Interaction of hallucinogenic rapid-acting antidepressants with mGlu2/3 receptor ligands as a window for more effective therapies.

The desire to find a gold-standard therapy for depression is still ongoing. Developing one universal and effective pharmacotherapy remains troublesome due to the high complexity and variety of symptoms. Over the last decades, the understanding of the mechanism of pathophysiology of depression and its key consequences for brain functioning have undergone significant changes, referring to the monoaminergic theory of the disease. After the breakthrough discovery of ketamine, research began to focus on the modulation of glutamatergic transmission as a new pharmacological target. Glutamate is a crucial player in mechanisms of a novel class of antidepressants, including hallucinogens such as ketamine. The role of glutamatergic transmission is also suggested in the antidepressant (AD) action of scopolamine and psilocybin. Despite fast, robust, and sustained AD action hallucinogens belonging to a group of rapid-acting antidepressants (RAA) exert significant undesired effects, which hamper their use in the clinic. Thus, the synergistic action of more than one substance in lower doses instead of monotherapy may alleviate the likelihood of adverse effects while improving therapeutic outcomes. In this review, we explore AD-like behavioral, synaptic, and molecular action of RAAs such as ketamine, scopolamine, and psilocybin, in combination with mGlu2/3 receptor antagonists.

The Potential of Scopolamine as an Antidepressant in Major Depressive Disorder: A Systematic Review of Randomized Controlled Trials.

Major depressive disorder is one of the most severe mental disorders. It strongly impairs daily functioning, and, in extreme cases, it can lead to suicide. Although different treatment options are available for patients with depression, there is an ongoing search for novel therapeutic agents, such as scopolamine (also known as hyoscine), that would offer higher efficacy, a more rapid onset of action, and a more favorable safety profile. The aim of our study was to review the current clinical evidence regarding the use of scopolamine, a promising therapeutic option in the treatment of depression. A systematic literature search was performed using PubMed, Embase, and CENTRAL databases up to 5 June 2023. We included randomized placebo-controlled or head-to-head clinical trials that compared the clinical efficacy and safety of scopolamine in the treatment of major depressive disorder. Two reviewers independently conducted the search and study selection and rated the risk of bias for each study. Four randomized controlled trials were identified in the systematic review. The included studies investigated the use of scopolamine administered as an oral, intramuscular, or intravenous drug, alone or in combination with other antidepressants. The results indicated that scopolamine exerts antidepressant effects of varying intensity. We show that not all studies confirmed a statistically and clinically significant reduction of depressive symptoms vs. placebo. A broader perspective on scopolamine use in antidepressant treatment should be confirmed in subsequent large randomized controlled trials assessing both effectiveness and safety. Therefore, studies directly comparing the effectiveness of scopolamine depending on the route of administration are required.

Potential use of psilocybin drugs in the treatment of depression.

INTRODUCTION: Depression is a common disabling psychiatric disorder, which - in extreme cases - may lead to suicide if untreated or inadequately treated. Despite the availability of various treatments for depression, including pharmacotherapy, there is still a need to search for new agents with higher effectiveness and faster onset of action, especially for patients with treatment-resistant depression. AREAS COVERED: A substance that has attracted considerable attention for nearly a decade is psilocybin, a natural psychedelic found in psilocybin mushrooms. In this study, we evaluated the efficacy and safety of psilocybin in the treatment of depression, based on pivotal randomized clinical trials. Moreover, we used findings from observational studies regarding recreational use. We also looked at ongoing clinical trials and discussed the registration status and clinical potential of the drug. EXPERT OPINION: Clinical phase I-II trials published to date reported promising results for psilocybin in the treatment of patients with major depressive disorder and treatment-resistant depression, in a relatively short time after administration. However, before psilocybin is approved for use and administered to patients with depression, the results of large ongoing phase III clinical trials are needed to confirm its efficacy and safety and to change the way it is perceived by physicians and patients.

Design and Synthesis of New Quinazolin-4-one Derivatives with Negative mGlu7 Receptor Modulation Activity and Antipsychotic-Like Properties.

Following the glutamatergic theory of schizophrenia and based on our previous study regarding the antipsychotic-like activity of mGlu7 NAMs, we synthesized a new compound library containing 103 members, which were examined for NAM mGlu7 activity in the T-REx 293 cell line expressing a recombinant human mGlu7 receptor. Out of the twenty-two scaffolds examined, active compounds were found only within the quinazolinone chemotype. 2-(2-Chlorophenyl)-6-(2,3-dimethoxyphenyl)-3-methylquinazolin-4(3H)-one (A9-7, ALX-171, mGlu7 IC50 = 6.14 µM) was selective over other group III mGlu receptors (mGlu4 and mGlu8), exhibited satisfactory drug-like properties in preliminary DMPK profiling, and was further tested in animal models of antipsychotic-like activity, assessing the positive, negative, and cognitive symptoms. ALX-171 reversed DOI-induced head twitches and MK-801-induced disruptions of social interactions or cognition in the novel object recognition test and spatial delayed alternation test. On the other hand, the efficacy of the compound was not observed in the MK-801-induced hyperactivity test or prepulse inhibition. In summary, the observed antipsychotic activity profile of ALX-171 justifies the further development of the group of quinazolin-4-one derivatives in the search for a new drug candidate for schizophrenia treatment.

Where do we go next in antidepressant drug discovery? A new generation of antidepressants: a pivotal role of AMPA receptor potentiation and mGlu2/3 receptor antagonism.

INTRODUCTION: Major depressive disorder remains a prevalent world-wide health problem. Currently available antidepressant medications take weeks of dosing, do not produce antidepressant response in all patients, and have undesirable ancillary effects. AREAS COVERED: The present opinion piece focuses on the major inroads to the creation of new antidepressants. These include N-methyl-D-aspartate (NMDA) receptor antagonists and related compounds like ketamine, psychedelic drugs like psilocybin, and muscarinic receptor antagonists like scopolamine. The preclinical and clinical pharmacological profile of these new-age antidepressant drugs is discussed. EXPERT OPINION: Preclinical and clinical data have accumulated to predict a next generation of antidepressant medicines. In contrast to the current standard of care antidepressant drugs, these compounds differ in that they demonstrate rapid activity, often after a single dose, and effects that outlive their presence in brain. These compounds also can provide efficacy for treatment-resistant depressed patients. The mechanism of action of these compounds suggests a strong glutamatergic component that involves the facilitation of AMPA receptor function. Antagonism of mGlu2/3 receptors is also relevant to the antidepressant pharmacology of this new class of drugs. Based upon the ongoing efforts to develop these new-age antidepressants, new drug approvals are predicted in the near future.

New 1,2,4-oxadiazole derivatives with positive mGlu4 receptor modulation activity and antipsychotic-like properties.

Considering the allosteric regulation of mGlu receptors for potential therapeutic applications, we developed a group of 1,2,4-oxadiazole derivatives that displayed mGlu4 receptor positive allosteric modulatory activity (EC50 = 282-656 nM). Selectivity screening revealed that they were devoid of activity at mGlu1, mGlu2 and mGlu5 receptors, but modulated mGlu7 and mGlu8 receptors, thus were classified as group III-preferring mGlu receptor agents. None of the compounds was active towards hERG channels or in the mini-AMES test. The most potent in vitro mGlu4 PAM derivative 52 (N-(3-chloro-4-(5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl)phenyl)picolinamide) was readily absorbed after i.p. administration (male Albino Swiss mice) and reached a maximum brain concentration of 949.76 ng/mL. Five modulators (34, 37, 52, 60 and 62) demonstrated significant anxiolytic- and antipsychotic-like properties in the SIH and DOI-induced head twitch test, respectively. Promising data were obtained, especially for N-(4-(5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl)-3-methylphenyl)picolinamide (62), whose effects in the DOI-induced head twitch test were comparable to those of clozapine and better than those reported for the selective mGlu4 PAM ADX88178.

Pharmaco-Electroencephalography-Based Assessment of Antidepressant Drug Efficacy-The Use of Magnesium Ions in the Treatment of Depression.

Pharmaco-electroencephalography (pharmaco-EEG) is a technique used to assess the effects of psychotropic medications on the bioelectrical activity of the brain. The purpose of this study was to assess the treatment response with the use of the Hamilton Depression Rating Scale (HDRS) and via EEG. Over an 8-week period, we analyzed electroencephalographic tracings of 91 patients hospitalized for major depression at the Medical University of Warsaw. Thirty-nine of those patients received tricyclic antidepressants (TCAs), 35 received fluoxetine, and 17 received fluoxetine augmented with magnesium (Mg) ions. All patients had their serum drug levels monitored. The highest proportion of patients (88.2%) who showed adequate responses to treatment was observed in the fluoxetine+Mg group, whereas the lowest rates of treatment response were observed in the TCA group (58.3%). This difference was statistically significant (p = 0.029, Phi = 0.30). Our study demonstrated a relationship between achieving remission (HDRS ≤ 6 at week 8 of treatment) and obtaining a positive pharmaco-EEG profile 6 h after administration of the first dose in the group receiving fluoxetine augmented with Mg ions (p = 0.035, Phi = 0.63).

The Trace Kynurenine, Cinnabarinic Acid, Displays Potent Antipsychotic-Like Activity in Mice and Its Levels Are Reduced in the Prefrontal Cortex of Individuals Affected by Schizophrenia.

Cinnabarinic acid (CA) is a kynurenine metabolite that activates mGlu4 metabotropic glutamate receptors. Using a highly sensitive ultra-performance liquid chromatography/tandem mass spectrometry (UPLC/MS-MS) method, we found that CA is present in trace amounts in human brain tissue. CA levels were largely reduced in the prefrontal cortex (PFC) of individuals affected by schizophrenia. This reduction did not correlate with age, sex, duration of the disease, and duration and type of antipsychotic medication and might, therefore, represent a trait of schizophrenia. Interestingly, systemic treatment with low doses of CA (<1 mg/kg, i.p.) showed robust efficacy in several behavioral tests useful to study antipsychotic-like activity in mice and rats and attenuated MK-801-evoked glutamate release. CA failed to display antipsychotic-like activity and inhibit excitatory synaptic transmission in mice lacking mGlu4 receptors. These findings suggest that CA is a potent endogenous antipsychotic-like molecule and reduced CA levels in the PFC might contribute to the pathophysiology of schizophrenia.

Developments in the discovery and design of intranasal antidepressants.

INTRODUCTION: Depression remains a major cause of morbidity worldwide; consequently, there is a need in neuropsychiatry for new antidepressants with a rapid onset of action. Intranasal administration of antidepressants is an attractive and promising approach to the treatment of mental disorders, as this route is noninvasive, offers a fast onset of action and improved drug bioavailability, allows a drug dose reduction, as well as gives the possibility to bypass the blood-brain barrier and reduce the number of systemic side effects. AREAS COVERED: This review is a comprehensive discussion of the available intranasal drugs that have found application as antidepressants. The results of relevant clinical studies are presented. Additionally, the use of nanotechnology-based formulations for enhancing the intranasal delivery of antidepressants is briefly described. EXPERT OPINION: Intranasal drug delivery has a huge potential for antidepressant administration, but its use in the treatment of central nervous system disorders is currently very limited. The nasal route of antidepressant delivery is noninvasive, improves drug bioavailability, as well as allows to overcome the problem with the blood-brain barrier, gastrointestinal absorption, and first-pass metabolism. In our opinion, fast-acting intranasal antidepressants will be widely used in the treatment of mental disorders in the future.

The functional cooperation of 5-HT1A and mGlu4R in HEK-293 cell line.

BACKGROUND: The serotonin 5-HT1A receptor (5-HT1AR) and metabotropic glutamate receptor 4 (mGlu4) have been implicated as sites of antipsychotic drug action. 5-HT1AR belongs to the A class of G protein-coupled receptors (GPCRs); mGlu4 is a representative of class C GPCRs. Both receptors preferentially couple with Gi protein to inhibit cAMP formation. The present work aimed to examine the possibility of mGlu4 and 5-HT1A receptor cross-talk, the phenomenon that could serve as a molecular basis of the interaction of these receptor ligands observed in behavioral studies. METHODS: First, in vitro studies were performed to examine the pharmacological modulation of interaction of the mGlu4 and 5-HT1A receptors in the T-REx 293 cell line using SNAP- or HALO-tag and cAMP accumulation assay. Next, the colocalization of these two receptors was examined in some regions of the mouse brain by applying RNAScope dual fluorescence in situ hybridization, immunohistochemical labeling, and proximity ligation assay (PLA). RESULTS: The ex vivo and in vitro results obtained in the present work suggest the existence of interactions between mGlu4 and 5-HT1A receptors. The changes were observed in cAMP accumulation assay and were dependent on expression and activation of mGlu4R in T-REx 293cell line. Moreover, the existence of spots with proximity expression of both receptors were showed by PLA, immunofluorescence labeling and RNAscope methods. CONCLUSION: The existence of interactions between mGlu4 and 5-HT1A receptors may represent another signaling pathway involved in the development and treatment psychiatric disorders such as schizophrenia or depression.

Efficacy of single and repeated administration of ketamine in unipolar and bipolar depression: a meta-analysis of randomized clinical trials.

BACKGROUND: Due to unmet clinical needs for efficient drugs with a rapid onset of antidepressant effects, we aimed to evaluate the efficacy of single-dose ketamine in different subgroups of patients with major depression and establish whether repeated ketamine administration could be a viable strategy to maintain treatment gains. METHODS: Electronic databases (Medline via PubMed, Embase, Cochrane Library, Trip Database) were systematically searched until February 22, 2019, for published peer-reviewed randomized controlled trials (RCTs) concerning a single and repeated administration of ketamine in patients with major depression. All relevant RCTs were selected and critically appraised, and a meta-analysis of eligible studies was performed. RESULTS: A total of 20 studies were included in the meta-analysis. The largest effect of ketamine vs. controls in reducing depressive symptoms was observed at 24 h (SMD = - 0.89; 95% CI - 1.24; - 0.53; p < 0.00001); however, a significant difference was shown for up to 7 days after a single dose. Significant differences compared with controls were observed for up to 7 days in treatment-resistant patients and when ketamine was added to ongoing antidepressant treatment, while there were no significant differences at 7 days when ketamine was used as monotherapy. In patients with major depression, initial antidepressant effects of ketamine were maintained during repeated dosing. At 2-3 weeks of repeated ketamine treatment, significant reduction of depression severity scores was observed: SMD = - 0.70; 95% CI - 1.15; - 0.25 or SMD = - 0.81; 95% CI - 1.41; - 0.20 (depending on the dosing regimen used); p ≤ 0.009 vs placebo. CONCLUSIONS: Our meta-analysis revealed rapid and robust antidepressant effects of single-dose ketamine in patients with treatment-resistant depression (TRD). By pooling data from RCTs, we showed for the first time that repeated ketamine administration is effective in sustaining initial antidepressant effects observed after single dosing.

Efficacy and safety of intranasal esketamine for the treatment of major depressive disorder.

Introduction: In March 2019, intranasal esketamine was approved by the Food and Drug Administration (FDA) for the treatment of treatment-resistant depression (TRD) in adults. This review presents the results of clinical trials underlying the FDA approval of intranasal esketamine.Areas covered: Esketamine's efficacy and safety in TRD were assessed in 5 phase III studies: three 4-week, placebo-controlled studies, and two long-term trials. One short-term trial showed statistically significant antidepressant effects of esketamine vs placebo, while a long-term withdrawal study showed that esketamine is significantly beneficial in terms of extending time to relapse, compared to placebo. Two other short-term trials did not meet the prespecified statistical tests for showing efficacy, although improvement in depressive symptoms from baseline to the end of week 4 favors esketamine over placebo.Expert opinion: Intranasal esketamine is a new treatment option for people with TRD. The main benefit of esketamine is rapid onset of antidepressant activity, but the effects of prolonged treatment are still preliminary. The main concerns relate to the safety aspects of prolonged esketamine therapy, when considering its abuse potential. While data for esketamine use over a long period of time is lacking, its use should be carefully monitored.

Reimbursement Status and Recommendations Related to Orphan Drugs in European Countries.

Objective: To review the reimbursement recommendations issued by selected European health technology assessment agencies for orphan drugs and the reimbursement status of these drugs; to assess the relationship between the type of recommendation and reimbursement status. Methods: The list of orphan drugs to be included in the analysis was obtained from the European Medicines Agency and Orphanet. Seven European states were included in the analysis: Belgium, England, France, Germany, Poland, Scotland, and Spain. For all identified orphan drugs, relevant data on the reimbursement status and type of recommendation were collected for each country. The relationship between the type of recommendation and reimbursement status was evaluated separately for each considered country, using Cohen's kappa coefficient for the measurement of agreement; sub-analyses for oncology and metabolic drugs were performed. Results: Most reimbursement recommendations for orphan drugs were positive (71%), while approximately 17% were negative and almost 13% were conditional. The highest percentage of positive reimbursement recommendations was observed in Spain (97%) and France (95%) and the highest percentage of negative reimbursement recommendations was revealed for Poland (49%). On average, 65% of the 163 analyzed orphan drugs were reimbursed from public funds. The highest number of reimbursed orphan drugs was observed in Germany (n = 148), while the lowest, in Poland (n = 41). Considering all analyzed drugs, the highest agreement between recommendations and reimbursement status was observed for Spain (value of 1), and the lowest, for Germany (κ = -0.03). Conclusions: On average, more than 60% of identified orphan drugs were reimbursed from public funds in the included countries, and the majority of reimbursement recommendations were found to be positive. The agreement between reimbursement recommendations and reimbursement status differed between the countries, but overall, it did not show any patterns, as it ranged from -0.03 to 1 (κ coefficient).

Role of AMPA receptor stimulation and TrkB signaling in the antidepressant-like effect of ketamine co-administered with a group II mGlu receptor antagonist, LY341495, in the forced swim test in rats.

Ketamine has been shown to induce a rapid antidepressant effect on patients with depression. In many animal models, both rapid and sustained antidepressant activities were also found in response to an antagonist of group II metabotropic glutamate receptors, LY341495, and its mechanism of action seemed to be similar in many ways to the action of ketamine. It has also been found that LY341495 enhanced the antidepressant-like activity of sub-effective doses of ketamine in rats without inducing adverse effects. Here, we investigated the role of AMPA receptor and TrkB receptor activation in the antidepressant-like effects of ketamine (3 mg/kg) co-administered with LY341495 (0.1 mg/kg), in the forced swim test in rats, at three time points (40 min, 3 h and 24 h) after joint administration of the tested compounds. It was found that the AMPA receptor antagonist NBQX (10 mg/kg) reversed the antidepressant effect of ketamine co-administered with LY341495 at all tested time points, whereas the TrkB receptor antagonist ANA-12 contributed to blockade of the effect of ketamine and LY341495 3 h after their joint administration. These results indicate that activation of AMPA receptor and BDNF-related signaling may play a role in the mechanism of antidepressant action of ketamine co-administered with LY341495.

Depression and schizophrenia viewed from the perspective of amino acidergic neurotransmission: Antipodes of psychiatric disorders.

Depression and schizophrenia are burdensome, costly serious and disabling mental disorders. Moreover the existing treatments are not satisfactory. As amino-acidergic (AA) neurotransmitters built a vast majority of brain neurons, in this article we plan to focus on drugs influencing AA neurotransmission in both diseases: we will discuss several facts concerning glutamatergic and GABA-ergic neurotransmission in these diseases, based mainly on preclinical experiments that used stimulators and/or blockers of both neurotransmitter systems. In general a picture emerges showing, that treatments that increase excitatory effects (with either antagonists or agonists) tend to evoke antidepressant effects, while treatments that increase inhibitory effects tend to display antipsychotic properties. Moreover, it seems that the antidepressant activity of a given compound excludes it as a potential antipsychotic and vice versa.

Simultaneous activation of muscarinic and GABAB receptors as a bidirectional target for novel antipsychotics.

Recent preclinical studies point to muscarinic and GABAB receptors as novel therapeutic targets for the treatment of schizophrenia. This study was aimed to assess the role of muscarinic and GABAB receptor interactions in animal models of schizophrenia, using positive allosteric modulators (PAMs) of GABAB receptor (GS39783), muscarinic M4 (VU0152100) and M5 (VU0238429) receptor, and partial allosteric agonist of M1 receptor (VU0357017). DOI-induced head twitches, social interaction and novel object recognition tests were used as the models of schizophrenia. Analyses of DOI-induced increases in sEPSCs (spontaneous excitatory postsynaptic currents) were performed as complementary experiments to the DOI-induced head twitch studies. Haloperidol-induced catalepsy and the rotarod test were used to examine the adverse effects of the drugs. All three activators of muscarinic receptors were active in DOI-induced head twitches. When administered together with GS39783 in subeffective doses, only the co-administration of VU0152100 and GS39783 was effective. The combination also reduced the frequency but not the amplitude of DOI-induced sEPSCs. Neither VU0357017 nor VU0238429 were active in social interaction test when given alone, and also the combination of VU0152100 and GS39783 failed to reverse MK-801-induced deficits observed in this test. All muscarinic activators when administered alone or in combination with GS39783 reversed the MK-801-induced disruption of memory in the novel object recognition test, and their actions were blocked by specific antagonists. None of the tested compounds or their combinations influenced the motor coordination of the animals. The compounds had no effect on haloperidol-induced catalepsy and did not induce catalepsy when administered alone. Pharmacokinetic analysis confirmed lack of possible drug-drug interactions after combined administration of GS39783 with VU0357017 or VU0152100; however, when the drug was co-administered with VU0238429 its ability to pass the blood-brain barrier slightly decreased, suggesting potential drug-drug interactions. Our data show that modulation of cholinergic and GABAergic systems can potentially be beneficial in the treatment of the positive and cognitive symptoms of schizophrenia without inducing the adverse effects typical for presently used antipsychotics.

Antibiotic consumption and antimicrobial resistance in Poland; findings and implications.

Background: The problem of inappropriate use of antibiotics and the resulting growth in antimicrobial resistance (AMR) has implications for Poland and the world. The objective of this paper was to compare and contrast antibiotic resistance and antibiotic utilisation in Poland in recent years versus other European countries, including agreed quality indicators, alongside current AMR patterns and ongoing policies and initiatives in Poland to influence and improve antibiotic prescribing. Methods: A quantitative ten-year analysis (2007-2016) of the use of antibiotics based on European Centre for Disease Prevention and Control (ECDC) data combined with a literature review on AMR rates and antimicrobial stewardship initiatives. Results: The system of monitoring AMR and appropriate strategies to address AMR rates remain underdeveloped in Poland. The role of microbiological diagnostics and efforts to prevent infections is currently underestimated by physicians. Overall, Poland had one of the highest rates of total consumption of antibiotics in the analysed European countries. Total consumption of antibacterials for systemic use and relative consumption of beta-lactamase sensitive penicillins were characterized by small but statistically significant average annual increases between 2007 and 2016 (from 22.2 DIDs to 23.9 DIDs and from 0.8 to 1.3%, respectively). Conclusions: The integrated activities around appropriate antibiotic prescribing in the pre- and post-graduate training of physicians and dentists seem to be particularly important, as well as changes in policies on prescribing antibiotics within ambulatory care. AMR and appropriate prescribing of antibiotics should be the focus of health policy actions in Poland.

Reimbursement of Orphan Drugs in Europe in Relation to the Type of Authorization by the European Medicines Agency and the Decision Making Based on Health Technology Assessment.

Objective: To assess shares of reimbursed orphan drugs and agreement in reimbursement decision-making in different European Union member states as well as to define odds for reimbursement influenced by the presence of conditional approval or exceptional circumstances granted by the European Medicines Agency (EMA) or by type of the disease. Methods: The list of authorized drugs with current orphan designations was collected from the website of the EMA. For each drug, the information regarding conditional approval or approval under exceptional circumstances was collected. The reimbursement statuses were available on national reimbursement or HTA agencies websites. The agreement for reimbursement decisions between selected countries was assessed using the κ coefficient for the measurement of agreement. The impact of the EMA's conditional approval as well as approval under exceptional circumstances was assessed using the logistic regression and presented as odds ratio. Results: The percentage of reimbursed orphan drugs varied significantly from 27% in Poland to 88% in Denmark, with an average value of 51% (p < 0.0001). Regarding the reimbursement status, the highest, substantial agreement was observed between Spain and Italy, and the lowest agreement was observed between Germany and England, with κ of 0.64 and 0.01, respectively. Conditional approval status significantly decreased the chance for reimbursement in France, Italy, and Spain by 77-80%; however, approval granted under exceptional circumstances had significant impact only in Germany with 85% decrease in chances for reimbursement. The type of the disease (oncology or metabolic) was significantly associated with both conditional approval (p of 0.03-oncology drugs were more likely to be conditionally approved then the rest of analyzed drugs) and exceptional circumstances (p of 0.02-drugs for metabolic diseases were more likely to be approved under exceptional circumstances). Conclusions: Access to reimbursed orphan drugs varies significantly across EU countries. The highest, substantial agreement in reimbursement decisions was observed between Italy and Spain and the lowest between Germany and England. Conditional approval and approval under exceptional circumstances were significant negative predictors of reimbursement in some countries and they were significantly associated with the type of the disease (oncology or metabolic).

Negative Allosteric Modulators of mGlu7 Receptor as Putative Antipsychotic Drugs.

The data concerning antipsychotic-like activity of negative allosteric modulators (NAMs)/antagonists of mGlu7 receptors are limited. The only available ligands for this receptor are MMPIP and ADX71743. In the present studies, we used stable cell line expressing mGlu7 receptor and it was shown that both compounds dose-dependently potentiated forskolin elevated cAMP concentration in the T-REx 293 cells, showing their inverse agonist properties. Subsequently, pharmacokinetic studies were performed. Both compounds were given intraperitoneally (i.p.) at the dose of 10 mg/kg and reached Cmax 0.25-0.5 h after administration, and then they declined rapidly, ADX71743 being almost undetectable 2 h after administration, while the concentration of MMPIP was still observed, suggesting that the concentration of MMPIP was more stable. Finally, we investigated the role of both mGlu7 receptor NAMs in animal models of schizophrenia. Behavioral tests commonly used in antipsychotic drug discovery were conducted. Both tested compounds dose-dependently inhibited MK-801-induced hyperactivity (MMPIP at 15 mg/kg; ADX at 5 and 15 mg/kg) and DOI-induced head twitches (MMPIP at 5, 10, 15 mg/kg; ADX at 2.5, 5, 10 mg/kg). Moreover, the same effects were noticed in novel object recognition test, where MMPIP (5, 10, 15 mg/kg) and ADX71743 (1, 5, 15 mg/kg) reversed MK-801-induced disturbances. In the social interaction test, antipsychotic activity was observed only for ADX71743 (5, 15 mg/kg). ADX71743 at the dose 2.5 mg/kg reversed MK-801-induced disruption in prepulse inhibition while MMPIP at 10 mg/kg reversed MK-801-induced disruption in spatial delayed alternation. The present studies showed that mGlu7 receptor may be considered as a putative target for antipsychotic drugs, though more studies are needed due to limited number of available ligands.