Aripiprazole in pediatric psychosis and bipolar disorder: a clinical review

Aripiprazole, A Drug that Displays Partial Agonism and Functional Selectivity

BACKGROUND

The treatment of schizophrenia is challenging due to the wide range of symptoms (positive, negative, cognitive) associated with the disease. Typical antipsychotics that antagonize D2 receptors are effective in treating positive symptoms, but extrapyramidal side-effects (EPS) are a common occurrence. Atypical antipsychotics targeting 5-HT2A and D2 receptors are more effective at treating cognitive and negative symptoms compared to typical antipsychotics, but these drugs also result in side-effects such as metabolic syndromes.

OBJECTIVE

To identify evidence in the literature that elucidates the pharmacological profile of aripiprazole.s.

METHODS

We searched PubMed for peer reviewed articles on aripiprazole and its clinical efficacy, side-effects, pharmacology, and effects in animal models of schizophrenia symptoms.

RESULTS

Aripiprazole is a newer atypical antipsychotic that displays a unique pharmacological profile, including partial D2 agonism and functionally selective properties. Aripiprazole is effective at treating the positive symptoms of schizophrenia and has the potential to treat negative and cognitive symptoms at least as well as other atypical antipsychotics. The drug has a favorable side-effect profile and has a low propensity to result in EPS or metabolic syndromes. Animal models of schizophrenia have been used to determine the efficacy of aripiprazole in symptom management. In these instances, aripiprazole resulted in the reversal of deficits in extinction, pre-pulse inhibition, and social withdrawal. Because aripiprazole requires a greater than 90% occupancy rate at D2 receptors to be clinically active and does not produce EPS, this suggests a functionally selective effect on intracellular signaling pathways.

CONCLUSION

A combination of factors such as dopamine system stabilization via partial agonism, functional selectivity at D2 receptors, and serotonin-dopamine system interaction may contribute to the ability of aripiprazole to successfully manage schizophrenia symptoms. This review examines these mechanisms of action to further clarify the pharmacological actions of aripiprazole.

Aripiprazole and Acute Extrapyramidal Symptoms in Children and Adolescents: A Meta-Analysis

BACKGROUND

Both the US FDA and the European Medicines Agency (EMA) have approved aripiprazole for use in adolescents for specific indications. Given the assumed favorable side-effect profile of aripiprazole, its use in children and adolescents has increased for both official and off-label indications (anxiety disorders, eating disorders, personality disorders). However, several cases of children and adolescents with new-onset extrapyramidal symptoms (EPS) after commencing treatment with aripiprazole have been reported, and a more systematic appraisal of this possible risk is lacking.

OBJECTIVE

We conducted a systematic review and a meta-analysis to assess the evidence for acute EPS (acute dystonia, akathisia, Parkinsonism) associated with the use of aripiprazole in children and adolescents.

METHOD

We searched the MEDLINE and Embase databases (2003-10 April 2016) for clinical trials in pediatric patients (aged 0-18 years) using the keywords 'aripiprazole' (regardless of the formulation) and 'extrapyramidal symptoms'. We evaluated the abstracts of papers using the following exclusion criteria: (1) study design: case report, letter to the editor, editorial, or poster presentation data; (2) unrelated PICOS (population, intervention, comparators, outcomes, study) structure. We performed a meta-analysis, in which we used effect sizes with 95 % confidence intervals (CIs). To examine the homogeneity of the effect size distribution, we used a Q-statistic. When we observed heterogeneity in effect sizes, we assessed the possible influence of moderator variables (age and sex, mean dose, study duration, and method of measuring EPS incidence) and evaluated the suitability of either a fixed or a random model. Finally, we assessed the incidence of EPS in children and adolescents treated with aripiprazole compared with placebo.

RESULTS

An initial search via PubMed and Embase yielded 328 hits. A manual search of the reference lists of review papers revealed seven additional relevant articles. We included 41 studies, with 2114 pediatric patients, in the meta-analysis. For the analysis of the mean incidence of EPS, data were provided by 24 studies, with a total of 1446 pediatric patients. Meta-analysis revealed a mean EPS incidence of 17.1 % (95 % CI 0.128-0.223). In terms of the incidence of various extrapyramidal side effects, overall, no significant effects of age, sex, mean dose, study duration, or measuring method could be demonstrated. The side effects 'EPS', 'parkinsonism', and 'tremor' were significantly more common in children and adolescents treated with aripiprazole than in those treated with placebo.

CONCLUSION

Our meta-analysis provides evidence for a non-negligible incidence of acute EPS in children and adolescents treated with aripiprazole. Although the study has several limitations and further investigation is needed, these findings may help clinicians make more balanced treatment choices and more closely monitor the use of this drug in youth.

Profile of aripiprazole in the treatment of bipolar disorder in children and adolescents

Bipolar disorder is a pernicious illness. Compared with the later-onset form, early onset bipolar disorder is associated with worse psychosocial outcomes, and is characterized by rapid cycling and increased risks of substance abuse and suicide attempts. Controlling mood episodes and preventing relapse in this group of pediatric patients requires careful treatment. Here, we review the effectiveness of aripiprazole for bipolar disorder in children and adolescents, with discussion of this drug's unique pharmacological profile and various clinical study outcomes. Aripiprazole acts as a serotonin 5-HT2A receptor antagonist, as well as a partial agonist of the serotonin 5-HT1A and dopamine D2 receptors. It can be safely used in children and adolescents, as it is highly tolerated and shows lower rates of the side effects typically observed with other antipsychotic drugs, including sedation, weight gain, hyperprolactinemia, and extrapyramidal syndrome. The presently reviewed randomized controlled trials (RCTs) and non-RCTs generally reported aripiprazole to be effective and well-tolerated in children and adolescents with bipolar disorder. However, due to the limited number of RCTs, the present conclusions must be evaluated cautiously. Furthermore, aripiprazole cannot yet be considered a preferred treatment for children and adolescents with bipolar disorder, as there is not yet evidence that aripiprazole shows greater efficacy compared to other second-generation antipsychotics. Additional data are needed from future head-to-head comparison studies.

Practitioner review: Long-term pharmacological treatment of pediatric bipolar disorder

BACKGROUND

Although long-term treatment is a core aspect of the management of children and adolescents with bipolar disorder (BD), most clinical recommendations are based on results from short-term studies or adult data. In order to guide clinical practice, we review the efficacy and safety profile of mood stabilizers, antipsychotics, and other pharmacological strategies for the long-term treatment of BD in pediatric patients.

METHODS

A MEDLINE, EMBASE, Cochrane and PsycInfo search (inception through November 2013) was performed to identify prospective studies longer than 12 weeks assessing the use of pharmacological strategies for the long-term treatment of BD in pediatric patients (0-18 years of age).

RESULTS

Four randomized controlled trials (RCT) [three placebo-controlled (assessing aripiprazole (2) and flax oil), and one head-to-head comparison of lithium vs. divalproex], and thirteen noncontrolled studies (six open-label studies assessing lithium or anticonvulsants, five assessing second-generation antipsychotics (SGAs) and four assessing combination strategies) were included in the review. Aripiprazole has shown efficacy for relapse prevention in children with pediatric bipolar disorder (PBD) 4-9 years of age in one placebo-controlled RCT. Positive results have been reported in noncontrolled studies with quetiapine and lithium for relapse prevention, as well as with lithium, quetiapine, ziprasidone, and the combination of risperidone and divalproex or lithium for long-term symptom reduction in PBD. The most frequently reported adverse events in children and adolescents treated with lithium and anticonvulsants are gastrointestinal and neurological, whereas use of SGAs is mainly related to weight gain and sedation.

CONCLUSION

According to the limited empirical evidence, aripiprazole can be useful for relapse prevention in children with PBD. Given the lack of consistent efficacy data, clinical decision making should be based on individual clinical aspects and safety concerns.

The effects of novel and newly approved antipsychotics on serum prolactin levels: a comprehensive review

Since the 1970s, clinicians have increasingly become more familiar with hyperprolactinemia (HPRL) as a common adverse effect of antipsychotic medication, which remains the cornerstone of pharmacological treatment for patients with schizophrenia. Although treatment with second-generation antipsychotics (SGAs) as a group is, compared with use of the first-generation antipsychotics, associated with lower prolactin (PRL) plasma levels, the detailed effects on plasma PRL levels for each of these compounds in reports often remain incomplete or inaccurate. Moreover, at this moment, no review has been published about the effect of the newly approved antipsychotics asenapine, iloperidone and lurasidone on PRL levels. The objective of this review is to describe PRL physiology; PRL measurement; diagnosis, causes, consequences and mechanisms of HPRL; incidence figures of (new-onset) HPRL with SGAs and newly approved antipsychotics in adolescent and adult patients; and revisit lingering questions regarding this hormone. A literature search, using the MEDLINE database (1966-December 2013), was conducted to identify relevant publications to report on the state of the art of HPRL and to summarize the available evidence with respect to the propensity of the SGAs and the newly approved antipsychotics to elevate PRL levels. Our review shows that although HPRL usually is defined as a sustained level of PRL above the laboratory upper limit of normal, limit values show some degree of variability in clinical reports, making the interpretation and comparison of data across studies difficult. Moreover, many reports do not provide much or any data detailing the measurement of PRL. Although the highest rates of HPRL are consistently reported in association with amisulpride, risperidone and paliperidone, while aripiprazole and quetiapine have the most favorable profile with respect to this outcome, all SGAs can induce PRL elevations, especially at the beginning of treatment, and have the potential to cause new-onset HPRL. Considering the PRL-elevating propensity of the newly approved antipsychotics, evidence seems to indicate these agents have a PRL profile comparable to that of clozapine (asenapine and iloperidone), ziprasidone and olanzapine (lurasidone). PRL elevations with antipsychotic medication generally are dose dependant. However, antipsychotics having a high potential for PRL elevation (amisulpride, risperidone and paliperidone) can have a profound impact on PRL levels even at relatively low doses, while PRL levels with antipsychotics having a minimal effect on PRL, in most cases, can remain unchanged (quetiapine) or reduce (aripiprazole) over all dosages. Although tolerance and decreases in PRL values after long-term administration of PRL-elevating antipsychotics can occur, the elevations, in most cases, remain above the upper limit of normal. PRL profiles of antipsychotics in children and adolescents seem to be the same as in adults. The hyperprolactinemic effects of antipsychotic medication are mostly correlated with their affinity for dopamine D2 receptors at the level of the anterior pituitary lactotrophs (and probably other neurotransmitter mechanisms) and their blood-brain barrier penetrating capability. Even though antipsychotics are the most common cause of pharmacologically induced HPRL, recent research has shown that HPRL can be pre-existing in a substantial portion of antipsychotic-naïve patients with first-episode psychosis or at-risk mental state.

Repeated aripiprazole treatment causes dopamine D2 receptor up-regulation and dopamine supersensitivity in young rats

Aripiprazole is a second-generation antipsychotic that is increasingly being prescribed to children and adolescents. Despite this trend, little preclinical research has been done on the neural and behavioral actions of aripiprazole during early development. In the present study, young male and female Sprague-Dawley rats were pretreated with vehicle, haloperidol (1 mg/kg), or aripiprazole (10 mg/kg) once daily on postnatal days (PD) 10-20. After 1, 4, or 8 days (i.e. on PD 21, PD 24, or PD 28), amphetamine-induced locomotor activity and stereotypy, as well as dorsal striatal D2 receptor levels, were measured in separate groups of rats. Pretreating young rats with aripiprazole or haloperidol increased D2 binding sites in the dorsal striatum. Consistent with these results, dopamine supersensitivity was apparent when aripiprazole- and haloperidol-pretreated rats were given a test day injection of amphetamine (2 or 4 mg/kg). Increased D2 receptor levels and altered behavioral responding persisted for at least 8 days after conclusion of the pretreatment regimen. Contrary to what has been reported in adults, repeated aripiprazole treatment caused D2 receptor up-regulation and persistent alterations of amphetamine-induced behavior in young rats. These findings are consistent with human clinical studies showing that children and adolescents are more prone than adults to aripiprazole-induced side effects, including extrapyramidal symptoms.

Body mass index change in autism spectrum disorders: comparison of treatment with risperidone and aripiprazole

OBJECTIVE

The purpose of this study was to assess change in body mass index (BMI) and age- and gender-adjusted BMI Z-score in subjects ages 2-20 years with autism spectrum disorders (ASD), who were treated longitudinally with risperidone or aripiprazole at a tertiary care ASD clinic.

METHOD

As part of a larger project involving longitudinal drug treatment data in ASD, detailed demographic and treatment data were collected for 142 subjects ages 2-20 years who had been started on risperidone or aripiprazole for treatment of irritability. Mean age at start of treatment, treatment duration, final Clinical Global Impressions-Improvement Scale score, BMI change per year of treatment, and BMI Z-score change per year of treatment (primary outcome measure) were calculated for each drug treatment group. Group means were compared using t tests and Wilcoxon rank sum tests.

RESULTS

There was a statistically significant BMI and BMI Z-score increase in the risperidone and aripiprazole treatment groups individually. No statistically significant difference between the two treatment groups was noted in mean BMI change per year of treatment or BMI Z-score change per year of treatment.

CONCLUSIONS

In our review of long-term naturalistic treatment of irritability using risperidone versus aripiprazole in persons with ASD, a significant increase in both BMI and age- and gender-adjusted BMI Z-score was noted for each treatment group. No significant difference in BMI or BMI Z-score change was noted when the two treatment groups were compared. We conclude that in our patient population at a tertiary care ASD clinic, the effects of risperidone and aripiprazole on body weight gain in naturalistic long-term treatment are no different.

Weight gain and increase of body mass index among children and adolescents treated with antipsychotics: a critical review

We performed an updated review of the available literature on weight gain and increase of body mass index (BMI) among children and adolescents treated with antipsychotic medications. A PubMed search was conducted specifying the following MeSH terms: (antipsychotic agents) hedged with (weight gain) or (body mass index). We selected 127 reports, including 71 intervention trials, 42 observational studies and 14 literature reviews. Second-generation antipsychotics (SGAs), in comparison with first-generation antipsychotics, are associated with a greater risk for antipsychotic-induced weight gain although this oversimplification should be clarified by distinguishing across different antipsychotic drugs. Among SGAs, olanzapine appears to cause the most significant weight gain, while ziprasidone seems to cause the least. Antipsychotic-induced BMI increase appears to remain regardless of the specific psychotropic co-treatment. Children and adolescents seem to be at a greater risk than adults for antipsychotic-induced weight gain; and the younger the child, the higher the risk. Genetic or environmental factors related to antipsychotic-induced weight gain among children and adolescents are mostly unknown, although certain genetic factors related to serotonin receptors or hormones such as leptin, adiponectin or melanocortin may be involved. Strategies to reduce this antipsychotic side effect include switching to another antipsychotic drug, lowering the dosage or initiating treatment with metformin or topiramate, as well as non-pharmacological interventions. Future research should avoid some methodological limitations such as not accounting for age- and sex-adjusted BMI (zBMI), small sample size, short period of treatment, great heterogeneity of diagnoses and confounding by indication.