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Introduction: Major Depressive Disorder (MDD) is a common mental health disorder marked by sadness, hopelessness, and anhedonia. Various therapies exist, but their effectiveness is limited. Dextromethorphan hydrobromide combined with bupropion hydrochloride (Auvelity®) is a recently approved alternative for treating this condition in adults., Areas Covered: This review summarizes the neurobiology of major depression and delves into the pharmacology, efficacy, safety, and tolerability of dextromethorphan plus bupropion in adult patients. It is based on observational studies, clinical trials, and other secondary studies obtained through systematic literature searches., Expert Opinion: The combination of bupropion and dextromethorphan as a new pharmacotherapy for mental health is an interesting addition to the treatment options that can be used for MDD. The combination can be used in a range of scenarios, including as a first line therapy, as a second option when a patient has failed to achieve remission with a serotonin targeting agent, and for treatment resistant depression. Further research for other indications, including addiction disorders, may provide exciting results. Although a new combination, clinicians will be very familiar with both agents, increasing their acceptability. This pharmacotherapy also may bring increased impetus for discovering other combinations that may have beneficial synergistic effects.

Background: Therapeutic latency, lack of efficacy and adverse drug reactions are the major concerns in current antidepressant therapies. To overcome these treatment hurdles, add-on therapy to conventional antidepressant medications may lead to better therapeutic outcomes. The present randomised controlled trial has been planned to evaluate the efficacy and safety of add-on dextromethorphan to selective serotonin reuptake inhibitors (SSRIs) in major depressive disorder (MDD)., Methods and Analysis: A randomised, double-blind, add-on, placebo-controlled, group sequential design clinical trial will be conducted on patients with MDD who will be randomly assigned to the control and the test group in a 1:1 ratio. Patients in the test group will get dextromethorphan 30 mg once daily, whereas patients in the control group will receive a placebo once daily as an add-on to ongoing SSRI treatment for 8 weeks. All patients will be evaluated for the primary outcome (change in the Montgomery-Åsberg Depression Rating Scale score) and secondary outcomes (treatment response rate, remission rate, Clinical Global Impression, serum brain-derived neurotrophic factor, serum dextromethorphan and treatment-emergent adverse events) over the period of 8 weeks. Intention-to-treat analysis will be done for all parameters using suitable statistical tools., Ethics and Dissemination: This study was approved by the Institutional Ethics Committee of All India Institute of Medical Sciences, Bhubaneswar, India, and the study conformed to the provisions of the Declaration of Helsinki and ICMR's ethical guidelines for biomedical research on human subjects (2017). Written informed consent will be obtained from the participants before recruitment. The results of this study will be published in peer-reviewed publications., Trial Registration Number: NCT05181527., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Aim: We aim to describe the behavioral phenotype of children and adolescents with the good to intermediate attenuated form of non-ketotic hyperglycinemia (NKH) and to explore associations between the behavioral phenotype and age, sex, plasma glycine levels and drug treatment., Method: Parents of children with attenuated NKH completed questionnaires assessing maladaptive behavior, adaptive behavior, social communication, speech/language development and motor development in addition to demographic and medical questions., Results and Interpretation: Twelve children, age 6 to 21y, functioned at mild to severe intellectual disability levels. Their speech/language development was in line with their developmental quotient. Relative to their intellectual functioning, their motor development and communication were weaker in comparison to their general development. Their adaptive behavior, however, appeared a relative strength. There was no evidence for autism spectrum disorder occurring more frequently than expected, rather social skills, except for communication, were rated as a relative strength. Maladaptive behaviors with ADHD-like characteristics were present in more than two thirds of children. Maladaptive behaviors were significantly related to female sex and to taking dextromethorphan, but no significant relation between plasma glycine levels and behavior was found. Future studies will need to evaluate causality in the observed relation between dextromethorphan use and maladaptive behaviors. Clinicians should reconsider the benefit of dextromethorphan when presented with disruptive behaviors in children with attenuated NKH., (© 2024. The Author(s).)

For treatment of type 1 diabetes mellitus, a combination of immune-based interventions and medication to promote beta-cell survival and proliferation has been proposed. Dextromethorphan (DXM) is an N -methyl-D-aspartate receptor antagonist with a good safety profile, and to date, preclinical and clinical evidence for blood glucose-lowering and islet-cell-protective effects of DXM have only been provided for animals and individuals with type 2 diabetes mellitus. Here, we assessed the potential anti-diabetic effects of DXM in the non-obese diabetic mouse model of type 1 diabetes. More specifically, we showed that DXM treatment led to five-fold higher numbers of pancreatic islets and more than two-fold larger alpha- and beta-cell areas compared to untreated mice. Further, DXM treatment improved glucose homeostasis and reduced diabetes incidence by 50%. Our data highlight DXM as a novel candidate for adjunct treatment of preclinical or recent-onset type 1 diabetes., Competing Interests: A.W., T.M., E.M. and E.L. declare the following competing financial interests: these authors are inventors of the US patent 10,464,904 entitled “Dextrorphan-derivatives with suppressed central nervous activity”; and T.M. and E.L. are inventors of the US patent 9,370,511 entitled “Morphinan-derivatives for treating diabetes and related disorders.”, (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial-License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/).)

Nuedexta is a combination of dextromethorphan hydrobromide and quinidine sulfate and was approved by the Food and Drug Administration (FDA) in 2010 to treat pseudobulbar affect (PBA). There have since been anecdotal case reports of bulbar function improvements after Nuedexta treatment. Here, we review the off-label use of Nuedexta for improving bulbar function in people with ALS. Nuedexta has plausible mechanisms for protecting brain stem motor neurons via its effects on S1R and glutamate excitotoxicity. Recent clinical trials support that Nuedexta can improve bulbar function in PALS, with or without PBA. Nuedexta causes mild to moderate side effects. Based on this information, we support considering Nuedexta treatment for bulbar dysfunction in ALS patients with or without PBA.

Background: Major depressive disorder (MDD) affects millions of people and is the leading cause of disability worldwide. Patients report decreased quality of life and ability to perform activities of daily living. It is estimated that the current standard of care, which includes pharmacologic therapy with a selective serotonin reuptake inhibitor, is effective in 40%-60%. Additional treatment options are warranted. The combination of dextromethorphan (DEX) and bupropion (BUP) (Auveulty) was approved for treatment in 2022. This unique combination offers an interesting mechanism of action and favorable onset of action for patients with MDD., Pharmacodynamics and Pharmacokinetics: The mechanism of action of DEX-BUP when used in combination is unique. DEX is a noncompetitive N-methyl-d-aspartate receptor antagonist rapidly metabolized through the CYP450 2D6. BUP is an aminoketone and CYP2D6 inhibitor, which results in increased plasma levels of DEX through competitive CYP2D6 inhibition., Clinical Trials: In a phase 2 clinical study, the efficacy of DEX-BUP was compared with BUP alone in patients with clinically diagnosed MDD. At baseline, participants had moderate-to-severe depression using the Montgomery-Asberg Depression Rating Scale (MADRS) and Clinical Global Impressions Severity (CGI-S) scales. There was a significant overall reduction in MADRS and CGI-S scores in the treatment group compared with the BUP monotherapy with improvement observed as early as week 1 of treatment. Later, a phase 3 study was conducted comparing DEX-BUP 45 mg/105 mg with placebo in patients with moderate-to-severe MDD. Similarly, MADRS and CGI-S scores were significantly reduced in the treatment group. Adverse effects were similar in all groups., Therapeutic Advance: Clinical response to first line treatment options for MDD are reported to be 40%-60%. Availability of additional treatment options, particularly those with reduced time to efficacy, may improve overall treatment and patient quality of life. DEX-BUP is a combination option that has been shown to improve depression symptoms as early as 1 week after initiation., Competing Interests: The authors have no conflicts of interest to declare., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Accumulating evidence supports the use of higher doses of rifampicin for tuberculosis (TB) treatment. Rifampicin is a potent inducer of metabolic enzymes and drug transporters, resulting in clinically relevant drug interactions. To assess the drug interaction potential of higher doses of rifampicin, we compared the effect of high-dose rifampicin (40 mg/kg daily, RIF40) and standard-dose rifampicin (10 mg/kg daily, RIF10) on the activities of major cytochrome P450 (CYP) enzymes and P-glycoprotein (P-gp). In this open-label, single-arm, two-period, fixed-order phenotyping cocktail study, adult participants with pulmonary TB received RIF10 (days 1-15), followed by RIF40 (days 16-30). A single dose of selective substrates (probe drugs) was administered orally on days 15 and 30: caffeine (CYP1A2), tolbutamide (CYP2C9), omeprazole (CYP2C19), dextromethorphan (CYP2D6), midazolam (CYP3A), and digoxin (P-gp). Intensive pharmacokinetic blood sampling was performed over 24 hours after probe drug intake. In all, 25 participants completed the study. Geometric mean ratios (90% confidence interval) of the total exposure (area under the concentration versus time curve, RIF40 versus RIF10) for each of the probe drugs were as follows: caffeine, 105% (96%-115%); tolbutamide, 80% (74%-86%); omeprazole, 55% (47%-65%); dextromethorphan, 77% (68%-86%); midazolam, 62% (49%-78%), and 117% (105%-130%) for digoxin. In summary, high-dose rifampicin resulted in no additional effect on CYP1A2, mild additional induction of CYP2C9, CYP2C19, CYP2D6, and CYP3A, and marginal inhibition of P-gp. Existing recommendations on managing drug interactions with rifampicin can remain unchanged for the majority of co-administered drugs when using high-dose rifampicin. Clinical Trials registration number NCT04525235., Competing Interests: The authors declare no conflict of interest.

Objective: To determine objective and subjective endpoints most suitable for evaluating antitussive efficacy of dextromethorphan hydrobromide (DXM) in children. Spontaneous resolution of acute cough and large placebo effects are impediments to evaluating antitussive efficacy. Another impediment is paucity of age-appropriate, validated cough assessment tools., Methods: This was a multiple-dose, double-blind, placebo-controlled, randomized, pilot clinical study in children, aged 6-11 years, with cough due to the common cold. Eligible subjects met entry criteria and qualified by completing a run-in period where coughs were recorded with a cough monitor after they were dosed with sweet syrup. They were subsequently randomized to receive DXM or placebo over 4 days. Coughs were recorded during the initial 24 h; subjective assessments of cough severity and frequency were self-reported daily during treatment., Results: Data from 128 evaluable subjects (67 DXM; 61 placebo) were analyzed. Total coughs over 24-hours (primary endpoint) and cough frequency during daytime were reduced by 21.0% and 25.5%, respectively, with DXM relative to placebo. Also, greater reductions in cough severity and frequency were self-reported with DXM. These findings were statistically significant and medically relevant. No effects were detected between treatments for nighttime cough rates or impact of cough on sleep. Multiple doses of DXM and placebo were generally well-tolerated., Conclusion: Evidence of DXM antitussive efficacy was shown in children using objective and subjective assessment tools validated in pediatric populations. Diurnal variation of cough frequency over 24 h reduced the assay sensitivity needed to detect treatment differences at nighttime, as coughs/hour decreased during sleep for both groups., (© 2023 Consumer Healthcare Products Association. Pediatric Pulmonology published by Wiley Periodicals LLC.)

Objective: No efficacious treatments exist to improve or prolong bulbar functions of speech and swallowing in persons with amyotrophic lateral sclerosis (pALS). This study evaluated the short-term impact of dextromethorphan/quinidine (DMQ) treatment on speech and swallowing function in pALS., Methods: This was a cohort trial conducted between August 2019 to August 2021 in pALS with a confirmed diagnosis of probable-definite ALS (El-Escorial Criteria-revisited) and bulbar impairment (ALS Functional Rating Scale score ≤ 10 and speaking rate ≤ 140 words per minute) who were DMQ naïve. Efficacy of DMQ was assessed via pre-post change in the ALS Functional Rating Scale-Revised bulbar subscale and validated speech and swallowing outcomes. Paired t-tests, Fisher's exact, and χ 2 tests were conducted with alpha at 0.05., Results: Twenty-eight pALS enrolled, and 24 participants completed the 28-day trial of DMQ. A significant increase in ALSFRS-R bulbar subscale score pre- (7.47 ± 1.98) to post- (8.39 ± 1.79) treatment was observed (mean difference: 0.92, 95% CI: 0.46-1.36, p < 0.001). Functional swallowing outcomes improved, with a reduction in unsafe (75% vs. 44%, p = 0.003) and inefficient swallowing (67% vs. 58%, p = 0.002); the relative speech event duration in a standard reading passage increased, indicating a greater duration of uninterrupted speech (mean difference: 0.33 s, 95% CI: 0.02-0.65, p = 0.035). No differences in diadochokinetic rate or speech intelligibility were observed (p > 0.05)., Interpretation: Results of this study provide preliminary evidence that DMQ pharmacologic intervention may have the potential to improve or maintain bulbar function in pALS., (© 2023 The Authors. Annals of Clinical and Translational Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.)

Dextromethorphan (DXM) was introduced in 1958 as the first non-opioid cough suppressant and is indicated for multiple psychiatric disorders. It has been the most used over-the-counter cough suppressant since its emergence. However, individuals quickly noticed an intoxicating and psychedelic effect if they ingested large doses. DXM's antagonism at N -methyl-d-aspartate receptors (NMDAr) is thought to underly its efficacy in treating acute cough, but supratherapeutic doses mimic the activity of dissociative hallucinogens, such as phencyclidine and ketamine. In this Review we will discuss DXM's synthesis, manufacturing information, drug metabolism, pharmacology, adverse effects, recreational use, abuse potential, and its history and importance in therapy to present DXM as a true classic in chemical neuroscience.

Background and Objective: Cough is invariably encountered during flexible bronchoscopy despite sedation and topical anaesthetics. The ideal cough suppressant during flexible bronchoscopy is not known. We assessed the role of dextromethorphan premedication in relieving the cough during flexible bronchoscopy in adults., Methods: In this single-centre study, we randomized patients aged ≥18 years to receive dextromethorphan syrup 30 ml (90 mg) or an equal volume of placebo 1 h before the procedure. Patients rated their cough severity and discomfort on a visual analogue scale at the end of the procedure. Bronchoscopists also rated cough severity at the end of the procedure., Results: Out of 112 patients screened, 94 patients (median (interquartile range [IQR]) age 51 (36.25-60.75) years, male: female 2.13:1) were randomized to either the dextromethorphan (n = 47) or placebo (n = 47) groups. The patients-rated median (IQR) cough scores at the end of the procedure were 15 (10-23) mm in dextromethorphan versus 20 (12-45.5) mm in placebo groups (p = 0.03). Patients-rated median cough scores at 1 h (5 mm vs. 6 mm, p = 0.21), discomfort scores (12.5 mm vs. 12.5 mm, p = 0.49), and midazolam and lignocaine usage were similar between the two groups. The bronchoscopist-rated median cough score was non-significantly lower in the intervention compared to the placebo (26 mm vs. 35 mm, p = 0.09) groups., Conclusion: Dextromethorphan premedication 1 h before flexible bronchoscopy may have an additive effect on cough suppression under conscious sedation and topical lignocaine. Further trials are needed to reiterate our findings with certainty., (© 2023 Asian Pacific Society of Respirology.)

Auvelity, an extended-release fixed combination of dextromethorphan and bupropion, is approved for the treatment of major depressive disorder in adults.Like all antidepressants, dextromethorphan-bupropion carries a boxed warning that it may increase the risk of suicidal thoughts and behaviors in pediatric and young adult patients. Seizures can also occur and are more likely at higher doses.The most common adverse effects of dextromethorphan-bupropion include dizziness, nausea, headache, diarrhea, somnolence, dry mouth, sexual dysfunction, hyperhidrosis, anxiety, constipation, decreased appetite, and insomnia., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Despite the frequent use of symptomatic therapies in cough, evidence of their benefits is lacking., Objective: We compared the effectiveness of 3 symptomatic therapies and usual care in acute bronchitis., Methods: Multicenter, pragmatic, multiarm parallel group, open randomized trial in primary care (ClinicalTrials.gov, Identifier: NCT03738917) was conducted in Catalonia. Patients ≥18 with uncomplicated acute bronchitis, with cough<3 weeks as the main symptom, scoring ≥4 in either daytime or nocturnal cough (7-point Likert scale), were randomized to usual care, dextromethorphan 15 mg t.i.d., ipratropium bromide inhaler 20 µg 2 puffs t.i.d, or 30 mg of honey t.i.d., all taken for up to 14 days. The main outcome measure was the number of days with moderate-to-severe cough. A symptom diary was given. A second visit was scheduled at days 2-3 for assessing evolution, with 2 more visits at days 15 and 29 for clinical assessment, evaluation of adverse effects, re-attendance, and complications., Results: We failed to achieve the sample size scheduled due to the COVID-19 pandemic. We finally recruited 194 patients. The median number of days with moderate-to-severe cough (score ≥ 3) in the usual care arm was 5 (interquartile range [IQR], 4, 8.75), 5 in the ipratropium bromide arm (IQR, 3, 8), 5 in the dextromethorphan arm (IQR, 4, 9.75), and 6 in the honey arm (IQR, 3.5, 7). The same results were obtained in the Kaplan-Meier survival analysis for the median survival time of each arm with the usual care as the reference group., Conclusion: The symptomatic treatment evaluated has shown to be ineffective against cough., (© The Author(s) 2022. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Introduction: Major depressive disorder (MDD) is one of the leading causes of disability worldwide. However, many patients do not achieve an adequate clinical improvement with pharmacotherapies targeting monoamine receptors, and the onset of therapeutic benefit typically lags by 4-6 weeks. There is a significant need for mechanistically novel treatments with more rapid efficacy. Combinations of dextromethorphan, an oral N-methyl-D-aspartate (NMDA) receptor antagonist, can potentially fill this gap., Areas Covered: US Clinical Trials registration was systematically searched for studies examining the effects of dextromethorphan in mood disorders. Results were gathered via a PubMed search, adding also press releases, and poster presentations. Two case reports and eight clinical trials were identified for the treatment of MDD or treatment resistant depression (TRD); we also reviewed additional studies in bipolar disorder., Expert Opinion: Clinical studies show that the combinations of dextromethorphan with quinidine or bupropion have been effective in decreasing depressive symptomatology in MDD. However, dextromethorphan studies in adults with TRD or with bipolar depression have shown mixed results. The combination of dextromethorphan and bupropion is a well-tolerated, safe, and efficacious treatment option for adults with MDD. Additional studies analyzing the effects of dextromethorphan and bupropion for TRD and bipolar depression are needed.

Objectives: To evaluate efficacy and satisfaction of dextromethorphan as a non-narcotic adjuvant to current analgesic regimens for medication abortion., Study Design: We conducted a randomized, double-blinded, placebo-controlled trial. We randomized eligible participants (N = 156) 1:1 to adjunctively take dextromethorphan (loading dose 60 mg and two subsequent 30 mg doses at 2 and 5 hours after misoprostol administration) or placebo combined with usual-care nonsteroidal anti-inflammatory medications ± opioids for pain. Participants reported pain scores and satisfaction using a secure texting application at 2, 5, 8, and 24 hours after misoprostol administration. Our primary outcome was worst pain score and total analgesic use., Results: Baseline demographics of enrolled participants were similar between randomization arms. Worst pain scores for participants receiving dextromethorphan versus placebo (8.0 vs 7.0, p = 0.06) did not differ. Total milligram usage of ibuprofen (800 mg vs 610 mg, p =.62), acetaminophen (1000 mg vs 1300 mg, p = 0.62), and opioids (10 mg vs 15 mg, p = 0.51) did not differ between the randomization groups. Participants randomized to placebo were significantly more likely to be satisfied with their pain control (91% vs 75%, p = 0.02)., Conclusion: Dextromethorphan used adjunctively with standard analgesics did not reduce pain associated with medication abortion. Participants who received dextromethorphan reported decreased satisfaction with their pain control., Implications: Dextromethorphan used adjunctively with commonly used analgesic regimens did not reduce medication abortion associated pain. Many participants did not use analgesics as counseled, and nearly 25% used no analgesia during medication abortion., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Glioblastoma multiforme is the most common malignant primary brain tumor in adults. Despite new treatments developed including immunomodulation using vaccines and cell therapies, mortality remains high due to the resistance mechanisms presented by these tumor cells and the function of the blood-brain barrier that prevents the entry of most drugs. In this context of searching for new glioblastoma therapies, the study of the existing drugs to treat neurological disorder is gaining great relevance. The aim of this study was to determine, through a preliminary in vitro study on human glioblastoma (A172, LN229), anaplastic glioma (SF268) and neuroblastoma (SK-N-SH) cell lines, the possible antitumor activity of the active principles of several drugs (levomepromazine, haloperidol, lacosamide, valproic acid, levetiracetam, glatiramer acetate, fingolimod, biperiden and dextromethorphan) with the ability to cross the blood-brain barrier and that are commonly used in neurological disorders. Results showed that levetiracetam, valproic acid, and haloperidol were able to induce a relevant synergistic antitumor effect when associated with the chemotherapy currently used in clinic (temozolomide). Regarding the mechanism of action, haloperidol, valproic acid and levomepromazine caused cell death by apoptosis, while biperiden and dextromethorphan induced autophagy. Fingolimod appeared to have anoikis-related cell death. Thus, the assayed drugs which are able to cross the blood-brain barrier could represent a possibility to improve the treatment of neural tumors, though future in vivo studies and clinical trials will be necessary to validate it., (© 2022. The Author(s).)

Dextromethorphan (DXM) has been re-purposed several times over the past 7 decades: first as a cough suppressant, then as a compounded formulation with quinidine for treatment of pseudobulbar affect, and most recently as a compounded formulation with bupro-pion for treatment of major depressive disorder. The current article describes the history and purported mechanisms of action of DXM for each use and the uniquely rapid action and safety profile of the oral dextromethorphan- bupropion antidepressant formulation. [ Journal of Psychosocial Nursing and Mental Health Services, 60 (11), 9-11.].

An oral, fixed-dose combination of dextromethorphan hydrobromide [an uncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist and sigma-1 receptor agonist] and the antidepressant bupropion hydrochloride (an aminoketone and CYP2D6 inhibitor that increases dextromethorphan bioavailability) [AUVELITY TM ; dextromethorphan/bupropion], is being developed by Axsome Therapeutics, Inc. for the treatment of major depressive disorder (MDD), Alzheimer's disease agitation and smoking cessation. Dextromethorphan/bupropion was approved in the USA in August 2022 for the treatment of MDD in adults. This article summarizes the milestones in the development of dextromethorphan/bupropion leading to this first approval for the treatment of adults with MDD., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Introduction: Cough is one of the most common presenting symptoms of COVID-19, which can persist for weeks or months., Objective: The goal of this study was to evaluate the effectiveness of gabapentin (GBT) alone and in combination with montelukast (MTL) for improving cough., Methods: In this open-label randomized controlled clinical trial, eligible cases were patients hospitalized with moderate to severe COVID-19 who had cough with a Breathlessness, Cough, and Sputum Scale (BCSS) score of at least 2 based on its cough subscale. The participants were randomly assigned to three groups including two experimental groups and one control group. The first and second experimental groups received GBT and GBT/MTL, respectively, whereas the control group received dextromethorphan (DXM). Treatment duration was 5 days in all groups. Before and after the interventions, the severity of cough was evaluated using BCSS scale and Visual Analog Scale (VAS)., Results: A total of 180 patients were included; GPT, GPT/MTL, and DXM consisted of 76, 51, and 53 patients, respectively. There was no significant difference between the three groups in terms of age, gender, and comorbidities (P > 0.05). Regarding BCSS and VAS scores, there was significant reduction from the baseline values in all groups (P < 0.0001), with the change rate being significantly higher in DXM group. The amount of reduction of BCSS in the GPT/MTL group was significantly more than the GPT group, whereas there was no significant difference between the two groups regarding VAS score. Although the duration of hospitalization differed between the groups with the GPT/MTL group having the shortest duration, the difference was statistically significant only between the GPT and GPT/MTL groups (P < 0.0001)., Conclusion: GPT, both alone and in combination with MTL, improves cough frequency and severity in hospitalized patients with COVID-19, with the combination being more efficacious. This regimen may be useful in patients who cannot tolerate opioids., (© 2022 The Authors. The Clinical Respiratory Journal published by John Wiley & Sons Ltd.)

rs5758550 has been associated with enhanced transcription and suggested to be a useful marker of CYP2D6 activity. As there are limited and inconsistent data regarding the utility of this distant "enhancer" single nucleotide polymorphism (SNP), our goal was to further assess the impact of rs5758550 on CYP2D6 activity toward two probe substrates, atomoxetine (ATX) and dextromethorphan (DM), using in vivo urinary metabolite (DM; n = 188) and pharmacokinetic (ATX; n = 70) and in vitro metabolite formation (ATX and DM; n = 166) data. All subjects and tissues were extensively genotyped, the "enhancer" SNP phased with established CYP2D6 haplotypes either computationally or experimentally, and the impact on CYP2D6 activity investigated using several linear models of varying complexity to determine the proportion of variability in CYP2D6 activity captured by each model. For all datasets and models, the "enhancer" SNP had no or only a modest impact on CYP2D6 activity prediction. An increased effect, when present, was more pronounced for ATX than DM suggesting potential substate-dependency. In addition, CYP2D6*2 alleles with the "enhancer" SNP were associated with modestly higher metabolite formation rates in vitro, but not in vivo; no effect was detected for CYP2D6*1 alleles with "enhancer" SNP. In summary, it remains inconclusive whether the small effects detected in this investigation are indeed caused by the "enhancer" SNP or are rather due to its incomplete linkage with other variants within the gene. Taken together, there does not appear to be sufficient evidence to warrant the "enhancer" SNP be included in clinical CYP2D6 pharmacogenetic testing., (© 2021 The Authors. Clinical Pharmacology & Therapeutics © 2021 American Society for Clinical Pharmacology and Therapeutics.)

Ethnopharmacological Relevance: Fritillariae thunbergii Miq (FTM)exhibit versatile biological activities including the significant antitussive and expectorant activities. As a herbal medicine, the therapeutic effects of FTM may be expressed by multi-components which have complicated integration effects on multi-targets. With the time going, the different processing methods of FTM has been changed a lot. Thus，the study described the effect of processing methods to FTM and its quality., Material and Method: Studies were undertaken by using UHPLC-LTQ Orbitrap MS and pharmacodynamic models. All reagents were involved of analytical grade. While a HPLC-ELSD's method has been developed and validated, a certified Quality System is conformed to ICH requirements. The experimental animals followed the animal welfare guidelines., Aim of the Study: We aimed to found the differences after the different processing methods of FTM, and to demonstrate the changes could be selected as quality control indicators, and established a method for simultaneous determination of these for quality control., Results: we have previously found two new steroidal alkaloids: zhebeininoside and imperialine-3-β-D-glucoside from the different processing methods of FTM, which is the difference between the different processing methods of FTM, mainly on the steroidal alkaloids. The activity analysis of zhebeininoside, imperialine-3-β-D-glucoside, verticine and verticinone showed that the mouse model of cough expectorant has antitussive effect. The positive drug selected was dextromethorphan syrup. The positive group showed biological activity, but the blank group showed nothing. The model group showed illness which means that the model was effective. There are two ways of the mechanism of action of the expectorant action which can make sputum thin, reduce its viscosity, and be easy to cough up, or can accelerate the movement of mucous cilia in the respiratory tract and promote the discharge of sputum. In our study, the content of phenol red was significantly reduced in the administration group., Conclusions: To sum up, our results suggest that zhebeininoside and other three components cloud be selected as quality control indicators, and a method for simultaneous determination of zhebeininoside and other three components was established for quality control., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Dextromethorphan (DXM) acts as cough suppressant via its central action. Cell-protective effects of this drug have been reported in peripheral tissues, making DXM potentially useful for treatment of several common human diseases, such as type 2 diabetes mellitus (T2DM). Pancreatic islets are among the peripheral tissues that positively respond to DXM, and anti-diabetic effects of DXM were observed in two placebo-controlled, randomized clinical trials in humans with T2DM. Since these effects were associated with central side effects, we here developed chemical derivatives of DXM that pass the blood-brain barrier to a significantly lower extent than the original drug. We show that basic nitrogen-containing residues block central adverse events of DXM without reducing its anti-diabetic effects, including the protection of human pancreatic islets from cell death. These results show how to chemically modify DXM, and possibly other morphinans, as to exclude central side effects, while targeting peripheral tissues, such as pancreatic islets., Competing Interests: Declaration of interests S.O., A.W., D.H., T. M., E.M., and E. L. declare the following competing financial interests: these authors are inventors of the US patent 10,464,904 entitled “Dextrorphan-derivatives with suppressed central nervous activity”; and T.M. and E.L. are inventors of the US patent 9,370,511 entitled “Morphinan-derivatives for treating diabetes and related disorders.”, (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Aims: The present study examined the role of ventral tegmental area (VTA) serotonergic 5HT 1A receptors in dextromethorphan/morphine-induced anti-allodynia and the possible changes of corticolimbic cFos, brain-derived neurotrophic factor (BDNF), and glial fibrillary acidic protein (GFAP) following the treatments., Materials and Methods: The VTA cannulation and the chronic constriction of the sciatic nerve were performed in male Wistar rats. Flexion withdrawal thresholds to mechanical stimulation in the hind-limb were determined using von Frey hairs. The expressions of cFos, BDNF, and GFAP were evaluated using the Western blotting technique., Key Findings: BDNF (in the hippocampus), and GFAP (in the targeted sites) levels were increased following neuropathic pain. Morphine administration induced an anti-allodynic effect with a decrease in the amygdala BDNF level. Dextromethorphan/morphine-induced anti-allodynia was accompanied by the decrease of hippocampus/amygdala/PFC GFAP and amygdala cFos expressions. The PFC BDNF expression level was increased in dextromethorphan/morphine-treated rats. Intra-VTA microinjection of (S)-WAY100135 (1 µg/rat), a selective 5-HT 1A receptor antagonist, inhibited the anti-allodynic effect of dextromethorphan/morphine. This treatment increased the cFos level in the hippocampus and the amygdala while decreased the PFC level of cFos. The hippocampal BDNF expression was significantly increased, while the amygdala and the PFC expressions of BDNF were decreased under treatment. (S)-WAY100135 plus dextromethorphan/morphine increased the hippocampal/amygdala and PFC levels of GFAP., Significance: These findings indicate that dextromethorphan could potentiate the analgesic effect of morphine via the implication of the VTA serotonin 5-HT 1A receptors. It seems that the changes in the corticolimbic cFos/BDNF/GFAP signaling pathway may be involved in the observed anti-allodynic effect., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Influenza viruses are responsible for seasonal epidemics and sporadic pandemics of varying severity in humans, and additional treatment options are needed. High-throughput siRNA screens and a pre-clinical research model demonstrated that dextromethorphan (DM) has anti-viral activity as a cellular target for treatment of influenza. This study examined DM usage and hospitalization rates among patients with laboratory-confirmed influenza in a national cohort of United States veterans. We aimed to evaluate the potential drug repurposing of DM as a cellular target for the management of influenza utilizing a large, national claims and electronic health record database., Methods: This retrospective drug-disease association cohort study was conducted using data from the Veterans Affairs Informatics and Computing Infrastructure (VINCI). We used a cohort with laboratory-confirmed diagnosis of influenza and international classification of disease (ICD)-9/10 diagnosis codes of fever, cough, influenza, or acute upper respiratory infection in an outpatient setting. The study outcome is inpatient hospitalization (all-cause and respiratory) within 30 days of influenza diagnosis. We estimated the relative risk for all-cause and respiratory hospitalizations using Poisson generalized linear model (GLM) and a greedy nearest neighbor propensity score 1:1 matched sub-analysis for both hospitalization models., Findings: A total of 18,677 patients met the inclusion and exclusion criteria and were evaluated in our study. The cohorts consisted of 2801 patients dispensed DM and 15,876 untreated patients (no DM). The Poisson GLM adjusted for covariates demonstrated a relative risk reduction of 34% for all-cause hospitalizations (Relative Risk (RR) 0.66, 95% Confidence Interval (CI) 0.525-0.832) and 40% for respiratory hospitalizations (RR 0.597, 95% CI 0.423-0.843) in patients with influenza treated with DM., Conclusion: Influenza viruses continue to emerge and cause infection (including pandemics) in humans, so there remains a critical need to advance the understanding of influenza treatment. Our results demonstrated reduced hospitalization rates for influenza patients treated with DM. Further research on cellular targets and/or DM is warranted for the treatment of influenza., (© Published 2021. This article is a U.S. Government work and is in the public domain in the USA.)

Background: Pseudobulbar affect is a very distressing and underdiagnosed neuropsychiatric disorder that causes contextually inappropriate episodes of laughing and crying and general emotional incontinence. Although many proposed etiologies exist, the most widely accepted theory espouses the disruption of a corticopontine-cerebellar circuit that governs the modulation of emotional response. Pseudobulbar affect is commonly diagnosed secondary to primary neurological disorders such as amyotrophic lateral sclerosis, multiple sclerosis, and traumatic brain injury. Traditional pharmacological treatment of pseudobulbar affect is largely comprised of antidepressant therapy, including tricyclic antidepressants such as amitriptyline and selective serotonin reuptake inhibitors such as fluvoxamine. However, neither of these medication classes has been studied for the treatment of pseudobulbar affect in controlled trials, and their utility remains questionable., Case Presentation: We describe a case of a 62-year-old Caucasian man with history of traumatic brain injury, ischemic brainstem stroke, and depression who developed intractable pseudobulbar affect. This patient's intensely distressing symptoms were not alleviated by amitriptyline. However, after being placed on fixed-dose 20 mg/10 mg dextromethorphan/quinidine (Nuedexta), our patient experienced complete resolution of his symptoms. He has experienced no deleterious side effects., Conclusions: This case provides anecdotal evidence for the efficacy of dextromethorphan/quinidine in the treatment of pseudobulbar affect with remarkably swift and complete cessation of symptoms. As a secondary point, it is worth noting that our patient had experienced two devastating neurological traumas, both in anatomical areas that have been implicated in the corticopontine-cerebellar circuit thought to be responsible for pseudobulbar affect. However, only the second trauma, an acute left pontine infarction, produced symptoms of emotional disinhibition. The authors hope that reporting this case will provide both context for physicians managing this condition and hope for patients with this socially and psychiatrically damaging disease.

The outbreak of novel coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) virus continually led to infect a large population worldwide. SARS-CoV-2 utilizes its NSP6 and Orf9c proteins to interact with sigma receptors that are implicated in lipid remodeling and ER stress response, to infect cells. The drugs targeting the sigma receptors, sigma-1 and sigma-2, have emerged as effective candidates to reduce viral infectivity, and some of them are in clinical trials against COVID-19. The antipsychotic drug, haloperidol, exerts remarkable antiviral activity, but, at the same time, the sigma-1 benzomorphan agonist, dextromethorphan, showed pro-viral activity. To explore the potential mechanisms of biased binding and activity of the two drugs, haloperidol and dextromethorphan towards NSP6, we herein utilized molecular docking-based molecular dynamics simulation studies. Our extensive analysis of the protein-drug interactions, structural and conformational dynamics, residual frustrations, and molecular switches of NSP6-drug complexes indicates that dextromethorphan binding leads to structural destabilization and increase in conformational dynamics and energetic frustrations. On the other hand, the strong binding of haloperidol leads to minimal structural and dynamical perturbations to NSP6. Thus, the structural insights of stronger binding affinity and favorable molecular interactions of haloperidol towards viral NSP6 suggests that haloperidol can be potentially explored as a candidate drug against COVID-19. KEY MESSAGES: •Inhibitors of sigma receptors are considered as potent drugs against COVID-19. •Antipsychotic drug, haloperidol, binds strongly to NSP6 and induces the minimal changes in structure and dynamics of NSP6. •Dextromethorphan, agonist of sigma receptors, binding leads to overall destabilization of NSP6. •These two drugs bind with NSP6 differently and also induce differences in the structural and conformational changes that explain their different mechanisms of action. •Haloperidol can be explored as a candidate drug against COVID-19.

The effect of dextromethorphan (DXM) use in sensorineural hearing loss (SNHL) has not been fully examined. We conducted an animal model and nationwide retrospective matched-cohort study to explore the association between DXM use and SNHL. Eight-week-old CBA/CaJ hearing loss was induced by a white noise 118 dB sound pressure level for 3 h. DXM (30 mg/kg) was administered intraperitoneally for 5 days and boost once round window DXM socking. In population-based study, we examined the medical records over 40 years old in Taiwan's National Health Insurance Research Database between 2000 and 2015 to establish retrospective matched-cohort to explore the correlation between DXM use and SNHL. Using click auditory brainstem response (ABR), hearing threshold was measured as 48.6 ± 2.9 dB in control mice compared with 42.6 ± 7.0 dB in DXM mice, which differed significantly ( p = 0.002) on day 60 after noise exposure with a larger ABR wave I amplitude in DXM mice. In human study, we used a Cox regression hazard model to indicate that a significantly lower percentage individuals developed SNHL compared with and without DXM use (0.44%, 175/39,895 vs. 1.05%, 1675/159,580, p < 0.001). After adjustment for age and other variables [adjusted hazard ratio: 0.725 (95% confidence interval: 0.624-0.803, p < 0.001)], this study also demonstrated that DXM use appeared to reduce the risk of developing SNHL. This animal study demonstrated that DXM significantly attenuated noise-induced hearing loss. In human study, DXM use may have a protective effect against SNHL.

Dextromethorphan, a common over-the-counter cough suppressant, has potential for abuse. In the present commentary, we summarize findings to suggest extensive dextromethorphan overuse/abuse within the U.S. military community residing in Okinawa, Japan. We first compared sales of dextromethorphan-containing medications within the U.S. military community of Okinawa, Japan with sales within the U.S military community from the other nearby locations in the Pacific region. Our report revealed that dextromethorphan use is far more prevalent within the military community in Okinawa. To further substantiate the claim that dextromethorphan abuse is widespread in Okinawa's U.S. military community, a survey of medical records showed high rates of treatment provided for dextromethorphan intoxication. These findings motivated interventions established throughout the military community in Okinawa to combat dextromethorphan overuse. These stricter policy changes resulted in decreases in sales of dextromethorphan-containing medications as well as a substantial drop in hospital visits from dextromethorphan intoxication, suggesting that the interventions were largely effective and should be maintained., (Published by Oxford University Press on behalf of the Association of Military Surgeons of the United States 2020. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

NMDA receptors play crucial roles in excitatory synaptic transmission. Rare variants in GRIN2A encoding the GluN2A subunit are associated with a spectrum of disorders, ranging from mild speech and language delay to intractable neurodevelopmental disorders, including but not limited to developmental and epileptic encephalopathy. A de novo missense variant, p.Ser644Gly, was identified in a child with this disorder, and Grin2a knock-in mice were generated to model and extend understanding of this intractable childhood disease. Homozygous and heterozygous mutant mice exhibited altered hippocampal morphology at 2 weeks of age, and all homozygotes exhibited lethal tonic-clonic seizures by mid-third week. Heterozygous adults displayed susceptibility to induced generalized seizures, hyperactivity, repetitive and reduced anxiety behaviours, plus several unexpected features, including significant resistance to electrically-induced limbic seizures and to pentylenetetrazole induced tonic-clonic seizures. Multielectrode recordings of neuronal networks revealed hyperexcitability and altered bursting and synchronicity. In heterologous cells, mutant receptors had enhanced NMDA receptor agonist potency and slow deactivation following rapid removal of glutamate, as occurs at synapses. NMDA receptor-mediated synaptic currents in heterozygous hippocampal slices also showed a prolonged deactivation time course. Standard anti-epileptic drug monotherapy was ineffective in the patient. Introduction of NMDA receptor antagonists was correlated with a decrease in seizure burden. Chronic treatment of homozygous mouse pups with NMDA receptor antagonists significantly delayed the onset of lethal seizures but did not prevent them. These studies illustrate the power of using multiple experimental modalities to model and test therapies for severe neurodevelopmental disorders, while revealing significant biological complexities associated with GRIN2A developmental and epileptic encephalopathy., (© The Author(s) (2020). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Prior studies have demonstrated successful irritability treatment using dopaminergic antagonists in autistic patients. The purpose of this pilot study was to assess the effect of dextromethorphan/quinidine (DM/Q) in autistic adults (18-60 years of age). This was a randomized, blinded, crossover, study of 14 patients randomized to DM/Q or a placebo for 8 weeks, washed out for 4 weeks, then crossed over to the opposite treatment. There were no serious adverse events. Subjects were significantly lower on the Aberrant Behavioral Checklist for Irritability (ABC-IR) (F 1,10  = 7.42; p = 0.021). Improvements in aggression and Clinical Global Impression were also seen. The findings suggest that DM/Q is well-tolerated and associated with improvements in irritability and aggression in adults with autism.

Although currently available antidepressants increase monoamine levels soon after the start of treatment, therapeutic benefits are often delayed by several weeks and the majority of patients with major depressive disorder fail to achieve an adequate response to first- or second-line therapies targeting monoamines. The recent approval of the NMDA (N-methyl-d-aspartate) antagonist esketamine given intranasally for treatment-resistant depression has reinforced the need for agents with rapid onset with alternate mechanisms of action. Dextromethorphan/bupropion, an investigational medicine currently in development, is one such candidate.

Nonketotic hyperglycinemia (NKH) is a neuro-metabolic disorder caused by a deficiency in the glycine cleavage system (GCS) and glycine transporter 1 (GlyT1). A case of atypical late onset of NKH has been reported in a colony of captive-bred Vervet monkeys. The purpose of this study was to evaluate the effect of sodium benzoate and dextromethorphan in reducing glycine levels in hyperglycinemic monkeys. Twelve captive-bred Vervet monkeys were assigned into three groups consisting of four animals (control, valproate induced and cataract with spontaneous hyperglycinemia). Valproate was used to elevate glycine levels and the induced group was then treated with sodium benzoate and dextromethorphan together with group three to normalise glycine levels in cerebrospinal fluid (CSF) and plasma. Valproate induction elicited changes in phosphate, alkaline phosphatase and platelet count, however, no significant changes in the glycine levels were observed, and this might be due to the individual variability within the group. The treatment intervention was only obtained in the spontaneous group whereby the glycine levels were normalised in CSF and plasma. Therefore, it can be concluded that sodium benzoate and dextromethorphan treatment was effective and beneficial to the hyperglycinemic group.

Purpose: Intravenous ketamine is often prescribed in severe neuropathic pain. Oral N -methyl-D-aspartate receptor (NMDAR) antagonists might prolong pain relief, reducing the frequency of ketamine infusions and hospital admissions. This clinical trial aimed at assessing whether oral dextromethorphan or memantine might prolong pain relief after intravenous ketamine., Patients and Methods: A multicenter randomized controlled clinical trial included 60 patients after ketamine infusion for refractory neuropathic pain. Dextromethorphan (90 mg/day), memantine (20 mg/day) or placebo was given for 12 weeks (n=20 each) after ketamine infusion. The primary endpoint was pain intensity at one month. Secondary endpoints included pain, sleep, anxiety, depression, cognitive function and quality of life evaluations up to 12 weeks., Results: At 1 month, dextromethorphan maintained ketamine pain relief (Numeric Pain Scale: 4.01±1.87 to 4.05±2.61, p =0.53) and diminished pain paroxysms ( p =0.03) while pain intensity increased significantly with memantine and placebo ( p =0.04). At 3 months, pain remained lower than at inclusion ( p =0.001) and was not significantly different in the three groups. Significant benefits were observed on cognitive-affective domains and quality of life for dextromethorphan and memantine ( p <0.05)., Conclusions: Oral dextromethorphan given after ketamine infusion extends pain relief during one month and could help patients to better cope with pain. Future studies should include larger populations stratified on pharmacogenetics screening. Optimization of an oral drug that could extend ketamine antihyperalgesia, with fewer hospital admissions, remains a prime challenge in refractory neuropathic pain., Competing Interests: The authors report no conflicts of interest in this work.

Background: Central pain sensitization is often refractory to drug treatment. Dextromethorphan, an N-methyl-D-aspartate receptor antagonist, is antihyperalgesic in preclinical pain models. The hypothesis is that dextromethorphan is also antihyperalgesic in humans., Methods: This randomized, double-blind, placebo-controlled, crossover study explores the antihyperalgesic effect of single and repeated 30-mg dose of oral dextromethorphan in 20 volunteers, using the freeze-injury pain model. This model leads to development of primary and secondary hyperalgesia, which develops away from the site of injury and is associated with central sensitization and activation of N-methyl-D-aspartate receptor in the spinal cord. The primary outcome was antihyperalgesia calculated with the area under the curve of the percentage change in mechanical pain threshold (electronic von Frey) on the area of secondary hyperalgesia. The secondary outcomes were mechanical pain threshold on the area of primary hyperalgesia and cognitive (reaction time) effect., Results: Single 30-mg results are reported. Antihyperalgesia (% · min) is significantly higher on the area of secondary hyperalgesia with dextromethorphan than placebo (median [interquartile range]: 3,029 [746; 6,195] vs. 710 [-3,248; 4,439], P = 0.009, Hedge's g = 0.8, 95% CI [0.1; 1.4]). On primary hyperalgesia area, mechanical pain threshold 2 h after drug intake is significantly higher with dextromethorphan (P = 0.011, Hedge's g = 0.63, 95% CI [0.01; 1.25]). No difference in antinociception is observed after thermal painful stimuli on healthy skin between groups. Reaction time (ms) is shorter with placebo than with dextromethorphan (median [interquartile range]: 21.6 [-37.4; 0.1] vs. -1.2 [-24.3; 15.4], P = 0.015, Hedge's g = 0.75, 95% CI [0.12; 1.39]). Nonserious adverse events occurrence (15%, 3 of 20 volunteers) was similar in both groups., Conclusions: This study shows that low-dose (30-mg) dextromethorphan is antihyperalgesic in humans on the areas of primary and secondary hyperalgesia and reverses peripheral and central neuronal sensitization. Because dextromethorphan had no intrinsic antinociceptive effect in acute pain on healthy skin, N-methyl-D-aspartate receptor may need to be sensitized by pain for dextromethorphan to be effective.

Rolapitant [(Varubi), 5 S ,8 S )-8-[[(1 R )-1-[3,5 bis(trifluoromethyl phenyl]ethoxy]methyl]-8-phenyl-1,7-diazaspiro[4.5]decan-2-one] is a high-affinity NK1 receptor antagonist that was approved in September 2015 as a treatment for nausea and vomiting caused by chemotherapy. In vivo rolapitant moderately inhibits CYP2D6 for at least 7 days after one 180 mg dose. Due to the long inhibition time, we investigated rolapitant as a possible mechanism-based inactivator of CYP2D6. Rolapitant docked in the active site of CYP2D6 and displayed type I binding to CYP2D6 with a K s value of 1.2 ± 0.4 µ M. However, in NADPH-, time-, and concentration-dependent assays of CYP2D6 activity, no evidence for mechanism-based inactivation and no metabolites of rolapitant were observed. Stopped-flow binding studies yielded a k on / k off ( K d ) value of 6.2 µ M. The IC 50 value for rolapitant inhibition of CYP2D6 activity was 24 µ M, suggesting that inhibition is not due to tight binding of rolapitant to CYP2D6. By Lineweaver-Burk analysis, rolapitant behaved as a mixed, reversible inhibitor. The K i values of 20 and 34 µ M were determined by Dixon analysis, with bufuralol and dextromethorphan as reporter substrates, respectively, and drug-drug interaction modeling did not predict the reported in vivo inhibition. The interaction of rolapitant with CYP2D6 was also examined in 1 microsecond molecular dynamics simulations. Rolapitant adopted multiple low-energy binding conformations near the active site, but at distances not consistent with metabolism. Given these findings, we do not see evidence that rolapitant is a mechanism-based inactivator. Moreover, the reversible inhibition of CYP2D6 by rolapitant may not fully account for the moderate inhibition described in vivo., (Copyright © 2019 by The American Society for Pharmacology and Experimental Therapeutics.)

Introduction: Despite the frequent use of therapies in acute bronchitis, the evidence of their benefit is lacking, since only a few clinical trials have been published, with low sample sizes, poor methodological quality and mainly in children. The objective of this study is to compare the effectiveness of three symptomatic therapies (dextromethorphan, ipratropium or honey) associated with usual care and the usual care in adults with acute bronchitis., Methods and Analysis: This will be a multicentre, pragmatic, parallel group, open randomised trial. Patients aged 18 or over with uncomplicated acute bronchitis, with cough for less than 3 weeks as the main symptom, scoring ≥4 in either daytime or nocturnal cough on a 7-point Likert scale, will be randomised to one of the following four groups: usual care, dextromethorphan 30 mg three times a day, ipratropium bromide inhaler 20 µg two puffs three times a day or honey 30 mg (a spoonful) three times a day, all taken for up to 14 days. The exclusion criteria will be pneumonia, criteria for hospital admission, pregnancy or lactation, concomitant pulmonary disease, associated significant comorbidity, allergy, intolerance or contraindication to any of the study drugs or admitted to a long-term residence., Sample: 668 patients. The primary outcome will be the number of days with moderate-to-severe cough. All patients will be given a paper-based symptom diary to be self-administered. A second visit will be scheduled at day 2 or 3 for assessing evolution, with two more visits at days 15 and 29 for clinical assessment, evaluation of adverse effects, re-attendance and complications. Patients still with symptoms at day 29 will be called 6 weeks after the baseline visit., Ethics and Dissemination: The study has been approved by the Ethical Board of IDIAP Jordi Gol (reference number: AC18/002). The findings of this trial will be disseminated through research conferences and peer-review journals., Trial Registration Number: NCT03738917; Pre-results., Competing Interests: Competing interests: AM and CL report receiving research grants from Abbott Diagnostics., (© Author(s) (or their employer(s)) 2018. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Dextromethorphan, a wildly used over-the-counter antitussive drug, is reported to have anti-inflammatory effects. Previously, we and others have demonstrated that dextromethorphan at micromolar doses displays potent hepatoprotective effects and enhances mice survival in a sepsis model. Moreover, we also observed potent anti-inflammatory and neuroprotective effects of subpicomolar concentrations of dextromethorphan in rodent primary neuron-glial cultures. The purpose of this study was to provide a proof of principle that ultralow dose dextromethorphan displays anti-inflammatory and cytoprotective effects in animal studies. Here, we report that subpico- and micromolar doses of dextromethorphan showed comparable efficacy in protecting mice from lipopolysaccharide/d-galactosamine (LPS/GalN)-induced hepatotoxicity and mortality. Mice were given injections of dextromethorphan from 30 min before and 2, 4 h after an injection of LPS/GalN (20 μg/600 mg/kg). Our results showed that dextromethorphan at subpicomolar doses promoted survival rate in LPS/GalN-injected mice. Ultralow dose dextromethorphan also significantly reduced serum alanine aminotransferase activity, TNF-α level and liver cell damage of endotoxemia mice. Mechanistic studies using primary liver Kupffer cell cultures revealed that subpicomolar concentrations of dextromethorphan reduced the NADPH oxidase-generated superoxide free radicals from Kupffer cells, which in turn reduced the elevation of its downstream reactive oxygen species (iROS) to relieve the oxidative stress and decreased TNF-α production in Kupffer cells. Taken together, these findings suggest a novel therapeutic concept of using ultralow doses of dextromethorphan for the intervention of sepsis or septic shock., (Published by Elsevier B.V.)

Objective: We conducted a meta-analysis of controlled trials that used experimental models of acute pain and hyperalgesia to examine the analgesic effects of NMDA receptor (NMDAR) antagonists., Methods: Six major databases were systematically searched (to March 2018) for studies using human evoked pain models to compare NMDAR antagonists with no-intervention controls. Pain outcome data were analyzed with random-effects meta-analysis., Results: Searches identified 70 eligible trials (n = 1,069). Meta-analysis found that low-dose ketamine (<1 mg/kg) produced a decrease in hyperalgesic area (standardized mean difference 0.54, 95% confidence interval [CI] 0.34, 0.74, p < 0.001) and a 1.2-point decrease (95% CI 0.88, 1.44, p < 0.001) in pain ratings from 4.6 to 3.4 on a 0-10 scale (a 26% reduction). Similar analgesia was observed for acute and hyperalgesic models and was constant across the dosing range (0.03-1.00 mg/kg). Moderate to high variability in effect size was observed and mild side effects (e.g., sedation, sensory disturbance) were common. No effects of dextromethorphan were found., Conclusions: Findings provide robust evidence for analgesic and antihyperalgesic effects of ketamine, supporting its utility for acute and chronic pain management. However, pain relief was modest, suggesting ketamine may potentially be most useful when opioids are contraindicated, rapid analgesia is required, or for pain resistant to conventional medication., (© 2019 American Academy of Neurology.)

Importance: In 2010, the US Food and Drug Administration (FDA) approved a combination of dextromethorphan hydrobromide and quinidine sulfate for the treatment of pseudobulbar affect after studies in patients with amyotrophic lateral sclerosis (ALS) or multiple sclerosis (MS). This medication, however, may be commonly prescribed in patients with dementia and/or Parkinson disease (PD)., Objective: To investigate the prescribing patterns of dextromethorphan-quinidine, including trends in associated costs., Design, Setting, and Participants: This population-based cohort study of patients prescribed dextromethorphan-quinidine used data from 2 commercial insurance databases, Optum Clinformatics Data Mart and Truven Health MarketScan. The Medicare Part D Prescription Drug Program data set was used to evaluate numbers of prescriptions and total reported spending by the Centers for Medicare & Medicaid Services. Patients were included if they were prescribed dextromethorphan-quinidine from October 29, 2010, when the drug was approved, through March 1, 2017, for Optum and December 31, 2015, for Truven. Data were analyzed from December 1, 2017, through August 1, 2018., Main Outcomes and Measures: The proportion of patients prescribed dextromethorphan-quinidine with a diagnosis of MS, ALS, or dementia and/or PD, as well as the number of patients with a history of heart failure (a contraindication for the drug)., Results: In the commercial health care databases, 12 858 patients filled a prescription for dextromethorphan-quinidine during the study period. Mean (SD) age was 66.0 (18.5) years, 66.7% were women, and 13.3% had a history of heart failure. Combining results from both databases, few patients had a diagnosis of MS (8.4%) or ALS (6.8%); most (57.0%) had a diagnosis of dementia and/or PD. In the Medicare Part D database, the number of patients prescribed dextromethorphan-quinidine increased 15.3-fold, from 3296 in 2011 to 50 402 in 2016. Reported spending by Centers for Medicare & Medicaid Services on this medication increased from $3.9 million in 2011 to $200.4 million in 2016., Conclusions and Relevance: Despite approval by the FDA for pseudobulbar affect based on studies of patients with ALS or MS, dextromethorphan-quinidine appears to be primarily prescribed for patients with dementia and/or PD.

Competing Interests: Disclosure The authors report no conflicts of interest in this work., (© Georg Thieme Verlag KG Stuttgart · New York.)

Aims: A recent double-blind placebo-controlled crossover 70-day trial demonstrated that a fixed combination of dextromethorphan and quinidine (DM/Q) improves speech and swallowing function in most patients with amyotrophic lateral sclerosis. In this study, a subset of participants, many of whom did not substantially improve while on DM/Q, were re-evaluated using computer-based speech analyses and expert clinician ratings of the overall severity of speech impairment., Methods: Speech samples were recorded from the subset of 10 patients at four visits made at approximately 30-day intervals. The recordings were analysed by automated computer-based analysis of speech pausing patterns. Severity of speech impairment was rated by three experienced speech-language pathologists using direct magnitude estimation. Scores on patient-reported and clinician-administered scales of bulbar motor involvement were obtained at each visit., Results: The effects of DM/Q were detected on several of the objective speech measures, including total pause duration (s) (Cohen's d = 0.73, 95% confidence interval (CI) -1.70, 0.24), pause time (%) (d = 0.77, 95% CI -1.75, 0.21), and mean speech event duration (s) (d = 0.52, 95% CI -0.44, 1.47), but not on clinician ratings of speech or the speech components of the self-report or clinician-administered scales., Conclusions: These findings suggest that even patients with modest improvement while on DM/Q may experience quantifiable improvements in speech when assessed using sensitive and objective measures. This study provides additional evidence of the positive impact of DM/Q on one or more of the neural systems that control bulbar motor function and production of speech., (© 2018 The Authors. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.)

Glycine encephalopathy (GE), or nonketotic hyperglycinemia (NKH), is a rare recessive genetic disease caused by defective glycine cleavage and characterized by increased accumulation of glycine in all tissues. Here, based on new case reports of GLDC loss-of-function mutations in GE patients, we aimed to generate a zebrafish model of severe GE in order to unravel the molecular mechanism of the disease. Using CRISPR/Cas9, we knocked out the gldc gene and showed that gldc-/- fish recapitulate GE on a molecular level and present a motor phenotype reminiscent of severe GE symptoms. The molecular characterization of gldc-/- mutants showed a broad metabolic disturbance affecting amino acids and neurotransmitters other than glycine, with lactic acidosis at stages preceding death. Although a transient imbalance was found in cell proliferation in the brain of gldc-/- zebrafish, the main brain networks were not affected, thus suggesting that GE pathogenicity is mainly due to metabolic defects. We confirmed that the gldc-/- hypotonic phenotype is due to NMDA and glycine receptor overactivation, and demonstrated that gldc-/- larvae depict exacerbated hyperglycinemia at these synapses. Remarkably, we were able to rescue the motor dysfunction of gldc-/- larvae by counterbalancing pharmacologically or genetically the level of glycine at the synapse.