Evaluating the safety and efficacy of dextromethorphan/quinidine in the treatment of pseudobulbar affect

Dextromethorphan-Bupropion for the Treatment of Depression: A Systematic Review of Efficacy and Safety in Clinical Trials

BACKGROUND

A significant proportion of adults with major depressive disorder (MDD) do not respond to treatments which are currently used in clinical practice such as first-generation monoamine-based antidepressants.

OBJECTIVES

The objective of this systematic review was to assess the efficacy, safety, and mechanisms of action of AXS-05, a combination of the NMDA-receptor antagonist dextromethorphan with bupropion, in adults with MDD.

METHODS

We searched PubMed, Embase, Google Scholar, and ClinicalTrials.gov for current studies reporting on efficacy and/or safety of AXS-05 in patients with MDD. The search terms included: "AXS-05" OR "dextromethorphan and bupropion" AND "depression". Studies from database inception to January 2023 were evaluated. Risk of bias was assessed using the Cochrane Risk of Bias tool.

RESULTS

The search yielded 54 studies of which 5 were included. All studies had low risk of bias. Depression severity, measured with the Montgomery-Åsberg Depression Rating Scale (MADRS) significantly decreased as early as 1-week post-treatment from baseline when compared to a placebo-controlled group (LS mean difference 2.2; 95% CI 0.6-3.9; p = 0.007) and at 2 weeks compared to an active control group (LS mean difference 4.7; 95% CI 0.6-8.8; p = 0.024). Treatment efficacy could be maintained for up to 12 months with mean MADRS score reduction of 23 points from baseline. Clinical remission and response rates also improved at week 1 and were maintained for 12 months. The treatment was well-tolerated, with some transient adverse events reported.

CONCLUSION

Current evidence suggests that the combination of dextromethorphan and bupropion is a well-tolerated, rapid-acting treatment option for adults with MDD. Initial success with AXS-05 supports the mechanistic role of glutamatergeric and sigma 1 signaling in the pathophysiology of MDD.

Iranian clinical practice guideline for amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegeneration involving motor neurons. The 3-5 years that patients have to live is marked by day-to-day loss of motor and sometimes cognitive abilities. Enormous amounts of healthcare services and resources are necessary to support patients and their caregivers during this relatively short but burdensome journey. Organization and management of these resources need to best meet patients' expectations and health system efficiency mandates. This can only occur in the setting of multidisciplinary ALS clinics which are known as the gold standard of ALS care worldwide. To introduce this standard to the care of Iranian ALS patients, which is an inevitable quality milestone, a national ALS clinical practice guideline is the necessary first step. The National ALS guideline will serve as the knowledge base for the development of local clinical pathways to guide patient journeys in multidisciplinary ALS clinics. To this end, we gathered a team of national neuromuscular experts as well as experts in related specialties necessary for delivering multidisciplinary care to ALS patients to develop the Iranian ALS clinical practice guideline. Clinical questions were prepared in the Patient, Intervention, Comparison, and Outcome (PICO) format to serve as a guide for the literature search. Considering the lack of adequate national/local studies at this time, a consensus-based approach was taken to evaluate the quality of the retrieved evidence and summarize recommendations.

Low-volume plasma sampling for determination of dextromethorphan and dextrorphan in rat plasma: LC-MS/MS method and its application in pharmacokinetic study

Dextromethorphan (DM) and its metabolite dextrorphan (DX) continue to draw the attention of researchers owing to their diverse pharmacodynamics. Thus, there are possibilities for repurposing DM. Most of the pharmacodynamics of DM needs further validation in different preclinical models. Also, it is necessary to correlate the pharmacodynamics with relevant pharmacokinetics data. Multiple bioanalytical techniques developed for this purpose primarily use a high sample processing volume. Since sample volume is a limiting factor for many preclinical models, an effort was taken to develop an alternative method suitable for handling low sample processing volumes. An efficient solid-phase extraction technique, robust liquid chromatographic (LC) separation and highly sensitive tandem mass spectrometric detection (MS/MS) showed suitability for use of a 30 μl sample processing volume. This led to the development of a highly specific, selective, accurate and precise-bio-analytical method for simultaneous quantification of DM and DX in rat plasma. The validated method was linear in the range of 0.196-403.356 ng/ml for DM and 0.102-209.017 ng/ml for DX. The application of the method was demonstrated through the estimation of pharmacokinetic parameters that showed good congruence with earlier studies.

Pharmaceutical interventions for emotionalism after stroke

BACKGROUND

Antidepressants may be useful in the treatment of abnormal crying associated with stroke. This is an update of a Cochrane Review first published in 2004 and last updated in 2019.

OBJECTIVES

To evaluate the benefits and harms of pharmaceutical treatment in people with emotionalism after stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Register, CENTRAL, MEDLINE, Embase, four other databases, and three trials registers (May 2022).

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs comparing psychotropic medication to placebo in people with stroke and emotionalism (also known as emotional lability, pathological crying or laughing, emotional incontinence, involuntary emotional expression disorder, and pseudobulbar affect).

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, assessed risk of bias, extracted data from all included trials, and used GRADE to assess the certainty of the body of evidence. We calculated the mean difference (MD) or standardised mean difference (SMD) for continuous data and the risk ratio (RR) for dichotomous data, with 95% confidence intervals (CIs). We assessed heterogeneity using the I2 statistic. The primary emotionalism measures were the proportion of participants achieving at least a 50% reduction in abnormal emotional behaviour at the end of treatment, improved score on the Center for Neurologic Study - Lability Scale (CNS-LS) or Clinician Interview-Based Impression of Change (CIBIC), or diminished tearfulness.

MAIN RESULTS

We did not identify any new trials for this update. We included seven trials with a total of 239 participants. Two trials had a cross-over design, but outcome data were not available from the first phase (precross-over) in an appropriate format for inclusion as a parallel randomised controlled trial (RCT). Thus, the results of the review are based on five trials with a total of 213 participants. It is uncertain whether fluoxetine increases the number of people who have a 50% reduction in emotionalism when compared to placebo (risk ratio (RR) 0.26, 95% CI 0.09 to 0.77; P = 0.02; 1 trial, 19 participants) because the certainty of evidence is very low. Sertraline may lead to little to no difference in Center for Neurologic Study - Lability Scale (CNS-LS) scores and Clinician Interview-Based Impression of Change (CIBIC) scores when compared to placebo (RR 0.20, 95% CI 0.03 to 1.50; P = 0.12; 1 trial, 28 participants; low-certainty evidence). Antidepressants probably increase the number of people who experience a reduction in tearfulness (RR 0.32, 95% CI 0.12 to 0.86; P = 0.02; 3 trials, 164 participants; moderate-certainty evidence). No trials were found that evaluated the impact of other pharmaceutical interventions. Only two trial authors systematically recorded and reported adverse events, resulting in limited data on the potential harms of treatment. Six trials reported death as an adverse event and found no difference between the groups (antidepressants versus placebo) in the number of deaths reported (RR 0.59, 95% CI 0.08 to 4.50; P = 0.61; 172 participants; moderate-certainty evidence). This review provides very low- to moderate-certainty evidence that antidepressants may reduce the frequency and severity of emotionalism. The included trials were small and had some degree of bias.

AUTHORS' CONCLUSIONS

Antidepressants may reduce the frequency and severity of crying or laughing episodes when compared to placebo, based on very low-certainty evidence. Our conclusions must be qualified by several methodological deficiencies in the trials and interpreted with caution despite the effect being very large. The effect does not seem specific to one drug or class of drugs. More reliable data are required before appropriate conclusions can be made about the treatment of post-stroke emotionalism. Future trialists investigating the effect of antidepressants in people with emotionalism after stroke should consider developing and using a standardised method to diagnose emotionalism, determine severity, and assess change over time; provide treatment for a sufficient duration and follow-up to better assess rates of relapse or maintenance; and include careful assessment and complete reporting of adverse events.

Risks and benefits of current and novel drugs to treat agitation in Alzheimer's disease

INTRODUCTION

At present, no pharmacological interventions have been approved for the treatment of agitation in Alzheimer's disease (AD), an important neuropsychiatric symptom that has been linked to increased mortality and greater caregiver burden. Antipsychotics offer some benefit, but increase the risk of adverse events such as falls, extrapyramidal symptoms, stroke, and mortality. Over the past 10 years, several new and repurposed medications have shown promise for treating AD-associated agitation.

AREAS COVERED

We review the risks and benefits of emerging therapies for agitation in AD, which include newer atypical antipsychotics, selective serotonin reuptake inhibitors, cannabinoids, and dextromethorphan combination products. Other drugs such as mirtazapine, prazosin, and lithium are also discussed. Clinicaltrials.gov, PubMed/MEDLINE, EMBASE and Cochrane Central databases were searched for relevant studies from 1 January 2012 to 1 May 2022.

EXPERT OPINION

At the present time, there are no pharmacological interventions for the treatment of agitation in AD whose benefits clearly outweigh their potential safety concerns. Therefore, management of agitation in AD should primarily be based on non-pharmacological approaches. When medications are considered necessary, they should only be initiated with the caregiver's appreciation of their risks and benefits and with careful and ongoing assessment of their safety.

AVP-786 as a promising treatment option for Alzheimer's Disease including agitation

INTRODUCTION

To date, there is no FDA-approved treatment for agitation in Alzheimer's disease (AD). Medications currently used off-label have modest clinical efficacy and serious side effects.

AREAS COVERED

The authors review the pharmacology, mechanism of action, pharmacokinetics, efficacy, safety and tolerability data of AVP-786, for the treatment of agitation in AD.

EXPERT OPINION

AVP-786, the deuterated form of dextromethorphan/quinidine (AVP-923) which is an approved treatment for Pseudo-Bulbar Affect, emerges as a promising and safe treatment for agitation in AD. Deuteration is an innovative technology that accelerates drug development by conducting faster and less costly clinical trials. No phase II trial was conducted with AVP-786 for the treatment of agitation in AD; the decision to expedite the development of this drug was based on a successful phase II study with AVP-923. Phase III trials with AVP-786 (TRIAD-1 and TRIAD-2) showed mixed findings probably due to the difference in study design. Future phase III studies should use innovative study designs such as the Sequential Parallel Comparison Design to mitigate high placebo response, and the Cohen-Mansfield Agitation Inventory for agitation assessment. They should also include positron emission tomography studies to assess occupancy of various receptors in the brain after AVP-786 is administered.

Treatment of pseudobulbar affect in a mixed neurodegenerative disorder with compounded quinidine capsules and dextromethorphan cough syrup

An elderly woman admitted in our geriatric inpatient unit suffered from disturbing outbursts of crying and, less frequently, episodes of laughing. The patient was diagnosed with pseudobulbar affect related to a mixed neurodegenerative disorder. This condition is often underdiagnosed and undertreated, despite being relatively frequent in patients with neurodegenerative disorders. This case report describes the treatment of pseudobulbar affect in this patient. The only available treatment in Canada for this condition, antidepressants, was not effective for our patient. Dextromethorphan/quinidine is a good accepted alternative, but the combination is not marketed in Canada. To manage this problem, we used compounded quinidine capsules and dextromethorphan cough syrup. The crying of our patient improved significantly and rapidly after the initiation of this treatment. This case will help professionals to review their central role in treating this complex and disabling condition.

Pharmacotherapy for the Pseudobulbar Affect in Individuals Who Have Sustained a Traumatic Brain Injury: a Systematic Review

Pseudobulbar affect is a debilitating condition that significantly reduces quality of life for many individuals following traumatic brain injury (TBI). It is characterized by embarrassing and often uncontrollable episodes of crying or laughter. The aim of this systematic review was to evaluate the effectiveness of pharmacotherapy as compared to all other comparators for the management of pseudobulbar affect in adults who have sustained TBI. Six databases were searched, with additional hand searching of journals, clinical trials registries and international drug regulators to identify published and unpublished studies in English up to June 2018. Studies were eligible for this review if they included adults who had sustained a medically confirmed TBI and presented with pseudobulbar affect. All pharmacotherapy and comparator interventions were considered for inclusion, and study design was not limited to randomised controlled trials. Evidence quality was assessed using Joanna Briggs Institute Critical Appraisal Instruments. Two quasi-experimental studies examining the effectiveness of dextrometamorphan/quinidine (DM/Q) were identified. These studies reported that DM/Q was effective in reducing symptoms of pseudobulbar affect and had a positive safety profile, over follow-up periods of 3 months (n = 87) and 12 months (n = 23). However, both studies were limited by lack of a control group and a high dropout rate. The findings of twelve case reports examining the effectiveness of DM/Q (n = 6) and anti-depressants (n = 6) are also discussed. Further research is required to determine which pharmacological interventions provide the best outcomes for individuals with pseudobulbar affect following TBI, with consideration given to side effect profiles and financial costs.

Pathological Crying and Laughing in Motor Neuron Disease: Pathobiology, Screening, Intervention

Pathological crying and laughing (PCL) has significant quality-of-life implications in amyotrophic lateral sclerosis (ALS); it can provoke restrictive life-style modifications and lead to social isolation. Despite its high prevalence and quality of life implications, it remains surprisingly understudied. Divergent pathophysiological models have been proposed, centered on corticobulbar tract degeneration, prefrontal cortex pathology, sensory deafferentation, and impaired cerebellar gate-control mechanisms. Quantitative MRI techniques and symptom-specific clinical instruments offer unprecedented opportunities to elucidate the anatomical underpinnings of PCL pathogenesis. Emerging neuroimaging studies of ALS support the role of cortico-pontine-cerebellar network dysfunction in context-inappropriate emotional responses. The characterization of PCL-associated pathophysiological processes is indispensable for the development of effective pharmacological therapies.

Pseudobulbar Affect in Parkinsonian Disorders: A Review

Pseudobulbar affect (PBA) is a neurological symptom of inappropriate and uncontrollable laughter or crying that occurs secondary to a variety of neurological conditions, including parkinsonian disorders. PBA is a socially and emotionally debilitating symptom that has been estimated to affect 3.6% to 42.5% of the population with Parkinson's disease. While indexing measures and treatment options for PBA have been extensively studied in neurological conditions such as amyotrophic lateral sclerosis and multiple sclerosis, there has been considerably less attention given in the literature to PBA in parkinsonian disorders. The purpose of this review is to discuss the pathophysiology of PBA, its prevalence and impact on quality of life in parkinsonian disorders, and the treatment options currently available. Areas requiring further study, including the development of standardized, cross-culturally validated methods of symptom assessment, and evidence-based studies exploring the efficacy of current treatment options in parkinsonian disorders, are also highlighted.

Pharmacotherapy for the pseudobulbar affect in individuals who have sustained a traumatic brain injury: a systematic review protocol

REVIEW OBJECTIVE/QUESTION

The objective of this systematic review is to synthesize current evidence on the effectiveness of pharmacotherapy as compared to all comparators for the management of pseudobulbar affect in adults 16 years and over who have sustained a traumatic brain injury. The specific review question is: What is the effectiveness of pharmacotherapy for the management of pseudobulbar affect in adults 16 years and over who have sustained a traumatic brain injury?

Altered resting-state functional activity in isolated pontine infarction patients with pathological laughing and crying

We used resting-state functional magnetic resonance imaging to investigate the global spontaneous neural activity involved in pathological laughing and crying after stroke. Twelve pathological laughing and crying patients with isolated pontine infarction were included, along with 12 age- and gender-matched acute isolated pontine infarction patients without pathological laughing and crying, and 12 age- and gender-matched healthy controls. We examined both the amplitude of low-frequency fluctuation and the regional homogeneity in order to comprehensively evaluate the intrinsic activity in patients with post-stroke pathological laughing and crying. In the post-stroke pathological laughing and crying group, changes in these measures were observed mainly in components of the default mode network (medial prefrontal cortex/anterior cingulate cortex, middle temporal gyrus, inferior temporal gyrus, superior frontal gyrus, middle frontal gyrus and inferior parietal lobule), sensorimotor network (supplementary motor area, precentral gyrus and paracentral lobule), affective network (medial prefrontal cortex/anterior cingulate cortex, parahippocampal gyrus, middle temporal gyrus and inferior temporal gyrus) and cerebellar lobes (cerebellum posterior lobe). We therefore speculate that when disinhibition of the volitional system is lost, increased activation of the emotional system causes pathological laughing and crying.

AVP-786 for the treatment of agitation in dementia of the Alzheimer's type

INTRODUCTION

Agitation is common and distressing in patients with Alzheimer-type dementia, but safe, effective treatments remain elusive. Psychological treatments are first-line options, but they have limited efficacy. Off-label psychotropic medications are frequently used, but they also have limited effectiveness, and their use may have harmful side effects, including death. Areas covered: This review discusses the history leading to the conception of AVP-786 (deuterated (d6)-dextromethorphan/quinidine), its pharmacokinetic and pharmacodynamic profiles and safety issues, together with an overview of recent clinical trials. Data were found in the medical literature, in US and EU clinical trial registries and in information provided by the manufacturer. Expert opinion: AVP-786 is one of six investigational compounds in recent phase III clinical development for agitation in Alzheimer disease (AD). Quinidine and deuteration appear to prolong dextromethorphan's plasma half-life and facilitate brain penetration. The FDA granted fast-track designation to AVP-786 and allowed use of data generated on dextromethorphan-quinidine (AVP-923, Nuedexta®) for regulatory filings. AVP-923 reduced agitation in AD and was well tolerated in a phase II RCT that included more than 200 patients. A phase III clinical development program of AVP-786 for AD agitation was recently initiated. This program is expected to start generating results in July 2018.

Cutaneous Adverse Effects of Neurologic Medications

Life-threatening and benign drug reactions occur frequently in the skin, affecting 8 % of the general population and 2-3 % of all hospitalized patients, emphasizing the need for physicians to effectively recognize and manage patients with drug-induced eruptions. Neurologic medications represent a vast array of drug classes with cutaneous side effects. Approximately 7 % of the United States (US) adult population is affected by adult-onset neurological disorders, reflecting a large number of patients on neurologic drug therapies. This review elucidates the cutaneous reactions associated with medications approved by the US Food and Drug Administration (FDA) to treat the following neurologic pathologies: Alzheimer disease, amyotrophic lateral sclerosis, epilepsy, Huntington disease, migraine, multiple sclerosis, Parkinson disease, and pseudobulbar affect. A search of the literature was performed using the specific FDA-approved drug or drug classes in combination with the terms 'dermatologic,' 'cutaneous,' 'skin,' or 'rash.' Both PubMed and the Cochrane Database of Systematic Reviews were utilized, with side effects ranging from those cited in randomized controlled trials to case reports. It behooves neurologists, dermatologists, and primary care physicians to be aware of the recorded cutaneous adverse reactions and their severity for proper management and potential need to withdraw the offending medication.

Dextromethorphan: An update on its utility for neurological and neuropsychiatric disorders

Dextromethorphan (DM) is a commonly used antitussive and is currently the only FDA-approved pharmaceutical treatment for pseudobulbar affect. Its safety profile and diverse pharmacologic actions in the central nervous system have stimulated new interest for repurposing it. Numerous preclinical investigations and many open-label or blinded clinical studies have demonstrated its beneficial effects across a variety of neurological and psychiatric disorders. However, the optimal dose and safety of chronic dosing are not fully known. This review summarizes the preclinical and clinical effects of DM and its putative mechanisms of action, focusing on depression, stroke, traumatic brain injury, seizure, pain, methotrexate neurotoxicity, Parkinson's disease and autism. Moreover, we offer suggestions for future research with DM to advance the treatment for these and other neurological and psychiatric disorders.

Neuronal Dysregulation in Stroke-Associated Pseudobulbar Affect (PBA): Diagnostic Scales and Current Treatment Options

Until recently there was little understanding of the exact pathophysiology and treatment choices for stroke patients with Pseudobulbar affect (PBA). PBA is typically characterized by outbursts or uncontrollable laughing or crying and in the majority of patients, the outbursts being involuntary and incompatible with the patients' emotional state. PBA is a behavioral syndrome reported to be displayed in 28-52% of stroke patients with first or multiple strokes, and incidence may be higher in patients who have had prior stroke events, and higher in females. There is typically involvement of glutaminergic, serotoninergic and dopaminergic neuronal circuits of the corticolimbic-subcorticothalamic-pontocerebellar network. PBA is now understood to be a disinhibition syndrome in which specific pathways involving serotonin and glutamate are disrupted or modulated causing reduced cortical inhibition of a cerebellar/brainstem-situated "emotional" laughing or crying focal center. Stroke-induced disruption of one or more neuronal pathway circuits may "disinhibit" voluntary laughing and crying making the process involuntary. With a "new" treatment currently being marketed to treat PBA patients, this article will delve into the neurological and physiological basis for PBA in stroke, and review progress with the diagnosis and treatment of PBA.