Pharmacological treatment strategies for schizophrenia

Antipsychotic Drug-Induced Increases in Peripheral Catecholamines are Associated With Glucose Intolerance

The second-generation antipsychotic drugs are widely used in the field of psychiatry, for an expanding number of different conditions. While their clinical efficacy remains indispensable, many of the drugs can cause severe metabolic side-effects, resulting in an increased risk of developing cardiometabolic disorders. The physiological basis of these side-effects remains an ongoing area of investigation. In the present study, we examined the potential role of peripheral catecholamines in antipsychotic-induced glucose intolerance. Adult female rats were acutely treated with either the first-generation antipsychotic drug haloperidol (0.1, 0.5 or 1 mg/kg) or the second-generation drugs risperidone (0.25, 1.0 or 2.5 mg/kg), olanzapine (1.5, 7.5 or 15 mg/kg) or clozapine (2, 10 or 20 mg/kg) or vehicle. Fasting glucose levels were measured and then animals were subjected to the intraperitoneal glucose tolerance test. Levels of peripheral norepinephrine, epinephrine and dopamine were concurrently measured in the same animals 75, 105 and 135 min after drug treatment. All antipsychotics caused glucose intolerance, with strongest effects by clozapine > olanzapine > risperidone > haloperidol. Plasma catecholamines were also increased by drug treatment, with greatest effects for norepinephrine and epinephrine caused by clozapine > risperidone > olanzapine > haloperidol. Importantly, there were strong and statistically significant associations between norepinephrine/epinephrine levels and glucose intolerance for all drugs. These findings confirm that increases in peripheral catecholamines co-occur in animals that exhibit antipsychotic-induced glucose intolerance, and these effects are strongly associated with each other, providing further evidence for elevated catecholamines as a substrate for antipsychotic metabolic side-effects.

Parenteral Sustained Release Lipid Phase-Transition System of Ziprasidone: Fabrication and Evaluation for Schizophrenia Therapy

Introduction

Ziprasidone (ZP) is a novel atypical antipsychotic agent effective in the treatment of positive and negative symptoms of schizophrenia with low chances for extrapyramidal side effects (EPs) and cognitive deficits. ZP possesses poor oral bioavailability (~50%), short biological half-life (~2.5 h) and due to extensive first-pass metabolism, a repeated dose is administered which makes the therapy non-adherent, leading to patient non-compliance. Therefore, this is a first report of developing parenteral ZP loaded sustained release phospholipid based phase-transition system (ZP-LPS).

Methods

The ZP-LPS system was formulated by mixing of biocompatible materials including phospholipid E 80, medium chain triglyceride (MCT) and ethanol. Optimization was done by aqueous titration method using pseudo-ternary phase diagram and dynamic rheological measurements. In vivo depot formation was confirmed by gamma scintigraphy after subcutaneous injection. Biodegradation and biocompatibility studies were performed for its safety evaluation. Finally, the efficacy of the formulation was assessed by Morris water maze (MWM) test and dizocilpine (MK-801) was used to induce schizophrenia in Sprague-Dawley rats.

Results

Optimized ZP-LPS showed rapid gelation (2 min), highest change in viscosity (~48000 mPa.s) and sustained release of ZP over a period of 1 month. Gamma scintigraphy depicted that the low-viscosity ZP-LPS system undergo rapid in situ gelation. Biodegradation and biocompatibility studies revealed gradual degradation in size of depot over a period of 28 days without any inflammation at the injection site. In MWM test, escape latency, time spent and total distance in target quadrant were significantly improved (p < 0.001) in the ZP-LPS group in comparison to the MK-801 group when evaluated at day 0, day 7 and day 28. However, significant improvement (p < 0.001) was observed only at day 0 in ZP suspension group.

Conclusion

The overall result indicates that the novel ZP-LPS system is safe, biodegradable, and effective for the management of schizophrenia.

The physiology, signaling, and pharmacology of dopamine receptors

G protein-coupled dopamine receptors (D1, D2, D3, D4, and D5) mediate all of the physiological functions of the catecholaminergic neurotransmitter dopamine, ranging from voluntary movement and reward to hormonal regulation and hypertension. Pharmacological agents targeting dopaminergic neurotransmission have been clinically used in the management of several neurological and psychiatric disorders, including Parkinson's disease, schizophrenia, bipolar disorder, Huntington's disease, attention deficit hyperactivity disorder (ADHD(1)), and Tourette's syndrome. Numerous advances have occurred in understanding the general structural, biochemical, and functional properties of dopamine receptors that have led to the development of multiple pharmacologically active compounds that directly target dopamine receptors, such as antiparkinson drugs and antipsychotics. Recent progress in understanding the complex biology of dopamine receptor-related signal transduction mechanisms has revealed that, in addition to their primary action on cAMP-mediated signaling, dopamine receptors can act through diverse signaling mechanisms that involve alternative G protein coupling or through G protein-independent mechanisms via interactions with ion channels or proteins that are characteristically implicated in receptor desensitization, such as β-arrestins. One of the future directions in managing dopamine-related pathologic conditions may involve a transition from the approaches that directly affect receptor function to a precise targeting of postreceptor intracellular signaling modalities either directly or through ligand-biased signaling pharmacology. In this comprehensive review, we discuss dopamine receptor classification, their basic structural and genetic organization, their distribution and functions in the brain and the periphery, and their regulation and signal transduction mechanisms. In addition, we discuss the abnormalities of dopamine receptor expression, function, and signaling that are documented in human disorders and the current pharmacology and emerging trends in the development of novel therapeutic agents that act at dopamine receptors and/or on related signaling events.

Use and safety of antipsychotic drugs during pregnancy

The incidence of schizophrenia in the general population ranges from about 1% to 2%. Schizophrenia affects men and women equally, occurring in all cultures and socioeconomic classes. The peak age of onset in women is 25 to 35 years, which are also the peak childbearing years, and women with psychotic illnesses are likely to have more unplanned pregnancies than women without a psychotic illness. Not only are antipsychotic medications prescribed for schizophrenia, but, especially since the introduction of the second-generation (atypical) antipsychotics, these drugs are also used to treat other psychiatric illnesses such as bipolar disorder. As a result, there is an increase in the number of women requiring antipsychotic drug therapy who are likely to become pregnant. It is important to evaluate the safety of these drugs in pregnancy, as most women with a serious psychiatric illness cannot stop taking their medication, as this would interfere with their activities of daily living, especially taking care of an infant. In this review, we describe available up-to-date, evidence-based information regarding the safety of antipsychotic drugs that are currently used in pregnancy. These include first-generation (conventional) antipsychotics (eg, promethazine, chlorpromazine, prochlorperazine, haloperidol, perphenazine, trifluoperazine, loxapine, thioridazine, flupenthixol, fluphenazine) and second-generation antipsychotics (eg, clozapine, risperidone, olanzapine, quetiapine, ziprasidone, aripiprazole, paliperidone). To date, no definitive association has been found between use of antipsychotics during pregnancy and an increased risk of birth defects or other adverse outcomes. However, there is a paucity of information, with a lack of large, well designed, prospective comparative studies. The information presented here should therefore not be interpreted as conclusive with regard to the safety of these drugs, as more research is needed. Women who require treatment should always discuss the risks and benefits of pharmacotherapy with their physician and, if it is felt that treatment should be continued during pregnancy, the evidenced-based information presented here will be of help in this important decision.

Asenapine: a novel psychopharmacologic agent with a unique human receptor signature

Asenapine is a novel psychopharmacologic agent under development for the treatment of schizophrenia and bipolar disorder. We determined and compared the human receptor binding affinities and functional characteristics of asenapine and several antipsychotic drugs. Compounds were tested under comparable assay conditions using cloned human receptors. In comparison with the antipsychotics, asenapine showed high affinity and a different rank order of binding affinities (pKi) for serotonin receptors (5-HT1A [8.6], 5-HT1B [8.4], 5-HT2A [10.2], 5-HT2B [9.8], 5-HT2C [10.5], 5-HT5 [8.8], 5-HT6 [9.6] and 5-HT7 [9.9]), adrenoceptors (alpha1 [8.9], alpha2A [8.9], alpha2B [9.5] and alpha2C [8.9]), dopamine receptors (D1 [8.9], D2 [8.9], D3 [9.4] and D4 [9.0]) and histamine receptors (H1 [9.0] and H2 [8.2]). It had much lower affinity (pKi<or=5) for muscarinic receptors and was the only agent with affinity for H2 receptors. Relative to its D2 receptor affinity, asenapine had a higher affinity for 5-HT2C, 5-HT2A, 5-HT2B, 5-HT7, 5-HT6, alpha2B and D3 receptors, suggesting stronger engagement of these targets at therapeutic doses. Asenapine behaved as a potent antagonist (pKB) at 5-HT1A (7.4), 5-HT1B (8.1), 5-HT2A (9.0), 5-HT2B (9.3), 5-HT2C (9.0), 5-HT6 (8.0), 5-HT7 (8.5), D2 (9.1), D3 (9.1), alpha2A (7.3), alpha2B (8.3), alpha2C (6.8) and H1 (8.4) receptors. These functional effects differed from those of risperidone (pKB<5 for 5-HT6) and olanzapine (pKB<5 for 5-HT1A and alpha2). Our results indicate that asenapine has a unique human receptor signature, with binding affinity and antagonistic properties that differ appreciably from those of antipsychotic drugs.

The efficacy of aripiprazole in the treatment of multiple symptom domains in patients with acute schizophrenia: a pooled analysis of data from the pivotal trials

OBJECTIVE

To examine the efficacy of aripiprazole across symptoms in patients with acute exacerbation of schizophrenia or schizoaffective disorder.

METHODS

Data were pooled from five, 4-6-week acute studies. PANSS Total, Positive, Negative, and General Psychopathology Subscale improvements were analyzed, as well as all 30 individual PANSS items.

RESULTS

Aripiprazole had statistically significant decreases versus placebo on PANSS subscales at Week 4, similar to those seen with haloperidol. Aripiprazole-treated patients also showed significant decreases versus placebo in 26 of the 30 PANSS items (all p<0.05).

CONCLUSION

Aripiprazole demonstrates statistically and clinically significant efficacy across a range of symptoms in schizophrenia.

Use of antipsychotics and benzodiazepines in patients with psychiatric emergencies: results of an observational trial

BACKGROUND

Conventional antipsychotics augmented with benzodiazepines have been the standard acute treatment for psychiatric emergencies for more than 50 years. The inability of patients to give informed consent limits randomised, controlled studies. This observational study on immediate therapy for aggression and impulse control in acutely agitated patients (IMPULSE) evaluated the short-term effectiveness and tolerability of atypical and typical antipsychotic medications (AP) in a non-interventional setting.

METHODS

This was a comparative, non-randomised, prospective, open-label, observational study. Treatment over the first 5 days was classified according to whether any olanzapine, risperidone, or haloperidol was included or not. Documentations (PANSS-excited component, CGI-aggression, CGI-suicidality, tranquilisation score) were at baseline (day 1) and days 2-6 after start of AP.

RESULTS

During the short treatment-period, PANSS-EC and CGI-aggression scores improved in all cohorts. 68.7% of patients treated with olanzapine, 72.2% of patients treated with risperidone, and 83.3% of patients treated with haloperidol received concomitant benzodiazepines (haloperidol vs. non-haloperidol: p < 0.001). More patients treated with olanzapine (73.8%) were fully alert according to a tranquilisation score and active at day 2 than patients treated with risperidone (57.1%) or haloperidol (58.0%).

CONCLUSION

Current medication practices for immediate aggression control are effective with positive results present within a few days. In this study, concomitant benzodiazepine use was significantly more frequent in patients receiving haloperidol.

1-(1-Phenethylpiperidin-4-yl)-1-phenylethanols as Potent and Highly Selective 5-HT2A Antagonists

The discovery of a novel class of highly potent and selective 5-HT2A antagonists is reported herein. Selectivity for the serotonin 5-HT2A receptor was optimized, decreasing the affinity of these antagonists toward the adrenergic alpha1 and dopaminergic D2 receptors, and especially to the 5-HT2C receptor. A series of corresponding 7-substituted indoles is described for the first time as serotonergic ligands. The enantiomer R-(+)-1-(4-fluorophenyl)-1-{1-[2-(4-fluorophenyl)ethyl]piperidin-4-yl} ethanol (R-(+)-74) was identified to have superior affinity for the serotonergic 5-HT2A receptor [IC50=0.37 nM] and selectivity toward the dopaminergic D2- [IC50=2300 nM], adrenergic alpha1- [IC50=1000 nM] and 5-HT2C receptors [IC50=490 nM].