Current schizophrenia drugs: efficacy and side effects

A PDE10A inhibitor CPL500036 is a novel agent modulating striatal function devoid of most neuroleptic side-effects

Background: Phosphodiesterase 10A (PDE10A) is expressed almost exclusively in the striatum and its inhibition is suggested to offer potential treatment in disorders associated with basal ganglia. We evaluated the selectivity, cytotoxicity, genotoxicity, pharmacokinetics and potential adverse effects of a novel PDE10A inhibitor, CPL500036, in vivo. Methods: The potency of CPL500036 was demonstrated by microfluidic technology, and selectivity was investigated in a radioligand binding assay against 44 targets. Cardiotoxicity in vitro was evaluated in human ether-a-go-go related gene (hERG)-potassium channel-overexpressing cells by the patch-clamp method and by assessing key parameters in 3D cardiac spheroids. Cytotoxicity was determined in H1299, HepG2 and SH-SY5Y cell lines. The Ames test was used for genotoxicity analyses. During in vivo studies, CPL500036 was administered by oral gavage. CPL500036 exposure were determined by liquid chromatography-tandem mass spectrometry and plasma protein binding was assessed. The bar test was employed to assess catalepsy. Prolactin and glucose levels in rat blood were measured by ELISAs and glucometers, respectively. Cardiovascular safety in vivo was investigated in dogs using a telemetry method. Results: CPL500036 inhibited PDE10A at an IC50 of 1 nM, and interacted only with the muscarinic M2 receptor as a negative allosteric modulator with an IC50 of 9.2 µM. Despite inhibiting hERG tail current at an IC25 of 3.2 μM, cardiovascular adverse effects were not observed in human cardiac 3D spheroids or in vivo. Cytotoxicity in vitro was observed only at > 60 μM and genotoxicity was not recorded during the Ames test. CPL500036 presented good bioavailability and penetration into the brain. CPL500036 elicited catalepsy at 0.6 mg/kg, but hyperprolactinemia or hyperglycemic effects were not observed in doses up to 3 mg/kg. Conclusion: CPL500036 is a potent, selective and orally bioavailable PDE10A inhibitor with a good safety profile distinct from marketed antipsychotics. CPL500036 may be a compelling drug candidate.

Design, Synthesis and Biological Investigation of Flavone Derivatives as Potential Multi-Receptor Atypical Antipsychotics

The design of a series of novel flavone derivatives was synthesized as potential broad-spectrum antipsychotics by using multi-receptor affinity strategy between dopamine receptors and serotonin receptors. Among them, 7-(4-(4-(6-fluorobenzo[d]isoxazol-3-yl) piperidin- 1-yl) butoxy)-2,2-dimethylchroman-4-one (6j) exhibited a promising preclinical profile. Compound 6j not only showed high affinity for dopamine D₂, D₃, and serotonin 5-HT_1A, 5-HT_2A receptors, but was also endowed with low to moderate activities on 5-HT_2C, α₁, and H₁ receptors, indicating a low liability to induce side effects such as weight gain, orthostatic hypotension and QT prolongation. In vivo behavioral studies suggested that 6j has favorable effects in alleviating the schizophrenia-like symptoms without causing catalepsy. Taken together, compound 6j has the potential to be further developed as a novel atypical antipsychotic.

Polymorphs and pharmacokinetics of an antipsychotic drug candidate

A potent antipsychotic drug candidate, 7-(4-(4-(6-fluorobenzo[d]-isoxazol-3-yl)-piperidin-1-yl)butoxy)-4-methyl-8-chloro -2H-chromen-2-one mesylate(CY611), with good in vitro and in vivo antipsychotic effects was investigated for preformulation evaluation by crystallography methods. Three anhydrous polymorphs(Form I-III), a monohydrate(Form IV), and a NMP solvate(Form V) were discovered and characterized by powder X-ray diffraction, thermal analysis, attenuated total reflection-fourier transform infrared spectroscopy and scanning electron microscopy. Form I, monohydrate Form IV, and a NMP solvate Form V of the drug candidate were isolated, and their structures were determined by single crystal X-ray diffraction. IDR and relative stability experiment were performed. Although Form II has the fastest release rate in water, it easy transformed to monohydrate which has the lowest release rate. In vivo pharmacokinetic study showed that the Form III has the highest bioavailability at 35.4%. Considering the balance between the physicochemical properties, bioavailability and manufacturability of the available polymorphs, Form III may be the optimal form candidate for the eventual formulation.

Antipsychotic-like effects of a novel phosphodiesterase 10A inhibitor MT-3014 in rats

Phosphodiesterase (PDE) 10A is an attractive therapeutic target for schizophrenia. Here, we investigated the antipsychotic-like effects of a novel PDE10A inhibitor, 1-({2-(7-fluoro-3-methylquinoxalin-2-yl)-5-[(3R)-3-fluoropyrrolidin-1-yl]pyrazolo[1,5-α]pyrimidin-7-yl}amino)-2-methylpropan-2-ol hydrochloride (MT-3014) in rats. MT-3014 showed a potent and selective inhibitory effect against PDE10A (IC₅₀ = 0.357 nmol/L). Oral administration of MT-3014 (1.0-10 mg/kg) significantly increased the levels of cAMP, cGMP and cAMP response element-binding protein (CREB) phosphorylation in the rat striatum. MT-3014 decreased MK-801 (0.075 mg/kg)-induced hyperactivity (ED₅₀ = 0.30 mg/kg) in a dose-dependent manner, although it decreased spontaneous locomotion in control rats (ED₅₀ = 0.48 mg/kg); its effects were equivalent to those of risperidone. MT-3014 (0.3-3.0 mg/kg and 0.2 mg/kg) attenuated MK-801-induced prepulse inhibition deficits and cognitive deficits in rats, respectively, whereas risperidone attenuated MK-801-induced prepulse inhibition at only a high dose and failed to improve MK-801-induced cognitive deficits. Similar to risperidone (ID₅₀ = 0.63 mg/kg), MT-3014 suppressed the conditioned avoidance response (ID₅₀ = 0.32 mg/kg). Interestingly, MT-3014 did not elicit catalepsy and plasma prolactin increases at high doses. Furthermore, it also did not affect body weight. A positron emission tomography study using [¹¹C]IMA107 showed a plasma concentration-dependent increase in brain PDE10A occupancy after oral administration of MT-3014 within the pharmacological dose range in rats. Brain PDE10A occupancy corresponding to the ID₅₀ value in the conditioned avoidance response was approximately 60%, predicting the target occupancy in patients with schizophrenia. These results suggest that MT-3014 may be a novel antipsychotic drug, which is expected to have additional effects on cognitive impairment, without the prominent side effects associated with current atypical antipsychotics.

Combination of the phosphodiesterase 10A inhibitor, MR1916 with risperidone shows additive antipsychotic-like effects without affecting cognitive enhancement and cataleptic effects in rats

AIM

Phosphodiesterase 10A (PDE10A) inhibitors not only have antipsychotic-like effects but also cause cognitive enhancement without affecting extrapyramidal side effects in rodents, suggesting that PDE10A may be a novel approach for the treatment of schizophrenia. However, how a combination of PDE10A inhibitor with a currently available antipsychotic drug, risperidone contributes to the effect of each compound in rats remains unclear. The purpose of the present study was to examine the combination effects of MR1916 with a currently available antipsychotic drug, risperidone, in rats.

METHODS

We examined the combination effects of the PDE10A inhibitor, MR1916 with risperidone on conditioned avoidance response (CAR) to assess antipsychotic-like effects in rats. We also examined them on catalepsy as extrapyramidal side effects and novel object recognition test in cognitive functions in rats.

RESULTS

MR1916 (0.025-0.2 mg/kg, p.o.) and risperidone (0.75-6 mg/kg, p.o.) alone attenuated the CAR in a dose-dependent manner. The combination of MR1916 (0.025 mg/kg, p.o.) with risperidone (0.75 mg/kg, p.o.) significantly enhanced the attenuation of CAR without increasing the escape failure response. At the same dosage, the cataleptic effects were not enhanced by combined treatment of MR1916 with risperidone. Furthermore, the enhancement of object recognition memory induced by MR1916 (0.3 mg/kg, p.o.) was not affected by the combination with risperidone (0.75 mg/kg, p.o.).

CONCLUSION

The combination of MR1916 with risperidone may have additive antipsychotic-like effects without affecting extrapyramidal side effects, and the cognitive-enhancing effect of MR1916 may not be interfered with the addition of risperidone.

Antipsychotic-like effects of a novel phosphodiesterase 10A inhibitor T-251 in rodents

Phosphodiesterase 10A (PDE10A) is a dual-substrate PDE that hydrolyzes both cAMP and cGMP. PDE10A is selectively expressed in medium spiny neurons in the striatum, suggesting the potential of PDE10A inhibitors in the treatment of schizophrenia. This study presents the pharmacological profile of a novel PDE10A inhibitor, 2-[(E)-2-(7-fluoro-3-methylquinoxalin-2-yl)vinyl]-6-pyrrolidin-1-yl-N-(tetrahydro-2H-pyran-4-yl)pyrimidin-4-amine hydrochloride (T-251) in rodent models of schizophrenia. T-251 showed a potent inhibitory activity against human PDE10A (IC₅₀ = 0.050 nmol/L) and showed high selectivity over other PDE families which have over 10,000-fold IC₅₀ values. Oral administration of T-251 (0.1-1.0 mg/kg) increased cAMP and cGMP in the striatum in a dose-dependent manner. Oral administration of T-251 attenuated MK-801 induced hyperactivity (ED₅₀ = 0.68 mg/kg) and suppressed conditioned avoidance response (ID₅₀ = 0.87 mg/kg) in rats in a dose dependent manner. Furthermore, T-251 significantly attenuated MK-801 induced prepulse inhibition deficits and cognitive deficits in rats. Unlike haloperidol and olanzapine, T-251 (1.0-30 mg/kg) did not cause catalepsy in rats. Moreover, T-251 (0.6 and 6.0 mg/kg) did not increase plasma levels of prolactin at 1 h after administration, whereas haloperidol and olanzapine significantly increased them. The antipsychotic-like effects and cognitive enhancement of T-251 without catalepsy or plasma prolactin elevation observed in rats suggests that T-251 would be a novel antipsychotic with an improved side-effect profile.

Combined treatment with a selective PDE10A inhibitor TAK-063 and either haloperidol or olanzapine at subeffective doses produces potent antipsychotic-like effects without affecting plasma prolactin levels and cataleptic responses in rodents

Activation of indirect pathway medium spiny neurons (MSNs) via promotion of cAMP production is the principal mechanism of action of current antipsychotics with dopamine D₂ receptor antagonism. TAK‐063 [1‐[2‐fluoro‐4‐(1H‐pyrazol‐1‐yl)phenyl]‐5‐methoxy‐3‐(1‐phenyl‐1H‐pyrazol‐5‐yl)pyridazin‐4(1H)‐one] is a novel phosphodiesterase 10A inhibitor that activates both direct and indirect pathway MSNs through increasing both cAMP and cGMP levels by inhibition of their degradation. The activation of indirect pathway MSNs through the distinct mechanism of action of these drugs raises the possibility of augmented pharmacological effects by combination therapy. In this study, we evaluated the potential of combination therapy with TAK‐063 and current antipsychotics, such as haloperidol or olanzapine after oral administration. Combined treatment with TAK‐063 and either haloperidol or olanzapine produced a significant increase in phosphorylation of glutamate receptor subunit 1 in the rat striatum. An electrophysiological study using rat corticostriatal slices showed that TAK‐063 enhanced N‐methyl‐_D‐aspartic acid receptor‐mediated synaptic responses in both direct and indirect pathway MSNs to a similar extent. Further evaluation using pathway‐specific markers revealed that coadministration of TAK‐063 with haloperidol or olanzapine additively activated the indirect pathway, but not the direct pathway. Combined treatment with TAK‐063 and either haloperidol or olanzapine at subeffective doses produced significant effects on methamphetamine‐ or MK‐801‐induced hyperactivity in rats and MK‐801‐induced deficits in prepulse inhibition in mice. TAK‐063 at 0.1 mg/kg did not affect plasma prolactin levels and cataleptic response from antipsychotics in rats. Thus, TAK‐063 may produce augmented antipsychotic‐like activities in combination with antipsychotics without effects on plasma prolactin levels and cataleptic responses in rodents.

Acupuncture as Add-On Treatment of the Positive, Negative, and Cognitive Symptoms of Patients with Schizophrenia: A Systematic Review

Background: Schizophrenia is a severe psychiatric disorder that has a large impact on patients' lives. In addition to Western medicine, the use of additional treatments, such as acupuncture, in treating the positive, negative, and cognitive symptoms is increasing. Methods: We conducted a systematic review on the use of acupuncture as an add-on treatment for patients with schizophrenia that are in regular care, with a special focus on the treatment of the often accompanying sleep disorders. In this study, we searched the Medline, ScienceDirect, Cochrane Library, Scopus, and ERIC databases with a cut-off date of 31 December 2017, thereby following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) protocol. Results: Our search resulted in 26 eligible studies with 1181 patients with schizophrenia who received acupuncture treatment. Most studies showed limited evidence for the use of acupuncture as add-on therapy in the treatment of the positive, negative, and cognitive symptoms, but beneficial effects have been reported in the treatment of the accompanying sleep disorders. Conclusions: Limited evidence was found for the use of acupuncture as add-on therapy in the treatment of patients with schizophrenia; however, positive results were found in the treatment of sleep disorders, but this result needs to be confirmed in large, randomized, controlled trials.

TAK-063, a novel PDE10A inhibitor with balanced activation of direct and indirect pathways, provides a unique opportunity for the treatment of schizophrenia

The basal ganglia regulates motor, cognitive, and emotional behaviors. Dysfunction of dopamine system in this area is implicated in the pathophysiology of schizophrenia characterized by positive symptoms, negative symptoms, and cognitive deficits. Medium spiny neurons (MSNs) are principal output neurons of striatum in the basal ganglia. Similar to current antipsychotics with dopamine D₂ receptor antagonism or partial agonism, phosphodiesterase 10A (PDE10A) inhibitors activate indirect pathway MSNs, leading to the expectation of therapeutic potential for the treatment of psychosis. PDE10A inhibitors also activate direct pathway MSNs which may be associated with cognitive functions. These pathways have competing effects on antipsychotic-like activities and extrapyramidal symptoms in rodents. Therefore, careful consideration of activation pattern of these pathways by a PDE10A inhibitor is critical to produce potent efficacy and superior safety profiles. In this review, we outline the pharmacological profile of TAK-063, a novel PDE10A selective inhibitor. Our study revealed that off-rates of PDE10A inhibitors may characterize their pharmacological profiles via regulation of each MSN pathway. TAK-063, with a faster off-rate property, could provide a unique opportunity as a novel therapeutic approach to treatment of psychosis and cognitive deficits in schizophrenia. TAK-063 also has a therapeutic potential in other basal ganglia disorders.

FTBMT, a Novel and Selective GPR52 Agonist, Demonstrates Antipsychotic-Like and Procognitive Effects in Rodents, Revealing a Potential Therapeutic Agent for Schizophrenia

GPR52 is a Gs-coupled G protein-coupled receptor that is predominantly expressed in the striatum and nucleus accumbens (NAc) and was recently proposed as a potential therapeutic target for schizophrenia. In the current study, we investigated the in vitro and in vivo pharmacologic activities of a novel GPR52 agonist, 4-(3-(3-fluoro-5-(trifluoromethyl)benzyl)-5-methyl-1H-1,2,4-triazol-1-yl)-2-methylbenzamide (FTBMT). FTBMT functioned as a selective GPR52 agonist in vitro and in vivo, as demonstrated by the activation of Camp signaling in striatal neurons. FTBMT inhibited MK-801-induced hyperactivity, an animal model for acute psychosis, without causing catalepsy in mice. The c-fos expression also revealed that FTBMT preferentially induced neuronal activation in the shell of the Nac compared with the striatum, thereby supporting its antipsychotic-like activity with less catalepsy. Furthermore, FTBMT improved recognition memory in a novel object-recognition test and attenuated MK-801-induced working memory deficits in a radial arm maze test in rats. These recognitive effects were supported by the results of FTBMT-induced c-fos expression in the brain regions related to cognition, including the medial prefrontal cortex, entorhinal cortex, and hippocampus. Taken together, these findings suggest that FTBMT shows antipsychotic and recognitive properties without causing catalepsy in rodents. Given its unique pharmacologic profile, which differs from that of current antipsychotics, FTBMT may provide a new therapeutic option for the treatment of positive and cognitive symptoms of schizophrenia.

Pharmacological characterization of a novel potent, selective, and orally active phosphodiesterase 10A inhibitor, PDM-042 [(E)-4-(2-(2-(5,8-dimethyl-[1,2,4]triazolo[1,5-a]pyrazin-2-yl)vinyl)-6-(pyrrolidin-1-yl)pyrimidin-4-yl)morpholine] in rats: potential for the treatment of schizophrenia

Recently, we identified a novel phosphodiesterase 10A (PDE10A) inhibitor, PDM-042 ((E)-4-(2-(2-(5,8-dimethyl-[1,2,4]triazolo[1,5-a]pyrazin-2-yl)vinyl)-6-(pyrrolidin-1-yl)pyrimidin-4-yl)morpholine). PDM-042 showed potent inhibitory activities for human and rat PDE10A with IC ₅₀ values of less than 1 nmol/L and more than 1000-fold selectivity against other phosphodiesterases. Tritiated PDM-042, [³H]PDM-042, had high affinity for membranes prepared from rat striatum with a K_d value of 8.5 nmol/L. The specific binding of [³H]PDM-042 was displaced in a concentration-dependent manner by PDM-042 and another structurally unrelated PDE10A inhibitor, MP-10. In rat studies, PDM-042 showed excellent brain penetration (striatum/plasma ratio = 6.3), occupancy rate (86.6% at a dose of 3 mg/kg), and good oral bioavailability (33%). These data indicate that PDM-042 is a potent, selective, orally active, and brain-penetrable PDE10A inhibitor. In behavioral studies using rat models relevant to schizophrenia, PDM-042 significantly antagonized MK-801-induced hyperlocomotion (0.1-0.3 mg/kg) without affecting spontaneous locomotor activity and attenuated the conditioned avoidance response (CAR) (0.3-1 mg/kg). In tests for adverse effects, PDM-042 had a minimal effect on catalepsy, even at a much higher dose (10 mg/kg) than the minimal effective dose (0.3 mg/kg) in the CAR. Furthermore, PDM-042 had no effect on prolactin release or glucose elevation up to 3 mg/kg, while risperidone increased prolactin release and olanzapine enhanced glucose levels at doses near their efficacious ones in the CAR. Our results suggest that PDM-042 is a good pharmacological tool that can be used to investigate the role of PDE10A and may have therapeutic potential for the treatment of schizophrenia.

Characterization of binding and inhibitory properties of TAK-063, a novel phosphodiesterase 10A inhibitor

Phosphodiesterase 10A (PDE10A) inhibition is a novel and promising approach for the treatment of central nervous system disorders such as schizophrenia and Huntington’s disease. A novel PDE10A inhibitor, TAK-063 [1-[2-fluoro-4-(1H-pyrazol-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)-pyridazin-4(1H)-one] has shown high inhibitory activity and selectivity for human recombinant PDE10A2 in vitro; the half-maximal inhibitory concentration was 0.30 nM, and selectivity over other phosphodiesterases (PDEs) was more than 15000-fold. TAK-063 at 10 µM did not show more than 50% inhibition or stimulation of 91 enzymes or receptors except for PDEs. In vitro autoradiography (ARG) studies using rat brain sections revealed that [³H]TAK-063 selectively accumulated in the caudate putamen (CPu), nucleus accumbens (NAc), globus pallidus, substantia nigra, and striatonigral projection, where PDE10A is highly expressed. This [³H]TAK-063 accumulation was almost entirely blocked by an excess amount of MP-10, a PDE10A selective inhibitor, and the accumulation was not observed in brain slices of Pde10a-knockout mice. In rat brain sections, [³H]TAK-063 bound to a single high-affinity site with mean ± SEM dissociation constants of 7.2 ± 1.2 and 2.6 ± 0.5 nM for the CPu and NAc shell, respectively. Orally administered [¹⁴C]TAK-063 selectively accumulated in PDE10A expressing brain regions in an in vivo ARG study in rats. Striatal PDE10A occupancy by TAK-063 in vivo was measured using T-773 as a tracer and a dose of 0.88 mg/kg (p.o.) was calculated to produce 50% occupancy in rats. Translational studies with TAK-063 and other PDE10A inhibitors such as those presented here will help us better understand the pharmacological profile of this class of potential central nervous system drugs.

Characterization of the binding properties of T-773 as a PET radioligand for phosphodiesterase 10A

INTRODUCTION

Phosphodiesterase 10A (PDE10A) is a dual-substrate PDE that hydrolyzes both cAMP and cGMP and is selectively expressed in striatal medium spiny neurons. Recent studies have suggested that PDE10A inhibition is a novel approach for the treatment of disorders such as schizophrenia and Huntington's disease. A positron emission tomography (PET) occupancy study can provide useful information for the development of PDE10A inhibitors. We discovered T-773 as a candidate PET radioligand for PDE10A and investigated its properties by in vitro autoradiography and a PET study in a monkey.

METHODS

Profiling of T-773 as a PET radioligand for PDE10A was conducted by in vitro enzyme inhibitory assay, in vitro autoradiography, and PET study in a monkey.

RESULTS

T-773 showed a high binding affinity and selectivity for human recombinant PDE10A2 in vitro; the IC50 value in an enzyme inhibitory assay was 0.77nmol/L, and selectivity over other PDEs was more than 2500-fold. In autoradiography studies using mouse, rat, monkey, or human brain sections, radiolabeled T-773 selectively accumulated in the striatum. This selective accumulation was not observed in the brain sections of Pde10a-KO mice. The binding of [(3)H]T-773 to PDE10A in rat brain sections was competitively inhibited by MP-10, a selective PDE10A inhibitor. In rat brain sections, [(3)H]T-773 bound to a single high affinity site of PDE10A with Kd values of 12.2±2.2 and 4.7±1.2nmol/L in the caudate-putamen and nucleus accumbens, respectively. In a monkey PET study, [(11)C]T-773 showed good brain penetration and striatum-selective accumulation.

CONCLUSION

These results suggest that [(11)C]T-773 is a potential PET radioligand for PDE10A.

Elucidating the role of neurotensin in the pathophysiology and management of major mental disorders

Neurotensin (NT) is a neuropeptide that is closely associated with, and is thought to modulate, dopaminergic and other neurotransmitter systems involved in the pathophysiology of various mental disorders. This review outlines data implicating NT in the pathophysiology and management of major mental disorders such as schizophrenia, drug addiction, and autism. The data suggest that NT receptor analogs have the potential to be used as novel therapeutic agents acting through modulation of neurotransmitter systems dys-regulated in these disorders.

Trajectories of agouti-related protein and leptin levels during antipsychotic-associated weight gain in patients with schizophrenia

OBJECTIVE

Some but not all second-generation antipsychotics can induce considerable weight gain and metabolic syndrome. Although the exact biochemical mechanisms for these adverse effects are unclear, appetite-regulating neuropeptides of the central nervous system are thought to be implicated in this process. The hypothalamic mediator Agouti-related protein (AGRP) is inhibited by leptin and was shown to increase food intake. The aim of the present study was to investigate the trajectory of AGRP levels during antipsychotic-induced weight gain.

METHODS

As part of a controlled prospective clinical study, we determined indicators of body fat mass, plasma AGRP, and leptin levels in 16 patients with schizophrenia treated with ziprasidone and 21 patients with schizophrenia treated with olanzapine. Measurements by enzyme-linked immunosorbent assay were obtained before treatment (T0), after 4 weeks (T1), and after 3 months (T2) of treatment.

RESULTS

Whereas body mass index and leptin levels increased in patients treated with olanzapine compared to patients treated with ziprasidone, plasma AGRP levels did not differ among the treatment groups and did not change over time. Associations between AGRP and fat mass as well as appetite were disrupted in the olanzapine-treated patients but not in the ziprasidone group.

CONCLUSION

Future studies are needed to test whether the lack of a decrease in AGRP levels during weight gain in patients treated with olanzapine could perpetuate adverse metabolic long-term effects.

Slow dissociation of partial agonists from the D₂ receptor is linked to reduced prolactin release

In this study we investigated the correlation between affinity, efficacy, peripheral receptor occupancy, and kinetic properties of D₂ dopamine receptor ligands with time-course evaluations of prolactin release in rat blood. We profiled typical and atypical antipsychotic antagonists at D₂ receptors, the partial agonist aripiprazole, and four novel partial agonist compounds with different properties. Clozapine and quetiapine revealed lower prolactin release and fast dissociation kinetics, linking fast dissociation and prolactin-sparing properties. Surprisingly, haloperidol, a highly prolactin-releasing antagonist, shared intermediate dissociation properties. Factors other than kinetic properties may thus contribute to prolactin-releasing properties of antagonists. Partial agonists sharing similar efficacies and receptor occupancies differed markedly in their ability to induce hyperprolactinaemia. Aripiprazole moderately released prolactin even at high receptor occupancies, with slow dissociation from D₂ receptors. Other compounds displaying low affinities and fast dissociations released prolactin substantially, although less than haloperidol. The effect augmented after repeated administrations. Compounds with high affinities and slow dissociation rates stimulated moderate prolactin release at high receptor occupancies, reaching a ceiling effect at 50-60% occupancy. Moreover, the effect developed tolerance. In conclusion, we investigated the affinity and kinetic properties of D₂ partial agonists associated with their ability to induce prolactin release in blood. We propose that for D₂ partial agonists, at comparable intrinsic activities and peripheral occupancies, the prolactin-releasing properties are linked to their kinetic rate properties. Differently from D₂ antagonists, partial agonists display slow dissociation and high affinity associated with a low prolactin release profile.

Neuroprotection of paliperidone on SH-SY5Y cells against β-amyloid peptide(25-35), N-methyl-4-phenylpyridinium ion, and hydrogen peroxide-induced cell death

RATIONALE

Antipsychotic drugs (APDs) were widely used in treating schizophrenia. Some APDs were reported to have neuroprotective effects against neurotoxicants in the cell level.

OBJECTIVES

Thus, one typical APD (haloperidol) and three atypical APDs (paliperidone, olanzapine, and risperidone) were tested whether they provide neuroprotection against stressor-induced cell death of SH-SY5Y.

METHODS

Hydrogen peroxide, N-methyl-4-phenylpyridinium ion, and β-amyloid peptide were used to treat cells with or without preconditioning by APDs; cell survival and indicators of oxidative stress were measured, respectively.

RESULTS

Paliperidone has the lowest baseline cytotoxicity compared with other APDs at 24 h; in addition, the paliperidone group showed a better survival than the other APD groups (P < 0.05). In stressor challenging, with a fixed concentration of stressors, olanzapine provided the best neuroprotection at 100 μM against Aβ(25-35) and MPP(+) (P < 0.05). In contrast, paliperidone works finely at low concentrations (10 and 50 μM) against Aβ(25-35) and MPP(+) and solely protected SH-SY5Y from hydrogen peroxide. At 100 μM, paliperidone completely diminished cell reduction induced by different stressors, regardless of their dosages. Paliperidone was demonstrated with a higher oxidative stress-scavenging properties than other APDs in several aspects, such as generated bulk glutathione, low HNE, and protein carbonyl productions. Contradictorily, olanzapine, at 24 h, also enhanced HNE and protein carbonyl productions, which may underlie its induced cytotoxicity.

CONCLUSIONS

Different APDs exhibit variations against different stressors. Paliperidone might be useful not only in alleviating oxidative stress induced by Aβ(25-35) and MPP(+) but also in providing neuroprotection against hydrogen peroxide.

[A randomized controlled study on the impact of pharmacoeducation on a French patient population with schizophrenic and schizoaffective disorders]

OBJECTIVE

To evaluate the impact of a pharmacoeducation module both on hospital stay and on clinical and functional state in a French patient population with schizophrenic and schizoaffective disorders.

METHODS

After inclusion, 82 patients were randomly distributed in 2 groups, one group receiving the pharmacoeducation module and the other to be a control group. Data on the number of hospital stays and emergency visits, and the type of medication received, were compiled. Patients were evaluated with the Positive and Negative Syndrome Scale, Clinical Global Impression Scale, Barnes Akathisia Scale, Simpson-Angus Scale, Quality of Life Scale, and Global Assessment of Functioning; data were gathered at baseline, then each year for 2 years.

RESULTS

Among the 72 analyzed patients, those receiving pharmacoeducation had significantly lower total hospital stays, forced hospital stays, and emergency visits, compared with the control group patients. They also had more improvement in their symptomatology, autonomy, and quality of life. They presented less akathisia and less medication intake.

CONCLUSIONS

Pharmacoeducation can reduce the hospital stays of patients with schizophrenia and schizoaffective disorders, as well as improve their clinical and functional state, likely through better compliance.

Side-effects of antipsychotic medication and health-related quality of life in schizophrenia

OBJECTIVE

This analysis used data from the large (n = 1208) European Schizophrenia Cohort to examine the association between subjective side-effects of antipsychotic medication and the Mental and Physical Composite Scores (MCS; PCS) of the SF-36 scale.

METHOD

Relationships between the subjective evaluation of side-effects identified from the Subjective Side-Effects Scale and the adjusted mean score on the PCS and MCS were examined. Where appropriate, these associations of subjective side-effects were compared with those of the same side-effects measured objectively.

RESULTS

In this study, subjective side-effects of antipsychotic medication were linked either to both the PCS and the MCS or, in a few instances, to neither. Subjective evaluations of sexual side-effects were associated only with the MCS, those of sialorrhoea only with the PCS. Objective ratings of extrapyramidal side-effects were related neither to PCS nor to MCS.

CONCLUSION

These data suggest that side-effects, whether subjective or objective, may need to be considered individually in relation to their impact on quality of life.

Sexual dysfunction in patients with schizophrenia treated with conventional antipsychotics or risperidone

OBJECTIVE

To better understand sexual dysfunction in patients with schizophrenia and its associations with prolactin and reproductive hormones.

METHODS

This was a secondary analysis of an open-label, one-day study (N = 402). The primary objective of the study was to assess the prevalence of hyperprolactinemia in patients with schizophrenia who had been treated with conventional antipsychotics or risperidone. Other atypical antipsychotics available at the time of the study were not included due to a more favorable prolactin profile.

RESULTS

The majority of patients (59% of females and 60% of males) reported impairment of sexual function. In postmenopausal females, risk of impaired sexual interest was increased by 31% for every 10 ng/ml increase in prolactin (p = 0.035). In males, lower testosterone was associated with higher prolactin (p < 0.001) and with orgasmic (p = 0.004) and ejaculatory dysfunction (p = 0.028).

CONCLUSION

These findings suggest that hyperprolactinemia may be associated with sexual dysfunction. They also provide more information on the relationships between prolactin, reproductive hormones, and sexual dysfunction. Sexual dysfunction is an understudied yet important consideration in the treatment of schizophrenia. More attention is warranted in this area as it may provide opportunities for improved quality of life and adherence to treatment for patients.

ORIGINAL RESEARCH—EDUCATION: Sexual Counseling for Women in the Context of Physical Diseases—A Teaching Model for Physicians

INTRODUCTION

Chronic medical conditions are frequently associated with sexual difficulties and problems, which are often underreported and underdiagnosed. Patients may feel that sexual problems in the context of disease are not important enough to be mentioned to their physicians, and physicians may feel uncomfortable and sometimes incompetent. Furthermore, the diagnostic criteria of Diagnostic and Statistical Manual of Mental Disorders-IV and International Classification of Diseases-10 are focused on the phenomenology of the sexual response without any specificity regarding diseases.

AIM

To facilitate access for patients and physicians, we wanted to develop a tool for assessment and discussion of sexual problems in the context of disease. This tool should be broadly applicable, easy to use and learn for nonmental health professionals.

MAIN OUTCOME MEASURES

Content analysis with respect to the integration of general sexological and disease-specific dimensions. Formulation of a diagnostic and therapeutic algorithm that can be used as a teaching tool.

METHODS

Based on our experience as a liaison-consultation sexological division of the university hospital of Basel, we analyzed the sexological diagnostic workup performed with the following group of female patients: women with benign gynecologic conditions; women with incontinence; oncological patients (mammary carcinoma, genital carcinoma); neurological patients (multiple sclerosis, spine injury, Parkinson's); patients with metabolic and endocrine disorders (diabetes, metabolic syndrome, polycystic ovarian syndrome); and patients with mental health disorders (depression, anxiety disorder, schizophrenia). We extracted the commonly used steps in the workup to construct a tool with easy-to-remember elements, which would help the physician to evaluate patients' sexual problems and plan for referral or therapy.

RESULTS

We could differentiate three diagnostic dimensions. The first were person-related preexisting factors, such as sexual satisfaction and function, age, body image, and general well-being. The second were the disease-specific implications, which could be summarized under the 8 Ds: Danger, Destruction, Disfigurement, Disability and pain, Dysfunction, Dysregulation, Disease load, and Drugs. The third was the patient's and partner's general response to the disease determined by affective response, coping style, body image impact, and changes in relationship dynamics.

CONCLUSION

Sexual problems are frequent in many clinical conditions, but are not yet a routine part of diagnostic workup and therapeutic planning. We have developed a tool to help physicians in different clinical settings to evaluate sexual problems of the female patients with specific clinical conditions in order to facilitate access to recognition and possible treatment.

Schizophrenia proteomics: biomarkers on the path to laboratory medicine?

Over two million Americans are afflicted with schizophrenia, a debilitating mental health disorder with a unique symptomatic and epidemiological profile. Genomics studies have hinted towards candidate schizophrenia susceptibility chromosomal loci and genes. Modern proteomic tools, particularly mass spectrometry and expression scanning, aim to identify both pathogenic-revealing and diagnostically significant biomarkers. Only a few studies on basic proteomics have been conducted for psychiatric disorders relative to the plethora of cancer specific experiments. One such proteomic utility enables the discovery of proteins and biological marker fingerprinting profiling techniques (SELDI-TOF-MS), and then subjects them to tandem mass spectrometric fragmentation and de novo protein sequencing (MALDI-TOF/TOF-MS) for the accurate identification and characterization of the proteins. Such utilities can explain the pathogenesis of neuro-psychiatric disease, provide more objective testing methods, and further demonstrate a biological basis to mental illness. Although clinical proteomics in schizophrenia have yet to reveal a biomarker with diagnostic specificity, methods that better characterize the disorder using endophenotypes can advance findings. Schizophrenia biomarkers could potentially revolutionize its psychopharmacology, changing it into a more hypothesis and genomic/proteomic-driven science.