Insulin counter-regulatory factors, fibrinogen and C-reactive protein during olanzapine administration: effects of the antidiabetic metformin

Pathogenic Role of Fibrinogen in the Neuropathology of Multiple Sclerosis: A Tale of Sorrows and Fears

Multiple sclerosis (MS) is an autoimmune demyelinating neurodegenerative disease of the central nervous system (CNS) due to injury of the myelin sheath by immune cells. The clotting factor fibrinogen is involved in the pathogenesis of MS by triggering microglia and the progress of neuroinflammation. Fibrinogen level is correlated with MS severity; consequently, inhibition of the fibrinogen cascade may reduce MS neuropathology. Thus, this review aimed to clarify the potential role of fibrinogen in the pathogenesis of MS and how targeting of fibrinogen affects MS neuropathology. Accumulation of fibrinogen in the CNS may occur independently or due to disruption of blood-brain barrier (BBB) integrity in MS. Fibrinogen acts as transduction and increases microglia activation which induces the progression of inflammation, oxidative stress, and neuronal injury. Besides, brain fibrinogen impairs the remyelination process by inhibiting the differentiation of oligodendrocyte precursor cells. These findings proposed that fibrinogen is associated with MS neuropathology through interruption of BBB integrity, induction of neuroinflammation, and demyelination with inhibition of the remyelination process by suppressing oligodendrocytes. Therefore, targeting of fibrinogen and/or CD11b/CD18 receptors by metformin and statins might decrease MS neuropathology. In conclusion, inhibiting the expression of CD11b/CD18 receptors by metformin and statins may decrease the pro-inflammatory effect of fibrinogen on microglia which is involved in the progression of MS.

Pharmacological interventions for prevention of weight gain in people with schizophrenia

BACKGROUND

Antipsychotic-induced weight gain is an extremely common problem in people with schizophrenia and is associated with increased morbidity and mortality. Adjunctive pharmacological interventions may be necessary to help manage antipsychotic-induced weight gain. This review splits and updates a previous Cochrane Review that focused on both pharmacological and behavioural approaches to this problem.

OBJECTIVES

To determine the effectiveness of pharmacological interventions for preventing antipsychotic-induced weight gain in people with schizophrenia.

SEARCH METHODS

The Cochrane Schizophrenia Information Specialist searched Cochrane Schizophrenia's Register of Trials on 10 February 2021. There are no language, date, document type, or publication status limitations for inclusion of records in the register.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) that examined any adjunctive pharmacological intervention for preventing weight gain in people with schizophrenia or schizophrenia-like illnesses who use antipsychotic medications.

DATA COLLECTION AND ANALYSIS

At least two review authors independently extracted data and assessed the quality of included studies. For continuous outcomes, we combined mean differences (MD) in endpoint and change data in the analysis. For dichotomous outcomes, we calculated risk ratios (RR). We assessed risk of bias for included studies and used GRADE to judge certainty of evidence and create summary of findings tables. The primary outcomes for this review were clinically important change in weight, clinically important change in body mass index (BMI), leaving the study early, compliance with treatment, and frequency of nausea. The included studies rarely reported these outcomes, so, post hoc, we added two new outcomes, average endpoint/change in weight and average endpoint/change in BMI.

MAIN RESULTS

Seventeen RCTs, with a total of 1388 participants, met the inclusion criteria for the review. Five studies investigated metformin, three topiramate, three H2 antagonists, three monoamine modulators, and one each investigated monoamine modulators plus betahistine, melatonin and samidorphan. The comparator in all studies was placebo or no treatment (i.e. standard care alone). We synthesised all studies in a quantitative meta-analysis. Most studies inadequately reported their methods of allocation concealment and blinding of participants and personnel. The resulting risk of bias and often small sample sizes limited the overall certainty of the evidence. Only one reboxetine study reported the primary outcome, number of participants with clinically important change in weight. Fewer people in the treatment condition experienced weight gains of more than 5% and more than 7% of their bodyweight than those in the placebo group (> 5% weight gain RR 0.27, 95% confidence interval (CI) 0.11 to 0.65; 1 study, 43 participants; > 7% weight gain RR 0.24, 95% CI 0.07 to 0.83; 1 study, 43 participants; very low-certainty evidence). No studies reported the primary outcomes, 'clinically important change in BMI', or 'compliance with treatment'. However, several studies reported 'average endpoint/change in body weight' or 'average endpoint/change in BMI'. Metformin may be effective in preventing weight gain (MD -4.03 kg, 95% CI -5.78 to -2.28; 4 studies, 131 participants; low-certainty evidence); and BMI increase (MD -1.63 kg/m2, 95% CI -2.96 to -0.29; 5 studies, 227 participants; low-certainty evidence). Other agents that may be slightly effective in preventing weight gain include H2 antagonists such as nizatidine, famotidine and ranitidine (MD -1.32 kg, 95% CI -2.09 to -0.56; 3 studies, 248 participants; low-certainty evidence) and monoamine modulators such as reboxetine and fluoxetine (weight: MD -1.89 kg, 95% CI -3.31 to -0.47; 3 studies, 103 participants; low-certainty evidence; BMI: MD -0.66 kg/m2, 95% CI -1.05 to -0.26; 3 studies, 103 participants; low-certainty evidence). Topiramate did not appear effective in preventing weight gain (MD -4.82 kg, 95% CI -9.99 to 0.35; 3 studies, 168 participants; very low-certainty evidence). For all agents, there was no difference between groups in terms of individuals leaving the study or reports of nausea. However, the results of these outcomes are uncertain given the very low-certainty evidence.

AUTHORS' CONCLUSIONS

There is low-certainty evidence to suggest that metformin may be effective in preventing weight gain. Interpretation of this result and those for other agents, is limited by the small number of studies, small sample size, and short study duration. In future, we need studies that are adequately powered and with longer treatment durations to further evaluate the efficacy and safety of interventions for managing weight gain.

Clozapine induces metformin-resistant prediabetes/diabetes that is associated with poor clinical efficacy in patients with early treatment-resistant schizophrenia

BACKGROUND

Two distinct subtypes of treatment-resistant schizophrenia (TRS) have been recently reported, including early-treatment resistance (E-TR) and late-treatment resistance (L-TR). This study was to assess clozapine-induced metformin-resistant prediabetes/diabetes and its correlation with clinical efficacy in schizophrenia E-TR subtype.

METHODS

This prospective cohort study enrolled 230 patients with schizophrenia E-TR subtype and they were treated with adequate doses of clozapine for 16 weeks, during which patients with prediabetes/diabetes were assigned to receive add-on metformin. The main outcomes and measures included incidence of clozapine-induced prediabetes/diabetes and metformin-resistant prediabetes/diabetes, and the efficacy of clozapine as assessed by the Positive and Negative Syndrome Scale (PANSS) score.

RESULTS

Clozapine-induced prediabetes/diabetes occurred in 76.52% of patients (170 prediabetes and 6 diabetes), of which the blood sugar of 43 (24.43%) patients was controlled with metformin. Despite add-on metformin, 47.06% (74/170) of prediabetes patients progressed to diabetes. In total, the incidence of clozapine-induced metformin-resistant prediabetes/diabetes was 75.57% (133/176). On completion of 16-week clozapine treatment, 16.52% (38/230) patients showed clinical improvement with PANSS scores of ≥50% declining. Furthermore, clozapine-induced prediabetes/diabetes was significantly correlated with the poor clinical efficacy of clozapine for schizophrenia E-TR subtype.

CONCLUSIONS

The incidence of clozapine-induced metformin-resistant prediabetes/diabetes was considerably high in the schizophrenia E-TR subtype. Clozapine-induced metformin-resistant prediabetes/diabetes represents an independent risk factor that adversely affects the clinical efficacy of clozapine for the schizophrenia E-TR subtype. This study provided new evidence for re-evaluating the use of clozapine for TRS, especially E-TR subtype, and the use of metformin for the glycemic control of clozapine-induced prediabetes/diabetes.

A Naturalistic Randomized Placebo-Controlled Trial of Extended-Release Metformin to Prevent Weight Gain Associated With Olanzapine in a US Community-Dwelling Population

OBJECTIVE

This 24-week pilot study assessed the efficacy, tolerability, and safety of adjunctive metformin versus placebo for the prevention of olanzapine-associated weight gain in community-dwelling adult patients with schizophrenia, schizoaffective disorder, bipolar disorder, or major depression with psychotic features.

METHODS

In a double-blind study, 25 patients were randomly assigned to receive 24 weeks of either olanzapine plus metformin or olanzapine plus placebo. Metformin extended release was titrated to 2000 mg daily as tolerated. No other antipsychotics were allowed, whereas psychotropic medications including antidepressants and mood stabilizers were permitted. The primary outcome measures were change in body weight and homeostatic model assessment for insulin resistance from baseline to week 24.

RESULTS

The intent-to-treat population comprised patients who had 1 or more post-baseline visit. Mean change in body weight for the olanzapine plus metformin (O/M) group was 5.5 lb, which was less than the 12.8 lb gain for the olanzapine plus placebo (O/P) group (P < 0.05). Compared with O/P group who gained 7% of their body weight, patients in the O/M group gained 3% (P < 0.037). Body mass index change in the O/M group was 0.85 versus 2.02 in the O/P group (P < 0.045). There was a trend for a greater increase in baseline to end point homeostatic model assessment for insulin resistance and waist circumference in the O/P group versus the O/M group.

CONCLUSIONS

In this naturalistic sample of typical US community-dwelling patients, metformin was effective and well tolerated for the prevention of olanzapine-associated weight gain. Adjunctive metformin should be studied in a similar but larger population to determine its role in the prevention of olanzapine-associated weight gain.

The Relationships of Obesity-Related Genetic Variants With Metabolic Profiles and Response to Metformin in Clozapine-Treated Patients With Schizophrenia

Obesity-related genetic variants, including TMEM18 (rs6548238), SH2B1 (rs7498665), and GNPDA2 (rs10938397), have been shown to be associated with obesity in the general population. Our study aimed to test whether these genetic variants are associated with metabolic profiles and metformin treatment response in clozapine-treated schizophrenic patients. We recruited 107 clozapine-treated patients who were genotyped and measured their metabolic profiles. Fifty-five subjects, who had at least 1 metabolic abnormality in a range of measures, were subsequently randomized to a 24-week trial of metformin (n = 28) or placebo (n = 27). We examined the associations between TMEM18, SH2B1, GNPDA2 genetic variants and metabolic profiles at baseline in all patients and metabolic changes in the trial groups. We found a significant association between SH2B1 and blood pressure at baseline in all patients. In the metformin group, TMEM18 minor allele carriers had a greater reduction in insulin levels (P = 0.04). A significantly higher proportion of TMEM18 and GNPDA2 minor allele carriers (60% and 40%) lost more than 7% of their body weight after metformin treatment as compared with their homozygous counterparts (21.7% and 15.4%, P = 0.02 and 0.004, respectively).There were trends toward favorable metabolic changes in minor allele carrier groups. In the placebo group, no association between genetic variants and changes in metabolic profiles was found. In conclusion, the study results suggest that these genes might be associated with metabolic abnormalities and response to metformin in clozapine-treated patients with schizophrenia.

Therapeutic Use of Metformin in Prediabetes and Diabetes Prevention

People with elevated, non-diabetic, levels of blood glucose are at risk of progressing to clinical type 2 diabetes and are commonly termed 'prediabetic'. The term prediabetes usually refers to high-normal fasting plasma glucose (impaired fasting glucose) and/or plasma glucose 2 h following a 75 g oral glucose tolerance test (impaired glucose tolerance). Current US guidelines consider high-normal HbA1c to also represent a prediabetic state. Individuals with prediabetic levels of dysglycaemia are already at elevated risk of damage to the microvasculature and macrovasculature, resembling the long-term complications of diabetes. Halting or reversing the progressive decline in insulin sensitivity and β-cell function holds the key to achieving prevention of type 2 diabetes in at-risk subjects. Lifestyle interventions aimed at inducing weight loss, pharmacologic treatments (metformin, thiazolidinediones, acarbose, basal insulin and drugs for weight loss) and bariatric surgery have all been shown to reduce the risk of progression to type 2 diabetes in prediabetic subjects. However, lifestyle interventions are difficult for patients to maintain and the weight loss achieved tends to be regained over time. Metformin enhances the action of insulin in liver and skeletal muscle, and its efficacy for delaying or preventing the onset of diabetes has been proven in large, well-designed, randomised trials, such as the Diabetes Prevention Program and other studies. Decades of clinical use have demonstrated that metformin is generally well-tolerated and safe. We have reviewed in detail the evidence base supporting the therapeutic use of metformin for diabetes prevention.

C-reactive protein levels in schizophrenia: a review and meta-analysis

There is an impression in the literature that schizophrenia is associated with increased inflammation, including abnormal blood levels of the acute phase reactant C-reactive protein (CRP). We performed a meta-analysis of blood CRP levels to estimate the overall effect size, as well as a pooled analysis of the prevalence of an elevated CRP level in patients with schizophrenia and related disorders. We identified articles by searching PubMed, PsycInfo, and ISI, and the reference lists of identified studies. Eight studies met the inclusion criteria for the meta-analysis, and five studies were included in the pooled analysis. CRP levels were significantly increased in patients compared to controls (effect size=0.45, 95% confidence interval 0.34-0.55, p<0.001). There was a 28% prevalence of an elevated CRP level in patients with schizophrenia and related disorders. Our results support a growing body of literature that schizophrenia is associated with increased inflammation, although many studies did not control for potential confounding factors such as BMI and smoking. Given the high prevalence of elevated CRP, metabolic syndrome, and premature cardiovascular mortality, our findings also suggest that measurement of blood CRP levels may be germane to the clinical care of patients with schizophrenia and related disorders.

Antipsychotics' effects on blood levels of cytokines in schizophrenia: a meta-analysis

OBJECTIVES

Evidence-based medicine suggests that schizophrenia is associated with an inflammatory syndrome, but the extent to which this syndrome is normalized by antipsychotic treatment has yet to be determined.

METHODS

A systematic quantitative review of the effects of antipsychotics on peripheral cytokine levels in schizophrenia was performed, using follow-up studies providing in vivo cytokine assessments before and after treatment.

RESULTS

We retrieved 23 studies (total of 762 subjects) which showed that antipsychotic treatment significantly increases plasma levels of soluble interleukin-2 receptor and reduces the plasma levels of interleukin-1β and interferon-γ.

CONCLUSIONS

These results show that antipsychotics produce anti-inflammatory effects in schizophrenia.

Role of Omega-3 fatty acids in preventing metabolic disturbances in patients on olanzapine plus either sodium valproate or lithium: a randomized double-blind placebo-controlled trial

Background

Metabolic and cardiovascular side effects have been noted with the use of second generation antipsychotics (SGAs) and mood stabilizers. Since Omega-3 fatty acids have been known to prevent some cardiovascular risks, this preliminary study was designed to evaluate the cardiovascular benefits of omega-3 when added to the combinations of olanzapine with mood stabilizers.

Methods

This study was a randomized, double-blind, placebo-controlled, within-subject trial in adult psychiatric patients who were receiving olanzapine combined with lithium (Li) or valproate sodium (VPA). Omega-3 as fish oil with less than 1 g/day of EPA/DHA or its placebo was added to patients’ olanzapine and mood stabilizer regimens for 6 weeks. Metabolic parameters including anthropometric variables, lipid profile, metabolic syndrome indices, C-reactive protein, fibrinogen and lipoprotein (a) [(Lp) (a)] were assessed for participants.

Results

Forty one participants completed this study; 20 patients received omega-3 and 21 patients received placebo, added to their regimen of SGA and mood stabilizer. Omega-3 addition did not modulate anthropometric, metabolic syndrome and lipid parameter changes in 6 weeks. However, fibrinogen levels significantly decreased, Lp (a) did not increase and non-high-density lipoprotein cholesterol (non-HDL-C) did not go beyond its target level after omega-3 supplementation. Additionally, a significant inter-group effect was noted for Lp(a).

Conclusions

This study suggests that use of short-term omega-3 supplementation added to a combined regimen of olanzapine and mood stabilizer may have a small modulating effect on some cardiovascular risk factors. Trials in longer periods of time and with larger number of patients are needed to further evaluate the effects of omega-3 supplements on preventing cardiovascular risk factors.

This trial is registered at irct.ir and its Identifier is as following: IRCT138712231764N1

Amantadine for olanzapine-induced weight gain: a systematic review and meta-analysis of randomized placebo-controlled trials

OBJECTIVE

The objective of this study was to conduct a systematic review and meta-analysis of randomized placebo-controlled trials of amantadine for the treatment of olanzapine-induced weight gain.

METHODS

Studies were identified using online searches of PUBMED/MEDLINE and Cochrane database (CENTRAL), along with websites recording trial information such as ClinicalTrials.gov, Controlled-trials.com, and Clinicalstudyresults.org. Study eligibility criteria included randomized, double-blind clinical trials comparing amantadine with placebo for olanzapine-induced weight gain with body weight as an outcome measure and study duration of at least 12 weeks. The methodological quality of included trials was assessed using the Jadad Scale. Separate meta-analyses were undertaken for each outcome (body weight and frequency of weight loss >7%) and treatment effects were expressed as weighted mean differences (WMD) and Mantel-Haenszel odds ratio for continuous and categorical outcomes, respectively.

RESULTS

A systematic review of literature revealed six studies that had assessed amantadine for olanzapine-induced weight gain. Of these, two studies (n = 144) met the review inclusion criteria and were included in the final analysis. Meta-analysis was performed to see the effect size of the treatment on body weight and frequency of body weight loss >7%. For body weight change, WMD was -1.85 (95% confidence interval [CI] -3.31 to -0.39) kg with amantadine as compared with placebo; the overall effect was statistically significant (p = 0.01). For frequency of body weight loss >7%, Mantel-Haenszel odds ratio for weight loss was 3.72 (95% CI 1.19-11.62), favoring amantadine as compared with placebo, and the overall effect was significant (p = 0.02).

CONCLUSIONS

Existing data is limited to two studies, which support the efficacy of amantadine for olanzapine-induced weight gain and a significant proportion of patients might lose weight with amantadine compared with placebo.

Reprise: The effect of metformin on anthropometrics and insulin resistance in patients receiving atypical antipsychotic agents: A meta-analysis

Atypical antipsychotics are well-established agents for the treatment of various psychiatric illnesses, although they are associated with adverse metabolic effects. There have been a few methodologically sound studies that have assessed the approach of adding metformin to atypical antipsychotics to reduce body weight. A systematic literature review of MEDLINE, EMBASE, and Cochrane was performed from the earliest possible dates to December 31, 2008. Metformin was found to be associated with a decrease in weight, waist circumference, bmi, and insulin resistance (p&lt;0.005). The data supports the consideration of metformin for the reduction of metabolic effects developed from the atypical antipsychotics in clinical practice. Ultimately, additional rigorous controlled trials with the various antipsychotics and at different time points in the development of the metabolic effects are needed.

Metformin for weight reduction in non-diabetic patients on antipsychotic drugs: a systematic review and meta-analysis

Weight gain is a clinically important side effect of antipsychotic drug therapy. The aim of this study was to determine the effect of the antidiabetic drug metformin on antipsychotic-induced weight gain in non-diabetic patients. In a systematic literature review we identified 195 citations from which seven randomized, placebo-controlled studies (398 patients) were included in the final analysis. Studies in adults (n = 5) and in children (n = 2) were analysed separately. Compared with placebo, metformin treatment caused a significant body weight reduction in adult non-diabetic patients treated with atypical antipsychotics (4.8%, 95% CI 1.6 to 8.0) and in children (4.1%, 95% CI 2.2 to 6.0). There was evidence of substantial heterogeneity among studies, and when the analysis was restricted to patients with a manifest (>10%) body weight increase prior to randomisation metformin reduced weight by 7.5% (95% CI 2.9 to 12.0). The effect was larger in Asians (7.8%, 95% CI 4.4 to 11.2) than in Hispanics (2.0%, 95% CI 0.7 to 3.3). In conclusion, metformin has a pronounced weight-reducing effect in antipsychotic-treated patients, especially in those with a manifest weight gain. Although direct comparisons are lacking, the observed effect on body weight compares favourably with the effect of sibutramine and orlistat, approved for weight reduction. However, metformin is not approved for use in non-diabetic patients and it is still not generally advisable to recommend metformin to counteract antipsychotic-induced weight gain.

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.

The adjunctive use of metformin to treat or prevent atypical antipsychotic-induced weight gain: a review

Patients with schizophrenia have a greater incidence of being overweight or obese compared with the general population. Such individuals are often treated with second-generation (atypical) antipsychotics (SGAs), which are associated with weight gain, dyslipidemia, and other metabolic derangements. As a result, frequent monitoring of weight and other metabolic parameters is recommended. In addition, several pharmacologic strategies to help prevent or reduce SGA-induced weight gain have been proposed. Despite this, clinicians often struggle to manage obesity and metabolic issues in such patients. Metformin has attracted attention as a potential treatment option because it is thought to result in weight reduction and improved glycemic control in obese patients with and without type 2 diabetes mellitus. This article focuses on relevant pharmacologic aspects of metformin and reviews currently available evidence on the use of metformin as an augmentation agent for the treatment or prevention of SGA-induced weight gain.

Polymorphisms of the LEP- and LEPR genes, metabolic profile after prolonged clozapine administration and response to the antidiabetic metformin

BACKGROUND

The role of leptin in atypical antipsychotic-induced metabolic dysfunction was explored by assessing the anthropometric and metabolic profile and the response to metformin (MET) of clozapine- (CLZ) treated schizophrenia patients according to their single nucleotide polymorphisms (SNPs) in the leptin promoter (LEP2548/GA) and leptin receptor (LEPR Q223R) genes.

METHODS

Phase 1. Body mass index (BMI), waist circumference, serum glucose, HbA1C, lipids, leptin, cortisol, insulin resistance index (HOMA-IR), metabolic syndrome and the frequencies of SNPs were assessed in 56 CLZ-treated patients (78.6% males). Phase 2. Fifty two phase 1 subjects were randomly assigned to MET XR (n=23) (1000 mg/day) or placebo (n=29) for 14 weeks. Changes in anthropometric and biochemical variables were compared between the SNPs.

RESULTS

Phase 1. The QQ group displayed the lowest triglyceride levels (p<0.05). No other significant difference was observed. Phase 2. Change in anthropometric variables did not differ between the genotypes in any treatment group. After MET, glucose levels significantly increased in the GG group (p<0.05), whereas the HOMA-IR and the low density cholesterol significantly decreased in the QQ- but not in the (QR+RR) group (p<0.05). No differences were observed after placebo.

CONCLUSIONS

BW response to CLZ was not related to LEP- and LEPR-SNPs. The GG and (QR+RR) genotypes showed an unexpectedly opposite and blunted response to MET administration respectively.

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.

Changes in weight and metabolic parameters during treatment with antipsychotics and metformin: do the data inform as to potential guideline development? A systematic review of clinical studies

BACKGROUND

Changes in weight and metabolic parameters have been commonly reported in patients with schizophrenia. Metformin has been evaluated in clinical studies to prevent or reduce weight gain and changes in metabolic parameters in non-diabetic subjects. We undertook a systematic review of the efficacy and safety of metformin in reducing weight gain and metabolic abnormalities in non-diabetic subjects with schizophrenia or bipolar disorder taking antipsychotic medication to establish if these data could potentially drive guideline development.

METHODS

Medical databases were searched using terms including 'antipsychotic', 'atypical antipsychotic agent', 'antipsychotic agents', 'antipsychotic-drug' and 'metformin' and 'weight'. Studies reporting weight and/or metabolic outcomes in non-diabetic subjects with schizophrenia and bipolar disorder were included regardless of methodological type and subject age.

RESULTS

Nine randomised double-blind studies and two open cohort studies evaluating metformin and changes in weight in trials up to 16 weeks were identified. In all, 495 participants received antipsychotics (mostly olanzapine), and three studies were in subjects aged < 18 years. The adult studies predominantly utilised non-Caucasian subjects with chronic schizophrenia. Weight and lifestyle intervention programmes were provided to all cohorts in eight studies, which confounded interpretation of the data. In ten studies, the addition of metformin to antipsychotic treatment was associated with either significantly attenuated weight gain or weight loss compared with control groups. Nine studies measured various glucose parameters. In four studies, subjects prescribed metformin had significantly improved glucose parameters relative to controls. The two studies of metformin in patients with first-episode schizophrenia demonstrated the largest improvement in weight and glucose parameters.

CONCLUSIONS

Metformin may have some value in reducing or preventing weight gain and changes in metabolic parameters during treatment with antipsychotic medication particularly in first-episode psychosis; however, it has been predominantly studied short-term and in non-Caucasian populations. A number of new trials are due to report data 2009-2013 to aid definitive interpretation of the role of metformin. Further longer-term studies are warranted before definitive guidelines can be established.

Inflammatory markers in schizophrenia: comparing antipsychotic effects in phase 1 of the clinical antipsychotic trials of intervention effectiveness study

BACKGROUND

C-reactive protein (CRP), intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin are systemic inflammatory markers (IM) that positively correlate with cardiovascular (CV) risk. Despite the known CV effects of atypical antipsychotics, there is limited prospective data on IM changes during treatment.

METHODS

The IM outcomes were compared between antipsychotic treatment groups in the CATIE (Clinical Antipsychotic Trials of Intervention Effectiveness) schizophrenia trial phase 1 with subjects with laboratory assessments at baseline and 3 months (n = 789).

RESULTS

There were significant treatment differences in CRP, E-selectin, and ICAM-1 at 3 months, with a differential impact of baseline values on the CRP and ICAM-1 results. In overall comparisons, quetiapine and olanzapine had the highest median levels for CRP, and olanzapine for E-selectin and ICAM-1. Olanzapine was significantly different after baseline adjustment than perphenazine (p = .001) for E-selectin, and in those with low baseline CRP (<1 mg/L), olanzapine was significantly different than perphenazine (p < .001), risperidone (p < .001), and ziprasidone (p = .002) for CRP. Perphenazine had the lowest 3-month ICAM-1 levels in subjects with baseline ICAM-1 above the median, but the differences were not statistically significant versus olanzapine (p = .010), quetiapine (p = .010), and risperidone (p = .006) after controlling for multiple comparisons. The 18-month repeated measures CRP analysis confirmed the significantly higher values for olanzapine in those with low baseline CRP.

CONCLUSIONS

This analysis provides further evidence for differential antipsychotic metabolic liabilities as measured by changes in systemic inflammation. C-reactive protein might emerge as a useful target for CV risk outcomes in schizophrenia patients.

Adverse endocrine and metabolic effects of psychotropic drugs: selective clinical review

The article critically reviews selected, clinically significant, adverse endocrine and metabolic effects associated with psychotropic drug treatments, including hyperprolactinaemia, hyponatraemia, diabetes insipidus, hypothyroidism, hyperparathyroidism, sexual dysfunction and virilization, weight loss, weight gain and metabolic syndrome (type 2 diabetes mellitus, dyslipidaemia and hypertension). Such effects are prevalent and complex, but can be managed clinically when recognized. They encourage continued critical assessment of benefits versus risks of psychotropic drugs and underscore the importance of close coordination of psychiatric and general medical care to improve long-term health of psychiatric patients. Options for management of hyperprolactinaemia include lowering doses, switching to agents such as aripiprazole, clozapine or quetiapine, managing associated osteoporosis, carefully considering the use of dopamine receptor agonists and ruling out stress, oral contraceptive use and hypothyroidism as contributing factors. Disorders of water homeostasis may include syndrome of inappropriate antidiuretic hormone (SIADH), managed by water restriction or slow replacement by hypertonic saline along with drug discontinuation. Safe management of diabetes insipidus, commonly associated with lithium, involves switching mood stabilizer and consideration of potassium-sparing diuretics. Clinical hypothyroidism may be a more useful marker than absolute cut-offs of hormone values, and may be associated with quetiapine, antidepressant and lithium use, and managed by thyroxine replacement. Hyper-parathyroidism requires comprehensive medical evaluation for occult tumours. Hypocalcaemia, along with multiple other psychiatric and medical causes, may result in decreased bone density and require evaluation and management. Strategies for reducing sexual dysfunction with psychotropics remain largely unsatisfactory. Finally, management strategies for obesity and metabolic syndrome are reviewed in light of the recent expert guidelines, including risk assessment and treatments, such as monoamine transport inhibitors, anticonvulsants and cannabinoid receptor antagonists, as well as lifestyle changes.

Extended release metformin for metabolic control assistance during prolonged clozapine administration: a 14 week, double-blind, parallel group, placebo-controlled study

BACKGROUND

Clozapine is the most effective agent in treatment-resistant schizophrenia. However, it is frequently associated with excessive body weight (BW) gain, type 2 diabetes mellitus and hyperlipidemia. The antidiabetic metformin (MET) has proved effective to assist in BW control during olanzapine administration. Therefore, we aimed to test whether MET may improve the metabolic profile in patients under prolonged clozapine administration.

METHODS

In a double-blind, parallel group protocol, 61 patients (94.4% with schizophrenia) receiving clozapine (196.8+/-132 mg daily, range: 25-500) for more than 3 consecutive months (86.5+/-40.6 months, range: 4-168) were randomly allocated to extended release MET (n=31; 500 to 1000 mg daily) or placebo (n=30) group for 14 weeks. The BW, the body mass index, waist circumference, serum glucose, insulin, lipids, glycated hemoglobin (HBA1c), leptin and cortisol, and the HOMA-IR index were assessed at baseline, and weeks 7 and 14.

RESULTS

MET was well tolerated and the mental state was not impaired during the study. The protocol was completed by all the placebo subjects and by 24 MET-treated patients. In a complete analysis at week 14, without including data of the 7 dropouts, the MET group lost -1.87+/-2.9 kg, whereas the placebo group had a stable BW: 0.16+/-2.9 kg, p=0.01 for the between group comparisons (effect size: 0.70). Leptin levels also tended to decrease after MET (p=0.08). Insulin and the triglyceride-HDL-C ratio significantly decreased (p<0.05, effect size 0.59 and 1.99 respectively) and the HDL-C significantly increased (p=0.001, effect size 0.95) after MET.

CONCLUSIONS

MET improves metabolic control during prolonged clozapine administration.

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.

Effects of clozapine and olanzapine on cytokine systems are closely linked to weight gain and drug-induced fever

The second generation antipsychotics clozapine and olanzapine are known to cause weight gain. However, only clozapine is associated with drug-induced fever. Cytokines have been linked to the induction of both weight gain and drug-induced fever. We investigated these potential side effects of clozapine and olanzapine and studied their differential effects on cytokine secretion. Thirty patients suffering from schizophrenia, schizophreniform disorder or schizoaffective disorder were treated with either clozapine (mean modal dose: 266.7+/-77.9mg) or olanzapine (21.2+/-2.5mg) in a randomized, double-blind, 6-week study. Body mass index (BMI), tympanic temperature, and plasma levels of leptin and cytokines (tumor necrosis factor-alpha (TNF-alpha), soluble TNF receptor 1 and 2 (sTNFR-1/2), soluble interleukin-2 receptors (sIL-2R), interleukin-6) were determined weekly. BMI, leptin and cytokines significantly increased over time, except interleukin-6 and sTNFR-1 in the olanzapine group. All cytokines numerically increased compared to baseline already during the first week of treatment in both groups. Leptin, TNF-alpha, sTNFR-1, sTNFR-2 and sIL-2R levels correlated with the BMI. Five patients who received clozapine (33%) developed drug-induced fever (>/=38 degrees C). In these, interleukin-6 peak levels were significantly (p<0.01) higher than in those patients treated with clozapine who did not develop fever. In conclusion, increase of BMI appears to be related to clozapine's and olanzapine's similar effects on cytokine systems, whilst drug-induced fever appears to be related to clozapine's differential effects on interleukin-6.

Pharmacological management of atypical antipsychotic-induced weight gain

Excessive bodyweight gain was reported during the 1950s as an adverse effect of typical antipsychotic drug treatment, but the magnitude of bodyweight gain was found to be higher with the atypical antipsychotic drugs that were introduced after 1990. Clozapine and olanzapine produce the greatest bodyweight gain, ziprasidone and aripiprazole have a neutral influence, and quetiapine and risperidone cause an intermediate effect. In the CATIE study, the percentage of patients with bodyweight gain of >7% compared with baseline differed significantly between the antipsychotic drugs, i.e. 30%, 16%, 14%, 12% and 7% for olanzapine, quetiapine, risperidone, perphenazine (a typical antipsychotic) and ziprasidone, respectively (p<0.001). Appetite stimulation is probably a key cause of bodyweight gain, but genetic polymorphisms modify the bodyweight response during treatment with atypical antipsychotics. In addition to nutritional advice, programmed physical activity, cognitive-behavioural training and atypical antipsychotic switching, pharmacological adjunctive treatments have been assessed to counteract excessive bodyweight gain. In some clinical trials, nizatidine, amantadine, reboxetine, topiramate, sibutramine and metformin proved effective in preventing or reversing atypical antipsychotic-induced bodyweight gain; however, the results are inconclusive since few randomized, placebo-controlled clinical trials have been conducted. Indeed, most studies were short-term trials without adequate statistical power and, in the case of metformin, nizatidine and sibutramine, the results are contradictory. The tolerability profile of these agents is adequate. More studies are needed before formal recommendations on the use of these drugs can be made. Meanwhile, clinicians are advised to use any of these adjunctive treatments according to their individual pharmacological and tolerability profiles, and the patient's personal and family history of bodyweight gain and metabolic dysfunction.

Metformin for metabolic dysregulation in schizophrenic patients treated with olanzapine

The second generation antipsychotic drugs, such as risperidone, olanzapine, and quetiapine, 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 effect of metformin treatment on the olanzapine-induced metabolic disturbance in schizophrenic patients. Twenty-four schizophrenic subjects who had received olanzapine treatment at least 3 months were assigned to the therapy with metformin 1500 mg/day for 8 weeks. The metabolic parameters were quantitatively assessed at baseline, weeks 2, 4, and 8 by using the intravenous glucose tolerance test. After an 8-week treatment with metformin, the body weight, fasting levels of glucose, triglyceride, and insulin, insulin secretion, and insulin resistance significantly decreased. Half of study subjects with metabolic syndrome obtained improvement after the metformin trial. Subjects' psychopathological condition remained unchanged during the study period. The olanzapine-induced metabolic disturbance could be reversed after 8-week metformin treatment. Based on the results of this study, we hypothesize that metformin could modulate the effect of olanzapine-induced metabolic disturbance.

Comparison of the effects of pioglitazone and metformin on hepatic and extra-hepatic insulin action in people with type 2 diabetes

OBJECTIVE

To determine mechanisms by which pioglitazone and metformin effect hepatic and extra-hepatic insulin action.

RESEARCH DESIGN AND METHODS

Thirty-one subjects with type 2 diabetes were randomly assigned to pioglitazone (45 mg) or metformin (2,000 mg) for 4 months.

RESULTS

Glucose was clamped before and after therapy at approximately 5 mmol/l, insulin raised to approximately 180 pmol/l, C-peptide suppressed with somatostatin, glucagon replaced at approximately 75 pg/ml, and glycerol maintained at approximately 200 mmol/l to ensure comparable and equal portal concentrations on all occasions. Insulin-induced stimulation of glucose disappearance did not differ before and after treatment with either pioglitazone (23 +/- 3 vs. 24 +/- 2 micromol x kg(-1) x min(-1)) or metformin (22 +/- 2 vs. 24 +/- 3 micromol x kg(-1) x min(-1)). In contrast, pioglitazone enhanced (P < 0.01) insulin-induced suppression of both glucose production (6.0 +/- 1.0 vs. 0.2 +/- 1.6 micromol x kg(-1) x min(-1)) and gluconeogenesis (n = 11; 4.5 +/- 0.9 vs. 0.8 +/- 1.2 micromol x kg(-1) x min(-1)). Metformin did not alter either suppression of glucose production (5.8 +/- 1.0 vs. 5.0 +/- 0.8 micromol x kg(-1) x min(-1)) or gluconeogenesis (n = 9; 3.7 +/- 0.8 vs. 2.6 +/- 0.7 micromol x kg(-1) x min(-1)). Insulin-induced suppression of free fatty acids was greater (P < 0.05) after treatment with pioglitazone (0.14 +/- 0.03 vs. 0.06 +/- 0.01 mmol/l) but unchanged with metformin (0.12 +/- 0.03 vs. 0.15 +/- 0.07 mmol/l).

CONCLUSIONS

Thus, relative to metformin, pioglitazone improves hepatic insulin action in people with type 2 diabetes, partly by enhancing insulin-induced suppression of gluconeogenesis. On the other hand, both drugs have comparable effects on insulin-induced stimulation of glucose uptake.

Metformin as an adjunctive treatment to control body weight and metabolic dysfunction during olanzapine administration: a multicentric, double-blind, placebo-controlled trial

BACKGROUND

Excessive body weight gain (BWG) is a clinically relevant side effect of olanzapine administration. The primary objective of this study was to assess whether metformin prevents or reverses BWG in patients with schizophrenia or bipolar disorder under olanzapine administration. Secondarily we evaluated diverse metabolic variables.

METHODS

Eighty patients taking olanzapine (5-20 mg daily for more than 4 consecutive months) were randomly allocated to metformin (n=40; 850 to 2550 mg daily) or placebo (n=40) group in a 12-week double-blind protocol. Waist circumference (WC) body weight (BW), body mass index (BMI) fasting glucose, glycated hemoglobin (Hb1c), insulin, an insulin resistance index (HOMA-IR) lipids, leptin, c-reactive protein, fibrinogen, cortisol and the growth hormone (GH) were evaluated at baseline and at week 12 of treatment.

RESULTS

The metformin group lost 1.4+/-3.2 kg (p=0.01) and tended to decrease its leptin levels, whereas the placebo group maintained a stable weight: -0.18+/-2.8 kg (p=0.7). The HOMA-IR significantly increased after placebo (p=0.006) and did not change after metformin (p=0.8). No ostensible differences were observed in the other variables, even though metformin did not improve the lipid profile and the Hb1c levels.

CONCLUSIONS

Metformin may safely assist olanzapine-treated patients in body weight and carbohydrate metabolism control.