Revisiting loxapine: a systematic review

Optimisation of pharmacotherapy in psychiatry through therapeutic drug monitoring, molecular brain imaging and pharmacogenetic tests: focus on antipsychotics

BACKGROUND

For psychotic disorders (i.e. schizophrenia), pharmacotherapy plays a key role in controlling acute and long-term symptoms. To find the optimal individual dose and dosage strategy, specialized tools are used. Three tools have been proven useful to personalize drug treatments: therapeutic drug monitoring (TDM) of drug levels, pharmacogenetic testing (PG), and molecular neuroimaging.

METHODS

In these Guidelines, we provide an in-depth review of pharmacokinetics, pharmacodynamics, and pharmacogenetics for 50 antipsychotics. Over 30 international experts in psychiatry selected studies that have measured drug concentrations in the blood (TDM), gene polymorphisms of enzymes involved in drug metabolism, or receptor/transporter occupancies in the brain (positron emission tomography (PET)).

RESULTS

Study results strongly support the use of TDM and the cytochrome P450 (CYP) genotyping and/or phenotyping to guide drug therapies. Evidence-based target ranges are available for titrating drug doses that are often supported by PET findings.

CONCLUSION

All three tools discussed in these Guidelines are essential for drug treatment. TDM goes well beyond typical indications such as unclear compliance and polypharmacy. Despite its enormous potential to optimize treatment effects, minimize side effects and ultimately reduce the global burden of diseases, personalized drug treatment has not yet become the standard of care in psychiatry.

Discovery of a Small Molecule Activator of Slack (Kcnt1) Potassium Channels That Significantly Reduces Scratching in Mouse Models of Histamine-Independent and Chronic Itch

Various disorders are accompanied by histamine-independent itching, which is often resistant to the currently available therapies. Here, it is reported that the pharmacological activation of Slack (Kcnt1, KNa1.1), a potassium channel highly expressed in itch-sensitive sensory neurons, has therapeutic potential for the treatment of itching. Based on the Slack-activating antipsychotic drug, loxapine, a series of new derivatives with improved pharmacodynamic and pharmacokinetic profiles is designed that enables to validate Slack as a pharmacological target in vivo. One of these new Slack activators, compound 6, exhibits negligible dopamine D2 and D3 receptor binding, unlike loxapine. Notably, compound 6 displays potent on-target antipruritic activity in multiple mouse models of acute histamine-independent and chronic itch without motor side effects. These properties make compound 6 a lead molecule for the development of new antipruritic therapies targeting Slack.

Hauser-Kraus Annulation Initiated Multi-Cascade Reactions for Facile Access to Functionalized and Fused Oxazepines, Carbazoles and Phenanthridinediones

The Hauser-Kraus (H-K) annulation of N-unsubstituted 3-olefinic oxindoles with 3-nucleophilic phthalides triggers a cascade of ring expansion and ring contraction reactions through several regioselective steps in one pot. While oxazepines were isolated in the presence of stoichiometric amounts of base at room temperature, carbazoles and phenanthridinediones were the products in the presence of excess base and microwave irradiation. Mechanistic studies guided by stepwise reactions and control experiments revealed that the isolable oxazepine intermediate, formed via ring expansion of the H-K adduct, is the key precursor to carbazole and phenanthridinedione via decarboxylative regioselective cyclizations.

Loxapine in the Treatment of Manic and Psychotic Symptoms in an Individual Intolerant to Multiple Mood-Stabilizing and Antipsychotic Medications

First-line treatments for schizophrenia and schizoaffective disorder include antipsychotics and mood stabilizers, but their use may at times be limited due to severe adverse events. This case describes a 41-year-old male with a history of schizoaffective disorder and polysubstance use who was admitted to an inpatient psychiatry unit for acute manic and psychotic symptoms in the setting of absconding from his residential home and noncompliance with prescribed psychiatric medications. During his inpatient psychiatric hospitalization, he experienced DRESS (drug reaction with eosinophilia and systemic symptoms) with valproate, nephrogenic diabetes insipidus with lithium, potential neuroleptic malignant syndrome with risperidone, and orthostasis/tachycardia with clozapine. He ultimately achieved stabilization of manic and psychotic symptoms with loxapine without experiencing adverse events. This report highlights the potential utility of loxapine in individuals with schizoaffective disorder intolerant to standard mood-stabilizing and antipsychotic medications.

Therapeutic Potential of Dopamine and Related Drugs as Anti-Inflammatories and Antioxidants in Neuronal and Non-Neuronal Pathologies

Dopamine (DA), its derivatives, and dopaminergic drugs are compounds widely used in the management of diseases related to the nervous system. However, DA receptors have been identified in nonneuronal tissues, which has been related to their therapeutic potential in pathologies such as sepsis or septic shock, blood pressure, renal failure, diabetes, and obesity, among others. In addition, DA and dopaminergic drugs have shown anti-inflammatory and antioxidant properties in different kinds of cells.

AIM

To compile the mechanism of action of DA and the main dopaminergic drugs and show the findings that support the therapeutic potential of these molecules for the treatment of neurological and non-neurological diseases considering their antioxidant and anti-inflammatory actions.

METHOD

We performed a review article. An exhaustive search for information was carried out in specialized databases such as PubMed, PubChem, ProQuest, EBSCO, Scopus, Science Direct, Web of Science, Bookshelf, DrugBank, Livertox, and Clinical Trials.

RESULTS

We showed that DA and dopaminergic drugs have emerged for the management of neuronal and nonneuronal diseases with important therapeutic potential as anti-inflammatories and antioxidants.

CONCLUSIONS

DA and DA derivatives can be an attractive treatment strategy and a promising approach to slowing the progression of disorders through repositioning.

Seventy Years of Antipsychotic Development: A Critical Review

Since the mid-1950s discovery of the first effective antipsychotic medications (APM), we have only been able to improve the tolerability but not the overall efficacy of currently available APMs, as reflected by effectiveness trials in Europe and the United States. This inability to develop more effective APMs is attributable to multiple factors, including failure to create and use assessment tools to assess core symptom domains in schizophrenia, move beyond the dopaminergic hypothesis and to develop "me too" drugs, imposing ill-defined research domain criteria, and lacking federal funding for clinical trials. The classification of APMs is also confusing, including second-generation, partial agonists, and multimodal APMs in the same class of APMs, despite significant differences in their mechanisms of action. Other factors stagnating drug development include inadequate sample sizes to address heterogeneity, lack of statistical measures correlating with clinical significance, using the atheoretical basis of psychiatric diagnoses, failure to control placebo response, and high cost of newer and perhaps more tolerable APMs. Furthermore, there has been a failure to develop early predictors of antipsychotic response and various tools to optimize an APM response. Finally, some mental health providers are also responsible for the suboptimal use of APMs, by using excessive maintenance doses, often with irrational polypharmacy, further compromising effectiveness and medication adherence. However, some bright spots in antipsychotic development include improved tolerability of APMs and long-acting injectables to address the high prevalence of medication nonadherence. This review critically reviews 70 years of antipsychotic development, the reasons behind the failure to develop more effective APMs, and suggestions for future direction.

Discovery of antipsychotic loxapine derivatives against intracellular multidrug-resistant bacteria

The emergence and spread of multidrug-resistant bacteria highlight the need for new antibacterial interventions. A screening of 24 newly synthesized dibenzoxazepines identified a small molecule compound, SW14, with potent inhibitory activity against intracellular multidrug-resistant and fluoroquinolone-resistant strains of S. typhimurium in macrophages and epithelial cells. Moreover, intra-macrophagic Salmonella typhi, Yersinia enterocolitica, and Listeria monocytogenes and methicillin-resistant Staphylococcus aureus are also susceptible to SW14. Overall, our findings suggest that SW14 has a broad-spectrum activity against intracellular bacteria.

Actionable Predictive Factors of Homelessness in a Psychiatric Population: Results from the REHABase Cohort Using a Machine Learning Approach

BACKGROUND

There is a lack of knowledge regarding the actionable key predictive factors of homelessness in psychiatric populations. Therefore, we used a machine learning model to explore the REHABase database (for rehabilitation database-n = 3416), which is a cohort of users referred to French psychosocial rehabilitation centers in France.

METHODS

First, we analyzed whether the different risk factors previously associated with homelessness in mental health were also significant risk factors in the REHABase. In the second step, we used unbiased classification and regression trees to determine the key predictors of homelessness. Post hoc analyses were performed to examine the importance of the predictors and to explore the impact of cognitive factors among the participants.

RESULTS

&nbsp;First, risk factors that were previously found to be associated with homelessness were also significant risk factors in the REHABase. Among all the variables studied with a machine learning approach, the most robust variable in terms of predictive value was the nature of the psychotropic medication (sex/sex relative mean predictor importance: 22.8, σ = 3.4). Post hoc analyses revealed that first-generation antipsychotics (15.61%; p < 0.05 FDR corrected), loxapine (16.57%; p < 0.05 FWER corrected) and hypnotics (17.56%; p < 0.05 FWER corrected) were significantly associated with homelessness. Antidepressant medication was associated with a protective effect against housing deprivation (9.21%; p < 0.05 FWER corrected).

CONCLUSIONS

Psychotropic medication was found to be an important predictor of homelessness in our REHABase cohort, particularly loxapine and hypnotics. On the other hand, the putative protective effect of antidepressants confirms the need for systematic screening of depression and anxiety in the homeless population.

Fifty years of experience with loxapine for the rapid non-coercive tranquilization of acute behavioral disturbances in schizophrenia patients, and beyond

INTRODUCTION

Acute behavioral disturbances in psychosis, including agitation, comprise a heterogeneous group of manifestations varying in intensity and duration they last for. They require rapid, non-coercive treatments ranging from verbal de-escalation to the calming effect of pharmacological agents. The treatment goals are reduction of patient suffering and prevention of disease deterioration. Stabilizing rather than sedating is preferred to ensure improved compliance and a stronger therapeutic alliance. Furthermore, animal pharmacology and clinical studies on agitation reveal the robust calming and anxiolytic properties of loxapine.

AREAS COVERED

This review covers the pharmacological and clinical history of loxapine along with research developments. It emphasizes the advantages of its multiple formulations ranging from injectable forms and tablets to orally inhaled forms to attain rapid and fine-tuned tranquilization.

EXPERT OPINION

Rapid tranquillization is achieved within 2-6 hours using liquid orally-consumed loxapine, and within an hour or less with its IM or orally inhaled forms. Loxapine has been adopted in the management of a wide range of acute disturbances, such as agitation in psychosis. In the context of personalized medicine, key cellular and molecular elements of the schizophrenia phenotype were recently shown to be improved with loxapine.

Risk of Drug-induced Movement Disorders with Newer Antipsychotic Agents

Background:

The last decade has seen development of numerous novel antipsychotic drugs with unique mechanisms including long-acting formulations for clinical use. A comparative assessment of these new drugs with each other and previous antipsychotics have not been performed with regards to risk for drug-induced movement disorders (DIMD).

Methods:

Medline was searched from January 2010 to February 2022 for primary research articles and review articles in English using the search terms “extrapyramidal” and “tardive” with individual drug names of novel antipsychotics.

Results:

We identified articles describing the risk of DIMD with 6 novel antipsychotics, 4 novel formulations, and 3 experimental antipsychotics. Both short- and long-term data generally showed comparable to lower risk of DIMD with novel antipsychotics and recent long-acting formulations compared to previously marketed antipsychotics.

Discussion:

Several novel antipsychotics, particularly lumateperone and pimavanserin, show promise in being able to treat psychosis while reducing the risk of DIMD. Long-acting paliperidone may reduce risk of DIMD while other long-acting injectable formulations of SGA have similar risk of DIMD compared to oral formulations. New drug targets for treating psychosis without dopamine blockade also show promise.

Adverse Drug Reactions of Olanzapine, Clozapine and Loxapine in Children and Youth: A Systematic Pharmacogenetic Review

Children and youth treated with antipsychotic drugs (APs) are particularly vulnerable to adverse drug reactions (ADRs) and prone to poor treatment response. In particular, interindividual variations in drug exposure can result from differential metabolism of APs by cytochromes, subject to genetic polymorphism. CYP1A2 is pivotal in the metabolism of the APs olanzapine, clozapine, and loxapine, whose safety profile warrants caution. We aimed to shed some light on the pharmacogenetic profiles possibly associated with these drugs’ ADRs and loss of efficacy in children and youth. We conducted a systematic review relying on four databases, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 recommendations and checklist, with a quality assessment. Our research yielded 32 publications. The most frequent ADRs were weight gain and metabolic syndrome (18; 56.3%), followed by lack of therapeutic effect (8; 25%) and neurological ADRs (7; 21.8%). The overall mean quality score was 11.3/24 (±2.7). In 11 studies (34.3%), genotyping focused on the study of cytochromes. Findings regarding possible associations were sometimes conflicting. Nonetheless, cases of major clinical improvement were fostered by genotyping. Yet, CYP1A2 remains poorly investigated. Further studies are required to improve the assessment of the risk–benefit balance of prescription for children and youth treated with olanzapine, clozapine, and/or loxapine.

Dopamine Receptor Signaling Regulates Fibrotic Activation of Retinal Pigmented Epithelial Cells

Retinal pigmented epithelial (RPE) cells play an important role in retinal fibrotic diseases such as proliferative vitreoretinopathy (PVR). The purpose of this study was to elucidate the involvement of dopamine receptor signaling in regulating the fibrotic activation of RPE cells. Dopamine receptor expression, the effect of dopamine on fibrotic activity, and dopamine production were measured in the human RPE cell line ARPE-19. The fibrotic activation of RPE cells was evaluated in response to treatments with selective dopamine receptor agonists and antagonists by measuring gene expression, migration, proliferation, and fibronectin deposition. DRD2 and DRD5 are the dominant dopaminergic receptors expressed in ARPE-19 cells and TGFβ stimulates enhances autocrine release of dopamine which we show further exasperates fibrotic activation. Finally, treatment with D2 dopamine receptor antagonists or D5 dopamine receptor agonists inhibits profibrotic gene expression, migration, proliferation, and fibronectin deposition and thus may serve as effective mechanisms for treating retinal fibrosis including PVR.

Recent advances in drug delivery to the central nervous system by inhalation

INTRODUCTION

Drugs need to enter the systemic circulation efficiently before they can cross the blood-brain barrier and reach the central nervous system. Although the respiratory tract is not a common route of administration for delivering drugs to the central nervous system, it has attracted increasing interest in recent years for this purpose.

AREAS COVERED

In this article, we compare pulmonary delivery to three other common routes (parenteral, oral, and intranasal) for delivering drugs to the central nervous system, followed by summarising the devices used to aerosolise neurological drugs. Recent studies delivering drugs for different neurological disorders via inhalation are then discussed to illustrate the strengths of pulmonary delivery.

EXPERT OPINION

Recent studies provide strong evidence and rationale to support inhaling neurological drugs. Since inhalation can achieve improved pharmacokinetics and rapid onset of action for multiple drugs, it is a non-invasive and efficient method to deliver drugs to the central nervous system. Future research should focus on delivering other small and macro-molecules via the lungs for different neurological conditions.

Effect of Novel Antipsychotics on Energy Metabolism - In Vitro Study in Pig Brain Mitochondria

The identification and quantification of mitochondrial effects of novel antipsychotics (brexpiprazole, cariprazine, loxapine, and lurasidone) were studied in vitro in pig brain mitochondria. Selected parameters of mitochondrial metabolism, electron transport chain (ETC) complexes, citrate synthase (CS), malate dehydrogenase (MDH), monoamine oxidase (MAO), mitochondrial respiration, and total ATP and reactive oxygen species (ROS) production were evaluated and associated with possible adverse effects of drugs. All tested antipsychotics decreased the ETC activities (except for complex IV, which increased in activity after brexpiprazole and loxapine addition). Both complex I- and complex II-linked respiration were dose-dependently inhibited, and significant correlations were found between complex I-linked respiration and both complex I activity (positive correlation) and complex IV activity (negative correlation). All drugs significantly decreased mitochondrial ATP production at higher concentrations. Hydrogen peroxide production was significantly increased at 10 µM brexpiprazole and lurasidone and at 100 µM cariprazine and loxapine. All antipsychotics acted as partial inhibitors of MAO-A, brexpiprazole and loxapine partially inhibited MAO-B. Based on our results, novel antipsychotics probably lacked oxygen uncoupling properties. The mitochondrial effects of novel antipsychotics might contribute on their adverse effects, which are mostly related to decreased ATP production and increased ROS production, while MAO-A inhibition might contribute to their antidepressant effect, and brexpiprazole- and loxapine-induced MAO-B inhibition might likely promote neuroplasticity and neuroprotection. The assessment of drug-induced mitochondrial dysfunctions is important in development of new drugs as well as in the understanding of molecular mechanism of adverse or side drug effects.

Loxapine in patient with clozapine-resistant psychosis

Clozapine is recognized as the drug of choice for treatment-refractory schizophrenia, but use may be limited because of strict monitoring requirements and adverse effects including severe neutropenia, seizures, and myocarditis. Loxapine is a first-generation antipsychotic with similarities to clozapine in both structure and receptor binding. This case describes a 57-year-old male with a history of severe paranoid schizophrenia despite treatment with clozapine and other psychotropic agents, who experienced clinical improvement after a cross titration from clozapine to loxapine. Loxapine may be a reasonable alternative in patients with treatment-refractory schizophrenia who do not tolerate or respond to clozapine.

Considering Loxapine Instead of Clozapine: A Case Series and Literature Review

This case series highlights the importance of loxapine in psychiatric disorders when clozapine is unable to control agitation and psychotic symptoms due to medication noncompliance, intolerable side effects, or inadequate clinical outcomes. Loxapine is classified as a first-generation typical antipsychotic but displays atypical antipsychotic-like characteristics with structural similarity to clozapine. However, since the inception of second-generation antipsychotic medications, the role of loxapine in modern psychiatric practice has become limited. Loxapine has been underutilized due to concerns of side effects and lack of in-depth research about its safety, tolerability, and efficacy. This report revisits loxapine’s clinical utility through two well-studied long-term inpatient cases, where it played a crucial role in controlling psychotic symptoms and achieving better medication compliance by eliminating significant barriers, including monitoring regular differential complete blood counts. We aim to add to the current evidence and literature about the advantage of using loxapine for specific clinical scenarios in psychiatric practice.

Access to Benzoxazepines and Fully Substituted Indoles via HDDA Coupling

The HDDA-derived benzyne intermediate was captured by oxazolines based on the addition reaction of benzyne to the C═N double bond. Benzoxazepine derivatives, fused benzoxazepine derivatives, and fully substituted indoles are synthesized in one step. The reaction does not require any catalyst or additives. Possible reaction mechanisms are presented.

Application of Bivalent Bioisostere Concept on Design and Discovery of Potent Opioid Receptor Modulators

Here, we described the structural modification of previously identified μ opioid receptor (MOR) antagonist NAN, a 6α-N-7'-indolyl substituted naltrexamine derivative, and its 6β-N-2'-indolyl substituted analogue INTA by adopting the concept of "bivalent bioisostere". Three newly prepared opioid ligands, 25 (NBF), 31, and 38, were identified as potent MOR antagonists both in vitro and in vivo. Moreover, these three compounds significantly antagonized DAMGO-induced intracellular calcium flux and displayed varying degrees of inhibition on cAMP production. Furthermore, NBF produced much less significant withdrawal effects than naloxone in morphine-pelleted mice. Molecular modeling studies revealed that these bivalent bioisosteres may adopt similar binding modes in the MOR and the "address" portions of them may have negative or positive allosteric modulation effects on the function of their "message" portions compared with NAN and INTA. Collectively, our successful application of the "bivalent bioisostere concept" identified a promising lead to develop novel therapeutic agents toward opioid use disorder treatments.

Loxapine for Treatment of Patients With Refractory, Chemotherapy-Induced Neuropathic Pain: A Prematurely Terminated Pilot Study Showing Efficacy But Limited Tolerability

Neuropathic pain is a debilitating and commonly treatment-refractory condition requiring novel therapeutic options. Accumulating preclinical studies indicate that the potassium channel Slack (K_Na1.1) contributes to the processing of neuropathic pain, and that Slack activators, when injected into mice, ameliorate pain-related hypersensitivity. However, whether Slack activation might reduce neuropathic pain in humans remains elusive. Here, we evaluated the tolerability and analgesic efficacy of loxapine, a first-generation antipsychotic drug and Slack activator, in neuropathic pain patients. We aimed to treat 12 patients with chronic chemotherapy-induced, treatment-refractory neuropathic pain (pain severity ≥ 4 units on an 11-point numerical rating scale) in a monocentric, open label, proof-of-principle study. Patients received loxapine orally as add-on analgesic in a dose-escalating manner (four treatment episodes for 14 days, daily dose: 20, 30, 40, or 60 mg loxapine) depending on tolerability and analgesic efficacy. Patient-reported outcomes of pain intensity and/or relief were recorded daily. After enrolling four patients, this study was prematurely terminated due to adverse events typically occurring with first-generation antipsychotic drugs that were reported by all patients. In two patients receiving loxapine for at least two treatment episodes, a clinically relevant analgesic effect was found at a daily dose of 20-30 mg of loxapine. Another two patients tolerated loxapine only for a few days. Together, our data further support the hypothesis that Slack activation might be a novel strategy for neuropathic pain therapy. However, loxapine is no valid treatment option for painful polyneuropathy due to profound dopamine and histamine receptor-related side effects. Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT02820519.

Dopamine receptor antagonists as potential therapeutic agents for ADPKD

Autosomal dominant polycystic kidney disease (ADPKD) is caused mostly by mutations in polycystin-1 or polycystin-2. Fluid flow leads to polycystin-dependent calcium influx and nuclear export of histone deacetylase 5 (HDAC5), which facilitates the maintenance of renal epithelial architecture by de-repression of MEF2C target genes. Here, we screened a small-molecule library to find drugs that promotes nuclear export of HDAC5. We found that dopamine receptor antagonists, domperidone and loxapine succinate, stimulate export of HDAC5, even in Pkd1^–/–cells. Domperidone targets Drd3 receptor to modulate the phosphorylation of HDAC5. Domperidone treatment increases HDAC5 phosphorylation likely by reducing protein phosphatase 2A (PP2A) activity, thus shifting the equilibrium towards HDAC5-P and export from the nucleus. Treating Pkd1^–/–mice with domperidone showed significantly reduced cystic growth and cell proliferation. Further, treated mice displayed a reduction in glomerular cyst and increased body weight and activity. These results suggest that HDAC5 nucleocytoplasmic shuttling may be modulated to impede disease progression in ADPKD and uncovers an unexpected role for a class of dopamine receptors in renal epithelial morphogenesis.

Inhaled Loxapine for the Management of Acute Agitation in Bipolar Disorder and Schizophrenia: Expert Review and Commentary in an Era of Change

Agitation is a common and costly phenomenon associated with a number of psychiatric conditions including schizophrenia and bipolar disorder. Early identification and prompt intervention to relieve the symptoms of agitation are essential to avoid symptomatic escalation and emergence of aggressive behaviour. Recent consensus guidelines emphasise the need for non-coercive management strategies to protect the therapeutic alliance between patients and their healthcare providers—an alliance that is critical for the effective management of chronic psychiatric conditions. Rapid symptom relief and de-escalation of agitation are necessary to avoid the costly and traumatic use of coercive techniques of physical restraint and seclusion, which require admission and prolonged hospitalisation. Inhaled loxapine is approved for the treatment of acute agitation in patients with schizophrenia or bipolar disorder. Clinical studies have confirmed the efficacy, rapid onset of action, and safety and tolerability of this agent in the psychiatric emergency and hospital settings. Emerging data have indicated the potential for inhaled loxapine as a self-administered agent for use in the community setting without the direct supervision of a healthcare professional. We discuss the evolving treatment paradigm and the place of inhaled medications for acutely agitated patients both within and outside the emergency and hospital setting.

Examining the safety, efficacy, and patient acceptability of inhaled loxapine for the acute treatment of agitation associated with schizophrenia or bipolar I disorder in adults

Agitation is a common and serious symptom of bipolar mania and schizophrenia, and can be defined as excessive motor and verbal activity. If left unrecognized and untreated, agitation can evolve into aggression, resulting in potential patient and staff injury. An ideal treatment for agitation would have a rapid onset, cause calmness without sedation, and be tolerable, efficacious, and non-coercive, while managing the underlying condition. A novel approach for the treatment of agitation is inhaled loxapine. Inhaled loxapine is rapidly absorbed into the systemic circulation through the alveoli, resulting in a near immediate onset of action. The efficacy of inhaled loxapine was established in an extensive clinical development program that included persons with schizophrenia and bipolar mania. Additionally, inhaled loxapine has comparable efficacy to intramuscular ziprasidone, olanzapine, haloperidol, aripiprazole, and lorazepam, with the added benefit of being non-painful and non-traumatizing. Inhaled loxapine carries a bolded black box warning for bronchospasm, and as a result, in the US, requires enrollment in a Risk Evaluation and Mitigation Strategy program, and is contraindicated in those with pulmonary disease. Additionally, the use of inhaled loxapine can be associated with dysgeusia and throat irritation. Inhaled loxapine requires some degree of patient cooperation, and therefore may not be appropriate for all agitated patients.

Slack KNa Channels Influence Dorsal Horn Synapses and Nociceptive Behavior

The sodium-activated potassium channel Slack (Kcnt1, Slo2.2) is highly expressed in dorsal root ganglion neurons where it regulates neuronal firing. Several studies have implicated the Slack channel in pain processing, but the precise mechanism or the levels within the sensory pathway where channels are involved remain unclear. Here, we furthered the behavioral characterization of Slack channel knockout mice and for the first time examined the role of Slack channels in the superficial, pain-processing lamina of the dorsal horn. We performed whole-cell recordings from spinal cord slices to examine the intrinsic and synaptic properties of putative inhibitory and excitatory lamina II interneurons. Slack channel deletion altered intrinsic properties and synaptic drive to favor an overall enhanced excitatory tone. We measured the amplitudes and paired pulse ratio of paired excitatory post-synaptic currents at primary afferent synapses evoked by electrical stimulation of the dorsal root entry zone. We found a substantial decrease in the paired pulse ratio at synapses in Slack deleted neurons compared to wildtype, indicating increased presynaptic release from primary afferents. Corroborating these data, plantar test showed Slack knockout mice have an enhanced nociceptive responsiveness to localized thermal stimuli compared to wildtype mice. Our findings suggest that Slack channels regulate synaptic transmission within the spinal cord dorsal horn and by doing so establishes the threshold for thermal nociception.

PLACID study: A randomized trial comparing the efficacy and safety of inhaled loxapine versus intramuscular aripiprazole in acutely agitated patients with schizophrenia or bipolar disorder

The aim of the study was to investigate the efficacy and safety of inhaled loxapine compared with the intramuscular (IM) antipsychotic aripiprazole in acutely agitated patients with schizophrenia or bipolar I disorder. PLACID was an assessor-blind, parallel-group trial conducted in 23 centres in the Czech Republic, Germany, Spain, and Russia. Patients (aged 18-65 years) diagnosed with schizophrenia or bipolar I disorder experiencing acute agitation (Clinical Global Impression [CGI]-Severity score ≥ 4) while hospitalized or attending an emergency room were randomized to receive up to two doses of inhaled loxapine 9.1 mg or IM aripiprazole 9.75 mg (≥ 2 h between doses) during the 24-h study period. The primary efficacy endpoint was time to response (CGI-Improvement score 1 [very much improved] or 2 [much improved]). The primary analysis included randomized patients who provided informed consent (full analysis set [FAS]); the safety analysis included all patients who received study medication. The FAS comprised 357 patients (enrolled December 2, 2014 - October 31, 2016). The between-treatment difference in median time to CGI-Improvement response was 10 min (95% CI 0.0-30.0); p = 0.0005) in favour of inhaled loxapine (median [95% CI]: 50 min [30.0-50.0] vs 60 min [50.0-90.0] with IM aripiprazole); the difference was significant at 10 min (responders: 14% [loxapine] vs 4% [aripiprazole]; p = 0.001). There were no safety issues. Inhaled loxapine reduced agitation faster than IM aripiprazole, supporting its use as a first-line option for managing acute agitation in patients with schizophrenia or bipolar disorder.

Joint BAP NAPICU evidence-based consensus guidelines for the clinical management of acute disturbance: De-escalation and rapid tranquillisation

The British Association for Psychopharmacology and the National Association of Psychiatric Intensive Care and Low Secure Units developed this joint evidence-based consensus guideline for the clinical management of acute disturbance. It includes recommendations for clinical practice and an algorithm to guide treatment by healthcare professionals with various options outlined according to their route of administration and category of evidence. Fundamental overarching principles are included and highlight the importance of treating the underlying disorder. There is a focus on three key interventions: de-escalation, pharmacological interventions pre-rapid tranquillisation and rapid tranquillisation (intramuscular and intravenous). Most of the evidence reviewed relates to emergency psychiatric care or acute psychiatric adult inpatient care, although we also sought evidence relevant to other common clinical settings including the general acute hospital and forensic psychiatry. We conclude that the variety of options available for the management of acute disturbance goes beyond the standard choices of lorazepam, haloperidol and promethazine and includes oral-inhaled loxapine, buccal midazolam, as well as a number of oral antipsychotics in addition to parenteral options of intramuscular aripiprazole, intramuscular droperidol and intramuscular olanzapine. Intravenous options, for settings where resuscitation equipment and trained staff are available to manage medical emergencies, are also included.

The in Vitro Actions of Loxapine on Dopaminergic and Serotonergic Receptors. Time to Consider Atypical Classification of This Antipsychotic Drug?

BACKGROUND

The denomination of typical antipsychotic for loxapine has poor relation to current knowledge of the molecule's relevant modes of action.

MATERIALS AND METHODS

Competition binding experiments were performed on expressed human recombinant receptors in CHO cells and HEK-293 cells for D1 to D5, 5-HT1A, 5-HT2A, 5-HT2C, 5-HT4, 5-HT6, and 5-HT7. In vitro autoradiographies using [11C]-Raclopride [18F]-Altanserin [18F]-MPPF [11C]-SB207145, and [18F]-2FNQ1P were measured in brain tissue of a male primate followed by addition of increasing doses of loxapine succinate.

RESULTS

In cell cultures, the measured Kb confirmed high affinity of loxapine for the D2; intermediate affinity for the D1, D4, D5, 5-HT2C receptorsl and a lack of affinity toward D3, 5-HT1A, 5-HT4, 5-HT6, and 5-HT7 receptors. In brain tissue, PET autoradiographies showed a radiopharmaceutical displacement at low concentrations of loxapine on D2 and 5-HT2A receptors.

CONCLUSION

This preclinical study reveals that loxapine receptorial spectrum is close to an "atypical" profile (D2/5HT2A ratio, 1.14). Loxapine is rightly classified as a DS-RAn agent in the Neuroscience Based Nomenclature classification.

Extrapyramidal side effects of antipsychotics are linked to their association kinetics at dopamine D2 receptors

Atypical antipsychotic drugs (APDs) have been hypothesized to show reduced extrapyramidal side effects (EPS) due to their rapid dissociation from the dopamine D₂ receptor. However, support for this hypothesis is limited to a relatively small number of observations made across several decades and under different experimental conditions. Here we show that association rates, but not dissociation rates, correlate with EPS. We measured the kinetic binding properties of a series of typical and atypical APDs in a novel time-resolved fluorescence resonance energy transfer assay, and correlated these properties with their EPS and prolactin-elevating liabilities at therapeutic doses. EPS are robustly predicted by a rebinding model that considers the microenvironment of postsynaptic D₂ receptors and integrates association and dissociation rates to calculate the net rate of reversal of receptor blockade. Thus, optimizing binding kinetics at the D₂ receptor may result in APDs with improved therapeutic profile.

Atypical antipsychotics show reduced extrapyramidal side effects compared to first generation drugs. Here the authors use time-resolved FRET to measure binding kinetics, and show that side effects correlate with drug association rates to the D₂ receptor, while dissociation rates correlate with prolactin elevation.

Pharmacokinetics and Safety of Single-Dose Inhaled Loxapine in Children and Adolescents

This multisite open-label study sought to characterize the pharmacokinetics and safety of a single dose of inhaled loxapine in children and adolescents. Loxapine powder for oral inhalation was administered via a single-use handheld drug device to children and adolescents (aged 10-17 years) with any condition warranting chronic antipsychotic use. Patients were dosed according to body weight and cohort (<50 kg [n = 15], 2.5 or 5 mg; ≥50 kg [n = 15], 5 or 10 mg); the first 6 patients (cohort 1) enrolled in each weight group received the lower dose. Patients were enrolled in the higher-dose group (cohort 2) after an interim pharmacokinetic and safety analysis of data from cohort 1. Blood samples were collected for 48 hours after dosing to determine the pharmacokinetic profile of loxapine and its metabolites. Safety was assessed using adverse event (AE), laboratory value, physical/neurologic examination, vital sign, electrocardiogram, suicidality, and extrapyramidal symptom assessment. Thirty patients were enrolled and evaluable for pharmacokinetics. Loxapine plasma concentrations peaked by 2 to 5 minutes in most patients; systemic exposure increased with dose in both weight subgroups. Loxapine terminal elimination half-life was ∼13 to 17 hours. The most common AEs were sedation and dysgeusia. Sedation was severe in 1 patient in the <50-kg group (2.5-mg dose) and 1 patient in the ≥50-kg group (5-mg dose). No AEs indicative of bronchospasm or other serious AEs were reported. Inhaled loxapine was rapidly absorbed and generally well tolerated in pediatric patients; no new safety signals were observed.

Dopamine antagonists for treatment resistance in autism spectrum disorders: review and focus on BDNF stimulators loxapine and amitriptyline

INTRODUCTION

Drug development and repurposing are urgently needed for individuals with autism spectrum disorders (ASD) and psychiatric comorbidity, which often presents as aggression and self-injury. Areas covered: We review dopamine antagonists, including classical and atypical, as well as unconventional antipsychotics in ASD. The older antipsychotic loxapine is discussed in terms of preliminary albeit limited evidence in ASD. Emerging promise of amitriptyline in ASD is discussed, together with promising BDNF effects of loxapine and amitriptyline. Expert opinion: In ASD, pharmacotherapy and specifically dopamine antagonist drugs are often prescribed for challenging behaviors including aggression. The novel antipsychotics risperidone and aripiprazole have received most study in ASD and are FDA-approved for irritability in children with ASD over age 5 years; individuals with ASD are prone to weight gain, Type II diabetes and associated side effects. Low dose loxapine has properties of classical and novel antipsychotics but importantly appears more weight neutral, and with promising use in adolescents and adults with ASD. Amitriptyline appears effective in ASD for irritability, aggression, gastrointestinal problems, and insomnia, in children, adolescents and adults however our adult data on amitriptyline in ASD is still in preparation for publication. Both loxapine and amitriptyline may stimulate BDNF; further studies are warranted.

Rationale and design of the PLACID study: a randomised trial comparing the efficacy and safety of inhaled loxapine versus IM aripiprazole in acutely agitated patients with schizophrenia or bipolar disorder

BACKGROUND

The management of acute agitation manifesting in patients with schizophrenia or bipolar disorder requires swift pharmacological intervention to provide rapid symptomatic relief and prevent escalation to aggression and violence. Antipsychotic medications are widely used in this setting and the availability of an inhaled formulation with deep lung absorption of the antipsychotic loxapine has the potential to deliver a faster onset of therapeutic effect than the available intramuscular formulations of antipsychotics.

METHODS

The efficacy of inhaled loxapine and the alternative antipsychotic aripiprazole delivered via intramuscular (IM) injection will be compared in the Phase IIIb PLACID study. Adults (18-65 years) with a confirmed diagnosis of schizophrenia or bipolar I disorder presenting with acute agitation will be randomly assigned to open-label treatment in a 1:1 ratio. Clinical evaluation will be conducted by raters blinded to treatment assignment. The primary efficacy endpoint is time to response (defined as a Clinical Global Impression of Improvement [CGI-I] score of 1 [very much improved] or 2 [much improved]). Secondary endpoints will include the percentage of responders at different time points after dosing; the proportion of patients who receive 1 or 2 doses of study drug; time to second dose; time to rescue medication; satisfaction with study drug (evaluated using Item 14 of the Treatment Satisfaction Questionnaire for Medication); and safety and tolerability. Approximately 360 patients will be recruited with an interim analysis conducted once 180 patients have completed the study to decide whether to stop for futility or continue with or without an increase in the sample size up to additional 288 patients.

DISCUSSION

The PLACID trial will assess the efficacy and safety of inhaled loxapine with deep lung absorption compared with the IM antipsychotic, aripiprazole, in acutely agitated patients with schizophrenia or bipolar disorder. In the event that the median time to response of inhaled loxapine is significantly shorter than that of the intramuscular aripiprazole, the PLACID study has the potential to support the inhaled antipsychotic therapy as the standard of care in this setting.

TRIAL REGISTRATION

The study protocol was registered with the European Clinical Trials Database on the 31 October 2014 (EudraCT number 2014-000456-29 ).

The Role of Inhaled Loxapine in the Treatment of Acute Agitation in Patients with Psychiatric Disorders: A Clinical Review

Loxapine is a first generation antipsychotic, belonging to the dibenzoxazepine class. Recently, loxapine has been reformulated at a lower dose, producing an inhaled powder that can be directly administered to the lungs to treat the agitation associated with psychiatric disorders, such as schizophrenia and bipolar disorder. Thus, the aim of this narrative and clinical mini-review was to evaluate the efficacy and tolerability of inhaled loxapine in the treatment of acute agitation in patients with psychiatric disorders. The efficacy of inhaled loxapine has been evaluated in one Phase II trial on patients with schizophrenia, and in two Phase III trials in patients with schizophrenia and bipolar disorder. Moreover, there are two published case series on patients with borderline personality disorder and dual diagnosis patients. Inhaled loxapine has proven to be effective and generally well tolerated when administered to agitated patients with schizophrenia and bipolar disorder. Two case series have suggested that inhaled loxapine may also be useful to treat agitation in patients with borderline personality disorder and with dual diagnosis, but further studies are needed to clarify this point. However, the administration of inhaled loxapine requires at least some kind of patient collaboration, and is not recommended in the treatment of severe agitation in totally uncooperative patients. Moreover, the drug-related risk of bronchospasm must always be kept in mind when planning to use inhaled loxapine, leading to a careful patient assessment prior to, and after, administration. Also, the higher costs of inhaled loxapine, when compared to oral and intramuscular medications, should be taken into account when selecting it for the treatment of agitation.

The International College of Neuro-Psychopharmacology (CINP) Treatment Guidelines for Bipolar Disorder in Adults (CINP-BD-2017), Part 2: Review, Grading of the Evidence, and a Precise Algorithm

Background

The current paper includes a systematic search of the literature, a detailed presentation of the results, and a grading of treatment options in terms of efficacy and tolerability/safety.

Material and Methods

The PRISMA method was used in the literature search with the combination of the words 'bipolar,' 'manic,' 'mania,' 'manic depression,' and 'manic depressive' with 'randomized,' and 'algorithms' with 'mania,' 'manic,' 'bipolar,' 'manic-depressive,' or 'manic depression.' Relevant web pages and review articles were also reviewed.

Results

The current report is based on the analysis of 57 guideline papers and 531 published papers related to RCTs, reviews, posthoc, or meta-analysis papers to March 25, 2016. The specific treatment options for acute mania, mixed episodes, acute bipolar depression, maintenance phase, psychotic and mixed features, anxiety, and rapid cycling were evaluated with regards to efficacy. Existing treatment guidelines were also reviewed. Finally, Tables reflecting efficacy and recommendation levels were created that led to the development of a precise algorithm that still has to prove its feasibility in everyday clinical practice.

Conclusions

A systematic literature search was conducted on the pharmacological treatment of bipolar disorder to identify all relevant random controlled trials pertaining to all aspects of bipolar disorder and graded the data according to a predetermined method to develop a precise treatment algorithm for management of various phases of bipolar disorder. It is important to note that the some of the recommendations in the treatment algorithm were based on the secondary outcome data from posthoc analyses.

Inhaled loxapine for the urgent treatment of acute agitation associated with schizophrenia or bipolar disorder

BACKGROUND

Acute agitation is a serious complication of schizophrenia and bipolar disorder, which may escalate quickly to aggressive behavior. Rapid treatment is therefore important to calm and stabilize the patient, reducing the potential for harm to the patient and others, and allowing further assessment. Current guidelines suggest that where pharmacologic intervention is indicated, medication should preferably be non-invasive, should have a rapid onset and should control aggressive behavior in the short term without compromising the physician-patient relationship in the long term.

OBJECTIVES

This article presents an overview of a new inhaled formulation of the established antipsychotic loxapine, which aims to provide a more rapidly acting agent for the treatment of acute agitation without the disadvantages of intramuscular or intravenous injection.

DISCUSSION

Inhaled loxapine is rapidly absorbed with intravenous-like pharmacokinetics, with a time to maximum plasma concentration of 2 minutes and a plasma half-life of approximately 6 hours. In phase III studies, loxapine reduced agitation within 10 minutes of inhalation; agitation was decreased at all subsequent assessments during a 24-hour evaluation period. Inhaled loxapine was generally well tolerated with no undue sedation. The most common adverse events were dysgeusia, mild sedation, and dizziness. Inhaled loxapine is contraindicated in patients with asthma, COPD or other pulmonary disease associated with bronchospasm.

CONCLUSIONS

Inhaled loxapine rapidly reduces acute agitation in patients with schizophrenia or bipolar disorder and is generally well tolerated. The non-invasive route of delivery respects the patient's autonomy, reducing the perception of coercion or forced medication. Inhaled loxapine is therefore an effective and appropriate option for use in the emergency setting in patients with acute agitation.