Comparison of patients with benzodiazepine receptor agonist-related psychiatric disorders and over-the-counter drug-related psychiatric disorders before and after the COVID-19 pandemic: Changes in psychosocial characteristics and types of abused drugs

AIM

To investigate changes in the clinical characteristics of patients who abused benzodiazepine receptor agonists (BZRA) or over-the-counter (OTC) drugs before and after COVID-19 based on the 2018 and 2022 data of the "Nationwide Psychiatric Hospital (NPH) Survey on Drug-related Psychiatric Disorders."

METHOD

A total of 446 and 155 cases, and 435 and 273 cases, who mainly abused BZRAs or OTC drugs, respectively, were extracted from the database of the two NPH Surveys. Demographic variables, education, employment, criminal record, drug use during the previous year, psychiatric diagnosis, and types of abused drugs were compared between 2018 and 2022.

RESULT

A comparison of BZRA abusers revealed a decreased number of users during the previous year and an increase in the comorbidity rate of other disorders (F3 and F4 in ICD-10) in 2022. Etizolam, flunitrazepam, triazolam, and zolpidem were used most in both years, with an increase in zolpidem and a decrease in triazolam in 2022. A comparison of OTC drug abusers revealed a higher proportion of women and young patients in 2022. An increase in the comorbidity rate of F3 and F9 and a significant increase in the use of dextromethorphan products were observed in 2022, although codeine products were in the majority in both years.

CONCLUSION

By comparing NPH Surveys before and after the COVID-19 pandemic, both BZRA abusers and OTC drug abusers present complex pathologies, requiring tailor-made treatment. The younger OTC drug abusers were particularly evident among women, and the abuse of dextromethorphan-containing OTC drugs has increased alarmingly.

Effect of isotretinoin on CYP2D6 and CYP3A activity in patients with severe acne

AIMS

Previously, retinoids have decreased CYP2D6 mRNA expression in vitro and induced CYP3A4 in vitro and in vivo. This study aimed to determine whether isotretinoin administration changes CYP2D6 and CYP3A activities in patients with severe acne.

METHODS

Thirty-three patients (22 females and 11 males, 23.5 ± 6.0 years old) expected to receive isotretinoin treatment completed the study. All participants were genotyped for CYP2D6 and CYP3A5. Participants received dextromethorphan (DM) 30 mg orally as a dual-probe substrate of CYP2D6 and CYP3A activity at two study timepoints: pre-isotretinoin treatment and with isotretinoin for at least 1 week. The concentrations of isotretinoin, DM and their metabolites were measured in 2-h postdose plasma samples and in cumulative 0-4-h urine collections using liquid chromatography-mass spectrometry.

RESULTS

In CYP2D6 extensive metabolizers, the urinary dextrorphan (DX)/DM metabolic ratio (MR) (CYP2D6 activity marker) was numerically, but not significantly, lower with isotretinoin administration compared to pre-isotretinoin (geometric mean ratio [GMR] [90% confidence interval (CI)] 0.78 [0.55, 1.11]). The urinary 3-hydroxymorphinan (3HM)/DX MR (CYP3A activity marker) was increased (GMR 1.18 [1.03, 1.35]) and the urinary DX-O-glucuronide/DX MR (proposed UGT2B marker) was increased (GMR 1.22 [1.06, 1.39]) with isotretinoin administration compared to pre-isotretinoin.

CONCLUSIONS

Administration of isotretinoin did not significantly reduce CYP2D6 activity in extensive metabolizers, suggesting that the predicted downregulation of CYP2D6 based on in vitro data does not translate into humans. We observed a modest increase in CYP3A activity (predominantly CYP3A4) with isotretinoin treatment. The data also suggest that DX glucuronidation is increased following isotretinoin administration.

ALSUntangled #71: Nuedexta

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.

Cough elixir overdose causing toxic leuco-encephalopathy and serotonin syndrome

Acute toxic leukoencephalopathy and serotonin syndrome are rare neurological complications associated with various drugs and toxins, some of which overlap. However, the co-occurrence of these conditions is poorly documented. We present the case of a 14-year-old boy who suddenly developed altered consciousness and autonomic dysfunction after consuming excessive quantities of cough remedies containing dextromethorphan, chlorphenamine, dichlorobenzyl alcohol, and amylmetacreson. Magnetic resonance imaging of the brain revealed distinct white matter lesions. With supportive care, the patient rapidly improved, and the magnetic resonance imaging abnormalities disappeared. The swift resolution, typical magnetic resonance imaging findings, and a history of exposure to drugs affecting the central nervous system's serotonergic system suggested concurrent acute toxic leukoencephalopathy and serotonin syndrome. The components of cough medications can be hazardous in overdose due to their potential to enhance serotonin toxicity and cause direct or indirect central nervous system white matter damage. Early recognition and appropriate treatment are essential for recovery.

Drugs for depressionr

A selective serotonin reuptake inhibitor (SSRI) is generally used for initial treatment of major depressive disorder (MDD). A serotonin-norepinephrine reuptake inhibitor (SNRI), bupropion (Wellbutrin SR, and others), and mirtazapine (Remeron, and others) are reasonable alternatives. Improvement in symptoms can occur within the first two weeks of treatment with these drugs, but a substantial benefit may not be achieved for 4-8 weeks.

Double-Blind Comparison of the Two Hallucinogens Dextromethorphan and Psilocybin: Experience-Dependent and Enduring Psychological Effects in Healthy Volunteers

Rationale

N-methyl-D-aspartate receptor-mediated dissociatives and serotonergic hallucinogens are being increasingly used in therapeutic interventions that involve nonordinary states of consciousness and may represent a unique mental health paradigm wherein pharmacologically induced experiences are conducive to psychological well-being.

Objective

The aim of this study was to further understand how the phenomenological and health-promoting effects of high-dose dextromethorphan (DXM) compared to psilocybin in the same participants when administered under experimental conditions that are typical of therapeutic psychedelic trials.

Methods

Single, acute oral doses of DXM (400 mg/70 kg), psilocybin (10, 20, 30 mg/70 kg), and inactive placebo were administered under double-blind and psychologically supportive conditions to 20 healthy participants with histories of hallucinogen use. Ratings of personal meaning, spiritual significance, psychological challenge, and psychological insight attributed to acute drug experiences were assessed 7 h (at session end) and 1 week after each drug administration. Persisting psychological effects were assessed 1 week after each drug administration.

Results

High-dose DXM and psilocybin produced similar increases over placebo in ratings of drug experience that was predictive of psychological benefit at 1 week, even when expectancy effects were minimized. These effects tended to favor psilocybin in a dose-dependent manner and were limited by poor physical tolerability for DXM.

Conclusions

This analysis suggests the utility of exploring clinical applications of dissociatives that occur within the supportive contexts that are characteristic of psychedelic research and that prioritize the optimization of psychologically valuable drug experiences. This study was registered with ClinicalTrials.gov (NCT02033707).

Patterns of Cough Medication Prescribing among Patients with Chronic Cough in Florida: 2012-2021

Among patients with chronic cough (CC) in the 2012-2021 statewide OneFlorida Clinical Research Consortium database, we examined trends in cough medication (CM) prescribing prevalence over time in repeated cross-sectional analyses and identified distinct CM utilization trajectories using group-based trajectory modeling (GBTM) in a retrospective cohort study. Among eligible adults (≥18 years) without cancer/benign respiratory tumor diagnoses, we identified CC patients and non-CC patients with any cough-related diagnosis. In the GBTM analysis, we calculated the number of monthly prescriptions for any CMs (excluding gabapentinoids) during the 12 months from the first qualifying cough event to identify distinct utilization trajectories. From 2012 to 2021, benzonatate (9.6% to 26.1%), dextromethorphan (5.2% to 8.6%), and gabapentinoid (5.3% to 14.4%) use increased among CC patients, while opioid antitussive use increased from 2012 to 2015 and decreased thereafter (8.4% in 2012, 14.7% in 2015, 6.7% in 2021; all p < 0.001). Of 15,566 CC patients and 655,250 non-CC patients identified in the GBTM analysis, CC patients had substantial burdens of respiratory/non-respiratory comorbidities and healthcare service and concomitant medication use compared to non-CC patients. Among CC patients, GBTM identified three distinct CM utilization trajectories: (1) no CM use (n = 11,222; 72.1%); (2) declining CM use (n = 4105; 26.4%); and (3) chronic CM use (n = 239; 1.5%). CC patients in Florida had limited CM use with increasing trends in use of benzonatate, dextromethorphan, and gabapentinoids and a decreasing trend in opioid antitussive use. CC patients, particularly with chronic prescription CM use, experienced substantial disease burden.

Identification of a New Pyrrolyl Pyridoindole Alkaloid, Melpyrrole, and Flazin from Honey and Their Cough-Suppressing Effect in Guinea Pigs

The cough-suppressing effect of honey was demonstrated for the first time using a guinea pig model whereby cough was induced by citric acid and capsaicin, and a new pyrrolyl pyridoindole, 1-(5-(hydroxymethyl)-1H-pyrrol-2-yl)-9H-pyrido[3,4-b]indole-3-carboxylic acid (1), named melpyrrole, and flazin (2) were identified as the active principle components. The structures of 1 and 2 were estimated using a combination approach of an activity-guided survey and LC-MS/MS multivariate analysis and were finally established by total synthesis of 1 and comparison with an authentic standard for 2. Both compounds showed antitussive activity comparable to that of dextromethorphan in guinea pigs. Their antitussive effects were unaffected by an opioid antagonist and reversed by a nitric oxide (NO) synthase inhibitor, indicating that these natural products do not act directly on opiate receptors but through the NO signaling pathway.

An Open-Label Study of Adjunctive Dextromethorphan/Quinidine in Treatment-Resistant Depression

BACKGROUND

Approximately one third of individuals with major depressive disorder have treatment-resistant depression (TRD). Glutamatergic modulators such as the N -methyl- d -aspartate receptor antagonist ketamine have rapid and robust antidepressant effects, but their use has been limited by accessibility and route of administration. This open-label pilot study assessed the adjunctive antidepressant efficacy of dextromethorphan/quinidine (DM/Q) in TRD.

METHODS

Inpatients with TRD (n = 17, 40.8 ± 12.3 years; 9 females/8 males) received adjunctive open-label DM/Q (20 mg/10 mg) up to 3 times daily. The study had no set endpoint; participants were followed until they discontinued DM/Q or were discharged. Montgomery-Asberg Depression Rating Scale (MADRS) scores were obtained at baseline (before DM/Q administration) and regularly during hospitalization. Full response was defined as a ≥50% reduction in baseline MADRS score, partial response as a 25% to 50% decrease in baseline MADRS score, and nonresponse as a <25% reduction or an increase in baseline MADRS score.

RESULTS

The 17 inpatients received open-label DM/Q for 5.1 ± 2.7 weeks. Forty-seven percent of participants responded to DM/Q-12% achieved a full response and 35% achieved a partial response. The largest MADRS difference observed at any time point was -6.4 ± 8.4 (-21.0% ± 29.9%), and the MADRS difference observed at time of DM/Q discontinuation or hospital discharge was -4.8 ± 8.4 (-15.9% ± 29.7%). Twenty-four percent of participants experienced a nonserious adverse event; none experienced a serious adverse event.

CONCLUSIONS

In this open-label pilot study, 47% of participants responded to adjunctive DM/Q, which was well tolerated. Larger placebo-controlled trials are needed to determine the real-world efficacy of DM/Q.

Protection of pancreatic islets from oxidative cell death by a peripherally-active morphinan with increased drug safety

OBJECTIVE

Dextromethorphan (DXM) is a commonly used antitussive medication with positive effects in people with type 2 diabetes mellitus, since it increases glucose tolerance and protects pancreatic islets from cell death. However, its use as an antidiabetic medication is limited due to its central nervous side effects and potential use as a recreational drug. Therefore, we recently modified DXM chemically to reduce its blood-brain barrier (BBB) penetration and central side effects. However, our best compound interacted with the cardiac potassium channel hERG (human ether-à-go-go-related gene product) and the μ-opioid receptor (MOR). Thus, the goal of this study was to reduce the interaction of our compound with these targets, while maintaining its beneficial properties.

METHODS

Receptor and channel binding assays were conducted to evaluate the drug safety of our DXM derivative. Pancreatic islets were used to investigate the effect of the compound on insulin secretion and islet cell survival. Via liquor collection from the brain and a behavioral assay, we analyzed the BBB permeability. By performing intraperitoneal and oral glucose tolerance tests as well as pharmacokinetic analyses, the antidiabetic potential and elimination half-life were investigated, respectively. To analyze the islet cell-protective effect, we used fluorescence microscopy as well as flow cytometric analyses.

RESULTS

Here, we report the design and synthesis of an optimized, orally available BBB-impermeable DXM derivative with lesser binding to hERG and MOR than previous ones. We also show that the new compound substantially enhances glucose-stimulated insulin secretion (GSIS) from mouse and human islets and glucose tolerance in mice as well as protects pancreatic islets from cell death induced by reactive oxygen species and that it amplifies the effects of tirzepatide on GSIS and islet cell viability.

CONCLUSIONS

We succeeded to design and synthesize a novel morphinan derivative that is BBB-impermeable, glucose-lowering and islet cell-protective and has good drug safety despite its morphinan and imidazole structures.

Knowledge, Attitude, and the Practice of Community Pharmacists to Dispense Opioid-Related and Opioid-Containing Medication in Eastern Province, Saudi Arabia

Objectives

This study was done to evaluate the knowledge of community pharmacists-working in Saudi Arabia-regarding over-the-counter opioid-related and opioid-containing medications.

Materials and Methods

A quantitative cross-sectional study was conducted using an online questionnaire that was distributed through social media and taken to the community pharmacists in person. A total of 101 responders were reached in a period of around 3 weeks.

Results

Most of the pharmacists working in community pharmacies in Saudi Arabia are non-Saudi (85.15%), males (88.12%), and the majority are holders of bachelor's degrees (85.15%). More than half of the participants spend a considerably sufficient time with the patient 6-10 minutes (60.4%). The availability of a private counseling room in community pharmacies is significantly low (21.78%). Only (69.41%) of participants always counsel the patient before dispensing opioid-related medications. Most of the participants (84.76%) believe that all over-the-counter opioid-related and opioid-containing medications should be restricted to avoid drug abuse.

Conclusion

A little neglect from pharmacists' side regarding dispensing such medications was observed; thus, there is a significant need to raise their awareness regarding over-the-counter opioid abuse.

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.

Combinations of dextromethorphan for the treatment of mood disorders - a review of the evidence

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.

Improvement of depressive symptoms, after a suicide attempt, with dextromethorphan/bupropion combination treatment in a patient with treatment-resistant depression and psychiatric comorbidities

We admitted a 42-year-old patient with severe treatment-resistant depression and with psychiatric comorbidities. The patient attempted suicide 5 weeks after admission. Subsequently, we initiated dextromethorphan/bupropion based on prior evidence. As a result, the patient demonstrated an improvement in mood symptoms and a reduction in suicide risk, leading to her discharge.

Impact of Pregnancy and Vitamin A Supplementation on CYP2D6 Activity

The mechanism of cytochrome P450 2D6 (CYP2D6) induction during pregnancy has not been evaluated in humans. This study assessed the changes in CYP2D6 and CYP3A activities during pregnancy and postpartum, and the effect of vitamin A administration on CYP2D6 activity. Forty-seven pregnant CYP2D6 extensive metabolizers (with CYP2D6 activity scores of 1 to 2) received dextromethorphan (DM) 30 mg orally as a single dose during 3 study windows (at 25 to 28 weeks of gestation, study day 1; at 28 to 32 weeks of gestation, study day 2; and at ≥3 months postpartum, study day 3). Participants were randomly assigned to groups with no supplemental vitamin A (control) or with supplemental vitamin A (10 000 IU/day orally for 3 to 4 weeks) after study day 1. Concentrations of DM and its metabolites, dextrorphan (DX) and 3-hydroxymorphinan (3HM), were determined from a 2-hour post-dose plasma sample and cumulative 4-hour urine sample using liquid chromatography-mass spectrometry. Change in CYP2D6 activity was assessed using DX/DM plasma and urine metabolic ratios. The activity change in CYP3A was also assessed using the 3HM/DM urine metabolic ratio. The DX/DM urine ratio was significantly higher (43%) in pregnancy compared with postpartum (P = .03), indicating increased CYP2D6 activity. The DX/DM plasma ratio was substantially higher in the participants, with an activity score of 1.0 during pregnancy (P = .04) compared with postpartum. The 3HM/DM urinary ratio was significantly higher (92%) during pregnancy, reflecting increased CYP3A activity (P = .02). Vitamin A supplementation did not change CYP2D6 activity during pregnancy; however, plasma all-trans retinoic acid (atRA) concentrations were positively correlated with increased CYP2D6 activity during pregnancy and postpartum. Further research is needed to elucidate the mechanisms of increased CYP2D6 activity during pregnancy.

Two Cases of Dextromethorphan Overdose Reversed by Naloxone

We present two rare cases highlighting the rare toxicological manifestation of dextromethorphan (DXM). The DXM toxicity profile is predominantly hallucinations, agitation, irritability with seizures, and coma in severe overdose. The cases that follow are unique in the sense that both patients had features of opioid toxidrome, rarely manifested in DXM abuse. A young male and female in their mid-20s and early 30s, respectively, were brought to the emergency room for their excessive somnolence; both had reduced respiratory rate, bilaterally small pupils (sluggish reactive to light), and the rest of their examination findings were unremarkable. Primary stabilization in the form of noninvasive ventilation (NIV) trial and subsequent rapid sequence intubation (RSI) for persistent respiratory depression. Followed by the exhaustive exclusion of differentials, opioid-like toxidrome was treated with naloxone, and both patients made a good recovery and were discharged home in good health. The emergency physician should be prepared for the rare toxicological manifestations of commonly available over-the-counter medications among the youth. These case reports highlight the role of naloxone in DXM toxicity reversal.

Dextromethorphan premedication in the alleviation of cough during flexible bronchoscopy in adults: A randomized double-blind placebo-controlled trial

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.

Antipsychotic Drugs Efficacy in Dextromethorphan-Induced Psychosis

Psychosis is known as a broad term of symptoms that cause serious disorganization of behavior, thinking, and perception of reality. One of the medicines that recently gained much attention in terms of its psychotic potential is dextromethorphan (DXM). DXM, a widely used antitussive drug, is a commonly abused drug because of its euphoric, hallucinogenic, and dissociative properties. To date, DXM is a legally marketed cough suppressant that is neither a controlled substance nor a regulated chemical under the Controlled Substances Act. The management of DXM-related psychosis is dependent on the type of psychotic symptoms. Atypical neuroleptics (i.e., olanzapine, risperidone, quetiapine) and typical haloperidol have been used in symptomatic treatment due to their efficacy, especially in positive symptoms (hallucinations and delusions). These agents are also recognized as the preferred option in the symptomatic treatment of DXM-related psychosis due to their better efficacy and safety profile than typical haloperidol in the short-term course. The focus of the present review concerns the current stage of knowledge about DXM psychotic potency as well as the management of DXM-related psychoses with a special emphasis on atypical antipsychotic drugs (i.e., olanzapine, risperidone, quetiapine, and haloperidol).

Effectiveness of antitussives, anticholinergics, and honey versus usual care in adults with uncomplicated acute bronchitis: a multiarm randomized clinical trial

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.

Pharmacological Comparative Characterization of REL-1017 (Esmethadone-HCl) and Other NMDAR Channel Blockers in Human Heterodimeric N-Methyl-D-Aspartate Receptors

Excessive Ca²⁺ currents via N-methyl-D-aspartate receptors (NMDARs) have been implicated in many disorders. Uncompetitive NMDAR channel blockers are an emerging class of drugs in clinical use for major depressive disorder (MDD) and other neuropsychiatric diseases. The pharmacological characterization of uncompetitive NMDAR blockers in clinical use may improve our understanding of NMDAR function in physiology and pathology. REL-1017 (esmethadone-HCl), a novel uncompetitive NMDAR channel blocker in Phase 3 trials for the treatment of MDD, was characterized together with dextromethorphan, memantine, (±)-ketamine, and MK-801 in cell lines over-expressing NMDAR subtypes using fluorometric imaging plate reader (FLIPR), automated patch-clamp, and manual patch-clamp electrophysiology. In the absence of Mg²⁺, NMDAR subtypes NR1-2D were most sensitive to low, sub-μM glutamate concentrations in FLIPR experiments. FLIPR Ca²⁺ determination demonstrated low μM affinity of REL-1017 at NMDARs with minimal subtype preference. In automated and manual patch-clamp electrophysiological experiments, REL-1017 exhibited preference for the NR1-2D NMDAR subtype in the presence of 1 mM Mg²⁺ and 1 μM L-glutamate. Tau off and trapping characteristics were similar for (±)-ketamine and REL-1017. Results of radioligand binding assays in rat cortical neurons correlated with the estimated affinities obtained in FLIPR assays and in automated and manual patch-clamp assays. In silico studies of NMDARs in closed and open conformation indicate that REL-1017 has a higher preference for docking and undocking the open-channel conformation compared to ketamine. In conclusion, the pharmacological characteristics of REL-1017 at NMDARs, including relatively low affinity at the NMDAR, NR1-2D subtype preference in the presence of 1 mM Mg²⁺, tau off and degree of trapping similar to (±)-ketamine, and preferential docking and undocking of the open NMDAR, could all be important variables for understanding the rapid-onset antidepressant effects of REL-1017 without psychotomimetic side effects.

Evaluation of Cough Medication Use Patterns in Ambulatory Care Settings in the United States: 2003-2018

Using 2003−2018 National Ambulatory Medical Care Survey data for office-based visits and 2003−2018 National Hospital Ambulatory Medical Care Survey data for emergency department (ED) visits, we conducted cross-sectional analyses to examine cough medication (CM) use trends in the United States (US) ambulatory care settings. We included adult (≥18 years) patient visits with respiratory-infection-related or non-infection-related cough as reason-for-visit or diagnosis without malignant cancer or benign respiratory tumor diagnoses. Using multivariable logistic regressions, we examined opioid antitussive, benzonatate, dextromethorphan-containing antitussive, and gabapentinoid use trends. From 2003−2005 to 2015−2018, opioid antitussive use decreased in office-based visits (8.8% to 6.4%, Ptrend = 0.03) but remained stable in ED visits (6.3% to 5.9%, Ptrend = 0.99). In both settings, hydrocodone-containing antitussive use declined over 50%. Benzonatate use more than tripled (office-based:1.6% to 4.8%; ED:1.5% to 8.0%; both Ptrend < 0.001). Dextromethorphan-containing antitussive use increased in ED visits (1.8% to 2.6%, Ptrend = 0.003) but stayed unchanged in office-based visits (3.8% to 2.7%; Ptrend = 0.60). Gabapentinoid use doubled in office-based visits (1.1% in 2006−2008 to 2.4% in 2015−2018, Ptrend < 0.001) but was negligible in ED visits. In US office-based and ED ambulatory care settings, hydrocodone-containing antitussive use substantially declined from 2003 to 2018, while benzonatate use more than tripled, and dextromethorphan-containing antitussive and gabapentinoid use remained low (<3%).

Management of Toxicological Emergencies in the School Setting: An Overview for School Nurses Part 2

School nurses may encounter a variety of poisoning and overdose scenarios in the school setting. Youth have an increased risk for harm due to factors associated with substance use, self-harm, and exposure to more toxic ingestants. Poison Control Centers are uniquely qualified to assist the public and health professionals, including school nurses, with poisoning and overdose incidents and are available 24 hours per day. This article is Part 2 of a series of three articles and focuses on poisonings related to substances of abuse and addiction or as a result of social media challenges. Information includes expected clinical effects, potential for serious injury, and a reasonable approach to manage these exposures for the following substances of potential harm: alcohol, caffeine, dextromethorphan, inhalants, marijuana, tobacco, and nicotine replacement therapy. Part 3 of the series will discuss potential environmental hazards specific to the school setting.

NMDA Receptor Antagonists Increase the Release of GLP-1 From Gut Endocrine Cells

Type 2 diabetes mellitus (T2DM) remains one of the most pressing health issues facing modern society. Several antidiabetic drugs are currently in clinical use to treat hyperglycaemia, but there is a need for new treatments that effectively restore pancreatic islet function in patients. Recent studies reported that both murine and human pancreatic islets exhibit enhanced insulin release and β-cell viability in response to N-methyl-D-aspartate (NMDA) receptor antagonists. Furthermore, oral administration of dextromethorphan, an over-the-counter NMDA receptor antagonist, to diabetic patients in a small clinical trial showed improved glucose tolerance and increased insulin release. However, the effects of NMDA receptor antagonists on the secretion of the incretin hormone GLP-1 was not tested, and nothing is known regarding how NMDA receptor antagonists may alter the secretion of gut hormones. This study demonstrates for the first time that, similar to β-cells, the NMDA receptor antagonist MK-801 increases the release of GLP-1 from a murine L-cell enteroendocrine model cell line, GLUTag cells. Furthermore, we report the 3′ mRNA expression profiling of GLUTag cells, with a specific focus on glutamate-activated receptors. We conclude that if NMDA receptor antagonists are to be pursued as an alternative, orally administered treatment for T2DM, it is essential that the effects of these drugs on the release of gut hormones, and specifically the incretin hormones, are fully investigated.

Dextromethorphan Reduces Sign-Tracking but Not Goal-Tracking in Male Sprague-Dawley Rats

Sign-tracking is a well-known phenomenon in appetitive Pavlovian conditioning in which subjects approach the site of a conditioned stimulus (CS) associated with an appetitive unconditioned stimulus (US) even when the two are located separately. Control of sign-tracking may be important in rehabilitation from drug dependence to help ward off relapse. Recent studies have found success in using ketamine to reduce sign-tracking. In this study, we employed a similar but unscheduled drug, dextromethorphan (DXM), which affects many of the same molecular targets as ketamine, in an attempt to reduce sign-tracking in a standard paradigm. DXM was found to reduce sign-tracking at the doses examined in this study, while goal-tracking (approaching the site of the US rather than CS) was relatively unaffected. DXM offers advantages over ketamine in terms of use with patients and may have some utility in rehabilitation.

Dextromethorphan reduces prenatal lipopolysaccharide exposure-induced dopaminergic neuronal loss and cytokine changes in offspring

Maternal infection during pregnancy may affect fetal brain development and increase the risk of developing neurological and mental disorders later in life in offspring. In this study, we used low-dose lipopolysaccharide (LPS) injection to mimic mild maternal infection at a critical time window for fetal dopamine (DA) and serotonin (5-HT) neuron development. The affected offspring exhibited reduction of dopaminergic and serotonergic neurons and anxiety- and depression-related behaviors in adulthood. In the current study, we evaluated whether dextromethorphan (DM, 30 mg/kg), an over-the-counter antitussive drug with anti-inflammatory and neuroprotective properties, could reduce the adverse effects of maternal infection mimicked by LPS exposure. We discovered that DM application did not change the baseline serum interleukin-6 (IL-6) and tumor necrosis factor α (TNFα) levels in the LPS-exposed offspring. However, DM treatment could reduce the heightened immune responses induced by a postnatal LPS challenge test in prenatal LPS-exposed offspring. The neuroprotective effect of DM was only seen in DA neurons but not in 5-HT neurons. We concluded that DM treatment can partially protect the offspring against the adverse effects of LPS-induced maternal immune activation. The reduction in heightened immune responses and dopaminergic neuronal loss in LPS-exposed offspring could potentially reduce the risk of DA-related neurological and psychiatric disorders later in life.

The Impact of the CYP2D6 "Enhancer" Single Nucleotide Polymorphism on CYP2D6 Activity

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.

The Association Between Dextromethorphan Use and the Risk of Dementia

Dementia is one of neurodegenerative disease without preventive medicine currently. Dextromethorphan (DXM) has been reported to reduce neuronal damage and neurodegeneration in animal and human models. The effect of DXM on the dementia has not been fully examined. We examined the medical records over 40 years old in Taiwan's National Health Insurance Research Database between 2000 and 2015 to establish matched cohorts. We used a Cox regression hazard model to identify risk factors of dementia during 16 years of follow-up, and the results indicate that a significantly lower percentage of subjects with DXM use (P < .001) developed dementia compared with those without DXM use (11.38%, 4541/39 895 vs 18.66%, 29 785/159 580). After adjustment for age and other variables [adjusted hazard ratio: .567 (95% confidence interval: .413-.678, P < .001)], this study also demonstrated that DXM use appeared to reduce the risk of developing dementia. DXM use may potentially provide a protective effect against dementia.

Serotonin syndrome after an overdose of over-the-counter medicine containing dextromethorphan

Serotonin syndrome is a potentially life-threatening adverse reaction from therapeutic drug use, intentional self-poisoning, or inadvertent interactions between drugs. We report a case of the serotonin syndrome after an overdose of a commonly available over-the-counter cough medicine, Shin CONTAC sekidome daburu jizokusei. Over-the-counter drugs containing dextromethorphan may, in rare cases, cause health problems requiring hospitalization or worse. An appropriate explanation from the pharmacist at the time of purchase, although not mandatory, is recommended.

Infant dextromethorphan and dextrorphan exposure via breast milk from mothers who are CYP2D6 extensive metabolizers

The risk of infant exposure to dextromethorphan (DM) and its active metabolite, dextrorphan (DX), through breast milk has not been evaluated. In this study, bound and unbound DM and DX concentrations in breast milk and plasma at 2 h post-dose were measured in 20 lactating women (n = 20) following a single 30 mg oral dose of DM. The DM and DX concentrations in breast milk were positively correlated with their respective plasma concentrations. The breast milk-to-plasma (M/P) ratios of 1.0 and 1.6 and the unbound M/P ratios of 1.1 and 2.0 for DM and DX, respectively, suggested that DM and DX are extensively distributed into breast milk. The infant exposure following a single dose of 30 mg DM was estimated using the breast milk concentrations to be 0.33 ± 0.32 μg/kg/day and 1.8 ± 1.0 μg/kg/day for DM and DX, respectively. The steady-state infant exposure was estimated using the M/P ratios and previously reported AUC of DM and DX following repeated dosing of DM 60 mg orally twice daily to be 0.64 ± 0.22 μg/kg/day and 1.23 ± 0.38 μg/kg/day, respectively. Based on these estimated infant doses, the relative infant doses (RIDs) were estimated to be <1%, suggesting the infant is only exposed to a minor fraction of adult dose through breast milk; however, one nursing infant developed an erythematous rash during this study which warrants additional research to fully elucidate the risks of infant exposure to DM and DX through breast milk. This article is protected by copyright. All rights reserved.

Dextromethorphan Reduces Oxidative Stress and Inhibits Uremic Artery Calcification

Medial vascular calcification has emerged as a key factor contributing to cardiovascular mortality in patients with chronic kidney disease (CKD). Vascular smooth muscle cells (VSMCs) with osteogenic transdifferentiation play a role in vascular calcification. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitors reduce reactive oxygen species (ROS) production and calcified-medium-induced calcification of VSMCs. This study investigates the effects of dextromethorphan (DXM), an NADPH oxidase inhibitor, on vascular calcification. We used in vitro and in vivo studies to evaluate the effect of DXM on artery changes in the presence of hyperphosphatemia. The anti-vascular calcification effect of DXM was tested in adenine-fed Wistar rats. High-phosphate medium induced ROS production and calcification of VSMCs. DXM significantly attenuated the increase in ROS production, the decrease in ATP, and mitochondria membrane potential during the calcified-medium-induced VSMC calcification process (p < 0.05). The protective effect of DXM in calcified-medium-induced VSMC calcification was not further increased by NADPH oxidase inhibitors, indicating that NADPH oxidase mediates the effect of DXM. Furthermore, DXM decreased aortic calcification in Wistar rats with CKD. Our results suggest that treatment with DXM can attenuate vascular oxidative stress and ameliorate vascular calcification.

Peripherally active dextromethorphan derivatives lower blood glucose levels by targeting pancreatic islets

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.

Cytotoxic Lesion in the Splenium of Corpus Callosum Secondary to Subacute Methotrexate Neurotoxicity

Methotrexate neurotoxicity can present with a wide spectrum of neurologic symptoms and brain magnetic resonance imaging (MRI) typically demonstrates cerebral edema, demyelination, multifocal white matter necrosis, and atrophy relatively selective for the deep cerebral white matter. Here, we report a case of subacute methotrexate neurotoxicity in a 40-year-old man with B cell acute lymphoblastic leukemia. Brain MRI showed cytotoxic lesion in the splenium of corpus callosum and left middle cerebellar peduncle. Patient significantly improved 24 hours after receiving oral dextromethorphan. Methotrexate neurotoxicity should be suspected in any symptomatic patient receiving high dose of methotrexate or intrathecal methotrexate therapy. Dextromethorphan should be considered in these patients as it can modulate the excitatory responses to homocysteine and its metabolite which are usually elevated in such patients.

Substrate specificity of CYP2D6 genetic variants

Genetic variation in the gene encoding CYP2D6 is used to guide drug prescribing in clinical practice. However, genetic variants in CYP2D6 show substrate-specific effects that are currently not accounted for. With a systematic literature, we retrieved 22 original studies describing in vitro experiments focusing on CYP2D6 alleles (CYP2D6*1, *2, *10 and *17) and substrates. Allele activity (clearance of the allele of interest divided by the clearance of the wildtype) was extracted. The results support the hypothesis of the existence of substrate specificity of the CYP2D6*17-allele (higher debrisoquine clearance), a subtle effect of the CYP2D6*10-allele (lower dextromethorphan clearance) but no substrate-specific effect of the CYP2D6*2-allele. Although our results support substrate specificity, for most substrates data are too sparse and require further studies.

Drug repurposing of dextromethorphan as a cellular target for the management of influenza

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.

Effects of age and gender on the cytochrome P450 2D6 activity in a Korean population

WHAT IS KNOWN AND OBJECTIVE

Age and gender have been reported to play a crucial role in modulating the disposition of pharmacological agents, and to influence the activities of cytochrome P450 (CYP) 2D6, a drug-metabolizing enzyme involved in the disposition of clinically used drugs. In the present study, the effects of age and gender on the CYP2D6 activity were evaluated using dextromethorphan as a probe drug in humans.

METHODS

Healthy young (20 < age < 30 years, n = 60) and old age (age >60 years, n = 60) subjects were enrolled and were given 15 mg dextromethorphan orally. Blood samples were collected before and 3 h after medication. Dextromethorphan and its metabolite dextrorphan were measured using HPLC-fluorescence, and dextromethorphan metabolic ratio (MR, log [dextromethorphan/dextrorphan]) was used to evaluate the CYP2D6 activity.

RESULTS AND DISCUSSION

Mean (±SD) dextromethorphan MR was -2.42 ± 0.46 for the young male group, -2.28 ± 0.56 for the young female group, -2.46 ± 0.55 for the older male group and -2.34 ± 0.65 for the old female group. Based on our findings, the effects of age and gender on CYP2D6 activity were not statistically significant.

WHAT IS NEW AND CONCLUSION

The results of the present study indicate that age and gender play a minor role in the modulation of CYP2D6 activity in the Korean population.

Cardiovascular Complications of Opioid Use: JACC State-of-the-Art Review

Opioids are the most potent of all analgesics. Although traditionally used solely for acute self-limited conditions and palliation of severe cancer-associated pain, a movement to promote subjective pain (scale, 0 to 10) to the status of a "fifth vital sign" bolstered widespread prescribing for chronic, noncancer pain. This, coupled with rising misuse, initiated a surge in unintentional deaths, increased drug-associated acute coronary syndrome, and endocarditis. In response, the American College of Cardiology issued a call to action for cardiovascular care teams. Opioid toxicity is primarily mediated via potent μ-receptor agonism resulting in ventilatory depression. However, both overdose and opioid withdrawal can trigger major adverse cardiovascular events resulting from hemodynamic, vascular, and proarrhythmic/electrophysiological consequences. Although natural opioid analogues are devoid of repolarization effects, synthetic agents may be proarrhythmic. This perspective explores cardiovascular consequences of opioids, the contributions of off-target electrophysiologic properties to mortality, and provides practical safety recommendations.

Use of antitussive medications in acute cough in young children

Acute cough, a common complaint in young children, is often the result of a viral upper respiratory infection. Cough and cold remedies generate billions of dollars in annual sales in the United States, despite a lack of evidence of their efficacy and multiple warnings by the US Food and Drug Administration. The current article begins with the best available evidence for common over-the-counter (OTC) and prescription antitussive remedies in children. The article concludes with a discussion of the pros and cons for the use of antitussives in children with cough. In general, OTC antitussive medications should not be routinely used in children under 2 years of age. In certain cases, antitussives with minimal adverse profile and some evidence of benefit may be recommended after informed counseling.

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.

Low-Dose Dextromethorphan for the Treatment of Fibromyalgia Pain: Results from a Longitudinal, Single-Blind, Placebo-Controlled Pilot Trial

Objective

Fibromyalgia (FM) is a debilitating chronic pain condition with few treatment options. Central sensitization and neuroinflammation have been forwarded as models of FM pathophysiology, both of which indicate dextromethorphan (DXM) as a potential treatment. DXM is an NMDA-receptor antagonist and microglial modulator with anti-neuroinflammatory properties at low doses. It is available for clinical use but has not been tested as a treatment for FM at low dosages. This study evaluated the effectiveness of DXM in treating FM-associated symptoms.

Methods

In a single-blind, placebo-controlled trial, 14 women meeting the 2010 American College of Rheumatology criteria for FM received a placebo for five weeks, followed by 20 mg DXM for ten weeks, while providing daily symptom reports on a 0–100 scale. Pain and physical activity were the primary and secondary outcomes, respectively. Daily symptom ratings during the last four weeks of placebo were contrasted with ratings during the last four weeks of the active treatment using generalized estimating equations (GEE).

Results

DXM was well tolerated, and treatment adherence was high. Baseline pain was reduced by at least 20% in six participants. Self-reported daily pain and physical activity in the entire cohort were not significantly different between the placebo and DXM conditions, and the primary hypotheses were not supported. Exploratory analyses using the entire placebo and DXM data showed that pain was significantly lower in the DXM condition than in the placebo condition (b=−9.933, p=0.013).

Discussion

A strong clinical effect of DXM was not observed at the 20mg/day dosage.

Bioavailability of the Common Cold Medicines in Jellies for Oral Administration

Jellies for oral administration have been suggested as alternative dosage forms to conventional tablets for improved palatability and compliances for pediatric and geriatric patients. To evaluate the effect of jelly formulation on the bioavailability of cold medicines, two types of jellies were prepared for a fixed-dose combination of acetaminophen (AAP), chlorpheniramine maleate (CPM), dextromethorphan hydrobromide (DMH), and dl-methylephedrine hydrochloride (MEH). Jelly-S and Jelly-H were fabricated using carrageenan and locust bean gum in the absence and presence of xanthan gum, respectively. In vitro dissolution and in vivo absorption of the four drugs in the jellies were compared with other conventional formulations, a syrup and two types of immediate-release (IR) tablets with different hardness, Tablet-S (15 kPa) and Tablet-H (20 kPa). All the formulations exhibited more than 80% dissolution rate within 2 h even though the syrup, Jelly-S, and Tablet-S showed higher 30-min dissolution compared to Jelly-H and Tablet-H. The dissolution rates from the jellies decreased with increasing pH, which resulted in the slowest dissolution in pH 6.8 compared to the syrup and IR tablets. When administered orally to beagle dogs, all five formulations were determined not to be bioequivalent. However, Jelly-S and Jelly-H showed 0.82-1.05 of the geometric mean ratios (GMRs) of AUC_0-t for all four drugs compared to the syrup suggesting comparable absorption. In two IR tablets, GMRs of AUC_0-t were in a range of 0.55-0.95 indicating a tendency of lower absorption than the syrup and jellies. In conclusion, jelly can be a patient-centered formulation with comparable bioavailability to syrup.

Predicting steady-state endoxifen plasma concentrations in breast cancer patients by CYP2D6 genotyping or phenotyping. Which approach is more reliable?

In previous studies, steady-state Z-endoxifen plasma concentrations (ENDOss) correlated with relapse-free survival in women on tamoxifen (TAM) treatment for breast cancer. ENDOss also correlated significantly with CYP2D6 genotype (activity score) and CYP2D6 phenotype (dextromethorphan test). Our aim was to ascertain which method for assessing CYP2D6 activity is more reliable in predicting ENDOss. The study concerned 203 Caucasian women on tamoxifen-adjuvant therapy (20 mg q.d.). Before starting treatment, CYP2D6 was genotyped (and activity scores computed), and the urinary log(dextromethorphan/dextrorphan) ratio [log(DM/DX)] was calculated after 15 mg of oral dextromethorphan. Plasma concentrations of TAM, N-desmethyl-tamoxifen (ND-TAM), Z-4OH-tamoxifen (4OH-TAM) and ENDO were assayed 1, 4, and 8 months after first administering TAM. Multivariable regression analysis was used to identify the clinical and laboratory variables predicting log-transformed ENDOss (log-ENDOss). Genotype-derived CYP2D6 phenotypes (PM, IM, NM, EM) and log(DM/DX) correlated independently with log-ENDOss. Genotype-phenotype concordance was almost complete only for poor metabolizers, whereas it emerged that 34% of intermediate, normal, and ultrarapid metabolizers were classified differently based on log(DM/DX). Multivariable regression analysis selected log(DM/DX) as the best predictor, with patients' age, weak inhibitor use, and CYP2D6 phenotype decreasingly important: log-ENDOss = 0.162 - log(DM/DX) × 0.170 + age × 0.0063 - weak inhibitor use × 0.250 + IM × 0.105 + (NM + UM) × 0.210; (R2  = 0.51). In conclusion, log(DM/DX) seems superior to genotype-derived CYP2D6 phenotype in predicting ENDOss.

Cytochrome P450 2D6 polymorphism in eastern Indian population

OBJECTIVES:

Cytochrome P₄₅₀ 2D6 (CYP2D6) enzyme metabolizes a quarter of prescription drugs. Polymorphisms of CYP2D6 gene and resultant phenotypic variations in metabolic activity have been described in various populations. We assessed the prevalence of CYP2D6 activity phenotypes, employing dextromethorphan (DXM) as probe drug in subjects with at least two parental generations residing in eastern India.

MATERIALS AND METHODS:

Unrelated healthy subjects took 60 mg DXM after fasting overnight. Blood samples were collected 3 h after dosing and plasma separated. DXM and its primary metabolite dextrorphan (DXT) were measured by liquid chromatography with tandem mass spectrometry. The DXM-to-DXT metabolic ratio (MR) was obtained for each subject. Histogram of MR values suggested bimodal distribution. A polynomial regression equation derived through probit analysis was solved to identify the antimode of the MR values. Subjects with log(MR) < antimode were extensive metabolizers (EMs). Log(MR) ≥ antimode indicated poor metabolizers (PMs).

RESULTS:

We evaluated the results from 97 participants. The median MR was 0.209 (interquartile range: 0.090–0.609), while the antimode for MR was 3.055. From these, it was inferred that three subjects were PMs, while the rest were EMs. CYP2D6 polymorphism prevalence is low (3.09%; 95% confidence interval: 0.35%–6.54%) in the population of eastern India and matches the prevalence in other zones of the country.

CONCLUSIONS:

Differences in CYP2D6 activity has treatment implications and may lead to adverse events or therapeutic failure. Phenotyping of subjects receiving CYP2D6 metabolized drugs may help clinicians personalize treatment and avert adverse drug-drug interactions. However, the frequency of the PM phenotype is low in India, and routinely phenotyping for CYP2D6 activity will not be cost-effective. We cannot recommend it at this stage.

Dextromethorphan Attenuates Sensorineural Hearing Loss in an Animal Model and Population-Based Cohort Study

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.

Effects of Maribavir on P-Glycoprotein and CYP2D6 in Healthy Volunteers

Maribavir is an investigational drug being evaluated in transplant recipients with cytomegalovirus infection. To understand potential drug-drug interactions, we examined the effects of multiple doses of maribavir on cytochrome P450 (CYP) 2D6 and P-glycoprotein (P-gp) activity using probe substrates in healthy volunteers. During this phase 1 open-label study (NCT02775240), participants received the probe substrates digoxin (0.5 mg) and dextromethorphan (30 mg) before and after maribavir (400 mg twice daily for 8 days). Serial plasma samples were analyzed for digoxin, dextromethorpha, dextrorphan, and maribavir concentrations. Pharmacokinetic parameters were calculated (noncompartmental analysis) and analyzed with a linear mixed-effects model for treatment comparison to estimate geometric mean ratios (GMRs) and 90% confidence intervals (CIs). CYP2D6 polymorphisms were genotyped using polymerase chain reaction. Overall, 17 of 18 participants (94.4%) completed the study. All participants were genotyped as CYP2D6 intermediate/extensive metabolizers. GMR (90%CI) of digoxin Cmax , AUClast , and AUC0-∞ with and without maribavir was 1.257 (1.139-1.387), 1.187 (1.088-1.296), and 1.217 (1.110-1.335), respectively, outside the "no-effect" window (0.8-1.25). GMR (90%CI) of dextromethorphan AUClast and AUClast ratio of dextromethorphan/dextrorphan were 0.877 (0.692-1.112) and 0.901 (0.717-1.133), respectively, marginally outside the no-effect window, although large variability was observed in these pharmacokinetic parameters. Pharmacokinetic parameters of dextrorphan were unaffected. Maribavir inhibited P-gp activity but did not affect CYP2D6 activity. Maribavir's effect on the pharmacokinetics of P-gp substrates should be evaluated individually, and caution should be exercised with P-gp substrates with narrow therapeutic windows.

Evaluation of dextromethorphan with select antidepressant therapy for the treatment of depression in the acute care psychiatric setting

Introduction

Dextromethorphan (DXM), an N-methyl-D-aspartate receptor antagonist, may have ketamine-like antidepressant effects. Dextromethorphan is extensively metabolized via cytochrome P450 (CYP) 2D6, and its half-life in extensive metabolizers is 2 to 4 hours. The purpose of this study was to evaluate the effects of DXM in combination with a moderate-to-strong CYP2D6 inhibitor antidepressant on depression in an acute care psychiatric setting.

Methods

This was a single-center, retrospective chart review of adult patients with a depressive disorder diagnosis. Patients who received select antidepressant therapy with or without scheduled DXM were included. The primary outcome was the difference in time to improvement of depressive symptoms, which was an average composite of physician documentation, nurse documentation, and first time to 24 hours without as-needed anxiolytics or antipsychotics. The study group consisted of patients who received DXM with select antidepressant therapy, whereas the control group included those who received only select antidepressant therapy.

Results

A total of 40 patients were included. The median time to clinical improvement was 3.00 days and 2.83 days for the study group and control group, respectively (P = .986). The incidence of perceptual disturbances and delusions was higher in the study group as compared with the control group (55% and 35% vs 30% and 25%, respectively).

Discussion

Dextromethorphan was not associated with a rapid antidepressant effect. The commonly used dose of 30 mg daily may have been too low to have an effect; additionally, the most frequently utilized select antidepressant, bupropion, has moderately less CYP2D6 inhibition than fluoxetine and paroxetine.

Potential Negative Effects of Dextromethorphan as an Add-On Therapy to Methylphenidate in Children With ADHD

Objectives: Methylphenidate (MPH) is highly effective in controlling the symptoms of attention-deficit/hyperactivity disorder (ADHD), but some children with ADHD either do not respond to, or do not tolerate, treatment. Dextromethorphan (DM) is a neuroprotective agent which has been used in the treatment of neuropsychiatric disorders. This clinical trial had examined the effect of DM on the use of MPH in the children with ADHD. Methods: This randomized double-blind clinical trial had evaluated 44 male outpatients, aged between 6 and 12 years, with a diagnosis of ADHD. The study subjects were randomly assigned into one of the two groups: receiving MPH alone (15-60 mg per day) or MPH plus DM (30-60 mg per day) for 8 weeks. Assessments, comprising the Chinese version of the Child Behavior Checklist (CBCL-C) scale and the Swanson, Nolan and Pelham Questionnaire (SNAP)-IV rating tests conducted by parents and the serum cytokines measured by microarray and enzyme-linked immunosorband assay (ELISA), were compared between groups at baseline and at 8 weeks after the medication was started. Results: There were a significant decrease at the mean scores of both CBCL-C and SNAP-IV scales after 8 weeks of treatment, but no significant differences between MPH and MPH+DM groups. Compared with the MPH-only group, the mean scores of some psychometric parameters reported on the CBCL-C and SNAP-IV scales regarding time effects as well as the attention problems on the CBCL-C scale regarding group effect were significantly higher in the DM+MPH group. Although there were no significant differences in the levels of various serum cytokines between groups, the subjects in the DM-MPH group had relatively fewer and lower levels of adverse effects. Significant interactions were found between the withdrawn/depression item reported on the CBCL-C scale and tumor necrosis factor α (ခTNF-α) (p = 0.027), as well as between thought problems item on the CBCL-C and TNF-α (p = 0.028) in subjects who had received DM+MPH treatment. Conclusion: Following the trial, DM+MPH was not superior to MPH alone for the treatment of children with ADHD, yet DM may potentially have negative effects on ADHD symptoms when combined with MPH. Clinical Trial Registration: Clinicaltrials.gov, trial number: NCT01787136.