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Antimicrobial Agents and Chemotherapy Oct 2023Accumulating evidence supports the use of higher doses of rifampicin for tuberculosis (TB) treatment. Rifampicin is a potent inducer of metabolic enzymes and drug...
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.
Topics: Adult; Humans; Cytochrome P-450 CYP1A2; Midazolam; Cytochrome P-450 CYP2D6; Caffeine; Rifampin; Cytochrome P-450 CYP2C19; Cytochrome P-450 CYP3A; Dextromethorphan; Tolbutamide; Cytochrome P-450 CYP2C9; Cytochrome P-450 Enzyme System; Omeprazole; Drug Interactions; Tuberculosis, Pulmonary; Digoxin
PubMed: 37768317
DOI: 10.1128/aac.00683-23 -
Drug Design, Development and Therapy 2019Intravenous ketamine is often prescribed in severe neuropathic pain. Oral -methyl-D-aspartate receptor (NMDAR) antagonists might prolong pain relief, reducing the... (Randomized Controlled Trial)
Randomized Controlled Trial
PURPOSE
Intravenous ketamine is often prescribed in severe neuropathic pain. Oral -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, =0.53) and diminished pain paroxysms (=0.03) while pain intensity increased significantly with memantine and placebo (=0.04). At 3 months, pain remained lower than at inclusion (=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 (<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.
Topics: Administration, Oral; Adult; Aged; Analgesia; Dextromethorphan; Female; Humans; Infusions, Intravenous; Ketamine; Male; Memantine; Middle Aged; Neuralgia
PubMed: 31447547
DOI: 10.2147/DDDT.S207350 -
The Ceylon Medical Journal Sep 2008
Topics: Adolescent; Adult; Antitussive Agents; Behavior Therapy; Dextromethorphan; Humans; Life Style; Male; Nonprescription Drugs; Substance-Related Disorders; Young Adult
PubMed: 18982808
DOI: 10.4038/cmj.v53i3.256 -
Journal of UOEH 2024A woman in her 30s who was being treated for a mental illness with several psychotropic drugs was admitted to the hospital after being found in a state of...
A woman in her 30s who was being treated for a mental illness with several psychotropic drugs was admitted to the hospital after being found in a state of unconsciousness and respiratory arrest at home. She was pronounced dead 12 hours after she was discovered. Her autopsy revealed symmetrical hemorrhagic necrosis in the putamen on both sides of her cerebrum. Although many drugs were detected in her blood, all of those other than dextromethorphan (DXM) were within or below the therapeutic range. Her blood DXM was 1.73 μg/ml at admission and 1.61 μg/ml at autopsy, which were within the toxic range or coma-to-death range. The cause of death was diagnosed as DXM poisoning. DXM can cause hallucinations and euphoria if taken in excess, but since it is available as an over-the-counter drug at general pharmacies, an increasing number of young people are overdosing on it, mistakenly believing it to be a safe drug with few side effects. We believe that further social measures against DXM are necessary in Japan, such as disseminating correct knowledge in society and regulating over-the-counter sales.
Topics: Humans; Dextromethorphan; Female; Autopsy; Adult; Fatal Outcome
PubMed: 38839290
DOI: 10.7888/juoeh.46.221 -
Oncogene Mar 2021Smoking is one of the most impactful lifestyle-related risk factors in many cancer types including esophageal squamous cell carcinoma (ESCC). As the major component of...
Smoking is one of the most impactful lifestyle-related risk factors in many cancer types including esophageal squamous cell carcinoma (ESCC). As the major component of tobacco and e-cigarettes, nicotine is not only responsible for addiction to smoking but also a carcinogen. Here we report that nicotine enhances ESCC cancer malignancy and tumor-initiating capacity by interacting with cholinergic receptor nicotinic alpha 7 subunit (CHRNA7) and subsequently activating the JAK2/STAT3 signaling pathway. We found that aberrant CHRNA7 expression can serve as an independent prognostic factor for ESCC patients. In multiple ESCC mouse models, dextromethorphan and metformin synergistically repressed nicotine-enhanced cancer-initiating cells (CIC) properties and inhibited ESCC progression. Mechanistically, dextromethorphan non-competitively inhibited nicotine binding to CHRNA7 while metformin downregulated CHRNA7 expression by antagonizing nicotine-induced promoter DNA hypomethylation of CHRNA7. Since dextromethorphan and metformin are two safe FDA-approved drugs with minimal undesirable side-effects, the combination of these drugs has a high potential as either a preventive and/or a therapeutic strategy against nicotine-promoted ESCC and perhaps other nicotine-sensitive cancer types as well.
Topics: Animals; Carcinogenesis; Cell Line, Tumor; DNA Methylation; Dextromethorphan; Drug Repositioning; Electronic Nicotine Delivery Systems; Esophageal Squamous Cell Carcinoma; Female; Gene Expression Regulation, Neoplastic; Heterografts; Humans; Janus Kinase 2; Male; Metformin; Mice; Nicotine; SOXB1 Transcription Factors; STAT3 Transcription Factor; alpha7 Nicotinic Acetylcholine Receptor
PubMed: 33603170
DOI: 10.1038/s41388-021-01682-z -
Drug Metabolism and Disposition: the... Jun 2019Rolapitant [(Varubi), 5,8)-8-[[(1)-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...
Rolapitant [(Varubi), 5,8)-8-[[(1)-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 value of 1.2 ± 0.4 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 / ( ) value of 6.2 M. The IC value for rolapitant inhibition of CYP2D6 activity was 24 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 values of 20 and 34 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.
Topics: Catalytic Domain; Cytochrome P-450 CYP2D6; Cytochrome P-450 CYP2D6 Inhibitors; Dextromethorphan; Drug Interactions; Ethanolamines; Humans; Spiro Compounds
PubMed: 30952677
DOI: 10.1124/dmd.118.085928 -
JAMA Internal Medicine Feb 2019In 2010, the US Food and Drug Administration (FDA) approved a combination of dextromethorphan hydrobromide and quinidine sulfate for the treatment of pseudobulbar affect...
Assessment of Use of Combined Dextromethorphan and Quinidine in Patients With Dementia or Parkinson Disease After US Food and Drug Administration Approval for Pseudobulbar Affect.
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.
Topics: Aged; Amyotrophic Lateral Sclerosis; Dementia; Dextromethorphan; Drug Combinations; Excitatory Amino Acid Antagonists; Female; Humans; Male; Middle Aged; Multiple Sclerosis; Parkinson Disease; Pseudobulbar Palsy; Quinidine; United States; United States Food and Drug Administration
PubMed: 30615021
DOI: 10.1001/jamainternmed.2018.6112 -
Pain Physician Mar 2018Levorphanol is a long-acting opioid analgesic that is an optical isomer of dextrorphan, a metabolite of the over-the-counter cough suppressant dextromethorphan....
BACKGROUND
Levorphanol is a long-acting opioid analgesic that is an optical isomer of dextrorphan, a metabolite of the over-the-counter cough suppressant dextromethorphan. Providers prescribing levorphanol for pain management may need to assess compliance through urine drug testing, as this agent is subject to abuse. Therefore, it is important to differentiate between dextromethorphan and levorphanol ingestion.
OBJECTIVES
This article is the first to report urine concentrations of levorphanol/dextrorphan and 3-hydroxymorphinan in human urine and assesses the need for an enantiomeric analysis to distinguish between dextromethorphan and levorphanol ingestion.
STUDY DESIGN
Retrospective data review.
METHODS
Medication compliance test results were reviewed for 521 urine samples submitted to Aegis Sciences Corporation between July 2014 and July 2016. Samples were included in this analysis if dextromethorphan or levorphanol testing was requested by the ordering provider. Urine samples were hydrolyzed with beta-glucuronidase and analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). An enantiomeric analysis to distinguish levorphanol from dextrorphan and (-)-3-hydroxymorphinan (norlevorphanol) from (+)-3-hydroxymorphinan was not performed.
RESULTS
Nineteen urine samples with levorphanol listed as prescribed had median levorphanol/dextrorphan and 3-hydroxymorphinan concentrations of 1,881 ng/mL and 141 ng/mL, respectively. One-quarter of the urine samples with dextromethorphan listed as prescribed did not have any detectable dextromethorphan or 3-methoxymorphinan.
LIMITATIONS
An enantiomeric analysis was not utilized with the LC-MS/MS testing method; therefore, levorphanol could not be differentiated from dextrorphan, and (-)-3-hydroxymorphinan could not be differentiated from (+)-3-hydroxymorphinan. The hepatic and renal function for these patients was unknown; however, both could impact the metabolism, distribution, and excretion of levorphanol biomarkers in urine. The dextromethorphan and/or levorphanol dose and timing of last ingestion was also not assessed.
CONCLUSIONS
It may be impossible to distinguish between levorphanol and dextromethorphan ingestion based on urine biomarkers, unless dextromethorphan or 3-methoxymorphinan is present or an enantiomeric analysis is performed. Therefore, the potential exists for patients prescribed levorphanol to ingest dextromethorphan and appear compliant with levorphanol therapy. This should prompt clinicians to consider the parameters of their laboratory's testing method when interpreting levorphanol drug test results.
KEY WORDS
Levorphanol, dextrorphan, dextromethorphan, 3-hydroxymorphinan, urine testing, urine concentration, drug testing, medication compliance testing.
Topics: Biomarkers; Chromatography, Liquid; Dextromethorphan; Dextrorphan; Female; Humans; Levorphanol; Male; Retrospective Studies; Substance Abuse Detection
PubMed: 29565959
DOI: No ID Found -
Clinical Drug Investigation Aug 2012Dextromethorphan/quinidine (DMQ) is the first agent indicated for the treatment of pseudobulbar affect. Dextromethorphan, the active ingredient, is a low-affinity,... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND AND OBJECTIVE
Dextromethorphan/quinidine (DMQ) is the first agent indicated for the treatment of pseudobulbar affect. Dextromethorphan, the active ingredient, is a low-affinity, uncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist. This study evaluated the potential for a drug-drug interaction (DDI) of DMQ with memantine, which is also an NMDA receptor antagonist.
METHODS
This open-label, randomized, parallel-group study enrolled healthy adults who were randomized into one of two treatment groups. Group 1 subjects were administered memantine at a starting dose of 5 mg once daily, which was titrated over a 3-week period to a dose of 10 mg twice daily (every 12 hours) and continued for another 11 days to attain steady state; DMQ 30 mg (dextromethorphan 30 mg/quinidine 30 mg) every 12 hours was then added for a further 8 days. Group 2 subjects received DMQ 30 mg every 12 hours for 8 days to attain steady state; memantine was then added, titrated on the same schedule as in group 1, and continued at 10 mg every 12 hours for an additional 11 days. Pharmacokinetic blood sampling was performed to assess the primary endpoints of the 90% confidence intervals (CIs) for the geometric mean ratios of the areas under the plasma concentration-time curves (AUCs) for memantine, dextromethorphan, dextrorphan - the dextromethorphan metabolite - and quinidine during concomitant therapy versus monotherapy. Safety/tolerability and pharmacodynamic variables were also assessed.
RESULTS
A total of 52 subjects were randomized. In both group 1 (n = 23) and group 2 (n = 29), the 90% CIs for the ratios of the AUCs during concomitant therapy versus monotherapy were within the predefined range to indicate similarity (0.8-1.25) for memantine, dextromethorphan and dextrorphan, indicating no pharmacokinetic DDI. The 90% CI for the AUC ratio for quinidine was slightly above the predefined range; however, the mean AUC increased by only 25%. In both groups, incidence of adverse events was similar, and pharmacodynamic variables were either similar or slightly improved with DMQ added to memantine and memantine added to DMQ, compared to monotherapy with either agent.
CONCLUSION
Minimal pharmacokinetic and pharmacodynamic interactions were observed between memantine and DMQ, suggesting they can be coadministered without dose adjustment.
Topics: Adult; Dextromethorphan; Female; Humans; Male; Memantine; Middle Aged; Quinidine; Reference Values
PubMed: 22712629
DOI: 10.1007/BF03261905 -
Pharmacology, Biochemistry, and Behavior Mar 2016Combining effective treatments with diverse mechanisms of action for smoking cessation may provide better therapy by targeting multiple points of control in the neural...
Combining effective treatments with diverse mechanisms of action for smoking cessation may provide better therapy by targeting multiple points of control in the neural circuits underlying addiction. Previous research in a rat model has shown that dextromethorphan, which has α3β4 nicotinic and NMDA glutamatergic antagonist actions, significantly decreases nicotine self-administration. We have found in the rat model that the H1 histamine antagonist pyrilamine and the serotonin 5HT2C agonist lorcaserin also significantly reduce nicotine self-administration. The current studies were conducted to determine the interactive effects of dextromethorphan with pyrilamine and lorcaserin on nicotine self-administration in rats. Young adult female rats were fitted with jugular IV catheters and trained to self-administer a nicotine infusion dose of 0.03-mg/kg/infusion. In an initial dose-effect function study of dextromethorphan, we found a monotonic decrease in nicotine self-administration over a dose range of 1 to 30-mg/kg with the lowest effective dose of 3-mg/kg. Then, with two separate cohorts of rats, dextromethorphan (0, 3.3, and 10-mg/kg) interactions with pyrilamine (0, 4.43, and 13.3-mg/kg) were investigated as well as interactions with lorcaserin (0, 0.3125 and 0.625-mg/kg). In the pyrilamine-dextromethorphan interaction study, an acute dose of pyrilamine (13.3-mg/kg) as well as an acute dose of dextromethorphan caused a significant decrease in nicotine self-administration. There were mutually augmenting effects of these two drugs. The combination of dextromethorphan (10-mg/kg) and pyrilamine (13.3-mg/kg) significantly lowered nicotine self-administration relative to either 10-mg/kg of dextromethorphan alone (p<0.05) or 13.3-mg/kg of pyrilamine alone (p<0.0005). In the lorcaserin-dextromethorphan study, an acute dose of lorcaserin (0.312-mg/kg) as well as an acute dose of dextromethorphan (10-mg/kg) caused a significant decrease in nicotine self-administration replicating previous findings. Augmenting interactions were observed with dextromethorphan and pyrilamine as well as lorcaserin. These findings suggest that combination therapy may be more effective smoking cessation treatments than monotherapy.
Topics: Animals; Benzazepines; Dextromethorphan; Female; Histamine H1 Antagonists; Nicotine; Pyrilamine; Rats; Rats, Sprague-Dawley; Self Administration; Serotonin Receptor Agonists
PubMed: 26704812
DOI: 10.1016/j.pbb.2015.12.004