment models. A total of 519 plasma clozapine concentrations from 197 patients (138 males; mean +/- SD age, 38 +/- 13 years; schizophrenia spectrum disorder 98.2%) were included for the analysis. A 1-compartment model with first-order absorption and elimination best described the data. Apparent volume of distribution was fixed to a previously reported value in the literature of 7 L/kg.The population-predicted oral clearance of clozapine and norclozapine was 18.0 and 39.0 L/h, respectively; both the predicted clearance values vary nearly 6-fold (range, 9.18-59.06 and 16.29-97.84 L/h, respectively). For clozapine, smokers and males showed increased oral clearance by 6.0 and 4.5 L/h, respectively. For norclozapine, smokers and male gender were associated with an increased oral clearance of 11.3 and 7.6 L/h, respectively. The formulation of clozapine administered had an impact on the absorption rate with a Ka of 0.14/h for tablet and 10.3/h for the suspension form.The data suggest that smoking and male gender are associated with lower exposure to clozapine and norclozapine due to the higher oral clearance. These findings may account for some of the variability in clozapine exposure and have important implications for individualized drug dosing and therapeutic drug monitoring.

Long-term treatment with flupentixol results of a post-marketing surveillance study

Schizophrenia is one of the most expensive illnesses. Antipsychotics are an essential component of the acute and preventative treatment of this illness, and long-term treatment is necessary to decrease the risk of psychotic relapse. The efficacy and tolerability of flupentixol was evaluated in a post-marketing surveillance study (PMS) in schizophrenic patients receiving long-term treatment in routine clinical practice. Psychiatrists in office practice treated patients for approximately 10 weeks, with a subsequent follow-up period of up to 18 months. We here report on the follow-up period in 128 patients. The benefit for schizophrenic patients increased with the treatment duration of flupentixol as documented by the Clinical Global Impression (CGI). Subjective quality of life improved during the first study period, and this remained stable in the follow-up period. No increase in body weight was observed during the study. The relapse rate was much lower than in other studies. Anticholinergic medication was necessary for 22.7% of the patients at any time. More than 70% of the psychiatrists involved evaluated the treatment as very good or good. The results of this study suggest that flupentixol is a potent and safe antipsychotic for the long-term treatment of schizophrenia in routine clinical practice.

Respiratory, cardiovascular and other physiological consequences of smoking cessation

BACKGROUND

Smoking cessation is associated with substantial reductions in tobacco-related morbidity and mortality. Based on the current literature, the beneficial effects of quitting are particularly evident on pulmonary and cardiovascular function, but the negative physiological effects of cessation are less well documented.

SCOPE

The objective of this article was to review systematically data on the physiological effects of smoking cessation. Articles based upon clinical trials, randomised controlled trials and meta-analyses were selected from titles and abstracts obtained via a MEDLINE search (May 2003-May 2008). Additional studies were identified from the bibliographies of reviewed literature.

FINDINGS

Smoking cessation is associated with improved lung function and a reduction in the presence and severity of respiratory symptoms. These changes, apparent within months of quitting, are sustained with long-term abstinence. The underlying pathophysiologies of smoking-induced airway inflammation and endothelial dysfunction are partially reversed following cessation in healthy ex-smokers, but not in those with chronic obstructive pulmonary disease. Smoking cessation is also associated with substantially improved cardiovascular function and reduced risk of primary and secondary cardiovascular morbidity and mortality. Although the overall long-term health benefits are unquestionable, smoking cessation is also associated with other possible undesirable short-term physiological effects such as weight gain, hypertension, constipation and mouth ulcers; and altered activity of the enzyme cytochrome P450 1A2 (CYP1A2), which metabolises many commonly used drugs.

CONCLUSION

The negative physiological effects of smoking cessation may adversely affect a smoker's attempt to quit, and physicians should provide their smoking patients with motivation and regular encouragement and support when attempting to quit, whilst educating them on the health benefits of abstinence. Additionally, since cigarette smoke is a potent inducer of CYP1A2, patients attempting to quit smoking should have their dosages of drugs metabolised by this enzyme closely monitored.

Sex, race, and smoking impact olanzapine exposure

Response to antipsychotics is highly variable, which may be due in part to differences in drug exposure. The goal of this study was to evaluate the magnitude and variability of concentration exposure of olanzapine. Patients with Alzheimer's disease (n = 117) and schizophrenia (n = 406) were treated with olanzapine as part of the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE). Combined, these patients (n = 523) provided 1527 plasma samples for determination of olanzapine concentrations. Nonlinear mixed-effects modeling was used to determine the population pharmacokinetics of olanzapine, and patient-specific covariates were evaluated as potential contributors to variability in drug exposure. The population mean olanzapine clearance and volume of distribution were 16.1 L/h and 2150 L, respectively. Elimination of olanzapine varied nearly 10-fold (range, 6.66-67.96 L/h). Smoking status, sex, and race accounted for 26%, 12%, and 7% of the variability, respectively (P < .0001). Smokers cleared olanzapine 55% faster than non/past smokers (P < .0001). Men cleared olanzapine 38% faster than women (P < .0001). Patients who identified themselves as black or African American cleared olanzapine 26% faster than other races (P < .0001). Differences in olanzapine exposure due to sex, race, and smoking may account for some of the variability in response to olanzapine.

[Tobacco and schizophrenia: therapeutic aspects]

Although patients with have low motivations to quit smoking, smoking cessation treatment can be effective for these patients. Patients schizophrenia who achieve significant smoking reduction during a treatment intervention can at least maintain that level of reduction at 2 years. Cigarette smoking by patients with frequently goes unaddressed, contributing to excess mortality in this population. Behavioural interventions improve smoking cessation in schizophrenia patients. Nicotine replacement can substantially reduce withdrawal symptoms. Bupropion enhances smoking abstinence rates. Bupropion is well-tolerated and safe for use in schizophrenia patients: bupropion does not worsen clinical symptoms of schizophrenia. Atypical antipsychotics may reduce smoking consumption in schizophrenia patients, in particular clozapine. Atypical antipsychotic medication, in combination with the nicotine transdermal patch, significantly enhance the rate of smoking cessation. Interactions between smoking and antipsychotic medication - Smoking increases the metabolism of the antipsychotic medications by inducing the cytochrome P450 1A2 isoform. Smoking lowers the blood levels of typical or atypical antipsychotic medication, in particular haloperidol, chlorpromazine, olanzapine and clozapine. -Abstinence can increase many psychotropics' blood levels. Accordingly, smoking appears to reduce neuroleptic-induced parkinsonism. In contrast, smoking is a risk factor for tardive dyskinesia, independent of neuroleptic exposure.

Tobacco smoking in Egyptian schizophrenia patients with and without obsessive-compulsive symptoms

BACKGROUND

Nicotine dependence is common in schizophrenia patients but rare in patients with obsessive-compulsive disorder. Little is known, however, about smoking in schizophrenia patients with obsessive-compulsive symptoms (OCS) especially in a developing country, such as Egypt, that has the highest rate of tobacco consumption in the Middle East and North Africa.

OBJECTIVES

To test a hypothesis that nicotine dependence in schizophrenia patients with-OCS is lower than in those without-OCS.

RESULTS

Out of 87 consecutive schizophrenia patients attending a psychiatric out-patients clinic in Egypt, 34 patients (39%) had significant OCS, and a smoking rate (85.3%) not significantly lower than that of patients without-OCS (90.6%). Patients were reclassified by their Fagerström's scores into 3 groups of nicotine dependence: mild (37 patients), high (21 patients) and very high (29 patients). There were no differences between these groups in terms of YBOCS scores (F=0.324; p=0.724). When comparing PANSS scores of patients, with and without-OCS, those of the former group were higher on the positive symptoms (mean=24.2 versus 20.8; p=0.002), and anxiety/depression (mean=10.8 versus 10.1; p=0.03) but lower on the negative symptoms (mean=15.0 versus 19.4; p=0.000), disorganized thoughts (mean=14.5 versus 17.5; p=0.002), and uncontrolled hostility/excitement) (mean=7.5 versus 9.5; p=0.002). However, there was no significant between-group difference in the total PANSS scores.

CONCLUSIONS

The high and equal rates of smoking in patients with-, and without-OCS, and the lack of difference between YBOCS scores of mild, high and very high nicotine dependence groups undermined our initial hypothesis that nicotine dependence in schizophrenia patients with-OCS is lower than in those without them. Nevertheless, the finding of a distinctive PANSS scores, may support a suggestion that OCS in schizophrenia represent a distinct subtype or dimension.

Pharmacogenetics and pharmacogenomics of schizophrenia: a review of last decade of research

The last decade of research into the pharmacogenetics of antipsychotics has seen the development of genetic tests to determine the patients' metabolic status and the first attempts at personalization of antipsychotic treatment. The most significant results are the association between drug metabolic polymorphisms, mainly in cytochrome P450 genes, with variations in drug metabolic rates and side effects. Patients with genetically determined CYP2D6 poor metabolizer (PMs) status may require lower doses of antipsychotic. Alternatively, CYP2D6 ultrarapid matabolizers (UMs) will need increased drug dosage to obtain therapeutic response. Additionally, polymorphisms in dopamine and serotonin receptor genes are repeatedly found associated with response phenotypes, probably reflecting the strong affinities that most antipsychotics display for these receptors. In particular, there is important evidence suggesting association between dopamine 2 receptor (D2) polymorphisms (Taq I and -141-C Ins/Del) and a dopamine 3 receptor (D3) polymorphism (Ser9Gly) with antipsychotic response and drug-induced tardive dyskinesia. Additionally, there is accumulating evidence indicating the influence of a 5-HT2C polymorphism (-759-T/C) in antipsychotic-induced weight gain. Application of this knowledge to clinical practice is slowly gathering pace, with pretreatment determination of individual's drug metabolic rates, via CYP genotyping, leading the field. Genetic determination of patients' metabolic status is expected to bring clinical benefits by helping to adjust therapeutic doses and reduce adverse reactions. Genetic tests for the pretreatment prediction of antipsychotic response, although still in its infancy, have obvious implications for the selection and improvement of antipsychotic treatment. These developments can be considered as successes, but the objectives of bringing pharmacogenetic and pharmacogenomic research in psychiatric clinical practice are far from being realized. Further development of genetic tests is required before the concept of tailored treatment can be applied to psychopharmatherapy. This review aims to summarize the key findings from the last decade of research in the field. Current knowledge on genetic prediction of drug metabolic status, general response and drug-induced side effects will be reviewed and future pharmacogenomic and epigenetic research will be discussed.

Cigarette smoking and overweight/obesity among individuals with serious mental illnesses: a preventive perspective

BACKGROUND

Cigarette smoking and lifestyle factors underlying overweight/obesity (such as unhealthy diet and physical inactivity) appear to play a major role in the excess medical morbidity and mortality among persons with serious mental illnesses. The literature on the prevalence, etiology, prevention, and treatment of these two risk factors, in the context of serious mental illnesses, are reviewed following a preventive approach.

METHODS

The review relied upon searches of the MEDLINE database, from 1996 through April 2006, restricted to the English language. Original research, review articles, and clinical guidelines relevant to the topics of cigarette smoking, unhealthy diet, physical inactivity, and overweight/obesity among individuals with serious mental illnesses were identified.

RESULTS

Compared to those without a mental illness, individuals with a current mental illness are more than twice as likely to smoke cigarettes and more than 50% more likely to be overweight/obese, presumably the product of unhealthy diet and physical inactivity. Various biological, iatrogenic, and social factors place psychiatric patients at risk for these and other adverse health behaviors. Studies suggest that many of the same preventive approaches developed for general medical populations are likely to be effective in persons with serious mental disorders, though specialized approaches also are needed. Domains of prevention include primary prevention (population-based strategies to reduce the incidence of these adverse health behaviors), secondary prevention (early detection and treatment), and tertiary prevention (pharmacological and psychosocial treatments to reduce the burden of illness among those with the behaviors in question). However, mental health clinicians commonly lack the training or expertise to provide these services.

CONCLUSIONS

The high prevalence, adverse effects, and efficaciousness of treatments for smoking and obesity in persons with serious mental illnesses suggest the importance of addressing these problems in this population. Both further research and dissemination efforts are needed to ensure that patients with serious mental illnesses receive the appropriate preventive and clinical services for these two adverse health conditions.

Lack of effect of growth hormone replacement therapy on CYP1A2 and xanthine oxidase activities in growth hormone–deficient children

BACKGROUND AND OBJECTIVES

The recombinant human growth hormone (rhGH) is being increasingly used for a number of metabolic alterations. GH is the main regulator of several hepatic drug metabolizing enzymes in rodents. In addition, GH could play a major role in defining the interface between pharmacogenetics and development. However, little is known about the effect of GH on the activity of hepatic enzymes in children. The aim of this study was to determine the effect of rhGH replacement therapy for 4 weeks on CYP1A2 and xanthine oxidase (XO) activities in children.

METHODS

We used caffeine as a probe drug to assess the enzyme activities at two points in time: before starting GH treatment (day 0) and after 4 weeks on rhGH therapy (day A). A total of 31 GH-deficient children (age range: 4.1-13.1 years, mean age: 9.88+/-2.89 years) participated. Urinary concentrations of caffeine and metabolites were determined by high-performance liquid chromatography (HPLC) to calculate the metabolite ratios: (AFMU+1X+1U)/17U for CYP1A2 and 1U/(1X+1U) for XO.

RESULTS

Four weeks of GH substitution did not importantly alter the markers of the enzyme activities measured in this study. Median values and 95% confidence intervals (CI) at baseline were 5.17 (3.87-5.59) for the CYP1A2 ratio and 0.62 (0.56-0.65) for the XO ratio. These values, after treatment, were 4.57 (3.90-5.97) for the CYP1A2 marker and 0.62 (0.59-0.67) for the XO ratio. Data comparison between periods showed lack of statistically significant differences (P>0.05). The relative changes measured by the ratios of medians and 90% CI were 1.14 (0.90-1.31) and 0.99 (0.94-1.06) for CYP1A2 and XO, respectively.

CONCLUSIONS

The absence of significant changes in the markers of enzyme activities CYP1A2 and XO suggests that rhGH replacement therapy of GH-deficient children for 4 weeks could not noticeably modify the efficacy or toxicity of substrates of these metabolic enzymes.

Improving the care of individuals with schizophrenia and substance use disorders: consensus recommendations

National attention continues to focus on the need to improve care for individuals with co-occurring mental illnesses and substance use disorders, as emphasized in the 2003 President's New Freedom Commission Report on Mental Health and recent publications from the Substance Abuse and Mental Health Services Administration (SAMHSA). These reports document the need for best practice recommendations that can be translated into routine clinical care. Although efforts are underway to synthesize literature in this area, few focused recommendations are available that include expert opinion and evidence-based findings on the management of specific co-occurring disorders, such as schizophrenia and addiction. In response to the need for user-friendly recommendations on the treatment of schizophrenia and addiction, a consensus conference of experts from academic institutions and state mental health systems was organized to 1) frame the problem from clinical and systems-level perspectives; 2) identify effective and problematic psychosocial, pharmacological, and systems practices; and 3) develop a summary publication with recommendations for improving current practice. The results of the consensus meeting served as the foundation for this publication, which presents a broad set of recommendations for clinicians who treat individuals with schizophrenia. "Integrated treatment" is the new standard for evidence-based treatment for this population and recommendations are given to help clinicians implement such integrated treatment. Specific recommendations are provided concerning screening for substance use disorders in patients with schizophrenia, assessing motivation for change, managing medical conditions that commonly occur in patients with dual diagnoses (e.g., cardiovascular disease, liver complications, lung cancer, HIV, and hepatitis B or C infections) and selecting the most appropriate medications for such patients to maximize safety and minimize drug interactions, use of evidence-based psychosocial interventions for patients with dual diagnoses (e.g., Dual Recovery Therapy, modified cognitive-behavioral therapy, modified motivational enhancement therapy, and the Substance Abuse Management Module), and key pharmacotherapy principles for treating schizophrenia, substance use disorders, and comorbid anxiety, depression, and sleep problems in this population. Finally the article reviews programmatic and systemic changes needed to overcome treatment barriers and promote the best outcomes for this patient population. An algorithm summarizing the consensus recommendations is provided in an appendix.

An inter-ethnic comparison study of clozapine dosage, clinical response and plasma levels

The present study investigated clozapine dosage, plasma clozapine and metabolite levels, clinical and side-effect profiles in Asian versus Caucasian patients with chronic schizophrenia who were on stable maintenance treatment. Twenty Asian patients from Singapore and 20 Caucasian patients from Australia were systematically evaluated with the following rating scales: Positive and Negative Syndrome Scale for Schizophrenia, drug attitude scale (DAI-10), drug adverse reaction profile (Liverpool University Neuroleptic Side-effect Rating Scale), extrapyramidal side-effects scales (Abnormal Involuntary Movement Scale, Simpson and Angus Scale). Cigarette and caffeine consumption were recorded and steady-state plasma clozapine and metabolites levels were measured. Although Asian patients received a significantly lower mean clozapine dose (176 mg/day) than the Caucasian group (433 mg/day, P<0.001), plasma clozapine levels were similar between the groups. As a result, Asian patients had more than twice the effective clozapine concentration to dose ratio (P<0.001). The findings remained significant even after controlling for gender, body mass index, cigarette, alcohol and caffeine use. Conversely, the plasma metabolites (desmethylclozapine and clozapine N-oxide) to clozapine ratios were higher in the Caucasian patients (P<0.01). Compared to Caucasian patients, Asian patients appeared to have a lower dosage requirement for clinical efficacy. Hence, appropriate dose adjustment should be considered in Asian patients receiving maintenance clozapine therapy in clinical practice.

Warum rauchen Schizophreniepatienten?

Patients suffering from schizophrenia are known to show an increased prevalence of nicotine addiction. The aim of this paper is to elucidate the relationship between schizophrenia and (chronic) use of nicotine. Nicotine seems to improve cognitive functions critically affected in schizophrenia, in particular sustained attention, focused attention, working memory, short-term memory, and recognition memory. Furthermore, several studies using evoked potentials (P50 paradigm) and prepulse inhibition of the acoustic startle reflex suggest that deficient preattentive information processing, a core feature of schizophrenia illness, is improved following treatment with nicotine. Smoking can also improve extrapyramidal secondary effects of antipsychotic medication and it induces cytochrome P4501A2, an enzyme system involved in the metabolism of several antipsychotics. There is substantial evidence that nicotine could be used by patients with schizophrenia as a "self-medication" to improve deficits in attention, cognition, and information processing and to reduce side effects of antipsychotic medication. Possible pharmacotherapeutic approaches for the regulation of abnormal neurotransmission at nicotinic acetylcholine receptors are discussed.