Investigational drugs in recent clinical trials for treatment-resistant depression.

INTRODUCTION: The authors describe the medications for treatment-resistant depression (TRD) in phase II/III of clinical development in the EU and USA and provide an opinion on how current treatment can be improved in the near future. Areas covered: Sixty-two trials were identified in US and EU clinical trial registries that included six investigational compounds in recent phase III development and 12 others in recent phase II clinical trials. Glutamatergic agents have been the focus of many studies. A single intravenous dose of the glutamatergic modulator ketamine produces a robust and rapid antidepressant effect in persons with TRD; this effect continues to remain significant for 1 week. This observation was a turning point that opened the way for other, more selective glutamatergic modulators (intranasal esketamine, AVP-786, AVP-923, AV-101, and rapastinel). Of the remaining compounds, monoclonal antibodies open highly innovative therapeutic options, based on new pathophysiological approaches to depression. Expert commentary: Promising new agents are emerging for TRD treatment. Glutamatergic modulators likely represent a very promising alternative to monoaminergic antidepressant monotherapy. We could see the arrival of the first robust and rapid acting antidepressant drug in the near future, which would strongly facilitate the ultimate goal of recovery in persons with TRD.

Therapeutic improvements expected in the near future for schizophrenia and schizoaffective disorder: an appraisal of phase III clinical trials of schizophrenia-targeted therapies as found in US and EU clinical trial registries.

INTRODUCTION: In this review, the authors describe medications in phase III of clinical development for schizophrenia and schizoaffective disorder, and provide an opinion on how current treatment can be improved in the near future. AREAS COVERED: Recent (post 2013) phase III clinical trials of schizophrenia-targeted therapies were found in US and EU clinical trial registries. Two hundred fifty-three trials were identified, that included 16 investigational compounds. The antipsychotics brexpiprazole and cariprazine have been approved in the US, and although both are dopamine D2 receptor partial agonists, they differ markedly in their pharmacodynamic profiles. Encenicline and valbenazine are first-in-class candidates for treatment of cognitive impairment associated with schizophrenia (CIAS) and tardive dyskinesia, respectively. Eleven add-on compounds were previously approved for other therapeutic indications and are for the most part being studied at academic medical centers and smaller pharmaceutical companies for negative symptoms and CIAS or for specific populations (comorbidities, antipsychotic-induced obesity). EXPERT OPINION: Promising new agents are emerging for schizophrenia and schizoaffective disorder. In addition to better-tolerated antipsychotics that treat positive symptoms, we could see the arrival of the first effective drug for negative symptoms and CIAS, which would strongly facilitate the ultimate goal of recovery in persons with schizophrenia.

Potential serotonergic agents for the treatment of schizophrenia.

INTRODUCTION: For the last 30 years, drugs targeting serotonin receptors (5-HTR) have been intensively investigated in schizophrenia. New drugs targeting 5-HTRs are under development in patients with schizophrenia. AREAS COVERED: In this review, the authors describe the recent clinical trials for schizophrenia with selective serotonergic agents and provide an opinion on how the investigated drugs can help to fulfil current treatment needs. Clinical trials were found in US and EU clinical trial registries and in the medical literature. Relevant 5-HTR antagonists active in animal models of schizophrenia were also analysed. EXPERT OPINION: Antipsychotics reduce positive symptoms of schizophrenia (delusions, hallucinations and disordered thought), but have undesirable side effects. Moreover, satisfactory treatment of negative symptoms (apathy, poverty of speech, lack of interest in social interactions) and cognitive dysfunction is currently not available. The selective 5-HT2CR full agonist vabicaserin showed antipsychotic efficacy with fewer side effects than olanzapine. Adjunctive pimavanserin (a selective 5-HT2AR inverse agonist) facilitated antipsychotic dose and side-effect reductions. Selective 5-HT3R antagonists (ondansetron, tropisetron and granisetron) showed positive results on negative symptoms and/or cognitive impairments in phase II trials. Adjunctive ondansetron has now entered a phase III trial for such indications. Finally, 5-HTA5R and 5-HT7R antagonists have shown procognitive actions in animal models of schizophrenia. These novel serotonergic drugs seem promising for improving the current treatment of schizophrenia.

Investigational drugs for anxiety in patients with schizophrenia.

INTRODUCTION: Anxiety is a frequent symptom of schizophrenia, which is highly associated with an increased risk of relapse and suicide. The effect of antipsychotics on this clinical dimension is not specific and the common practice of prescribing benzodiazepines remains unsatisfactory. AREAS COVERED: The authors review recent well-designed clinical trials for anxiety in patients with schizophrenia. The content includes information derived from trial databases, regulatory authorities and scientific literature. EXPERT OPINION: Anxiety in schizophrenia has severe consequences and specific clinical features, which require a specific therapy, beyond benzodiazepines. In these past 2 years, two compounds (the anticonvulsant/anxiolytic pregabalin and the atypical antipsychotic quetiapine) were on Phase III/IV clinical trials for schizophrenia, with comorbid anxiety as a primary outcome measure. Potential for success is high, given their strong rationale and the clinical experience with both drugs. Anxiety (as a symptom) was a secondary outcome measure in trials for schizophrenia involving seven other compounds (lurasidone, amisulpride, bitopertin, oxytocin, famotidine, cannabidiol and the L-theanine and pregnenolone combination). Primary completion date is expected in the next 2 years. In spite of ancient positive results and a strong rationale, aripiprazole and related compounds were not in recent clinical trials. The authors believe that these compounds deserve more attention.

Bipolar disorder: recent clinical trials and emerging therapies for depressive episodes and maintenance treatment.

Bipolar disorder (BD) is one of the world's ten most disabling conditions. More options are urgently needed for treating bipolar depressive episodes and for safer, more tolerable long-term maintenance treatment. We reviewed 30 recent clinical trials in depressive episodes (eight tested compounds) and 14 clinical trials in maintenance treatment (ten tested compounds). Positive results in Phase III trials, regulatory approval and/or new therapeutic indications were obtained with some of the developing drugs, particularly for depressive episodes. The current BD pipeline is encouraging with promising new compounds, acting on novel pharmacological targets and on specific aspects of bipolar depression.

Psychopathological correlates of lifetime anxiety comorbidity in bipolar I patients: findings from a French national cohort.

BACKGROUND: Despite numerous studies on the comorbidity of bipolar and anxiety disorders, there is no satisfactory psychopathological model for their overlap. METHOD: 1,090 hospitalized patients meeting DSM-IV criteria for a manic episode of bipolar I disorder were subtyped according to the presence or not of lifetime anxiety comorbidity and assessed for demographic, illness course, clinical, associated condition, temperament, and treatment characteristics. RESULTS: Lifetime anxiety comorbidity, defined as presence of at least one anxiety disorder in lifetime, was found in 27.2% (n = 297) of the sample. Compared to patients without such a comorbidity (n = 793), those who had it experienced a higher number of mood episodes and suicide attempts in the previous year, more stressors, organic disorders and less free intervals; furthermore, they showed more temperaments with depressive features and complex treatment. At study entry, they also experienced manic episodes with higher levels of depression, psychosis and hostility. The following independent variables were associated with lifetime anxiety comorbidity: higher scores on the Montgomery-Asberg Depression Rating Scale, depressive temperament, irritable temperament, higher scores on the Scale for the Assessment of Positive Symptoms, episodes without free intervals and at least one stressor before the index episode. CONCLUSIONS: Factors associated with lifetime anxiety comorbidity in bipolar I patients may be integrated into a comprehensive diathesis-stress model emphasizing the role of irritable temperament as a source of mood instability and stress, and interacting with other temperamental characteristics to trigger the outbreak of both anxiety and bipolar symptoms.

Risk factors associated with lifetime suicide attempts in bipolar I patients: findings from a French National Cohort.

Risk factors that may be associated with suicide attempts in bipolar disorder are still a matter of debate. We compared demographic, illness course, clinical, and temperamental features of suicide attempters vs those of nonattempters in a large sample of bipolar I patients admitted for an index manic episode. One thousand ninety patients (attempters = 382, nonattempters = 708) were included in the study. Multivariate analysis evidenced 8 risk factors associated with lifetime suicide attempts as follows: multiple hospitalizations, depressive or mixed polarity of first episode, presence of stressful life events before illness onset, younger age at onset, no free intervals between episodes, female sex, higher number of previous episodes, and cyclothymic temperament. These characteristics may help identify subjects at risk for suicide attempt throughout the course of bipolar disorder. We finally propose to integrate such characteristics into a stress-diathesis model of suicidal behavior, adapted to bipolar patients.

Factors associated with rapid cycling in bipolar I manic patients: findings from a French national study.

INTRODUCTION: Despite numerous explanatory hypotheses, few studies have involved a large national clinical sample examining risk factors in the occurrence of rapid cycling during the course of bipolar illness. METHODS: From 1,090 manic bipolar I disorder inpatients included in a multicenter national study in France, 958 could be classified as rapid or nonrapid cyclers and assessed for demographic, illness course, clinical, psychometric, temperament, comorbidity, and treatment characteristics. RESULTS: Rapid cycling bipolar disorder occurred in 9% (n=86) of the study group. Compared to nonrapid cyclers (n=872), patients with rapid cycling experienced the onset of their illness at a younger age, a higher number of prior episodes, more depression during the first episode, and more suicide attempts. At study entry, they also experienced manic episodes with more depressive and anxious symptoms, but less psychotic features. The following independent variables were associated with rapid cycling: longer duration of illness, antidepressant treatment, episodes with no free intervals, cyclothymic temperament, lower scores on the Scale for Assessment of Positive Symptoms and presence of thyroid disorder. Retrospective study limited to bipolar I disorder inpatients; several factors previously associated with rapid cycling were not assessed. CONCLUSION: Our findings may confirm previous descriptions, according to which rapid cycling develops later in the course of illness following a sensitization process triggered by antidepressant use or thyroid dysfunction, in patients with a depression-mania-free interval course, and cyclothymic temperament.

Cyamemazine metabolites: effects on human cardiac ion channels in-vitro and on the QTc interval in guinea pigs.

Monodesmethyl cyamemazine and cyamemazine sulfoxide, the two main metabolites of the antipsychotic and anxiolytic phenothiazine cyamemazine, were investigated for their effects on the human ether-à-go-go related gene (hERG) channel expressed in HEK 293 cells and on native I(Na), I(Ca), I(to), I(sus) or I(K1) of human atrial myocytes. Additionally, cyamemazine metabolites were compared with terfenadine for their effects on the QT interval in anaesthetized guinea pigs. Monodesmethyl cyamemazine and cyamemazine sulfoxide reduced hERG current amplitude, with IC50 values of 0.70 and 1.53 microM, respectively. By contrast, at a concentration of 1 microM, cyamemazine metabolites failed to significantly affect I(Na), I(to), I(sus) or I(K1) current amplitudes. Cyamemazine sulfoxide had no effect on I(Ca) at 1 microM, while at this concentration, monodesmethyl cyamemazine only slightly (17%), albeit significantly, inhibited I(Ca) current. Finally, cyamemazine metabolites (5 mg kg(-1) i v.) were unable to significantly prolong QTc values in the guinea pig. Conversely, terfenadine (5 mg kg(-1) i.v.) significantly increased QTc values. In conclusion, cyamemazine metabolite concentrations required to inhibit hERG current substantially exceed those necessary to achieve therapeutic activity of the parent compound in humans. Moreover, cyamemazine metabolites, in contrast to terfenadine, do not delay cardiac repolarization in the anaesthetized guinea pig. These non-clinical findings explain the excellent cardiac safety records of cyamemazine during its 30 years of extensive therapeutic use.

Toward the delineation of mania subtypes in the French National EPIMAN-II Mille Cohort. Comparisons with prior cluster analytic investigations.

BACKGROUND: Knowledge about psychopathologic presentations of mania in current clinical practice has to be refined in order to improve diagnosis and treatment. METHODS: One thousand ninety manic patients included in the French National Study EPIMAN-II Mille were submitted to a cluster analysis on the basis of multiple variables related to the history of bipolar illness and symptoms of the current episode. RESULTS: Four clusters were identified: "classic mania" (29.3% of patients) with less severe mania; "psychotic mania" (22.7%) with psychotic symptoms, more severe mania, younger age and social impairment; "depressive mania" (30.4%) characterized by female gender, suicide attempts, high number of previous episodes and residual symptoms; and "dual mania" (17.6%) characterized by male gender, substance use, earlier onset and poor compliance. Patients groups also differed in manic symptoms, marital status, stressors preceding illness onset, prior diagnoses, first episode polarity and temperamental characteristics. LIMITATIONS: Cross-sectional assessment of patients. CONCLUSIONS: In comparing our findings with those of four prior cluster analytic studies, we integrate clinical characteristics of mania subtypes found in this very large representative French sample in contemporary practice, we suggest how such convergence of data may help improve earlier recognition, differential response to different treatments, and prevention of these subtypes. We finally suggest that such subtyping might provide clues to phenotype delineation suitable for pharmacogenetic investigations.

Affinity of cyamemazine metabolites for serotonin, histamine and dopamine receptor subtypes.

Animal and human pharmacological studies indicate that the antipsychotic action of cyamemazine results from blockade of dopamine D(2) receptors, its anxiolytic properties from serotonin 5-HT(2C) receptor antagonism and the low incidence of extrapyramidal side effects from a potent 5-HT(2A) receptor antagonistic action. Cyamemazine is metabolized in monodesmethyl cyamemazine and cyamemazine sulfoxide, which are not known for their affinities for serotonin, dopamine and other brain receptor types considered to mediate central nervous systems effects of drugs. Hence, metabolite affinities were determined in human recombinant receptors expressed in CHO cells (hD(2) and hD4.4 receptors, h5-HT(1A), h5-HT(2A), h5-HT(2C) and h5-HT(7) receptors and hM(1), hM(2) and hM(3) receptors) and HEK-293 cells (h5-HT(3) receptors) or natively present in rat cerebral cortex (non-specific alpha(1)- and alpha(2)-adrenoceptors, GABA(A) and GABA(B) receptors) and guinea pig cerebellum (H(1) central histamine receptors) membranes. Monodesmethyl cyamemazine showed a neurotransmitter receptor profile similar to that of its parent compound cyamemazine, i.e.: high affinity for h5-HT(2A) receptors (K(i)=1.5 nM), h5-HT(2C) receptors (K(i)=12 nM) and hD(2) receptors (K(i)=12 nM). Cyamemazine sulfoxide showed high affinity for h5-HT(2A) receptors (K(i)=39 nM) and histamine H(1) receptors (K(i)=15 nM) and a reduced affinity for D(2) and 5-HT(2C) receptors. Therefore, monodesmethyl cyamemazine can contribute to enhance and prolong the therapeutic actions of cyamemazine. Further investigation is required to see if the high affinities of cyamemazine sulfoxide for H(1) and 5-HT(2A) receptors are of therapeutic benefit against sleep onset insomnia and/or sleep maintenance insomnia respectively.

Two-year study of relapse prevention by a new education program in schizophrenic patients treated with the same antipsychotic drug.

It is not clear whether patient's psycho-education enhances compliance to antipsychotic treatments and reduces the number of relapses. Here we investigated the impact of a new psycho-educational program (SOLEDUC) on the one- and two-years rate of relapse (primary outcome measure) and a number of clinical assessments (secondary outcome measures). This was a multicentric French clinical trial (51 centers) of Phase IV, open, controlled, randomized, consisting in two parallel groups: the Soleduc group (N=111) and the control group (N=109). All subjects received a variable dose over the 2-year period of the same antipsychotic drug (amisulpride). Soleduc consisted of a 7-session program (1h per session), presented three times (at baseline, 6-months and 12-months). Patients in the control group received a non-specific psychosocial training for an equivalent period of time. The models of Andersen-Gill (AG) and Prentice, Williams and Peterson (PWP) were used to analyze relapses. Patients in the Soleduc group attended 14.8+/-6.1 sessions (mean+/-SD), including 17 patients who never attended a session. Intent to treat analysis showed less patients relapsing in the Soleduc group as compared to the control group (21.6% versus 28.4% after 1 year and 84.4% versus 90.8% after 2years), but the differences were not statistically significant. Relapse risk was significantly reduced for patients who followed at least 7 modules (p=0.015 AG-test; p<0.001 PWP-test). In conclusion, no significant differences in relapse rates were found between patients attending the Soleduc program and the control group. Attendance of at least 7 out of 21 program sessions was required to see a modest, but significant two-year relapse prevention in schizophrenia. Other well designed studies are required to evaluate the medical impact of patient's education programs.

Characterization of human cytochrome P450 enzymes involved in the metabolism of cyamemazine.

Recombinant human liver microsomal enzymes of the cytochrome P450 family (CYP1A2, CYP2A6, CYP3A4, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1) were used to determine the metabolic fate of the antipsychotic anxiolytic agent cyamemazine. An LC/MS-MS tandem methodology was developed specifically for identifying the presence of cyamemazine and its metabolites in reaction media. All P450 enzymes investigated, with the exception of CYP2A6 and CYP2E1, degraded cyamemazine, albeit to a different extent, with CYP1A2, CYP2C8 and CYP2C19 being the most efficient (>80%). However, in microsomes prepared from native human hepatocytes, only relatively specific competitors (inhibitors and/or substrates) of CYP1A2, CYP2C8, CYP2C9 and CYP3A4 reduced notably the degradation cyamemazine. The main routes of cyamemazine biotransformation are N-mono-demethylation (CYP1A2, CYP3A4 and CYP2C8) and mono-oxidation (either S-oxidized or hydroxylated derivatives which could not be discriminated because characterized by the same mass value) by CYP1A2 and CYP2C9. Secondary metabolic routes yields N,N-di-demethylated and N-demethylated mono-oxidized products. Thus, under in vitro conditions, cyamemazine is extensively degraded by at least four distinct P450 enzymes, into two primary hydrophilic metabolites. These results suggest that cyamemazine detoxification process is unlikely to be significantly impaired by co-administration of therapeutic agents that are substrates of the CYP metabolic system.

Effects of cyamemazine on hERG, INa, ICa, Ito, Isus and IK1 channel currents, and on the QTc interval in guinea pigs.

The antipsychotic and anxiolytic phenothiazine, cyamemazine, was investigated for its effects on the hERG (human ether-à-go-go related gene) channel expressed in HEK 293 cells and on native INa, ICa, Ito, Isus, or IK1 of human atrial myocytes. Moreover, cyamemazine and terfenadine were compared for their effects on the QT interval in anesthetized guinea pigs. Cyamemazine reduced hERG current amplitude with an IC50 value of 470 nM. Cyamemazine 1 microM failed to significantly affect INa, Ito, Isus, or IK1 amplitudes and slightly decreased ICa (18%). For comparison, haloperidol (30 nM) and olanzapine (300 nM) reduced hERG current amplitude by 44.2+/-3.9% and 49.7+/-4.2%, respectively. The cardiac safety ratio of cyamemazine, calculated from the IC50/receptor affinity ratios, is 81 and 313 against dopamine D2 receptors and 5-HT2A receptors, respectively. In guinea pigs, QT and QTcBazett were not significantly modified by intravenous cyamemazine when compared to the effects produced by the vehicle. Conversely, terfenadine (5 mg/kg iv) increased significantly QTcBazett (+58 ms), QTcFrediricia (+83 ms) and QTcVan de Water (+78 ms). In conclusion, cyamemazine concentrations required to inhibit hERG current exceed substantially those necessary to achieve therapeutic activity in humans. Moreover, cyamemazine, in contrast to terfenadine, does not delay cardiac repolarization in the anesthetized guinea pig. These non-clinical findings confirm the excellent cardiac safety records of cyamemazine during its 30 years of extensive therapeutic use.

Neuroprotective effect of riluzole in acute noise-induced hearing loss.

Riluzole has been reported to protect against the deleterious effect of cerebral ischemia by blocking glutamatergic neurotransmission. Here, we investigated whether acoustic trauma-induced cochlear excitotoxicity could be attenuated by riluzole. Cumulative intracochlear perfusion of riluzole completely abolished single-nerve fiber activity in the guinea pig cochlea and the compound action potential of the auditory nerve. Guinea pigs treated with riluzole (100 microM) showed significantly less hearing threshold shift than untreated guinea pigs, and presented no sign of dendritic damage in the cochlea observable by electron microscopy. When coapplied with glutamate, riluzole did not prevent glutamate-induced swelling of auditory nerve dendrites, suggesting that the protective effect of riluzole was mediated principally by inhibition of glutamate release from sensory inner hair cells.

Affinity of cyamemazine, an anxiolytic antipsychotic drug, for human recombinant dopamine vs. serotonin receptor subtypes.

Animal studies indicate that the anxiolytic properties of the antipsychotic agent cyamemazine may result from blockade of serotonin 5-HT(2C) receptors and to a lesser extent from blockade of serotonin 5-HT(3) receptors. Here, we used human recombinant receptors to determine the relative affinity of cyamemazine for serotonin and dopamine receptor subtypes. In addition, cyamemazine was tested in other brain receptor types and subtypes which are considered to mediate central nervous systems effects of drugs. Hence, cyamemazine affinity was determined in human recombinant receptors expressed in CHO cells (hD(2), hD(3), and hD(4.4) receptors, h5-HT(1A), h5-HT(2A), h5-HT(2C), and h5-HT(7), and hM(1), hM(2), hM(3), hM(4), and hM(5) receptors), L-cells (hD(1) receptor), and HEK-293 cells (h5-HT(3) receptors) or natively present in N1E-115 cells (5-HT(3) receptors) or in rat cerebral cortex (non-specific alpha(1)- and alpha(2)-adrenoceptors, GABA(A) and GABA(B) receptors, H(3) histamine receptors), and guinea-pig cerebellum (H(1) central and H(2) histamine receptors) membranes. Similarly to atypical antipsychotics, cyamemazine exhibited high affinity for: (i) h5-HT(2A) receptors (K(i)=1.5+/-0.7 nM, mean+/-SEM, N=3) and this was four times higher than for hD(2) receptors (K(i)=5.8+/-0.8 nM), (ii) h5-HT(2C) receptors (K(i)=11.8+/-2.2nM), and (iii) 5-HT(7) receptors (K(i)=22 nM). Conversely, cyamemazine exhibited very low affinity for h5-HT(3) receptors (K(i)=2.9+/-0.4 microM). In conclusion, similarly to atypical antipsychotic agents, cyamemazine, possesses high affinity for h5-HT(2A), h5-HT(2C), and h5-HT(7) receptors, a feature which can explain its low propensity to cause extrapyramidal adverse reactions in clinical practice. The high affinity for h5-HT(2C) receptors, but not for h5-HT(3) receptors, can account for the anxiolytic activity of cyamemazine in human subjects.

5-HT2A receptor antagonist properties of cyamemazine in rat and guinea pig smooth muscle.

5-HT(2A) receptor antagonism seems to explain the low incidence of extrapyramidal side effects with atypical neuroleptics. Whether the neuroleptic cyamemazine, which at low doses is also devoid of extrapyramidal side effects, possesses 5-HT(2A) receptor antagonist properties is unknown. Cyamemazine was tested for its ability to antagonize 5-HT(2A)-mediated responses in isolated rat aorta and guinea pig trachea and to displace [3H]ketanserin specifically bound to rat brain membranes. In isolated rat aorta, cyamemazine potently and competitively antagonized serotonin-dependent contractions (pA(2)=8.82+/-0.26, n=7; Schild's slope=1.02+/-0.29). In this test, cyamemazine was of similar potency as ketanserin (pA(2)=8.23). In isolated guinea pig trachea, cyamemazine reduced maximum contractile responses to serotonin with pIC(50)=7.92+/-0.35, (n=4), whereas ketanserin exhibited a pIC(50)=8.79. Finally, cyamemazine displaced [3H]ketanserin specifically bound to rat brain membranes with pK(i)=8.76+/-0.53 (n=3). In conclusion, cyamemazine behaves as a potent antagonist at 5-HT(2A) receptors, which compares well with the reference compound, ketanserin. Whether this 5-HT(2A) receptor antagonist action of cyamemazine can explain its low incidence of extrapyramidal side effects deserves further investigation.