Harnessing Intranasal Delivery Systems of Sumatriptan for the Treatment of Migraine.

Sumatriptan (ST) is a commonly prescribed drug for treating migraine. The efficiency of several routes of ST administration has been investigated. Recently, the intranasal route with different delivery systems has gained interest owing to its fast-acting and effectiveness. The present study is aimed at reviewing the available studies on novel delivery systems for intranasal ST administration. The oral route of ST administration is common but complicated with some problems. Gastroparesis in patients with migraine may reduce the absorption and effectiveness of ST upon oral use. Furthermore, the gastrointestinal (GI) system and hepatic metabolism can alter the pharmacokinetics and clinical effects of ST. The bioavailability of conventional nasal liquids is low due to the deposition of a large fraction of the delivered dose of a drug in the nasal cavity. Several delivery systems have been utilized in a wide range of preclinical and clinical studies to enhance the bioavailability of ST. The beneficial effects of the dry nasal powder of ST (AVP-825) have been proven in clinical studies. Moreover, other delivery systems based on microemulsions, microspheres, and nanoparticles have been introduced, and their higher bioavailability and efficacy were demonstrated in preclinical studies. Based on the extant findings, harnessing novel delivery systems can improve the bioavailability of ST and enhance its effectiveness against migraine attacks. However, further clinical studies are needed to approve the safety and efficacy of employing such systems in humans.

Population pharmacokinetic analysis of ulotaront in subjects with schizophrenia.

Ulotaront (SEP-363856) is a trace amine-associated receptor 1 agonist with 5-HT1A agonist activity in phase III development for the treatment of schizophrenia. The efficacy of ulotaront is not mediated by blockade of D2 or 5-HT2A receptors. The aim of this study was to evaluate the population pharmacokinetics (PopPKs) of ulotaront in adult subjects using pooled data from seven phase I studies, one phase II acute study, and one 6-month extension study. Single and multiple (up to 7 days) oral doses (5-150 mg/day) were studied in both healthy adult subjects (with intensive serial plasma sampling) and adult patients with schizophrenia (some with intensive and some with sparse plasma sampling). Ulotaront was well-absorbed and exhibited dose-proportionality in doses ranging from 10 to 100 mg, in mean maximum concentration, area under the concentration-time curve, and minimum concentration. Moderate interindividual variability was observed in concentration-time profiles. The estimated median time to maximal concentration was 2.8 h and the median effective half-life was 7 h, corresponding to an exposure accumulation ratio of 1.10 at steady-state with daily dosing. There was no indication of time-dependent changes in PKs after up to 12 weeks of daily dose administration. No clinically meaningful effects on ulotaront PK parameters were observed based on race, age, sex, formulation (capsule or tablet), or clinical status (healthy volunteer vs. patient with schizophrenia); body weight was the only meaningful covariate.

The selective 5-HT1A receptor agonist, NLX-112, exerts anti-dyskinetic effects in MPTP-treated macaques.

BACKGROUND: Long-term treatment of Parkinson's disease (PD) with l-DOPA typically leads to development of l-DOPA induced dyskinesia (LID). Amantadine, an NMDA antagonist, attenuates LID, but with limited efficacy and considerable side-effects. NLX-112 (also known as befiradol or F13640), a highly selective and efficacious 5-HT1A receptor agonist, reduced LID when tested in rodent and marmoset models of PD. METHODS: The effects of NLX-112 (0.03, 0.1 and 0.3 mg/kg PO) on established LID evoked by acute challenge with l-DOPA (27.5 ± 3.8 mg/kg PO) were assessed in MPTP-treated cynomolgus macaques. Amantadine (10 mg/kg PO) was tested as a positive control. Plasma exposure of NLX-112 (0.1 mg/kg PO) was determined. RESULTS: NLX-112 significantly and dose-dependently reduced median LID levels by up to 96% during the first hour post-administration (0.3 mg/kg). Moreover, NLX-112 reduced the duration of 'bad on-time' associated with disabling LID by up to 48% (0.3 mg/kg). In contrast, NLX-112 had negligible impact on the anti-parkinsonian benefit of l-DOPA. NLX-112 exposure peaked at ~50 ng/ml at 30 min post-administration but decreased to ~15 ng/ml at 2h. Amantadine reduced by 42% 'bad on-time' associated with l-DOPA, thereby validating the model. CONCLUSION: These data show that, in MPTP-lesioned cynomolgus macaques, NLX-112 exerts robust anti-dyskinetic effects, without reducing the anti-parkinsonian benefit of l-DOPA. These observations complement previous findings and suggest that selective and high efficacy activation of 5-HT1A receptors by NLX-112 may constitute a promising approach to combat LID in PD, providing an alternative for patients in whom amantadine is poorly tolerated or without useful effect.

Why is the therapeutic effect of acute antimigraine drugs delayed? A review of controlled trials and hypotheses about the delay of effect.

In randomised controlled trials (RCTs) of oral drug treatment of migraine attacks, efficacy is evaluated after 2 hours. The effect of oral naratriptan 2.5 mg with a maximum blood concentration (Tmax ) at 2 hours increases from 2 to 4 hours in RCTs. To check whether such a delayed effect is also present for other oral antimigraine drugs, we hand-searched the literature for publications on RCTs reporting efficacy. Two triptans, 3 nonsteroidal anti-inflammatory drugs (NSAIDs), a triptan combined with an NSAID and a calcitonin gene-related peptide receptor antagonist were evaluated for their therapeutic gain with determination of time to maximum effect (Emax ). Emax was compared with known Tmax from pharmacokinetic studies to estimate the delay to pain-free. The delay in therapeutic gain varied from 1-2 hours for zolmitriptan 5 mg to 7 hours for naproxen 500 mg. An increase in effect from 2 to 4 hours was observed after eletriptan 40 mg, frovatriptan 2.5 mg and lasmiditan 200 mg, and after rizatriptan 10 mg (Tmax  = 1 h) from 1 to 2 hours. This strongly indicates a general delay of effect in oral antimigraine drugs. A review of 5 possible effects of triptans on the trigemino-vascular system did not yield a simple explanation for the delay. In addition, Emax for triptans probably depends partly on the rise in plasma levels and not only on its maximum. The most likely explanation for the delay in effect is that a complex antimigraine system with more than 1 site of action is involved.

1,3-Dioxane as a scaffold for potent and selective 5-HT1AR agonist with in-vivo anxiolytic, anti-depressant and anti-nociceptive activity.

A series of compounds generated by ring expansion/opening and molecular elongation/simplification of the 1,3-dioxolane scaffold were prepared and tested for binding affinity at 5-HT1AR and α1 adrenoceptors. The compounds with greater affinity were selected for further functional studies. N-((2,2-diphenyl-1,3-dioxan-5-yl)methyl)-2-(2-methoxyphenoxy)ethan-1-ammonium hydrogen oxalate (12) emerged as highly potent full agonist at the 5-HT1AR (pKi 5-HT1A = 8.8; pD2 = 9.22, %Emax = 92). The pharmacokinetic data in rats showed that the orally administered 12 has a high biodistribution in the brain compartment. Thus, 12 was further investigated in-vivo, showing an anxiolytic and antidepressant effect. Moreover, in the formalin test, 12 was able to decrease the late response to the noxious stimulus, indicating a potential use in the treatment of chronic pain.

Synthesis and evaluation of two new candidate high-affinity full agonist PET radioligands for imaging 5-HT1B receptors.

INTRODUCTION: The serotonin 1B receptor subtype is of interest in the pathophysiology and treatment of depression, anxiety, and migraine. Over recent years 5-HT1B receptor binding in human brain has been examined with PET using radioligands that are partial but not full agonists. To explore how the intrinsic activity of a PET radioligand may affect imaging performance, two high-affinity full 5-HT1B receptor agonists (AZ11136118, 4; and AZ11895987, 5) were selected from a large compound library and radiolabeled for PET examination in non-human primates. METHODS: [11C]4 was obtained through Pd(0)-mediated insertion of [11C]carbon monoxide between prepared iodoarene and homochiral amine precursors. [11C]5 was obtained through N-11C-methylation of N-desmethyl precursor 6 with [11C]methyl triflate. [11C]4 and [11C]5 were studied with PET in rhesus or cynomolgus monkey. [11C]4 was studied with PET in mice and rats to measure brain uptake and specific binding. Ex-vivo experiments in rats were performed to identify whether there were radiometabolites in brain. Physiochemical parameters for [11C]4 (pKa, logD and conformational energetics) were evaluated. RESULTS: Both [11C]4 and [11C]5 were successfully produced in high radiochemical purity and in adequate amounts for PET experiments. After intravenous injection of [11C]4, brain radioactivity peaked at a low level (0.2 SUV). Pretreatment with tariquidar, an inhibitor of the brain P-gp efflux transporter, increased brain exposure four-fold whereas pretreatment with a high pharmacological dose of the 5-HT1B antagonist, AR-A000002, had no effect on the binding. Ex-vivo experiments in rats showed no radiometabolites entering brain. [11C]5 also failed to enter monkey brain under baseline conditions. CONCLUSIONS: [11C]4 and [11C]5 show too low brain uptake and specific binding to be useful PET radioligands. Low brain uptake is partly ascribed to efflux transporter action as well as unfavorable conformations.

Efficacy of ADAM Zolmitriptan for the Acute Treatment of Difficult-to-Treat Migraine Headaches.

OBJECTIVE: To understand the efficacy of zolmitriptan applied with Adhesive Dermally Applied Microarray (ADAM) in treating types of migraine (those with severe headache pain, the presence of nausea, treatment ≥2 hours after migraine onset, or migraine present upon awakening) that are historically considered to be less responsive to oral medications. BACKGROUND: ADAM is an investigational system for intracutaneous drug administration. In a pivotal Phase 2b/3 study (ZOTRIP, N = 321 in the modified intention-to-treat population), ADAM zolmitriptan 3.8 mg provided superior pain freedom and freedom from patients' usual most bothersome associated symptom (MBS), compared with placebo at 2 hours post-dose. We undertook a post hoc analysis of data from the ZOTRIP trial to examine these same outcomes in subsets of patients whose migraine characteristics have been associated with poorer outcomes when treated with oral medications. METHODS: The ZOTRIP trial was a multicenter, randomized, double-blind, placebo-controlled, parallel group Phase 2b/3 study conducted at 36 sites in the United States. Presented here are post hoc subgroup analyses of patients with nausea (n = 110) or severe pain (n = 72) at baseline, those whose treatment was delayed 2 or more hours after onset (n = 75), and those who awoke with migraine (n = 80). The Cochran-Mantel-Haenszel test was used to assess whether patients in the ADAM zolmitriptan 3.8 mg group had superior treatment outcomes compared with placebo. RESULTS: In patients with nausea, 2-hour pain freedom was achieved in 44% (26/59) in the ADAM zolmitriptan 3.8 mg group and 14% (7/51) in the placebo group (P = .005) (odds ratio = 5.11, 95% CI: 1.96-13.30), and 2-hour MBS freedom was achieved in 68% (40/59) in the active treatment group and 45% (23/51) of those receiving placebo (P = .009) (odds ratio = 2.86, 95% CI: 1.28-6.43). For those with severe pain, corresponding pain-free values were 26% (10/39) and 15% (5/33) (P = .249) (odds ratio = 2.14, 95% CI: 0.60-7.62), and MBS-free values were 64% (25/39) and 42% (14/33) (P = .038) (odds ratio = 2.86, 95% CI: 1.05-7.79). Among participants who awoke with migraine, 44% (16/36) and 16% (7/44) were pain-free in the ADAM zolmitriptan 3.8 mg and placebo groups, respectively (P = .006) (odds ratio = 4.29, 95% CI: 1.50-12.31), and 72% (26/36) vs 39% (17/44) were MBS-free, respectively (P = .003) (odds ratio = 4.40, 95% CI: 1.61-12.05). In those whose treatment was delayed ≥2 hours, pain freedom in the active treatment group and placebo group were 33% (12/36) and 10% (4/39), respectively (P = .017) (odds ratio = 4.33, 95% CI: 1.24-15.10), and MBS freedom was achieved in 69% (25/36) and 41% (16/39), respectively, in the delayed treatment group (P = .014) (odds ratio = 3.37, 95% CI: 1.27-8.95). No significant effects (overall interaction P = .353) were observed in logistical regression models of treatment by subgroup interaction. CONCLUSION: Severe pain, delayed treatment, awakening with a headache, and the presence of nausea are factors that predict a poorer response to acute migraine treatment. In these post hoc analyses of subgroups of patients with each of these characteristics in the ZOTRIP trial, participants receiving ADAM zolmitriptan 3.8 mg displayed nearly uniformly better headache responses (2-hour headache freedom and 2-hour MBS freedom) compared with those who received placebo.

18F-F13640 preclinical evaluation in rodent, cat and primate as a 5-HT1A receptor agonist for PET neuroimaging.

Serotonin 1A receptors are known to play an important role in many psychiatric and neurodegenerative disorders. Currently, all available 5-HT1A receptor PET radiopharmaceuticals that are radiolabeled with fluorine-18 are antagonists. As agonists bind preferentially to the high-affinity state of receptors, it would be of great interest to develop agonist radioligands which could provide a measure of the functional 5-HT1A receptors in pathophysiological processes. The 5-HT1A receptor agonist candidates we recently proposed had promising in vitro properties but were not optimal in terms of PET imaging. F13640, a.k.a befiradol or NLX-112, is a 5-HT1A receptor agonist with a high affinity (Ki = 1 nM) and a high selectivity that would be suitable for a potential PET radiopharmaceutical. With propose here the first preclinical evaluation of 18F-F13640. 18F-F13640's nitro-precursor was synthesized and radiolabeled via a fluoro-nucleophilic substitution. Its radiopharmacological characterization included autoradiographic studies, metabolic studies, and in vivo PET scans in rat, cat and non-human primate. Some of the results were compared with the radiotracer 18F-MPPF, a 5-HT1A receptor antagonist. The radiochemical purity of 18F-F13640 was > 98%. In vitro binding pattern was consistent with the 5-HT1A receptor distribution. Metabolic studies revealed that the radiotracer rapidly entered the brain and led to few brain radiometabolites. Although 18F-F13640 in vivo binding was blocked by the 5-HT1A antagonist WAY-100635 and the 5-HT1A agonist 8-OH-DPAT, the distribution pattern was markedly different from antagonist radiotracers in the three species, suggesting it provides novel information on 5-HT1A receptors. Preliminary studies also suggest a high sensitivity of 18F-F13640 to endogenous serotonin release. 18F-F13640 has suitable characteristics for probing in vitro and in vivo the 5-HT1A receptors in high-affinity state. Quantification analyses with kinetic modeling are in progress to prepare the first-in-man study of 18F-F13640.

Pharmacokinetics and Skin Tolerability of Intracutaneous Zolmitriptan Delivery in Swine Using Adhesive Dermally Applied Microarray.

Adhesive Dermally Applied Microarray (ADAM) is a new drug-delivery system that uses microprojections (340-µm long) for intracutaneous drug self-administration. We formulated zolmitriptan, a well-accepted and commonly used migraine medication, for administration using ADAM. In vivo studies were conducted in female prepubescent Yorkshire pigs using ADAM 1.9-mg zolmitriptan applied to the inner thigh and left in place for 1 h. Pharmacokinetic studies showed that the ADAM 1.9-mg zolmitriptan was delivered with high efficiency (85%) and high absolute bioavailability (77%). Furthermore, in vivo evaluation showed a rapid systemic absorption with a median Tmax of 15 min. Skin biopsies of the treatment sites showed a mean depth of microprojection penetration of 105.4 ± 3.6 µm. Mass spectrometry imaging showed that the zolmitriptan after 1 h of patch wear time was predominantly localized to the dermis. ADAM zolmitriptan was well tolerated with a transient mild-to-moderate erythema response. The findings in these studies, particularly the rapid zolmitriptan absorption profile after intracutaneous administration, provided validation to advance ADAM zolmitriptan development.

A coupled bimodal SPECT-CT imaging and brain kinetics studies of zolmitriptan-encapsulated nanostructured polymeric carriers.

The present investigation deals with preparation and characterization of anti-migraine zolmitriptan (ZMT) nanostructured polymeric carriers for nose to brain drug targeting. The drug-loaded colloidal nanocarriers of ZMT were prepared by modified ionic gelation of cationic chitosan with anionic sodium tripolyphosphate and characterized for particle size, zeta potential, and entrapment efficiency. Further, in order to investigate nose to brain drug targeting, biodistribution, and brain kinetics studies were performed using 99mtechnetium radiolabeled nanocarriers (99mTc-ZMTNP) in Swiss albino mice. The results were compared with intranasal pure drug solution (99mTc-ZMT) and intravenous nanocarriers (99mTc-ZMTNP). A single photon emission computerized tomography (SPECT) radioimaging studies were also carried out to visualize and confirm brain uptake of nanocarriers. The optimized nanocarriers showed particle size of 161 nm, entrapment efficiency of 80.6%, and zeta potential of + 23.7 mV. The pharmacokinetic parameters, Cmax, and AUC0-∞ values for ZMT concentration in the brain expressed as percent radioactivity per gram of brain in intranasal and intravenous route of administration were calculated. The brain Cmax and AUC0-∞ values found in three groups, intranasal 99mTc-ZMTNP, intranasal 99mTc-ZMT, and intravenous 99mTc-ZMTNP were (0.427 and 1.889), (0.272 and 0.7157), and (0.204 and 0.9333), respectively. The higher Cmax values of intranasal 99mTc-ZMTNP suggests better brain uptake as compared to other routes of administration. The significant higher values of nose to brain targeting parameters namely, drug targeting index (5.57), drug targeting efficiency (557.08%), and nose to brain drug direct transport (82.05%) confirmed drug targeting to brain via nasal route. The coupled bimodal SPECT-CT scintigrams confirm the brain uptake of intranasal 99mTc-ZMTNP demonstrating major radioactivity accumulation in brain. This study conclusively demonstrated the greater uptake of ZMT-loaded nanocarriers by nose to brain drug targeting, which proves promising drug delivery system.

Cerebral serotonin release correlates with [11C]AZ10419369 PET measures of 5-HT1B receptor binding in the pig brain.

Positron emission tomography (PET) can, when used with appropriate radioligands, non-invasively capture temporal and spatial information about acute changes in brain neurotransmitter systems. We here evaluate the 5-HT1B receptor partial agonist PET radioligand, [11C]AZ10419369, for its sensitivity to detect changes in endogenous cerebral serotonin levels, as induced by different pharmacological challenges. To enable a direct translation of PET imaging data to changes in brain serotonin levels, we compared the [11C]AZ10419369 PET signal in the pig brain to simultaneous measurements of extracellular serotonin levels with microdialysis after various acute interventions (saline, escitalopram, fenfluramine). The interventions increased the cerebral extracellular serotonin levels to two to six times baseline, with fenfluramine being the most potent pharmacological enhancer of serotonin release. The interventions induced a varying degree of decline in [11C]AZ10419369 binding in the brain, consistent with the occupancy competition model. The observed correlation between changes in the extracellular serotonin level in the pig brain and the 5-HT1B receptor occupancy indicates that [11C]AZ10419369 binding is sensitive to changes in endogenous serotonin levels to a degree equivalent to that reported of [11C]raclopride to dopamine, a much used approach to detect in vivo change in cerebral dopamine.

Population Pharmacokinetic Analysis of Zolmitriptan and Its Metabolite in Adults and Adolescents to Support Dose Selection in Children With Migraine.

Zolmitriptan is a serotonin (5-HT) 1B/1D receptor agonist effective for the treatment of migraine. This analysis aimed to develop a population pharmacokinetic (PK) model for zolmitriptan and its active metabolite in adults and adolescents and provide appropriate dosing regimens to be used in clinical trials for children 6-11 years old. The data from a single-dose clinical study of 5.0-mg zolmitriptan nasal spray (ZNS) conducted in adult and adolescent patients with migraine between migraine attacks was applied. Similar plasma concentration profiles of zolmitriptan and its metabolite, 183C91, were observed in adults and adolescents. A 1-compartment model with first-order absorption and first-order elimination reasonably described the zolmitriptan PK. With a portion of elimination of zolmitriptan being treated as the conversion from zolmitriptan to 183C91, the disposition of 183C91 was described by a 1-compartment model with first-order elimination. The estimated typical apparent volume of distribution and clearance of zolmitriptan were 136 L and 121 L/h, respectively, with 56.5% and 42.6% between-subject variability, respectively. Based on the simulation results with the final population PK model, a body weight-based dosing scheme of 5.0 and 2.5 mg ZNS in children greater than and less than 50 kg is recommended to achieve exposures similar to those of the adult and adolescent population administered 5.0 mg ZNS. The recommended doses for children to achieve exposure similar to that observed in adults given 2.5 mg ZNS are 2.5 mg (≥50 kg) and 1.0 mg (15-50 kg). These dosing regimens could be used in future clinical trials.

The pharmacodynamic effects of combined administration of flibanserin and alcohol.

WHAT IS KNOWN AND OBJECTIVE: Flibanserin is a serotonin 5-HT1A agonist and 5-HT2A antagonist approved for the treatment of acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women. Because of the increased risk of hypotension- and syncope-related adverse events (AEs) observed with coadministration of flibanserin and alcohol, alcohol use is contraindicated. To provide a more comprehensive understanding of the interaction between flibanserin and alcohol, the results of a dedicated phase 1 alcohol-interaction study and a pooled analysis of phase 3 studies of premenopausal women with HSDD are presented. METHODS: In the phase 1 study, healthy participants (males [n=23] and females [n=2]) were randomly assigned to one of five sequence groups, which determined the order in which they were to receive flibanserin 100 mg or placebo, with or without ethanol 0.4 g/kg or 0.8 g/kg. Change from baseline in seated blood pressure, orthostatic vital signs, AEs and visual analogue scale sedation outcomes were examined. Blood samples were collected at baseline and for up to 4 hours after dosing to determine flibanserin area under the plasma concentration-time curve from 0 to 4 hours (AUC0-4 ). Pooled data from five phase 3 studies of patients receiving flibanserin 100 mg once daily (n=1543), or placebo (n=1905), were analysed. RESULTS: In the phase 1 study, the incidence of hypotension and syncope increased when flibanserin was coadministered with ethanol. Sedation increased 20% and 27% from baseline with flibanserin plus ethanol 0.4 g/kg and 0.8 g/kg, respectively, at 4 hours post-dose. In the pooled analysis of phase 3 studies, 58.2% and 63.6% of participants receiving flibanserin or placebo, respectively, reported baseline alcohol use. In patients receiving flibanserin, fatigue and dizziness occurred more frequently in patients with vs. without alcohol use. WHAT IS NEW AND CONCLUSION: Results from this study suggest that increased incidence of hypotension- and syncope-related events may result from a pharmacodynamic interaction between flibanserin and alcohol, although the clinical significance of these interactions in real-world populations remains unclear.

AVP-825: a novel intranasal delivery system for low-dose sumatriptan powder in the treatment of acute migraine.

INTRODUCTION: Migraine is a common, disabling disorder, and many patients remain dissatisfied with existing treatments. AVP-825 (ONZETRA® Xsail®) is a Breath Powered® exhalation delivery system for low-dose sumatriptan nasal powder (22 mg) that has been recently approved for use in the treatment of acute migraine with or without aura in adults. AVP-825 takes advantage of unique features of nasal anatomy and physiology to avoid limitations typically seen with other types of intranasal medication delivery. Areas covered: This review provides a summary of the pharmacology, clinical efficacy and tolerability of AVP-825 in clinical studies to date and also provides an overview of the unique aspects of the delivery system. Expert commentary: AVP-825 represents an improvement in nasal delivery of sumatriptan for migraine. PK studies indicate a distinct advantage of AVP-825 over traditional liquid nasal sprays in terms of absorption time, which may underlie the early efficacy observed with AVP-825. It offers the benefits of non-oral medications at a comparatively low sumatriptan dose, without the limitations associated with more invasive approaches. AVP-825 is suitable for use across multiple phases of a migraine attack from use as an early intervention to use in a more advanced migraine with nausea, given the non-oral application.

Discovery of SMP-304, a novel benzylpiperidine derivative with serotonin transporter inhibitory activity and 5-HT1A weak partial agonistic activity showing the antidepressant-like effect.

We report the discovery of a novel benzylpiperidine derivative with serotonin transporter (SERT) inhibitory activity and 5-HT1A receptor weak partial agonistic activity showing the antidepressant-like effect. The 3-methoxyphenyl group and the phenethyl group of compound 1, which has weak SERT binding activity, but potent 5-HT1A binding activity, were optimized, leading to compound 35 with potent and balanced dual SERT and 5-HT1A binding activity, but also potent CYP2D6 inhibitory activity. Replacement of the methoxy group in the left part of compound 35 with a larger alkoxy group, such as ethoxy, isopropoxy or methoxy-ethoxy group ameliorated CYP2D6 inhibition, giving SMP-304 as a candidate. SMP-304 with serotonin uptake inhibitory activity and 5-HT1A weak partial agonistic activity, which could work as a 5-HT1A antagonist, displayed faster onset of antidepressant-like effect than a representative SSRI paroxetine in an animal model.

Synthesis, biological evaluation and molecular modeling of 1-oxa-4-thiaspiro- and 1,4-dithiaspiro[4.5]decane derivatives as potent and selective 5-HT1A receptor agonists.

Recently, 1-(1,4-dioxaspiro[4,5]dec-2-ylmethyl)-4-(2-methoxyphenyl)piperazine (1) was reported as a potent 5-HT1AR agonist with a moderate 5-HT1AR selectivity. In an extension of this work a series of derivatives of 1, obtained by combining different heterocyclic rings with a more flexible amine chain, was synthesized and tested for binding affinity and activity at 5-HT1AR and α1 adrenoceptors. The results led to the identification of 14 and 15 as novel 5-HT1AR partial agonists, the first being outstanding for selectivity (5-HT1A/α1d = 80), the latter for potency (pD2 = 9.58) and efficacy (Emax = 74%). Theoretical studies of ADME properties shows a good profile for the entire series and MDCKII-MDR1 cells permeability data predict a good BBB permeability of compound 15, which possess a promising neuroprotective activity. Furthermore, in mouse formalin test, compound 15 shows a potent antinociceptive activity suggesting a new strategy for pain control.

Adjunctive brexpiprazole for the treatment of major depressive disorder.

INTRODUCTION: The lifetime prevalence of major depressive episodes in the United States is nearly 17%. Clinical trials and clinical effectiveness studies have demonstrated that many patients will fail to achieve remission using traditional monotherapy, contributing to significant morbidity and suffering. Because of this, augmentation strategies have been proposed to improve both treatment response and remission. Areas covered: Brexpiprazole is a second generation antipsychotic (SGA) approved by the US FDA in 2015 as an add-on treatment to an antidepressant medication for the treatment of adults with MDD, based on the results of two large-scale, randomized, placebo-controlled trials. It is thought to exert its antidepressant effect by a partial agonism of both the dopamine D2 and serotonin 5HT1A receptors. In addition, it also has potent antagonistic activity at 5HT2A, α1B and α2 C receptors, which may also contribute to monoamine transmission regulation. Expert Opinion: Overall, the tolerability of brexpiprazole is promising with relatively low rates of side effects and discontinuation rates, thus establishing it as a new option for the treatment of depression.

Marmoset Serotonin 5-HT1A Receptor Mapping with a Biased Agonist PET Probe 18F-F13714: Comparison with an Antagonist Tracer 18F-MPPF in Awake and Anesthetized States.

BACKGROUND: In vivo mapping by positron emission tomography of the serotonin 1A receptors has been hindered by the lack of suitable agonist positron emission tomography probes. 18F-labeled F13714 is a recently developed biased agonist positron emission tomography probe that preferentially targets subpopulations of serotonin 1A receptors in their "active state," but its brain labeling pattern in nonhuman primate has not been described. In addition, a potential confound in the translatability of PET data between nonhuman animal and human arise from the use of anesthetics that may modify the binding profiles of target receptors. METHODS: Positron emission tomography scans were conducted in a cohort of common marmosets (n=4) using the serotonin 1A receptor biased agonist radiotracer, 18F-F13714, compared with a well-characterized 18F-labeled antagonist radiotracer, 18F-MPPF. Experiments on each animal were performed under both consciousness and isoflurane-anesthesia conditions. RESULTS: 18F-F13714 binding distribution in marmosets by positron emission tomography differs markedly from that of the 18F-MPPF. Whereas 18F-MPPF showed highest binding in hippocampus and amygdala, 18F-F13714 showed highest labeling in other regions, including insular and cingulate cortex, thalamus, raphe, caudate nucleus, and putamen. The binding potential values of 18F-F13714 were about one-third of those observed with 18F-MPPF, with marked individual- and region-specific differences under isoflurane-anesthetized vs conscious conditions. CONCLUSIONS: These findings highlight the importance of investigating the brain imaging of serotonin 1A receptors using agonist probes such as 18F-F13714, which may preferentially target subpopulations of serotonin 1A receptors in specific brain regions of nonhuman primate as a biased agonist.