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Journal of Neurochemistry Aug 2023N-methyl-D-aspartate receptors (NMDAR), ionotropic glutamate receptors, mediate a slow component of excitatory synaptic transmission in the central nervous system and...
N-methyl-D-aspartate receptors (NMDAR), ionotropic glutamate receptors, mediate a slow component of excitatory synaptic transmission in the central nervous system and play a key role in normal brain function and development. Genetic variations in GRIN genes encoding NMDAR subunits that alter the receptor's functional characteristics are associated with a wide range of neurological and neuropsychiatric conditions. Pathological GRIN variants located in the M2 re-entrant loop lining the channel pore cause significant functional changes, the most consequential alteration being a reduction in voltage-dependent Mg inhibition. Voltage-dependent Mg block is a unique feature of NMDAR biology whereby channel activation requires both ligand binding and postsynaptic membrane depolarization. Thus, loss of NMDAR Mg block will have a profound impact on synaptic function and plasticity. Here, we choose 11 missense variants within the GRIN1, GRIN2A, and GRIN2B genes that alter residues located in the M2 loop and significantly reduce Mg inhibition. Each variant was evaluated for tolerance to genetic variation using the 3-dimensional structure and assessed for functional rescue pharmacology via electrophysiological recordings. Three FDA-approved NMDAR drugs-memantine, dextromethorphan, and ketamine-were chosen based on their ability to bind near the M2 re-entrant loop, potentially rectifying dysregulated NMDAR function by supplementing the reduced voltage-dependent Mg block. These results provide insight of structural determinants of FDA-approved NMDAR drugs at their binding sites in the channel pore and may further define conditions necessary for the use of such agents as potential rescue pharmacology.
PubMed: 37649269
DOI: 10.1111/jnc.15942 -
Acta Medica Philippina 2024Lung cancer is the leading cause of cancer death worldwide. It may present as airway obstruction in a patient with endobronchial masses. Endobronchial brachytherapy...
Lung cancer is the leading cause of cancer death worldwide. It may present as airway obstruction in a patient with endobronchial masses. Endobronchial brachytherapy (EBBT) has been shown to provide palliative therapy. It is the insertion of a radioactive material near the mass to reduce tumor size, thereby improving airway obstruction. This is the first case of EBBT done in our institution during the COVID-19 pandemic. A 53-year-old male, 60 kg, ASA Physical Status 2 for hypertension, smoker, malignancy, and previous pulmonary tuberculosis patient, presented with a cough and dyspnea. An endobronchial mass almost obstructing the right mainstem bronchus was seen on a computed tomography (CT) scan. He was diagnosed with squamous cell carcinoma of the lung and underwent radiotherapy and erlotinib chemotherapy. On repeat CT scan, there was no noted decrease in the size of the mass. EBBT was suggested, and a multi-disciplinary team was formed for the planned procedure. Pulmonology, radiation oncology, and anesthesiology teams were identified, and thorough planning was done prior to the actual procedure. Three fractions of EBBT were done under sedation using midazolam, fentanyl, and dexmedetomidine infusion. Lidocaine spray and transtracheal block were also performed as adjuncts prior to sedation. The procedure went as planned, and points for improvement were discussed for subsequent fractions. Due to persistent cough and discomfort from the catheter, additional ipratropium nebulization for minimization of secretions, and oral dextromethorphan for cough suppression were incorporated. After each fraction, the patient was monitored post-procedure for any side effects both from the radiotherapy and anesthetic technique. Qualitative reduction in mass size was noted in subsequent fractions. The patient was able to complete 3 fractions and was advised to follow-up after a month. EBBT is an emerging palliative and treatment modality for lung cancer, especially for intraluminal masses. Anesthetic considerations will depend on each case's characteristics such as airway anatomy, patient comfort and capacity, and procedural requirements. Conscious sedation with topical anesthesia is an adequate and appropriate anesthetic option, especially in cases where severe airway obstruction may compromise ventilation if airway reflexes are blunted. A multidisciplinary approach with different services and stakeholders is important for the proper planning, execution, and management of such patients.
PubMed: 38836083
DOI: 10.47895/amp.v58i9.8839 -
Journal of Clinical Pharmacology May 2024This study investigated the differences in the pharmacokinetics (PK) of dextromethorphan and desipramine in healthy African volunteers to understand the effect of...
Investigation of the Differences in the Pharmacokinetics of CYP2D6 Substrates, Desipramine, and Dextromethorphan in Healthy African Subjects Carrying the Allelic Variants CYP2D6*17 and CYP2D6*29, When Compared with Normal Metabolizers.
This study investigated the differences in the pharmacokinetics (PK) of dextromethorphan and desipramine in healthy African volunteers to understand the effect of allelic variants of the human cytochrome P450 2D6 (CYP2D6) enzyme, namely the diplotypes of CYP2D6*1/*2 (*1*1, *1*2, *2*2) and the genotypes of CYP2D6*17*17 and CYP2D6*29*29. Overall, 28 adults were included and split into 3 cohorts after genotype screening: CYP2D6*1/*2 (n = 12), CYP2D6*17*17 (n = 12), and CYP2D6*29*29 (n = 4). Each subject received a single oral dose of dextromethorphan 30 mg syrup on day 1 and desipramine 50 mg tablet on day 8. The PK parameters of area under the plasma concentration-time curve from time of dosing to time of last quantifiable concentration (AUC), and extrapolated to infinity (AUC), and the maximum plasma concentration (C) were determined. For both dextromethorphan and desipramine, AUC and C were higher in subjects of the CYP2D6*29*29 and CYP2D6*17*17 cohorts, as compared with subjects in the CYP2D6*1/*2 diplotype cohort and with normal metabolizers from the literature. All PK parameters, including AUC, C, and the elimination half-life, followed a similar trend: CYP2D6*17*17 > CYP2D6*29*29 > CYP2D6*1/*2. The plasma and urinary drug/metabolite exposure ratios of both drugs were higher in subjects of the CYP2D6*17*17 and CYP2D6*29*29 cohorts, when compared with subjects in the CYP2D6*1/*2 diplotype cohort. All adverse events were mild, except in 1 subject with CYP2D6*17*17 who had moderately severe headache with desipramine. These results indicate that subjects with CYP2D6*17*17 and CYP2D6*29*29 genotypes were 5-10 times slower metabolizers than those with CYP2D6*1/*2 diplotypes. These findings suggest that dose optimization may be required when administering CYP2D6 substrate drugs in African patients. Larger studies can further validate these findings.
Topics: Humans; Dextromethorphan; Desipramine; Cytochrome P-450 CYP2D6; Adult; Male; Female; Genotype; Young Adult; Alleles; Healthy Volunteers; Area Under Curve; Black People; Middle Aged; Half-Life; Antidepressive Agents, Tricyclic
PubMed: 37803948
DOI: 10.1002/jcph.2366 -
European Journal of Clinical... Aug 2023A therapeutic agent that targets both viral replication and the hyper-reactive immune response would offer a highly desirable treatment for severe acute respiratory...
PURPOSE
A therapeutic agent that targets both viral replication and the hyper-reactive immune response would offer a highly desirable treatment for severe acute respiratory syndrome corona virus 2 (SARS-CoV-2, coronavirus disease 2019, COVID-19) management. Emvododstat (PTC299; 4-chlorophenyl 6-chloro-1-[4-methoxyphenyl]-1,3, 4,9-tetrahydro-2H-pyrido[3,4-b]indole-2-carboxylate) was found to be a potent inhibitor of immunomodulatory and inflammation-related processes by inhibition of dihydroorotate dehydrogenase to reduce the severity of SARS-CoV-2 infections This drug interaction study was performed to determine if emvododstat was an inhibitor of CYP2D6.
METHODS
Potential drug-drug interactions between emvododstat and a CYP2D6 probe substrate (dextromethorphan) were investigated by measuring plasma dextromethorphan and metabolite (dextrorphan) concentrations before and after emvododstat administration. On day 1, 18 healthy subjects received an oral dose of 30 mg dextromethorphan followed by a 4-day washout period. On day 5, subjects received an oral dose of 250 mg emvododstat with food. Two hours later, 30 mg dextromethorphan was administered.
RESULTS
When given with emvododstat, plasma dextromethorphan concentrations increased substantially, while metabolite levels (dextrorphan) remained essentially the same. Maximum plasma dextromethorphan concentration (C) increased from 2006 to 5847 pg/mL. Dextromethorphan exposure (AUC) increased from 18,829 to 157,400 h·pg/mL for AUC and from 21,585 to 362,107 h·pg/mL for AUC following administration of emvododstat. When dextromethorphan parameters were compared before and after emvododstat, least squares mean ratios (90% confidence interval) were found to be 2.9 (2.2, 3.8), 8.4 (6.1, 11.5), and 14.9 (10.0, 22.1) for C, AUC, and AUC, respectively.
CONCLUSION
Emvododstat appears to be a strong CYP2D6 inhibitor. No drug-related treatment emergent adverse effects (TEAEs) were considered to be severe or serious.
TRIAL REGISTRATION
EudraCT 2021-004626-29, 11 May 2021.
Topics: Humans; Cytochrome P-450 CYP2D6; Dextromethorphan; Dihydroorotate Dehydrogenase; SARS-CoV-2; Dextrorphan; COVID-19; Drug Interactions
PubMed: 37278823
DOI: 10.1007/s00228-023-03513-4 -
Dermatitis : Contact, Atopic,... Apr 2024Although psychedelic and hallucinogenic substances have gained popularity for therapeutic use, their dermatologic adverse effects are poorly characterized. This review... (Review)
Review
Although psychedelic and hallucinogenic substances have gained popularity for therapeutic use, their dermatologic adverse effects are poorly characterized. This review characterizes the cutaneous reactions associated with psychedelic and hallucinogenic drugs. A review of PubMed and Scopus was conducted from the inception of databases to August 31, 2023. Search terms included drug names and classes (cannabis, MDMA, ecstasy, 3,4-methylenedioxymethamphetamine, psychedelics, hallucinogens, peyote, marijuana, lysergic acid diethylamide, LSD, ketamine, dimethyltryptamine, DMT, phencyclidine, PCP, dextromethorphan, psilocybin, and ayahuasca), and dermatosis terms (dermatitis, contact dermatitis, drug eruption, skin reaction, and urticaria). Studies were included if there was an association with a psychedelic or hallucinogenic and any cutaneous reaction; studies without both components were excluded. Twenty-two studies met inclusion criteria, describing reactions to cannabis (10 studies), MDMA (5 studies), ketamine (4 studies), and psilocybin (3 studies). Forty total patients were included. Among cannabis-related reactions, the most common reaction was type I hypersensitivity by topical exposure (n = 21). Three patients reported type IV hypersensitivity reactions to contact with cannabis or cannabis-derived oils, all of whom experienced vesicular contact dermatitis. Two additional patients presented with an erythema-multiforme-like reaction and acute generalized exanthematous pustulosis after systemic administration, respectively. MDMA was associated with acneiform eruptions (2 cases), an urticarial eruption, a guttate psoriasis-like reaction, a fixed drug eruption, and Stevens-Johnson syndrome (1 case). Four patients reported type I hypersensitivity reactions to ketamine. Four patients reported vesicular eruptions, cyanosis, or widespread jaundice to psilocybin. Of the cases, 8 patients had cutaneous reactions that resolved with drug cessation, 10 resolved with cessation plus treatment, and resolution in 7 cases was not reported. Zero studies were found describing other psychedelic or hallucinogenic compounds. Further research is required to characterize reactions and treatments linked to the variety of extant psychedelics and hallucinogens.
PubMed: 38634840
DOI: 10.1089/derm.2023.0292 -
Progress in Neuro-psychopharmacology &... Jun 2024The various pharmacological interventions, ranging from mood stabilizers and antipsychotics to antidepressants, reflect the diff/iculty of treating depressive/manic... (Review)
Review
BACKGROUND
The various pharmacological interventions, ranging from mood stabilizers and antipsychotics to antidepressants, reflect the diff/iculty of treating depressive/manic symptomatology of bipolar disorder (BD). Among a broad range of mechanisms implicated, immune dysregulation may contribute to the increased inflammation that influences the course of BD. Inflammatory, neurotrophic and oxidative stress factors may be identified as promising peripheral biomarkers in brain functioning, perhaps serving as predictors of an effective response to treatment for BD. The present systematic review aimed to examine the evidence supporting the pharmacotherapeutic value of inflammatory and neurotrophic biomarkers in BD.
METHODS
PubMed, PsychINFO, Scopus and Web of Science were searched from inception to May 2024 by two independent reviewers. A total of 40 studies with 3371 patients with diagnosis and intervention of BD were selected.
RESULTS
Inconsistencies in the effects of pharmacological treatments on the connection between the expected anti-inflammatory response and symptomatologic improvement were identified. Mood stabilizers (lithium), antipsychotics (quetiapine), antidepressants (ketamine) or their combination were described to increase both pro-inflammatory (TNFα, IL-6) and anti-inflammatory (IL-4, IL-8) factors. Other medications, such as memantine and dextromethorphan, autoimmune (infliximab) non-steroidal anti-inflammatory (aspirin, celecoxib) drugs, antidiabetics (pioglitazone), and even dietary supplementation (omega-3), or their combination, clearly decrease inflammatory factors (TNFα, IL-6, IL-1β, C-reactive protein) and/or increase the neurotrophic factor BDNF in BD patients.
CONCLUSION
Inflammation in BD requires further investigation to understand the underlying immunologic mechanism, to identify predictors of treatment response, and to make informed decisions about the use and development of more effective pharmacological interventions for BD.
PubMed: 38879067
DOI: 10.1016/j.pnpbp.2024.111056 -
Journal of Molecular Neuroscience : MN Jan 2024Hypothalamus is central to food intake and satiety. Recent data unveiled the expression of N-methyl-D-aspartate receptors (NMDAR) on hypothalamic neurons and their...
Hypothalamus is central to food intake and satiety. Recent data unveiled the expression of N-methyl-D-aspartate receptors (NMDAR) on hypothalamic neurons and their interaction with GABA and serotoninergic neuronal circuits. However, the precise mechanisms governing energy homeostasis remain elusive. Notably, in females, the consumption of progesterone-containing preparations, such as hormonal replacement therapy and birth control pills, has been associated with hyperphagia and obesity-effects mediated through the hypothalamus. To elucidate this phenomenon, we employed the progesterone-induced obesity model in female Swiss albino mice. Four NMDAR modulators were selected viz. dextromethorphan (Dxt), minocycline, d-aspartate, and cycloserine. Obesity was induced in female mice by progesterone administration for 4 weeks. Mice were allocated into 7 groups, group-1 as vehicle control (arachis oil), group-2 (progesterone + arachis oil), and group-3 as positive-control (progesterone + sibutramine); other groups were treated with test drugs + progesterone. Various parameters were recorded like food intake, thermogenesis, serum lipids, insulin, AST and ALT levels, organ-to-body weight ratio, total body fat, adiposity index, brain serotonin levels, histology of liver, kidney, and sizing of fat cells. Dxt-treated group has shown a significant downturn in body weight (p < 0.05) by a decline in food intake (p < 0.01), organ-to-liver ratio (p < 0.001), adiposity index (p < 0.01), and a rise in body temperature and brain serotonin level (p < 0.001). Dxt demonstrated anti-obesity effects by multiple mechanisms including interaction with hypothalamic GABA channels and anti-inflammatory and free radical scavenging effects, improving the brain serotonin levels, and increasing insulin release from the pancreatic β-cells.
Topics: Female; Mice; Animals; N-Methylaspartate; Receptors, N-Methyl-D-Aspartate; Serotonin; Progesterone; Peanut Oil; Obesity; Hypothalamus; Insulins; gamma-Aminobutyric Acid
PubMed: 38240858
DOI: 10.1007/s12031-023-02178-z -
Drug Metabolism and Disposition: the... Mar 2024Tree shrews are a nonprimate species used in a range of biomedical studies. Recent genome analysis of tree shrews found that the sequence identities and the numbers of...
Tree shrews are a nonprimate species used in a range of biomedical studies. Recent genome analysis of tree shrews found that the sequence identities and the numbers of genes of cytochrome P450 (CYP or P450), an important family of drug-metabolizing enzymes, are similar to those of humans. However, tree shrew P450s have not yet been sufficiently identified and analyzed. In this study, novel CYP2D8a and CYP2D8b cDNAs were isolated from tree shrew liver and were characterized, along with human CYP2D6, dog CYP2D15, and pig CYP2D25. The amino acid sequences of these tree shrew CYP2Ds were 75%-78% identical to human CYP2D6, and phylogenetic analysis showed that they were more closely related to human CYP2D6 than rat CYP2Ds, similar to dog and pig CYP2Ds. For tree shrew CYP2D8b, two additional transcripts were isolated that contained different patterns of deletion. The gene and genome structures of are generally similar in dogs, humans, pigs, and tree shrews. Tree shrew CYP2D8a mRNA was most abundantly expressed in liver, among the tissue types analyzed, similar to dog CYP2D15 and pig CYP2D25 mRNAs. Tree shrew CYP2D8b mRNA was also expressed in liver, but at a level 7.3-fold lower than CYP2D8a mRNA. Liver microsomes and recombinant protein of both tree shrew CYP2Ds metabolized bufuralol and dextromethorphan, selective substrates of human CYP2D6, but the activity level of CYP2D8a greatly exceeded that of CYP2D8b. These results suggest that tree shrew CYP2D8a and CYP2D8b are functional drug-metabolizing enzymes, of which CYP2D8a is the major CYP2D in liver. SIGNIFICANCE STATEMENT: Novel tree shrew CYP2D8a and CYP2D8b cDNAs were isolated from liver. Their amino acid sequences were 75%-78% identical to human CYP2D6. For CYP2D8b, two additional transcripts contained different patterns of deletion. Tree shrew CYP2D8a mRNA was abundantly expressed in liver, similar to dog CYP2D15 and pig CYP2D25 mRNAs. Recombinant tree shrew CYP2Ds catalyzed the oxidation of bufuralol and dextromethorphan. Tree shrew CYP2D8a and CYP2D8b are functional drug-metabolizing enzymes, of which CYP2D8a is the major CYP2D in liver.
Topics: Humans; Rats; Swine; Animals; Dogs; Cytochrome P-450 CYP2D6; Dextromethorphan; Tupaia; Tupaiidae; Phylogeny; Shrews; Cytochrome P-450 Enzyme System; Microsomes, Liver; RNA, Messenger; Ethanolamines
PubMed: 38262704
DOI: 10.1124/dmd.123.001603 -
Journal of Clinical Psychopharmacology
Topics: Humans; Guaifenesin; Dextromethorphan; Antitussive Agents; Nephrolithiasis
PubMed: 38227627
DOI: 10.1097/JCP.0000000000001815 -
Urology Case Reports Sep 2023Both guaifenesin and dextromethorphan are routinely available nonprescription medications that are also common drugs of abuse amongst young adults. We describe a...
Both guaifenesin and dextromethorphan are routinely available nonprescription medications that are also common drugs of abuse amongst young adults. We describe a presentation of guaifenesin and dextromethorphan misuse resulting in acute renal failure due to bilateral nephrolithiasis. The patient underwent placement of bilateral ureteral stents but again formed small renal stones bilaterally. While most renal calculi are not drug-induced, this case highlights the potential for nephrolithiasis after guaifenesin and dextromethorphan ingestion. It suggests that in this combination ingestion multiple mechanisms lead to a prolonged period of nephrolith formation.
PubMed: 37455782
DOI: 10.1016/j.eucr.2023.102481