A review of atypical antipsychotic drugs versus conventional medication in schizophrenia

Atypical antipsychotics are replacing conventional antipsychotics for the treatment of schizophrenia. They are considered to be at least as effective as conventional agents, with most producing fewer extrapyramidal symptoms. This review presents the evidence from published meta-analyses and describes differences in clinical effectiveness and tolerability between conventional and atypical antipsychotic agents. In addition, it discusses some of the more significant adverse effects including tardive dyskinesia, weight gain, diabetes and sudden death. Results from meta-analyses are conflicting, with some finding no significant advantages on measures of efficacy or tolerability for atypical antipsychotics over moderate daily doses of conventional drugs. Other results have shown that some atypical drugs have at least minor efficacy advantages over conventional comparators. Atypical antipsychotics exhibit a much reduced risk for tardive dyskinesia compared with conventional drugs. However, weight gain is more common with some atypical drugs (especially clozapine and olanzapine). Both conventional and atypical antipsychotics have been associated with diabetes, with most reports implicating both clozapine and olanzapine. Finally, atypical antipsychotics (unlike conventional drugs) have little or no effect on QT and are not associated with sudden death.     

Tolerability of atypical antipsychotics.

Atypical antipsychotics are expected to be better tolerated than older antipsychotics because of their lower propensity to cause certain adverse effects. All atypical drugs have been shown to cause fewer acute extrapyramidal symptoms (EPS) than a standard typical agent (usually haloperidol) and some (clozapine, sertindole and quetiapine) appear to cause these effects no more often than placebo. In the longer term, clozapine, olanzapine and (less robustly) other atypical antipsychotics are thought to cause less tardive dyskinesia than typical antipsychotics. Problems caused by hyperprolactinaemia occur less often with some atypical antipsychotics than with typical drugs although risperidone and amisulpride appear to have no advantages in this respect. Other adverse effects may occur as frequently with some atypical antipsychotics as with some typical drugs. Clozapine, risperidone and quetiapine are known to cause postural hypotension; clozapine, olanzapine and quetiapine are clearly sedative; and anticholinergic effects are commonly seen with clozapine, and, much less frequently, with olanzapine. Some adverse effects are more frequent with atypical drugs. Idiosyncratic effects seem particularly troublesome with clozapine and, to a lesser extent, sertindole, olanzapine and zotepine. Bodyweight gain is probably more problematic with atypical antipsychotics than with typical drugs. Overall tolerability, as judged by withdrawals from therapy, is not clearly proven to be better with atypical drugs, although some individual trials do indicate an advantage with atypical agents. Differences in tolerability between individual atypical antipsychotics have not been clearly shown. The tolerability profile of atypical drugs certainly benefits from a lower incidence of acute EPS effects, along with less certain or less uniform benefits in symptomatic hyperprolactinaemia or tardive dyskinesia. Other, perhaps more trivial, adverse effects militate against their good tolerability, and effects such as bodyweight gain may severely reduce tolerability. Without clear advantages in tolerability in patient groups used in trials, drug choice in regard to adverse effects should continue to be on a patient to patient basis.     

Extrapyramidal symptoms with atypical antipsychotics : incidence, prevention and management.

The treatment of schizophrenia changed drastically with the discovery of antipsychotic medications in the 1950s, the release of clozapine in the US in 1989 and the subsequent development of the atypical or novel antipsychotics. These newer medications differ from their conventional counterparts, primarily based on their reduced risk of extrapyramidal symptoms (EPS). EPS can be categorised as acute (dystonia, akathisia and parkinsonism) and tardive (tardive dyskinesia and tardive dystonia) syndromes. They are thought to have a significant impact on subjective tolerability and adherence with antipsychotic therapy in addition to impacting function. Unlike conventional antipsychotic medications, atypical antipsychotics have a significantly diminished risk of inducing acute EPS at recommended dose ranges. These drugs may also have a reduced risk of causing tardive dyskinesia and in some cases may have the ability to suppress pre-existing tardive dyskinesia. This paper reviews the available evidence regarding the incidence of acute EPS and tardive syndromes with atypical antipsychotic therapy. Estimates of incidence are subject to several confounds, including differing methods for detection and diagnosis of EPS, pretreatment effects and issues surrounding the administration of antipsychotic medications. The treatment of acute EPS and tardive dyskinesia now includes atypical antipsychotic therapy itself, although other adjunctive strategies such as antioxidants have also shown promise in preliminary trials. The use of atypical antipsychotics as first line therapy for the treatment of schizophrenia is based largely on their reduced risk of EPS compared with conventional antipsychotics. Nevertheless, EPS with these drugs can occur, particularly when prescribed at high doses. The EPS advantages offered by the atypical antipsychotics must be balanced against other important adverse effects, such as weight gain and diabetes mellitus, now known to be associated with these drugs.     

Atypical antipsychotic agents: a critical review.

The pharmacology, efficacy, and adverse effects of atypical antipsychotic agents when used to treat schizophrenia and other disorders are reviewed. Atypical antipsychotic agents were developed in response to problems with typical agents, including lack of efficacy in some patients, lack of improvement in negative symptoms, and troublesome adverse effects, especially extrapyramidal symptoms (EPSs) and tardive dyskinesia CTD). Atypical antipsychotics differ from typical psychotics in their "limbic-specific" dopamine type 2 (D2)-receptor binding and high ratio of serotonin type 2 (5-HT2)-receptor binding to D2 binding. In clinical trials in patients with non-treatment-resistant schizophrenia, risperidone and olanzapine were superior to placebo for positive and negative symptoms. Risperidone and olanzapine were superior to haloperidol on some measures. Quetiapine was better than placebo but was not better than typical antipsychotics. Head-to-head comparisons of atypical antipsychotics in non-treatment-resistant schizophrenia have been inconclusive. Clozapine remains the standard agent for treatment-resistant schizophrenia. Atypical agents are substantially more expensive than their typical antipsychotic counterparts. To fully determine the overall efficiency of these drugs, other potential benefits, such as improved quality of life, need to be factored in. Atypical antipsychotics are associated with a decreased capacity to cause EPSs, TD, neuroleptic malignant syndrome, and hyperprolactinemia. Clozapine carries a risk of agranulocytosis; the white blood cell count must be monitored. Atypical antipsychotics are increasingly being used for indications other than schizophrenia, such as the management of aggression, mania, and depression. Atypical antipsychotics are often considered first-line agents for treating schizophrenia and are promising treatment alternatives for other psychiatric and neurologic conditions.     

A systematic review of meta-analyses of the efficacy of oral atypical antipsychotics for the treatment of adult patients with schizophrenia

Introduction: Meta-analyses are a convenient way for clinicians and researchers to review data regarding different interventions. Meta-analyses can overcome many of the limitations of individual studies, namely the power to detect differences, and help resolve the results of inconsistent studies.

Areas covered: This paper is a review of meta-analyses of oral atypical antipsychotics for the treatment of schizophrenia, located through PubMed and the Cochrane Database of Systematic Reviews. A total of 91 meta-analyses were identified that included efficacy outcome data for the 10 atypical antipsychotics available in the USA (11 focused on clozapine, 17 for risperidone, 8 for olanzapine, 5 for quetiapine, 3 for ziprasidone, 10 for aripiprazole, 5 for paliperidone, 1 for iloperidone, 0 for asenapine or lurasidone, and 31 others that were classified more broadly). These include Cochrane Reviews and other similarly executed reports, as well as pooled analyses meta-tagged in PubMed as a meta-analysis.

Expert opinion: In general, there is heterogeneity among the atypical antipsychotics in terms of efficacy, with clozapine evidencing consistent superiority over typical antipsychotics, trailed behind by olanzapine and risperidone. Meta-analyses generally do not support efficacy differences between the other atypical antipsychotics compared with the older typical agents. Although this review is focused on efficacy, other considerations are also important, including the large tolerability differences among all the agents and the need to individualize medication choice based on past history of therapeutic response, past history of tolerability issues and the individual's personal values and preferences.     

Atypical antipsychotic tolerability and switching strategies in bipolar disorder

Importance to the field: Atypical antipsychotics have unequivocally advanced the pharmacotherapy of bipolar disorders. These broad-spectrum treatments offer efficacy against core symptoms of acute mania, mixed state, depressed and maintenance phases of the disorder. Atypical antipsychotics are not, however, a panacea and are associated with several problematic tolerability and safety concerns. For example, emerging evidence militates against the original notion that atypical agents are without risk for extrapyramidal side effects and possibly tardive dyskinesia when compared to their therapeutic predecessors, the conventional antipsychotics. Although classified together, atypical antipsychotics are heterogeneous in their tolerability and safety profile, an issue relevant to individualizing treatment selection and switching antipsychotics for optimal clinical management.

Areas covered in this review: This article reviews relevant adverse events attributable to the use of atypical antipsychotics and strategies for switching these agents, with particular attention to the bipolar disorder population.

What the reader will gain: The reader will gain both a perspective of treatment-emergent adverse events associated with atypical agents in the treatment of bipolar disorder and a precise analysis of common adverse events that frequently lead to treatment discontinuation and/or switching to a separate agent.

Take home message: Atypical antipsychotics provide for a different array of treatment-emergent adverse events than conventional agents. The therapeutic index of treatment is a ratio of the relative benefit divided by the probability of harm (i.e., side effects). Taken together, the atypical antipsychotics offer an improved therapeutic index when compared to conventional agents in bipolar disorder. Nevertheless, atypicals fall short of the ideal, necessitating frequent discontinuation and switching.     

Atypical antipsychotic-induced diabetes mellitus: how strong is the evidence?

Atypical antipsychotics offer significant improvements over older, conventional antipsychotic agents. However, recently the newer agents have been linked to medical morbidity including hyperglycaemia, diabetes mellitus, bodyweight gain and abnormal lipid levels. Even more concerning, because of a significant risk of death, there have been numerous case reports of patients treated with clozapine or olanzapine developing diabetic ketoacidosis shortly after initiation of the drug. Much of the information concerning the medical morbidity of diabetes mellitus is based on case reports, retrospective chart reviews, naturalistic studies and cross-sectional studies. While definitive studies have yet to be reported, mounting evidence suggests that the atypical antipsychotic agents, particularly clozapine and olanzapine, may significantly impair glucose metabolism and increase the risk of diabetes in patients with schizophrenia. Diabetic ketoacidosis, although it appears to be uncommon, is of great concern secondary to the risk of death. Patients treated with atypical antipsychotic agents should be routinely screened for diabetes and other metabolic abnormalities including raised lipid levels. Patients with risk factors for diabetes should be monitored more closely. Reports and clinical experience suggest that in a case of atypical antipsychotic-associated diabetes or diabetic ketoacidosis, discontinuation of the antipsychotic agent may result in complete resolution of the hyperglycaemia and diabetes.     

Antipsychotic drugs in bipolar disorder

Antipsychotic drugs are useful in the treatment of acute mania and as maintenance treatment. While both typical and atypical antipsychotic drugs are able to diminish manic symptoms, agitation and aggression in acute mania, the atypical antipsychotic drugs enjoy a number of advantages, including significantly less extrapyramidal symptoms, diminished risk of tardive dyskinesia, lack of increase in serum prolactin levels (with the exception of risperidone), improvement in cognition, and possible decrease in suicidality. Most of the atypical antipsychotic drugs have been found to be effective as an add-on treatment (with mood stabilizers and antidepressant drugs) and sometimes as monotherapy in treatment-resistant bipolar patients. Long-acting typical neuroleptic drugs may be useful in the treatment of non-compliant bipolar patients. A small number of patients with schizophrenia treated with risperidone, olanzapine, or quetiapine experience a first episode of hypomania or mania. It is not apparent if this is a true drug-induced event or coincidental. Side-effects of note with the atypical antipsychotic drugs are weight gain (most prominently with olanzapine and clozapine), sedation, and agranulocytosis (clozapine). Atypical antipsychotic drugs are recommended for use in bipolar disorder for acute treatment, maintenance treatment, and for treatment-resistant patients.     

The use of atypical antipsychotics in the management of schizophrenia

Long-term drug treatment of schizophrenia with conventional antipsychotics has limitations: an estimated quarter to one third of patients are treatment-resistant; conventional antipsychotics have only a modest impact upon negative symptoms (poverty of thought, social withdrawal and loss of affect); and adverse effects, particularly extrapyramidal symptoms (EPS). Newer, so-called atypical, antipsychotics such as olanzapine, risperidone, sertindole and clozapine (an old drug which was re-introduced in 1990) are claimed to address these limitations. Atypical agents are, at a minimum, at least as effective as conventional drugs such as haloperidol. They also cause substantially fewer extrapyramidal symptoms. However, some other adverse effects are more common than with conventional drugs. For example, clozapine carries a significant risk of serious blood disorders, for which special monitoring is mandatory; it also causes troublesome drowsiness and increased salivation more often than conventional agents. Some atypical agents cause more weight gain or QT prolongation than older agents. The choice of therapy is, therefore, not straightforward. At present, atypical agents represent an advance for patients with severe or intolerable EPS. Most published evidence exists to support the use of clozapine, which has also been shown to be effective in schizophrenia refractory to conventional agents. However, the need for compliance with blood count monitoring and its sedative properties make careful patient selection important. The extent of any additional direct benefit offered by atypical agents on negative symptoms is not yet clear. The lack of a depot formulation for atypical drugs may pose a significant practical problem. To date, only two double-blind studies in which atypical agents were compared directly have been published. Neither provides compelling evidence for the choice of one agent over another. Atypical agents are many times more expensive than conventional drugs. Although drug treatment constitutes only a small proportion of the costs of managing schizophrenia, the additional annual cost of the use of atypical agents in, say, a quarter of the likely U.K. schizophrenic population would be about 56 M pound sterling. There is only limited evidence of cost-effectiveness. Atypical antipsychotics are not currently licensed for other conditions where conventional antipsychotics are commonly used, such as behaviour disturbance or dementia in the elderly. Their dose, and place in treatment in such cases have yet to be determined.     

Adverse effects of atypical antipsychotics : differential risk and clinical implications

Antipsychotic drugs can be of great benefit in a range of psychiatric disorders, including schizophrenia and bipolar disorder, but all are associated with a wide range of potential adverse effects. These can impair quality of life, cause stigma, lead to poor adherence with medication, cause physical morbidity and, in extreme cases, be fatal. A comprehensive overview of tolerability requires a review of all available data, including randomised controlled trials (RCTs), observational studies and postmarketing surveillance studies. Assessing the relative tolerability of atypical antipsychotics is hampered by the paucity of RCTs that compare these drugs head-to-head, and limited and inconsistent reporting of adverse effect data that makes cross-study comparisons difficult.Despite methodological problems in assessment and interpretation of tolerability data, important differences exist between the atypical antipsychotics in the relative risk of acute extrapyramidal symptoms (highest risk: higher doses of risperidone), hyperglycaemia and dyslipidaemia (highest risk: clozapine and olanzapine), hyperprolactinaemia (highest risk: amisulpride and risperidone), prolongation of heart rate-corrected QT interval (QTc) [highest risk: ziprasidone and sertindole] and weight gain (highest risk: clozapine and olanzapine). Sedation, antimuscarinic symptoms, postural hypotension, agranulocytosis and seizures are more common with clozapine than with other atypical antipsychotics. The variation in their tolerability suggests that it is misleading to regard the atypical antipsychotics as a uniform drug class, and also means that the term 'atypical antipsychotic' has only limited usefulness. Differences between the atypical agents in terms of efficacy and pharmacodynamic profiles also support this view. As tolerability differs between specific conventional and atypical drugs, we conclude that broad statements comparing the relative risk of specific adverse effects between 'atypical' and 'conventional' antipsychotics are largely meaningless; rather, comparisons should be made between specific atypical and specific conventional drugs. Adverse effects are usually dose dependent and can be influenced by patient characteristics, including age and gender. These confounding factors should be considered in clinical practice and in the interpretation of research data. Selection of an antipsychotic should be on an individual patient basis. Patients should be involved in prescribing decisions and this should involve discussion about adverse effects.     

Current therapy issues and unmet clinical needs in the treatment of schizophrenia: a review of the new generation antipsychotics

This review discusses the atypical antipsychotics, focusing on the possibility of symptom reduction with a minimum of side-effects. A selective review of clinically relevant reports, studies and meta-analyses is presented. The results from clinical trials suggest that atypical agents improve negative and affective symptoms, and cognitive functioning more than typical antipsychotics, but that the pattern of effects on these domains, as well as on suicidality, appears to differ. In clinical trials, the newer drugs generally have less extrapyramidal side-effects (EPS) than typical antipsychotics. However, amisulpride, risperidone, olanzapine and ziprasidone still show evidence of a dose-related increase in EPS, whereas clozapine, quetiapine, sertindole and aripiprazole do not. Weight gain, increased blood lipids/cholesterol, and insulin resistance/type 2 diabetes are emerging as significant treatment-associated concerns, particularly for clozapine and olanzapine. Sedation has been reported for all the newer compounds except sertindole. The considerable variation in benefit/risk profiles of the atypical compounds can help the clinician to select the most appropriate treatment for individual patients.     

Dose response and atypical antipsychotics in schizophrenia

Based on information from clinical trials, both the efficacy and adverse effects of conventional antipsychotics in the treatment of schizophrenia are dose related. The overlapping nature of these dose-response profiles limits the use of these agents. Atypical antipsychotics provide greater relief across the comorbid symptom domains of schizophrenia, but dose-response studies and clinical experience have revealed that some of these drugs also have dose limitations. This article reviews the dose-response relationships of the atypical antipsychotics as presented predominantly in pivotal, randomised studies (double-blind and otherwise).Limited data indicate that clozapine shows dose-related efficacy up to 600 mg/day in patients with treatment-resistant schizophrenia. However, higher dosages of clozapine may be associated with the risk of seizures. Risperidone demonstrates dose-related adverse events that compromise efficacy. The dose-response relationships for ziprasidone, quetiapine and aripiprazole are less well established. The efficacy of olanzapine appears to be dose related within the recommended dosage range of 10-20 mg/day, but clinical trials that have explored higher dosages suggest improved efficacy. Furthermore, the higher doses are not associated with a significantly increased incidence of adverse events.Further studies are clearly needed to fully characterise the dose-response relationships of atypical antipsychotics.     

A systematic review of meta-analyses of the efficacy of oral atypical antipsychotics for the treatment of adult patients with schizophrenia

INTRODUCTION: Meta-analyses are a convenient way for clinicians and researchers to review data regarding different interventions. Meta-analyses can overcome many of the limitations of individual studies, namely the power to detect differences, and help resolve the results of inconsistent studies. AREAS COVERED: This paper is a review of meta-analyses of oral atypical antipsychotics for the treatment of schizophrenia, located through PubMed and the Cochrane Database of Systematic Reviews. A total of 91 meta-analyses were identified that included efficacy outcome data for the 10 atypical antipsychotics available in the USA (11 focused on clozapine, 17 for risperidone, 8 for olanzapine, 5 for quetiapine, 3 for ziprasidone, 10 for aripiprazole, 5 for paliperidone, 1 for iloperidone, 0 for asenapine or lurasidone, and 31 others that were classified more broadly). These include Cochrane Reviews and other similarly executed reports, as well as pooled analyses meta-tagged in PubMed as a meta-analysis. EXPERT OPINION: In general, there is heterogeneity among the atypical antipsychotics in terms of efficacy, with clozapine evidencing consistent superiority over typical antipsychotics, trailed behind by olanzapine and risperidone. Meta-analyses generally do not support efficacy differences between the other atypical antipsychotics compared with the older typical agents. Although this review is focused on efficacy, other considerations are also important, including the large tolerability differences among all the agents and the need to individualize medication choice based on past history of therapeutic response, past history of tolerability issues and the individual's personal values and preferences.     

Comparison between risperidone, olanzapine, and clozapine in the management of chronic schizophrenia: a naturalistic prospective 12-week observational study

Risperidone, olanzapine, and clozapine are three atypical antipsychotic medications commonly used in the management of chronic schizophrenia. While they offer advantages with regard to clinical efficacy and side-effect profile, few studies have compared them in a naturalistic prospective observational manner. This study therefore investigated their comparative efficacy over 12 weeks including illness characteristics and adverse effects. One hundred thirty-one patients (76 M, 55 F) with DSMI-V schizophrenia or schizoaffective disorder were treated with risperidone (n = 38), olanzapine (n = 38), or clozapine (n = 55). All patients showed a significant decrease of Positive and Negative Syndrome Scale (PANSS)-positive scores. Decreases in tardive dyskinesia and impulsivity scores were noted with clozapine and olanzapine, respectively. No differences between the medications were noted on depression, anxiety, EPS, or overt aggression scores. Olanzapine and clozapine appeared to be more effective in females. Males showed a decreased sexual performance irrespective of the medication and those treated with risperidone and clozapine showed greater proportional reduction of overt aggression. Clozapine-treated patients showed significant increased weight, increased glucose levels, and lowered sexual performance. Risperidone patients tended to exhibit reduced cholesterol levels. Higher creatine kinase (CK) levels were noted in risperidone-treated patients. While cautious given the nature of the study design, results suggest differences in the response to various atypical antipsychotic medications regarding efficacy and side-effect susceptibility.     

Bodyweight gain associated with atypical antipsychotics: epidemiology and therapeutic implications

Atypical antipsychotic medications are associated with different adverse effects and efficacy profiles compared with conventional antipsychotics (i.e. less extrapyramidal symptoms, improved-efficacy against negative symptoms and cognitive deficits, and most often a greater ability to improve patients' quality of life). However, the atypical antipsychotics may be associated with clinically significant bodyweight gain, increasing the risk of medical comorbidity, including diabetes mellitus, hypertension, cardiovascular disease and hyperlipidaemia. This literature review assesses the various bodyweight gain liabilities associated with atypical antipsychotics, as well as the effects of bodyweight gain on quality of life. The issue of prevention and management of this often neglected adverse effect is also examined. Most studies reviewed indicate that clozapine and olanzapine are associated with more bodyweight gain than the other atypical antipsychotics. There are potential factors that place certain patients at greater risk for bodyweight gain, including low pretreatment body mass index, young age and being of female gender. Furthermore, bodyweight gain associated with the use of atypical antipsychotics has been reported to be associated with clinical improvement, although this has not been substantiated widely. It is unclear whether increased medical comorbidity, including diabetes mellitus, coronary artery disease and/or elevated triglyceride levels, is secondary to the bodyweight gain associated with atypical antipsychotics, or the result of the agents themselves. A patient's quality of life may be greatly affected by excessive bodyweight gain; either by increased comorbid medical illness, an increased relapse rate associated with noncompliance, or the social stigma associated with being obese. However, most studies reveal that treatment with atypical antipsychotic medications is associated with improved quality of life compared with that achieved with conventional antipsychotic medications. Because bodyweight is an important health risk associated with atypical antipsychotics, prevention and effective management of bodyweight are paramount in preventing comorbid medical illness, relapse and possible noncompliance.     

Quetiapine, clozapine, and olanzapine in the treatment of tardive dyskinesia induced by first-generation antipsychotics: a 124-week case report

Our report of a patient with severe tardive dyskinesia (TD) who has been exposed to both typical antipsychotic and clozapine, olanzapine and quetiapine during a 124-week follow-up period supports the possible beneficial effect of atypical antipsychotics on pre-existing symptoms of TD. Persistently high AIMS scores during all the periods of treatment with typical antipsychotics contrast strongly with the drop in scores that occurs in strict chronological sequence after switching to both clozapine (45%), olanzapine (27.8%) and quetiapine (85%). Since the reversal to haloperidol from the three atypical agents was systemically associated with a return to high AIMS scores, it seems likely that the improvement noted with clozapine, olanzapine and quetiapine represents a temporary symptomatic effect rather than a sustained resolution of the disorder. The olanzapine-clozapine-quetiapine rank order of increasing effectiveness against TD symptoms suggests that this property, although shared by the atypical antipsychotics, is to some degree drug-specific. Patient- and/or drug-dependent mechanisms may be involved in this gradient of effect.     

Olanzapine: an atypical antipsychotic for schizophrenia

Olanzapine is a serotonin-dopamine receptor antagonist primarily used in the treatment of psychotic illnesses. It has been shown in numerous large trials to be as equally effective as haloperidol in the acute treatment and maintenance treatment of schizophrenia. However, olanzapine was shown to be more effective than haloperidol in the treatment of negative symptoms and to cause significantly fewer extrapyramidal symptoms. Furthermore, early reports suggest that olanzapine produces less tardive dyskinesia than haloperidol, though longer follow-up data are needed. Current studies have failed to demonstrate the efficacy of olanzapine in the treatment of refractory schizophrenia. One comparison trial of olanzapine versus risperidone has indicated similar efficacy. Clinical trials in acute mania have found olanzapine to be more effective than placebo. However, there is no role for olanzapine monotherapy in bipolar disorder given current studies. Although olanzapine has shown a low rate of extrapyramidal symptoms, it is not without adverse effects. Clinically significant weight gain has been noted with olanzapine in each of the large clinical trials. The degree of weight gain is similar to clozapine and probably greater than that observed with risperidone. The long-term medical consequence of atypical antipsychotic-induced weight gain is not known at this time. While generally considered first-line drugs from an efficacy and adverse effect standpoint, pharmacoeconomic studies are needed to justify the large acquisition cost of olanzapine compared to typical agents.     

Olanzapine: an atypical antipsychotic for schizophrenia

Olanzapine is a serotonin-dopamine receptor antagonist primarily used in the treatment of psychotic illnesses. It has been shown in numerous large trials to be as equally effective as haloperidol in the acute treatment and maintenance treatment of schizophrenia. However, olanzapine was shown to be more effective than haloperidol in the treatment of negative symptoms and to cause significantly fewer extrapyramidal symptoms. Furthermore, early reports suggest that olanzapine produces less tardive dyskinesia than haloperidol, though longer follow-up data are needed. Current studies have failed to demonstrate the efficacy of olanzapine in the treatment of refractory schizophrenia. One comparison trial of olanzapine versus risperidone has indicated similar efficacy. Clinical trials in acute mania have found olanzapine to be more effective than placebo. However, there is no role for olanzapine monotherapy in bipolar disorder given current studies. Although olanzapine has shown a low rate of extrapyramidal symptoms, it is not without adverse effects. Clinically significant weight gain has been noted with olanzapine in each of the large clinical trials. The degree of weight gain is similar to clozapine and probably greater than that observed with risperidone. The long-term medical consequence of atypical antipsychotic-induced weight gain is not known at this time. While generally considered first-line drugs from an efficacy and adverse effect standpoint, pharmacoeconomic studies are needed to justify the large acquisition cost of olanzapine compared to typical agents.     

Aripiprazole, a novel atypical antipsychotic drug

Before the 1990s, treatment of psychoses centered on conventional agents whose tolerability was limited by extrapyramidal side effects (EPS). The past decade has seen the emergence of a newer generation of antipsychotic agents, first with clozapine and followed shortly by risperidone, olanzapine, quetiapine, and ziprasidone. These agents have been touted as providing better negative symptom efficacy, less impaired cognition, and lower risk of extrapyramidal syndromes. However, evolving evidence suggests that several drugs in this class may be associated with significant weight gain and lipid abnormalities. Aripiprazole, a new atypical antipsychotic drug, displayed efficacy similar to that of haloperidol and risperidone and superior to that of placebo in numerous clinical trials. Aripiprazole does not cause significant prolactin elevation and is associated with a low rate of clinically significant weight gain compared with other atypical antipsychotics. Patients receiving aripiprazole experienced EPS at a rate similar to that seen with placebo. Aripiprazole provides a new treatment option with limited adverse effects for patients in need of antipsychotic therapy.