Oral antipsychotic update: a brief review of new and investigational agents for the treatment of schizophrenia

Pioglitazone is superior to quetiapine, clozapine and tamoxifen at alleviating experimental autoimmune encephalomyelitis in mice

Recent evidence suggests that clozapine and quetiapine (atypical antipsychotics), tamoxifen (selective-estrogen receptor modulator) and pioglitazone (PPARγ agonist) may improve functional recovery in multiple sclerosis (MS). We have compared the effectiveness of oral administration of these drugs, beginning at peak disease, at reducing ascending paralysis, motor deficits and demyelination in mice subjected to experimental autoimmune encephalomyelitis (EAE). Mice were immunized with an immunogenic peptide corresponding to amino acids 35-55 of the myelin oligodendrocyte glycoprotein (MOG_35-55) in complete Freund's adjuvant and injected with pertussis toxin to induce EAE. Unlike clozapine, quetiapine and tamoxifen, administration of pioglitazone beginning at peak disease decreased both clinical scores and lumbar white matter loss in EAE mice. Using kinematic gait analysis, we found that pioglitazone also maintained normal movement of the hip, knee and ankle joints for at least 44 days after MOG_35-55 immunization. This long-lasting preservation of hindleg joint movements was accompanied by reduced white matter loss, microglial and macrophage activation and the expression of pro-inflammatory genes in the lumbar spinal cords of EAE mice. These results support clinical findings that suggest pioglitazone may reduce the progressive loss of motor function in MS by decreasing inflammation and myelin damage.

A Long-Term, Open-Label Study to Evaluate the Safety and Tolerability of Brexpiprazole as Maintenance Treatment in Adults with Schizophrenia

BACKGROUND

Brexpiprazole is a serotonin-dopamine activity modulator with efficacy in acute schizophrenia and relapse prevention. The aim of this Phase 3, multicenter study was to assess the long-term safety, tolerability, and efficacy of treatment with brexpiprazole flexible-dose 1-4 mg/d.

METHODS

Patients rolled over into this 52-week open-label study (amended to 26 weeks towards the end) from 3 randomized, double-blind, placebo-controlled Phase 3 studies. De novo patients, not part of the previous studies, were also enrolled. The primary outcome variable was the frequency and severity of treatment-emergent adverse events. Efficacy was assessed as a secondary objective using the Positive and Negative Syndrome Scale and the Personal and Social Performance scale.

RESULTS

A total of 1072 patients was enrolled (952 for 52 weeks and 120 for 26 weeks), 47.4% of whom completed the study. Among patients who took at least one dose of brexpiprazole, 14.6% discontinued due to treatment-emergent adverse events, most commonly schizophrenia (8.8%) and psychotic disorder (1.5%). Treatment-emergent adverse events with an incidence of ≥5% were schizophrenia (11.6%), insomnia (8.6%), weight increased (7.8%), headache (6.4%), and agitation (5.4%). Most treatment-emergent adverse events were mild or moderate in severity. The mean increase in body weight from baseline to week 26 was 1.3 kg and to week 52 was 2.1 kg. There were no clinically relevant findings related to prolactin, lipids, and glucose, or QT prolongation. On average, patients' symptoms and functioning showed continual improvement.

CONCLUSIONS

Treatment with brexpiprazole 1-4 mg/d was generally well tolerated for up to 52 weeks in patients with schizophrenia.

CLINICALTRIALS.GOV IDENTIFIER

NCT01397786 (https://clinicaltrials.gov/show/NCT01397786).

Dopamine Targeting Drugs for the Treatment of Schizophrenia: Past, Present and Future

Schizophrenia is a chronic and debilitating neuropsychiatric disorder affecting approximately 1% of the world's population. This disease is associated with considerable morbidity placing a major financial burden on society. Antipsychotics have been the mainstay of the pharmacological treatment of schizophrenia for decades. The traditional typical and atypical antipsychotics demonstrate clinical efficacy in treating positive symptoms, such as hallucinations and delusions, while are largely ineffective and may worsen negative symptoms, such as blunted affect and social withdrawal, as well as cognitive function. The inability to treat these latter symptoms may contribute to social function impairment associated with schizophrenia. The dysfunction of multiple neurotransmitter systems in schizophrenia suggests that drugs selectively targeting one neurotransmission pathway are unlikely to meet all the therapeutic needs of this heterogeneous disorder. Often, however, the unintentional engagement of multiple pharmacological targets or even the excessive engagement of intended pharmacological targets can lead to undesired consequences and poor tolerability. In this article, we will review marketed typical and atypical antipsychotics and new therapeutic agents targeting dopamine receptors and other neurotransmitters for the treatment of schizophrenia. Representative typical and atypical antipsychotic drugs and new investigational drug candidates will be systematically reviewed and compared by reviewing structure-activity relationships, pharmacokinetic properties, drug metabolism and safety, pharmacological properties, preclinical data in animal models, clinical outcomes and associated side effects.

A review of the pharmacology, efficacy and tolerability of recently approved and upcoming oral antipsychotics: an evidence-based medicine approach

Evidence-based medicine (EBM) is a broad concept, but the key elements include the incorporation of clinical judgment (which requires clinical experience) together with relevant scientific evidence while remaining mindful of the individual patient's values and preferences. Using the framework and philosophy of EBM, this systematic review summarizes the pharmacology, efficacy, and tolerability of newly approved oral antipsychotics, including iloperidone, asenapine, and lurasidone, and outlines what is known about agents that are in late-stage clinical development, such as cariprazine, brexpiprazole, zicronapine, bitopertin, and EVP-6124. Potential advantages and disadvantages of these agents over existing antipsychotics are outlined, centered on clinically relevant issues such as the potential for weight gain and metabolic abnormalities, potential association with somnolence/sedation, extra-pyramidal side effects, akathisia, and prolongation of the electrocardiogram (ECG) QT interval, as well as practical issues regarding dosing instructions, titration requirements, and drug-drug interactions. Lurasidone appears to be best in class in terms of minimizing untoward alterations in body weight and metabolic variables. However, iloperidone, asenapine, lurasidone, and cariprazine differ among themselves in terms of on-label dosing frequency (once daily for lurasidone and, presumably, cariprazine versus twice daily for iloperidone and asenapine), the need for initial titration to a therapeutic dose for iloperidone and possibly cariprazine, requirement to be taken sublingually for asenapine, requirement for administration with food for lurasidone, lengthening of the ECG QT interval (greater for iloperidone than for asenapine and no effect observed with lurasidone), and adverse effects such as akathisia (seen with cariprazine, lurasidone, and asenapine but not with iloperidone) and sedation (most notable with asenapine).

Cariprazine: chemistry, pharmacodynamics, pharmacokinetics, and metabolism, clinical efficacy, safety, and tolerability

INTRODUCTION

Cariprazine is an atypical antipsychotic in clinical development for the treatment of schizophrenia and bipolar mania/mixed episodes.

AREAS COVERED

The purpose of this review is to describe the chemistry, pharmacodynamic profile, pharmacokinetics, and clinical profile of cariprazine.

EXPERT OPINION

Cariprazine is a dopamine D3-preferring D3/D2 receptor partial agonist. Doses ≥ 1.5 mg/d yielded 69 - 75% D2/D3 receptor occupancy as measured in positron emission tomography scans. Mean half-life for cariprazine was 2 - 5 d over a dose range of 1.5 - 12.5 mg. Cariprazine produces two clinically relevant metabolites: desmethyl-cariprazine and didesmethyl-cariprazine, the latter having a longer half-life than cariprazine. Exposure to didesmethyl-cariprazine exceeded that of the parent drug. Cariprazine is metabolized by CYP3A4 and to a lesser extent by CYP2D6. The efficacy and safety of cariprazine have been so far investigated only in a few short-term (unpublished) clinical trials; however, three studies in schizophrenia and three studies in bipolar mania/mixed episodes evidenced a statistically significant therapeutic effect compared to placebo for cariprazine at doses ranging from 1.5 to 12 mg/d. There does not appear to be clinically relevant adverse effects of cariprazine on metabolic variables. Commonly encountered adverse events associated with cariprazine include insomnia, extrapyramidal symptoms, akathisia, sedation, nausea, dizziness, and constipation.

Cariprazine in schizophrenia: clinical efficacy, tolerability, and place in therapy

Cariprazine is a dopamine D3-preferring D3/D2 receptor partial agonist in late-stage clinical development for the treatment of schizophrenia, as well as for bipolar disorder (manic/mixed and depressive episodes), and as an adjunctive agent for the treatment of major depressive disorder. Four phase 2 or 3, 6-week, randomized controlled trials in acute schizophrenia have been completed and reported as poster presentations or in press releases by the manufacturer. Superiority over placebo on the Positive and Negative Syndrome Scale total score was evidenced for cariprazine in daily doses of 1.5, 3.0, 4.5, 6.0, 1.5-4.5, 3.0-6.0, and 6.0-9.0 mg. A randomized controlled trial for the prevention of relapse of schizophrenia is ongoing. In short-term, randomized controlled trials, cariprazine does not appear to adversely impact metabolic variables, prolactin, or the electrocardiogram (ECG) QT interval. In the fixed-dose study of cariprazine that tested 1.5, 3.0, and 4.5 mg/day, the most commonly encountered adverse events were insomnia, extrapyramidal disorder, sedation, akathisia, nausea, dizziness, vomiting, anxiety, and constipation. However, the differences in incidence versus placebo for these events were generally small. If approved by regulatory authorities, cariprazine would join aripiprazole as the second dopamine receptor partial agonist antipsychotic available for clinical use. Cariprazine differs from aripiprazole in terms of dopamine D3 receptor selectivity. Further studies would be helpful to discern the distinguishing features of cariprazine from other second-generation antipsychotics.