Effects of olanzapine and ziprasidone on glucose tolerance in healthy volunteers

A double blind, placebo-controlled, randomized crossover study of the acute metabolic effects of olanzapine in healthy volunteers

Background and Rationale

Atypical antipsychotics exhibit metabolic side effects including diabetes mellitus and obesity. The adverse events are preceded by acute worsening of oral glucose tolerance (oGTT) along with reduced plasma free fatty acids (FFA) and leptin in animal models. It is unclear whether the same acute effects occur in humans.

Methodology/Principal Findings

A double blind, randomized, placebo-controlled crossover trial was conducted to examine the potential metabolic effects of olanzapine in healthy volunteers. Participants included male (8) and female (7) subjects [18–30 years old, BMI 18.5–25]. Subjects received placebo or olanzapine (10 mg/day) for three days prior to oGTT testing. Primary endpoints included measurement of plasma leptin, oral glucose tolerance, and plasma free fatty acids (FFA). Secondary metabolic endpoints included: triglycerides, total cholesterol, high- and low-density lipoprotein cholesterol, heart rate, blood pressure, body weight and BMI. Olanzapine increased glucose Area Under the Curve (AUC) by 42% (2808±474 vs. 3984±444 mg/dl·min; P = 0.0105) during an oGTT. Fasting plasma leptin and triglycerides were elevated 24% (Leptin: 6.8±1.3 vs. 8.4±1.7 ng/ml; P = 0.0203) and 22% (Triglycerides: 88.9±10.1 vs. 108.2±11.6 mg/dl; P = 0.0170), whereas FFA and HDL declined by 32% (FFA: 0.38±0.06 vs. 0.26±0.04 mM; P = 0.0166) and 11% (54.2±4.7 vs. 48.9±4.3 mg/dl; P = 0.0184), respectively after olanzapine. Other measures were unchanged.

Conclusions/Significance

Olanzapine exerts some but not all of the early endocrine/metabolic changes observed in rodent models of the metabolic side effects, and this suggest that antipsychotic effects are not limited to perturbations in glucose metabolism alone. Future prospective clinical studies should focus on identifying which reliable metabolic alterations might be useful as potential screening tools in assessing patient susceptibility to weight gain and diabetes caused by atypical antipsychotics.

Trial Registration

ClinicalTrials.gov NCT00741026

Impact of olanzapine or risperidone treatment on insulin sensitivity in schizophrenia or schizoaffective disorder

AIM

To assess changes in insulin sensitivity in non-diabetic adults with schizophrenia or schizoaffective disorder treated with olanzapine or risperidone.

METHODS

One hundred and thirty patients were randomly assigned to 12 weeks double-blind treatment with olanzapine or risperidone. Insulin sensitivity was measured using a two-step euglycaemic, hyperinsulinaemic clamp procedure. Whole-body adiposity was measured using dual-energy X-ray absorptiometry. The primary endpoint was the within-group change from baseline in insulin sensitivity normalized to fat-free mass (M(ffm) /I) during the clamp procedure's low-insulin phase, using an analysis of covariance model including the covariate weight change.

RESULTS

Forty-one olanzapine-treated and 33 risperidone-treated patients completed baseline and endpoint clamp measurements. Mean M(ffm) /I during the low-insulin phase declined 9.0% (p = 0.226) in olanzapine-treated patients and 13.2% (p = 0.047) in risperidone-treated patients (between-group difference p = 0.354). During the high-insulin phase, M(ffm) /I declined 10.4% (p = 0.036) in olanzapine-treated patients and 2.1% (p = 0.698) in risperidone-treated patients (between-group difference p = 0.664). Changes in M(ffm) /I correlated inversely with changes in body weight and adiposity, which were generally higher in olanzapine-treated patients. Significant within-group increases in fasting glucose, but not haemoglobin A1c (HbA1c), were observed during olanzapine treatment. The fasting glucose change was not correlated with M(ffm) /I changes.

CONCLUSIONS

Small, but statistically significant, decrements in insulin sensitivity were observed in olanzapine- and risperidone-treated patients at 1 of 2 insulin doses tested. Significant increases in fasting glucose and insulin and total fat mass were observed only in olanzapine-treated patients. Changes in insulin sensitivity correlated significantly with changes in weight or adiposity, but not with changes in glucose.

Olanzapine promotes fat accumulation in male rats by decreasing physical activity, repartitioning energy and increasing adipose tissue lipogenesis while impairing lipolysis

Olanzapine and other atypical antipsychotics cause metabolic side effects leading to obesity and diabetes; although these continue to be an important public health concern, their underlying mechanisms remain elusive. Therefore, an animal model of these side effects was developed in male Sprague-Dawley rats. Chronic administration of olanzapine elevated fasting glucose, impaired glucose and insulin tolerance, increased fat mass but, in contrast to female rats, did not increase body weight or food intake. Acute studies were conducted to delineate the mechanisms responsible for these effects. Olanzapine markedly decreased physical activity without a compensatory decline in food intake. It also acutely elevated fasting glucose and worsened oral glucose and insulin tolerance, suggesting that these effects are adiposity independent. Hyperinsulinemic-euglycemic clamp studies measuring (14)C-2-deoxyglucose uptake revealed tissue-specific insulin resistance. Insulin sensitivity was impaired in skeletal muscle, but either unchanged or increased in adipose tissue depots. Consistent with the olanzapine-induced hyperglycemia, there was a tendency for increased (14)C-2-deoxyglucose uptake into fat depots of fed rats and, surprisingly, free fatty acid (FFA) uptake into fat depots was elevated approximately twofold. The increased glucose and FFA uptake into adipose tissue was coupled with increased adipose tissue lipogenesis. Finally, olanzapine lowered fasting plasma FFA, and as it had no effect on isoproterenol-stimulated rises in plasma glucose, it blunted isoproterenol-stimulated in vivo lipolysis in fed rats. Collectively, these results suggest that olanzapine exerts several metabolic effects that together favor increased accumulation of fuel into adipose tissue, thereby increasing adiposity.

Relationship between insulin resistance and C-reactive protein in a patient population treated with second generation antipsychotic medications

C-reactive protein (CRP) is an inflammatory marker associated with obesity, insulin resistance, and cardiovascular disease. A recent study found CRP levels to be higher in individuals treated with certain antipsychotic medications such as olanzapine; however, it is not clear whether this is associated directly with drug intake or indirectly with drug-associated weight gain and insulin resistance. The objective of this study was to explore the potential predictors of CRP including insulin resistance, components of the metabolic syndrome, psychiatric diagnosis, and antipsychotic medication in patients treated with antipsychotics. Sixty-four outpatients without diabetes being treated with a single second generation antipsychotic medication had direct measurements of insulin resistance at the end of a 180-min infusion of glucose, insulin, and octreotide (insulin suppression test) as well as components of the metabolic syndrome. Insulin resistance was the strongest predictor of CRP (r=0.52, P<0.001). When adjusted for insulin resistance, there was no significant relationship between CRP and any of the components of the metabolic syndrome criteria, specific drug treatment or psychiatric diagnoses. In conclusion, insulin resistance is strongly associated with CRP levels and likely contributes to earlier associations between CRP and certain antipsychotic treatments.

Beneficial effect of the insulin sensitizer (HSP inducer) BGP-15 on olanzapine-induced metabolic disorders

Olanzapine is a widely used atypical antipsychotic, with well known metabolic side effects such as weight gain, insulin resistance and blood glucose abnormalities. It has been previously shown in a phase II clinical trial that BGP-15, an amidoxim derivative has insulin-sensitizing effects. The aim of this study was to investigate the efficacy of BGP-15 for the treatment of olanzapine-induced metabolic side effects, in healthy volunteers. Thirty-seven (37) subjects (ages 18-55 years) with normal glucose metabolism were randomly assigned to 17 days of once-daily treatment with 400mg of BGP-15 or placebo and 5mg of olanzapine for 3 days followed by 10mg for 14 days. Total body and muscle tissue glucose utilization was determined by hyperinsulinemic-euglycemic clamp technique. As expected the 17-day olanzapine treatment provoked insulin resistance and body weight gain (p<0.05) in both groups. Administration of BGP-15 significantly reduced olanzapine-induced insulin resistance. The protective effect of BGP-15 on insulin stimulated glucose utilization had the highest magnitude in the values calculated for the muscle tissue (p=0.002). In healthy individuals BGP-15 was safe and well tolerated during the whole study period. It is suggested that BGP-15 can be a successful insulin sensitizer agent to prevent side effects of olanzapine treatment.

Clozapine treatment causes oxidation of proteins involved in energy metabolism in lymphoblastoid cells: a possible mechanism for antipsychotic-induced metabolic alterations

There is increasing concern about the serious metabolic side effects and neurotoxicity caused by atypical (second-generation) antipsychotics. In a previous study by our group (Walss-Bass et al. Int J Neuropsychopharmacol 2008;11:1097-104), using a novel proteomic approach, we showed that clozapine treatment in SKNSH cells induces oxidation of proteins involved in energy metabolism, leading us to hypothesize that protein oxidation could be a mechanism by which atypical antipsychotics increase the risk for metabolic alterations. In this study, the same proteomic approach was used to identify specific proteins oxidized after clozapine treatment in lymphoblastoid cell lines from patients with schizophrenia and normal controls. Cells were treated with 0 and 20 μM clozapine for 24 hours and protein extracts were labeled with 6-iodoacetamide fluorescein (6-IAF). The lack of incorporation of 6-IAF into the thiol group of cysteine residues is an indicator of protein oxidation. Labeled proteins were exposed to two dimensional electrophoresis, and differential protein labeling was assessed. Increased oxidation after clozapine treatment was observed in 9 protein spots (P<0.05). The following 7 proteins were identified by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) in those 9 spots: enolase, triosephosphate isomerase (TPI), glyceraldehyde-3-phosphate dehydrogenase (GAPD), Rho GDP dissociation inhibitor (GDI), cofilin, uridine monophosphate/ cytidine monophosphate (UMP-CMP) kinase, and translation elongation factor. Several of these proteins play important roles in energy metabolism and mitochondrial function. These results further support the hypothesis that oxidative stress may be a mechanism by which antipsychotics increase the risk of metabolic syndrome and diabetes.

The time-dependent change of insulin secretion in schizophrenic patients treated with olanzapine

The second generation antipsychotic drugs (SGAs) are effective in treating patients with schizophrenia and have been considered as the first line therapy. Recently, increasing attention has been drawn to the potential diabetogenic effect of these novel antipsychotics. The goal of this study was to evaluate the time-dependent effects of olanzapine treatment on pancreatic beta cell function in SGA-naïve schizophrenic patients. Forty-two schizophrenic subjects received olanzapine therapy for 8 weeks and thirty-three of them completed the trial. Of whom 33 completers (21 male, mean+/-SD age: 37.6+/-8.0 years) were inpatients and unexposed to SGA. The metabolic parameters were quantitatively assessed at weeks 0, 2, 4, and 8 by the intravenous glucose tolerance test. After 56-day olanzapine treatment, subjects had significant increases in body weight and as well as in the levels of triglyceride, total cholesterol, and low-density lipoprotein. Insulin secretion significantly decreased at week 2, returned to baseline at week 4, and significantly increased at week 8. Of the total samples, 18.2% and 33.3% of them met the criteria for significant weight gain and metabolic syndrome after 8-week olanzapine treatment, respectively. This study indicates that olanzapine-treated schizophrenic patients displayed biphasic changes in insulin secretion to a hyperglycemic challenge. The results of this study support that olanzapine might directly influence pancreatic beta cell function.

A parametric study of the acute effects of antipsychotic drugs on glucose sensitivity in an animal model

The therapeutic use of atypical antipsychotics is associated with a high incidence of metabolic side-effects. In the present study we examined the acute effects of both high and low-dose atypical antipsychotic drugs and one typical drug on alterations in glucose and insulin parameters using a rodent model. The effects of administration of clozapine (2mg/kg; 20mg/kg), olanzapine (1.5mg/kg; 15 mg/kg), risperidone (0.5mg/kg; 2.5mg/kg) and haloperidol (0.1mg/kg; 1.0mg/kg) on glucose sensitivity and insulin resistance were determined through HOMA-IR values in fasted rats and glucose clearance during a glucose tolerance test. Acute effects were determined 60, 180 or 360 min following drug administration. The atypical antipsychotics produced significant dose and time dependent effects on fasting plasma glucose and insulin concentrations, HOMA-IR values, insulin resistance and glucose intolerance. The greatest effect on glucose dysregulation was noted primarily with clozapine and olanzapine; however, all four treatments caused significant increases in fasting glucose and/or insulin levels with the high dose, 60 min post-drug administration. Together, these findings indicate that acute administration of antipsychotic drugs has potent effects on metabolic regulation of glucose and insulin sensitivities, which may contribute to metabolic side-effects seen in humans.

Relationship between body mass index and insulin resistance in patients treated with second generation antipsychotic agents

Second generation antipsychotics (SGAs) can increase weight gain and weight-induced insulin resistance. Recent studies have suggested weight-independent effects of certain SGAs on insulin resistance; however the magnitude of these effects and the relationship between BMI and insulin resistance in patients on SGAs are not established. To evaluate, the relationship between body mass index (BMI) and insulin resistance in 54 patients being stably treated with olanzapine (n=19), risperidone (n=16), or aripiprazole (n=19) was compared with data from a large reference population (n=201) not on SGAs. Insulin resistance was directly quantified by measuring the steady-state plasma glucose (SSPG) concentration during the insulin suppression test. The relationship between BMI and SSPG was similar between the SGA (r=0.58) and the reference population (r=0.50). When SSPG was standardized based on expected values for the reference population, patients on olanzapine had a higher degree of insulin resistance (mean z-score+/-SD, 0.68+/-0.9) than expected for level of BMI compared with those on aripiprazole (-0.25+/-1) and risperidone (-0.3+/-0.9), F(2,51)=6.28 (p=0.004). Thus, olanzapine group was 0.76 SD above the reference population or in the 78 percentile for insulin resistance. SSPG was correlated with fasting plasma insulin concentration (0.78 (0.64-0.87), p<0.001) but not fasting glucose concentration (0.15 (-0.13-0.40), p=0.29). In conclusion, BMI contributes a quarter to a third of the variance in insulin resistance in the SGA population similar to the reference population. Olanzapine also appears to have an independent effect on insulin resistance that is above and beyond obesity.

Metformin for atypical antipsychotic-induced weight gain and glucose metabolism dysregulation: review of the literature and clinical suggestions

Individuals receiving certain atypical antipsychotic medications are at risk of gaining weight and developing metabolic problems. There are no established drug treatments to prevent or counter these problems. However, the antihyperglycaemic agent metformin appears promising in some recent studies and we review the literature that evaluates metformin for limiting or reversing atypical antipsychotic drug-induced weight gain and glucose metabolism dysregulation. These studies suggest that metformin is beneficial if started early in antipsychotic drug treatment. Metformin has also been shown to prevent or delay the onset of type 2 diabetes mellitus in high-risk individuals from the general population. Based on these findings, we identify antipsychotic drug-treated patients who might benefit from metformin therapy and offer clinical guidelines for its use. Further long-term studies are needed to extend our observations and improve this strategy.

Mifepristone treatment of olanzapine-induced weight gain in healthy men

INTRODUCTION

Antipsychotic medications are associated with significant weight gain, type 2 diabetes mellitus, dyslipidemia, and increased cardiovascular risk. Suggested mechanisms of weight gain from antipsychotic medication include antagonism of histamine and serotonin receptors, and effects on the hypothalamic-pituitary-adrenal axis. The objective of this study was to determine if mifepristone, a glucocorticoid receptor antagonist, could prevent olanzapine-induced weight gain.

METHODS

This was a randomized, double-blind trial. Fifty-seven lean, healthy men (body mass index 18-25 kg/m(2)) aged 19-38 years were randomized to olanzapine (7.5 mg) (n=22), olanzapine (7.5 mg) plus mifepristone (600 mg) (n=24), or mifepristone (600 mg) (n=11) daily for 2 weeks in an institutional setting. Subjects were provided food ad libitum to accentuate weight gain. Body weight was measured daily.

RESULTS

The mean change in baseline weight was +3.2+/-0.9 kg in subjects receiving olanzapine versus +2.0+/-1.2 kg in those receiving olanzapine plus mifepristone (P<0.0001). Subjects receiving mifepristone alone had a similar degree of weight gain compared to those receiving olanzapine plus mifepristone. The olanzapine group had significant increases in waist circumference when compared with the olanzapine plus mifepristone group (3.7+/-1.3 cm vs. 2.2+/-1.9 cm, respectively; P=0.006). Fasting insulin and triglycerides increased more in the olanzapine group, although differences were not statistically significant.

CONCLUSION

Mifepristone was effective in attenuating the increase in weight associated with olanzapine treatment over a 2-week period. Longer-term studies are required to examine the durability and full magnitude of this response.

Hormonal markers of metabolic dysregulation in patients with severe mental disorders after olanzapine treatment under real-life conditions

OBJECTIVE

Dyslipidemia independent of body mass has previously been reported in humans after antipsychotic treatment. The present study investigated the levels of several metabolic regulatory hormones in psychiatric outpatients treated with different antipsychotics under real-life conditions.

METHODS

The study included cross-sectional data from 234 subjects on stable monotherapy with any of the following: olanzapine (n = 72), any other antipsychotic (n = 80), or no medications (n = 82). Groups were well matched for sex, body mass index (BMI), ethnicity, and smoking. After adjustment for differences in age and illness duration, groups were compared for the insulin resistance index (homeostatic model assessment of insulin resistance) and fasting concentrations of glucose, lipids, insulin, sex hormone-binding globulin (SHBG), adiponectin, leptin, and cortisol. Correlations were examined between serum olanzapine and hormonal levels, and between leptin concentrations and BMI in both sexes.

RESULTS

Significant intergroup differences in concentrations of insulin (P = 0.025), SHBG (P = 0.001), adiponectin (P = 0.017), and cortisol (P = 0.003) but no significant difference for homeostatic model assessment of insulin resistance (P = 0.051) were found, independent of body mass. Olanzapine-treated subjects had the highest insulin concentrations and the lowest SHBG, adiponectin, and cortisol concentrations. Olanzapine-treated female subjects had significantly higher leptin (P = 0.005) and lower SHBG (P = 0.023) concentrations than other subjects. In female subjects, serum olanzapine concentrations were correlated with hormonal levels, and a significant proportion of olanzapine-treated female subjects had abnormal correlations between serum leptin levels and BMI.

CONCLUSIONS

Alterations in several interrelated metabolic hormonal markers were associated with olanzapine treatment, independent of body mass, particularly in female subjects.

Potentiation of the antidepressant-like effect of fluoxetine by aripiprazole in the mouse tail suspension test

We examined the effect of the novel atypical antipsychotic drug aripiprazole alone or in combination with the selective serotonin reuptake inhibitor fluoxetine in the mouse tail suspension test. We also investigated the effect of aripiprazole on glucose metabolism. Combined treatment with aripiprazole and a sub-effective dose of fluoxetine significantly decreased the duration of immobility in the tail suspension test. Aripiprazole by itself did not affect the duration of immobility. While olanzapine significantly increased blood glucose level in the glucose tolerance test, aripiprazole did not affect glucose metabolism. We suggest that aripiprazole augments the antidepressant-like effect of fluoxetine without affecting glucose metabolism.

Pioglitazone in chronic hepatitis C not responding to pegylated interferon-alpha and ribavirin

BACKGROUND/AIMS

Insulin resistance reduces the response to interferon alfa-based therapy of chronic hepatitis C patients. It has been speculated that improvement of insulin sensitivity might increase the chances of responding to treatment of such individuals.

METHODS

We started a multicenter clinical trial of retreatment of chronic hepatitis C patients, who had failed to respond to the pegylated interferon alfa/ribavirin combination, with a triple therapy consisting in these same antivirals plus an insulin-sensitizer (pioglitazone) (The INSPIRED-HCV study).

RESULTS

None of the first five patients fulfilling the inclusion criteria and included in the trial achieved a satisfactory virological response after 12 weeks of retreatment, despite the fact that in at least three of them the insulin resistance score improved. As a result, the study was terminated.

CONCLUSIONS

Different schedules are warranted to improve insulin sensitivity prior to attempting retreatment of chronic hepatitis C patients with insulin resistance.

Antipsychotics and diabetes: an age-related association

BACKGROUND

Previous studies have reported an association between anti-psychotic medications and diabetes.

OBJECTIVE

To explore the association between antipsychotic medications and diabetes in patients of different ages.

METHODS

A retrospective analysis of a large health maintenance organization's drug claim database (3.7 million members) was performed. All patients treated with antipsychotic drugs during 1998-2004 were identified. Patients with diabetes were defined by a record of antidiabetic drug use during 2004. The prevalence of diabetes in different age groups treated with antipsychotics was compared with the prevalence of diabetes among enrollees in the same age groups not treated with antipsychotics.

RESULTS

Among 82,754 patients treated with antipsychotics, the association between diabetes and consumption of antipsychotics was strongest in the younger age groups and decreased with increasing age: for patients aged 0-24 years, OR 8.9 (95% CI 7.0 to 11.3); 25-44 years, OR 4.2 (95% CI 3.8 to 4.5); 45-54 years, OR 1.9 (95% CI 1.8 to 2.1); 55-64 years, OR 1.3 (95% CI 1.2 to 1.4); and 65 years or older, OR 0.93 (95% CI 0.9 to 1.0). However, the risk associated with atypical antipsychotics was lower than the risk associated with typical antipsychotics, with ORs ranging from 0.7 in patients 0-24 years old to 0.3 in those 65 years or older.

CONCLUSIONS

Antipsychotic drug use was associated with diabetes mellitus. This association was stronger in younger patients. In older adults, the difference was much smaller and, in some cases, there was no association. A lower risk was associated with atypical agents, as compared with typical antipsychotics. Clinicians should be aware that young adults treated with antipsychotics are at increased risk for diabetes.