Amantadine does not exacerbate positive symptoms in medicated, chronic schizophrenic patients: evidence from a double-blind crossover study

Amantadine for Antipsychotic-Related Weight Gain: Meta-Analysis of Randomized Placebo-Controlled Trials

PURPOSE

Weight gain associated with antipsychotics in schizophrenia has been an ongoing concern. This meta-analysis examined the efficacy and safety of amantadine as an adjunctive treatment of weight gain in schizophrenia by systematically searching and analyzing randomized controlled trials (RCTs). RCTs comparing adjunctive amantadine with placebo in adult patients with schizophrenia were included in the meta-analysis.

METHODS

Two independent investigators searched the literature and extracted data. Weighted and standardized mean differences (WMDs/SMDs) and risk ratio ± 95% confidence intervals were calculated.

RESULTS

Five RCTs (n = 265) with double-blinded design lasting 8.2 ± 5.9 weeks were included in the analysis. Amantadine outperformed placebo regarding weight reduction with moderate effect size (trials, 3; n = 205; WMD -2.22 kg; P = 0.001, I = 45%). Amantadine also outperformed placebo at endpoint in the negative symptom (the Positive and Negative Syndrome Scale [PANSS] [1 trial] and the Scale for the Assessment of Negative Symptoms [1 trial]) scores (trials, 2; n = 84; SMD, -0.56; P = 0.01, I = 12%), but not in the PANSS total scores (trials, 2) (SMD, -0.31; P = 0.16, I = 0%) and the positive symptom (PANSS [1 trial] and the Scale for the Assessment of Positive Symptoms [1 trial]) scores (SMD, 0.13; P = 0.54, I = 0%). Except for insomnia (P = 0.007; number needed to harm, 6; 95% confidence interval, 4-16), all-cause discontinuation (risk ratio, 1.12; P = 0.54, I = 0%) and other adverse events were similar between the amantadine and placebo groups.

CONCLUSIONS

According to this meta-analysis of 5 RCTs, adjunctive amantadine seems to be an effective option for attenuating antipsychotic-related weight gain in patients with schizophrenia. More RCTs are needed to inform clinical recommendations.

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.

Metabolic side effects of antipsychotic medication

The use of second-generation antipsychotics (SGAs) is associated with metabolic side effects including weight gain, diabetes mellitus and an atherogenic lipid profile. These adverse effects are not only the risk factors for cardiovascular disease, insulin resistance and diabetes mellitus leading to increased morbidity and mortality but may also impair the patient's adherence to treatment. SGAs in particular are associated with significant weight gain with clozapine and olanzapine carrying the highest risk, whereas newer agents, such as risperidone and aripiprazole, are considered to be less prone to cause weight gain. Consequently, a consensus development conference convened issuing recommendations on patient monitoring when treated with SGAs. The metabolic effects of antipsychotic drugs should be of concern when planning a patient's treatment strategy. Baseline screening and regular follow-up monitoring whose intervals should depend on the individual predisposition are advised. Possible therapeutical strategies for the management of drug-induced obesity include therapeutic approaches, such as life style change and pharmaceutical intervention. Drugs with a weight reducing effect become more important because of the lack of compliance with behavioural intervention. Topiramate, histamine-antagonists, dopaminergic- and serotoninergic agents have shown positive results in the management of psychotropic medication induced weight gain. However, further trials are required to support a specific therapeutical approach as well as studies to investigate the underlying mechanisms for future drug development.

A double-blind, cross-over comparison of the effects of amantadine or placebo on visuomotor and cognitive function in medicated schizophrenia patients

The present study aimed to test the hypothesis that dopamine agonists may enhance cognitive function. The effect of amantadine on neuropsychological function in medicated schizophrenia patients was investigated. The study comprised an add-on, double-blind, placebo-controlled, cross-over 6-week trial. Participants comprised 29 inpatients at Sha'ar Menashe Mental Health Center who were diagnosed with chronic schizophrenia or schizoaffective disorder. Amantadine 200 mg/day or identical placebo was added to ongoing antipsychotic treatment for 3 weeks. Study medications were then switched for an additional 3 weeks. Assessments were performed at baseline, and weeks 3 and 6, including cognitive and visuomotor assessments. Clinical ratings included positive, negative and depressive symptoms and extrapyramidal side-effects. Blood prolactin levels were assayed. A mixed model was used to examine differences in the data at the three assessment points. Amantadine was associated with improved visuomotor coordination compared to placebo. No significant changes in cognitive functions were noted. Clinical symptoms, extrapyramidal side-effects and blood prolactin levels were not altered. Amantadine improved visuomotor coordination independently of extrapyramidal side-effects but not cognitive function. Because prolactin concentrations were unchanged, the mechanism is more likely to involve glutaminergic NMDA than dopaminergic mechanisms. Further studies of amantadine with different doses and treatment duration, as well as more glutamate selective agents such as memantine, are indicated.

Amantadine for weight gain associated with olanzapine treatment

Patients with schizophrenia (Sch), schizoaffective, schizophreniform, or bipolar (BP) I disorders [Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV)]; not manic or acutely psychotic [Brief Psychiatric Rating Scale (BPRS) total score < or =45]; treated with olanzapine for 1-24 months; and who had gained > or =5% of their initial body weight were examined to determine whether amantadine could attenuate weight gain or promote weight loss. Olanzapine (Olz; 5-20 mg/day) was co-administered with double-blind treatment of 100-300 mg/day amantadine (Olz+Amt, n=60) or placebo (Olz+Plc, n=65). Visit-wise analysis of weight showed that weight change from baseline [last-observation-carried-forward (LOCF)] in the Olz+Amt group was significantly different from the Olz+Plc group at weeks 8 (P=0.042), 12 (P=0.029), and 16 (primary endpoint, mean+/-S.D.: -0.19+/-4.58 versus 1.28+/-4.26 kg, P=0.045). Mean BPRS total score, positive subscale, and anxiety-depression scores improved comparably in both groups, and Montgomery-Asberg Depression Rating Scale (MADRS) total score improved in the Olz+Amt group. Overall, amantadine was safe, was well tolerated, and attenuated weight gain or promoted weight loss in some patients who had gained weight during olanzapine therapy.

Special considerations in the treatment of patients with bipolar disorder and medical co-morbidities

BACKGROUND: The pharmacological treatment of bipolar disorder has dramatically improved with multiple classes of agents being used as mood-stabilizers, including lithium, anticonvulsants, and atypical antipsychotics. However, the use of these medications is not without risk, particularly when a patient with bipolar disorder also has comorbid medical illness. As the physician who likely has the most contact with patients with bipolar disorder, psychiatrists must have a high index of suspicion for medical illness, as well as a basic knowledge of the risks associated with the use of medications in this patient population. METHODS: A review of the literature was conducted and papers addressing this topic were selected by the authors. RESULTS AND DISCUSSION: Common medical comorbidities and treatment-emergent illnesses, including obesity, diabetes mellitus, dyslipidemia, cardiac disease, hepatic disease, renal disease, pulmonary disease and cancer are reviewed with respect to concomitant use of mood stabilizers. Guidance to clinicians regarding effective monitoring and treatment is offered. CONCLUSIONS: Mood-stabilizing medications are necessary in treating patients with bipolar disorder and often must be used in the face of medical illness. Their safe use is possible, but requires increased vigilance in monitoring for treatment-emergent illnesses and effects on comorbid medical illness.

Amantadine treatment of psychotropic-induced weight gain in children and adolescents: case series

OBJECTIVE

The purpose of this study was to explore whether amantadine would slow or reverse significant weight gain in children and adolescents treated with antipsychotics and/or mood stabilizers that may promote increases in weight.

METHODS

Eight boys and one girl ages 9-16 years and their parents consented to an open trial of amantadine 100 mg po bid or tid for weight gain in children. Side effects and body mass index were determined at baseline and during amantadine treatment.

RESULTS

A mean weight gain of 10.5 kg (19.9% mean increase in body weight) occurred from baseline to the beginning of amantadine treatment. Amantadine trial length averaged 14.5 weeks (range 4-33 weeks). A planned comparison using repeated measures analysis of variance demonstrated strong support for a "slowing weight gain" mechanism (p = 0.001) for weight gain and body mass. Weight loss was strongly correlated with length of amantadine treatment (p = < 0.05). One child experienced orthostatic hypotension with concomitant stimulant medication. No other side effects or exacerbation of psychiatric symptoms was reported.

CONCLUSIONS

Amantadine appears to stabilize weight gain related to psychotropic medications. Decreased weight and body mass index may occur with continued amantadine usage. Controlled trials of amantadine in children and adolescents taking weight-gain-inducing psychotropics are warranted.

Options for pharmacological management of obesity in patients treated with atypical antipsychotics

Obesity is associated with considerable morbidity and decreased life expectancy. Weight gain is a commonly encountered problem associated with antipsychotic treatment. We reviewed the literature regarding the mechanisms of weight gain in response to these agents and eight substances implicated as potential obesity prevention or treatment: orlistat, sibutramine, fluoxetine, topiramate, amantadine, nizatidine and cimetidine, and metformin. Weight gain in response to antipsychotic treatment may be mediated through serotonergic, dopaminergic, adrenergic, cholinergic, histaminergic and glutaminergic receptors. Sex hormone dysregulation and altered insulin sensitivity have also been implicated. Two compounds, orlistat and sibutramine, have been shown to help prevent weight gain following a hypocaloric diet, but orlistat requires compliance with a fat-reduced diet, and sibutramine is unsuitable for patients taking serotonergic agents. The weight reducing effect of fluoxetine, even in conjunction with a hypocaloric diet, is only transient. Topiramate, amantadine and metformin may have adverse side-effects potentially outweighing the weight reducing potential. The effectiveness of cimetidine and nizatedine remains unclear. The hazards of these agents in a psychiatric population are discussed. It is concluded that the current evidence does not support the general use of pharmacological interventions for overweight patients treated with antipsychotic medication, although individually selected patients may benefit.

Body weight gain induced by antipsychotic drugs: mechanisms and management

Long-term administration of typical and atypical antipsychotic drugs (AP) induces excessive weight gain which afflicts up to 50% of patients, impairs health and interferes with treatment compliance. Basic and clinical research has shown that AP may affect body weight through diverse mechanisms. Increased appetite is probably related to the interaction of AP with neuronal receptors to dopamine, serotonin and histamine. Additional metabolic-endocrine disruption of weight regulation may be related to the effects of AP-induced hyperprolactinaemia on gonadal-adrenal steroids and insulin sensitivity. In humans, programmed physical activity, dietary restriction, anorectic agents, and drugs that counteract hyperprolactinaemia have been shown to be successful in a limited number of studies. Two novel strategies could expand the available therapeutic options. First, in preclinical experiments in female rats the estradiol antagonist/agonist drug tamoxifen or estradiol itself have been shown to completely prevent the obesity provoked by the AP sulpiride, and to induce an endocrine-metabolic milieu that seems to counteract AP-induced obesity. Secondly, it has also been shown that oral antihyperglycaemic agents such as metformin may decrease body weight and counteract insulin resistance and hyperinsulinaemia which is correlated with several metabolic abnormalities in obese subjects. Lastly, estradiol replacement, tamoxifen and/or antihyperglycaemic agents are not devoid of significant side-effects, and these drugs have not been tested in obese psychiatric patients. Therefore, further research is needed before their clinical use may be recommended.