3-hydroxymorphinan enhances mitochondrial biogenesis and adipocyte browning through AMPK-dependent pathway.

3-hydroxymorphinan (3-HM), a metabolite of dextromethorphan, has previously been reported to have anti-inflammatory, anti-oxidative stress, and neuroprotective effects. However, its effect on energy metabolism in adipocytes remains unclear. Herein, we investigated 3-hydroxymorphinan (3-HM) effects on mitochondrial biogenesis, oxidative stress, and lipid accumulation in 3T3-L1 adipocytes. Further, we explored 3-HM-associated molecular mechanisms. Mouse adipocyte 3T3-L1 cells were treated with 3-HM, and various protein expression levels were determined by western blotting analysis. Mitochondria accumulation and lipid accumulation were measured by staining methods. Cell toxicity was assessed by cell viability assay. We found that treatment of 3T3-L1 adipocytes with 3-HM increased expression of brown adipocyte markers, such as uncoupling protein-1 (UCP-1) and peroxisome proliferator-activated receptor-gamma coactivator 1-alpha (PGC-1α). 3-HM promotes mitochondrial biogenesis and its-mediated gene expression. Additionally, 3-HM treatment suppressed mitochondrial ROS generation and superoxide along with improved mitochondrial complex I activity. We found that treatment of 3-HM enhanced AMPK phosphorylation. siRNA-mediated suppression of AMPK reversed all these changes in 3T3-L1 adipocytes. In sum, 3-HM promotes mitochondrial biogenesis and browning and attenuates oxidative stress and lipid accumulation in 3T3-L1 adipocytes via AMPK signaling. Thus, 3-HM-mediated AMPK activation can be considered a therapeutic approach for treating obesity and related diseases.

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.

N-Substituted-3-alkoxy-derivatives of dextromethorphan are functional NMDA receptor antagonists in vivo: Evidence from an NMDA-induced seizure model in rats.

Interest in developing NMDA receptor antagonists with reduced side-effects for neurological and psychiatric disorders has been re-energized by the recent introduction of esketamine into clinical practice for treatment-resistant depression. Structural analogs of dextromethorphan bind with low affinity to the NMDA receptor ion channel, have functional effects in vivo, and generally display a lower propensity for side-effects than that of ketamine and other higher affinity antagonists. As such, the aim of the present study was to determine whether a series of N-substituted-3-alkoxy-substituted dextromethorphan analogs produce their anticonvulsant effects through NMDA receptor blockade. Compounds were studied against NMDA-induced seizures in rats. Compounds were administered intracerebroventricularly in order to mitigate confounds of drug metabolism that arise from systemic administration. Comparison of the anticonvulsant potencies to their affinities for NMDA, σ1, and σ2 binding sites were made in order to evaluate the contribution of these receptors to anticonvulsant efficacy. The potencies to block convulsions were positively associated with their affinities to bind to the NMDA receptor ion channel ([3H]-TCP binding) (r = 0.71, p < 0.05) but not to σ1 receptors ([3H]-SKF 10047 binding) (r = -0.31, p = 0.46) or to σ2 receptors ([3H]-DTG binding) (p = -0.38, p = 0.36). This is the first report demonstrating that these dextromethorphan analogs are functional NMDA receptor antagonists in vivo. Given their potential therapeutic utility and favorable side-effect profiles, such low affinity NMDA receptor antagonists could be considered for further development in neurological (e.g., anticonvulsant) and psychiatric (e.g., antidepressant) disorders.

Analysis of Dextromethorphan and Three Metabolites in Decomposed Skeletal Tissues by UPLC-QToF-MS: Comparison of Acute and Repeated Drug Exposures.

Ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-QToF-MS) analysis of dextromethorphan (DXM) and its metabolites-dextrorphan, 3-methoxymorphinan (3-MEM) and 3-hydroxymorphinan-in skeletal remains of rats exposed to DXM under different dosing patterns is described. Rats (n = 20) received DXM in one of four dosing patterns: acute (ACU1 or ACU2-100 or 200 mg/kg, i.p.; n = 5, respectively) or repeated (REP1 or REP2-3 doses of 25 or 50 mg/kg, i.p., 30 min apart; n = 5, respectively). Drug-free animals (n = 5) served as negative controls. Following euthanasia, the animals decomposed to skeleton outdoors. Bones were sorted by animal and skeletal element (vertebra, femur, pelvis, tibia, rib and skull), washed, air-dried and pulverized prior to dynamic methanolic drug extraction, filtration/pass-through extraction and analysis by UPLC-QToF-MS in positive electrospray ionization mode. Analyte levels (expressed as mass-normalized response ratios, RR/m) differed significantly between ACU1 and ACU2 (Mann-Whitney (MW), P < 0.05) in all skeletal elements for all analytes investigated, and between REP1 and REP2 in most skeletal elements for 3-MEM and 3-HOM, but in all skeletal elements for DXM. Between ACU1 and ACU2, and between REP1 and REP2, analyte level ratios (RRi/RRj) differed significantly (MW, P < 0.05) in 3/6 to 6/6 skeletal elements, depending on the ratios concerned, with no analyte level ratio differing significantly between both ACU1 vs ACU2 and REP1 vs REP2. Kruskal-Wallis (KW) analysis showed skeletal element to be a main effect for all analyte levels and analyte level ratios in all ACU and REP groups examined (P < 0.05). For data pooled only according to exposure pattern, KW analysis showed dose pattern to be a main effect for both analyte levels and analyte level ratios (P < 0.05). These data illustrate a dependence of these measures on dose, dose pattern and skeletal element, suggesting that some exposure patterns may be distinguished by toxicological analysis of bone.

Design, Synthesis, and Biological Evaluation of Phenol Bioisosteric Analogues of 3-Hydroxymorphinan.

The neuroprotective agent 3-hydroxymorphinan (3-HM) is a well-documented and highly safe therapeutic intervention for the inflammatory-related effects of Parkinson's disease (PD). However, the bioavailability of 3-HM is very low due to the rapid first-pass metabolism of the phenolic moiety. In the present study, we sought to improve the metabolic stability and overall pharmacokinetic profile of 3-HM. Based on an iterative design process that a suitably arranged heterocycle with an NH group would serve as the metabolically stable isostere of the phenolic group, we designed and synthesized two analogues of 3-HM. Benzimidazolone compound 8 (imidazolone-morphinan) was comparable in activity to 3-HM against lipopolysaccharide (LPS)-induced inflammatory responses in microglial BV2 cells and in vivo animal experiments (MPTP-induced PD mouse model). Moreover, the in vitro study showed that imidazolone-morphinan was non-toxic to microglia, indicating its high safety. Considering the favourable and unique preclinical profiles, compound 8 was nominated as a candidate for further clinical development.

Identifying Levorphanol Ingestion Using Urine Biomarkers in Health Care Patients.

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.

The Psychostimulant Khat (Catha edulis) Inhibits CYP2D6 Enzyme Activity in Humans.

The use of khat (Catha edulis) while on medication may alter treatment outcome. In particular, the influence of khat on the metabolic activities of drug-metabolizing enzymes is not known. We performed a comparative 1-way crossover study to evaluate the effect of khat on cytochrome P450 (CYP)2D6 and CYP3A4 enzyme activity. After 1 week of khat abstinence, baseline CYP2D6 and CYP3A4 metabolic activities were determined in 40 Ethiopian male volunteers using 30 mg dextromethorphan (DM) as a probe drug and then repeated after 1 week of daily use of 400 g fresh khat leaves. Urinary concentrations of cathinone and cathine were determined to monitor the subjects' compliance to the study protocol. Genotyping for CYP2D6*3 and CYP2D6*4 was done. Plasma DM, dextrorphan and 3-methoxymorphinan concentrations were quantified. CYP2D6 and CYP3A4 enzyme activities were assessed by comparing plasma log DM/dextrorphan and log DM/methoxymorphinan metabolic ratio (MR) respectively in the presence and absence of khat. Cytochrome 2D6 MR was significantly increased from baseline by concurrent khat use (paired t test, P = 0.003; geometric mean ratio, 1.38; 95% confidence interval [95% CI], 1.12-1.53). Moreover, the inhibition of CYP2D6 activity by khat was more pronounced in CYP2D6*1/*1 compared with CYP2D6*1/*4 genotypes (P = 0.01). A marginal inhibition of CYP3A4 activity in the presence of khat was observed (P = 0.24). The mean percentage increase of CYP2D6 and CYP3A4 MR from baseline by khat use was 46% (95% CI, 20-72) and 31% (95% CI, 8-54), respectively. This is the first report linking khat use with significant inhibition of CYP2D6 metabolic activity in humans.

Dual Therapeutic Effects of C-10068, a Dextromethorphan Derivative, Against Post-Traumatic Nonconvulsive Seizures and Neuroinflammation in a Rat Model of Penetrating Ballistic-Like Brain Injury.

Post-traumatic seizures can exacerbate injurious outcomes of severe brain trauma, yet effective treatments are limited owing to the complexity of the pathology underlying the concomitant occurrence of both events. In this study, we tested C-10068, a novel deuterium-containing analog of (+)-N-methyl-3-ethoxymorphinan, in a rat model of penetrating ballistic-like brain injury (PBBI) and evaluated the effects of C-10068 on PBBI-induced nonconvulsive seizures (NCS), acute neuroinflammation, and neurofunctional outcomes. NCS were detected by electroencephalographic monitoring. Neuroinflammation was evaluated by immunohistochemical markers, for example, glial fibrillary acidic protein and major histocompatibility complex class I, for activation of astrocytes and microglia, respectively. Neurofunction was tested using rotarod and Morris water maze tasks. Three infusion doses of C-10068 (1.0, 2.5, and 5.0 mg/kg/h × 72 h) were tested in the antiseizure study. Neuroinflammation and neurofunction were evaluated in animals treated with 5.0 mg/kg/h × 72 h C-10068. Compared to vehicle treatment, C-10068 dose dependently reduced PBBI-induced NCS incidence (40-50%), frequency (20-70%), and duration (30-82%). The most effective antiseizure dose of C-10068 (5.0 mg/kg/h × 72 h) also significantly attenuated hippocampal astrocyte activation and perilesional microglial reactivity post-PBBI. Within C-10068-treated animals, a positive correlation was observed in reduction in NCS frequency and reduction in hippocampal astrocyte activation. Further, C-10068 treatment significantly attenuated astrocyte activation in seizure-free animals. However, C-10068 failed to improve PBBI-induced motor and cognitive functions with the dosing regimen used in this study. Overall, the results indicating that C-10068 exerts both potent antiseizure and antiinflammatory effects are promising and warrant further investigation.

Effect of Curcuma longa on CYP2D6- and CYP3A4-mediated metabolism of dextromethorphan in human liver microsomes and healthy human subjects.

Effect of Curcuma longa rhizome powder and its ethanolic extract on CYP2D6 and CYP3A4 metabolic activity was investigated in vitro using human liver microsomes and clinically in healthy human subjects. Dextromethorphan (DEX) was used as common probe for CYP2D6 and CYP3A4 enzymes. Metabolic activity of CYP2D6 and CYP3A4 was evaluated through in vitro study; where microsomes were incubated with NADPH in presence and absence of Curcuma extract. In clinical study phase-I, six healthy human subjects received a single dose (30 mg) of DEX syrup, and in phase-II DEX syrup was administered with Curcuma powder. The enzyme CYP2D6 and CYP3A4 mediated O- and N-demethylation of dextromethorphan into dextrorphan (DOR) and 3-methoxymorphinan (3-MM), respectively. Curcuma extract significantly inhibited the formation of DOR and 3-MM, in a dose-dependent and linear fashion. The 100 µg/ml dose of curcuma extract produced highest inhibition, which was about 70 % for DOR and 80 % for 3-MM. Curcuma significantly increases the urine metabolic ratio of DEX/DOR but the change in DEX/3-MM ratio was statistically insignificant. Present findings suggested that curcuma significantly inhibits the activity of CYP2D6 in in vitro as well as in vivo; which indicates that curcuma has potential to interact with CYP2D6 substrates.

Neuropsychotoxic and neuroprotective potentials of dextromethorphan and its analogs.

Dextromethorphan (3-methoxy-17-methylmorphinan) has complex pharmacologic effects on the central nervous system. Although some of these effects are neuropsychotoxic, this review focuses on the neuroprotective effects of dextromethorphan and its analogs. Some of these analogs, particularly dimemorfan (3-methyl-17-methylmorphinan) and 3-hydroxymorphinan, have promising neuroprotective properties with negligible neuropsychotoxic effects. Their neuroprotective effects, the mechanisms underlying these effects, and their therapeutic potential for the treatment of diverse neurodegenerative disorders are discussed.

Simultaneous quantification of dextromethorphan and its metabolites dextrorphan, 3-methoxymorphinan and 3-hydroxymorphinan in human plasma by ultra performance liquid chromatography/tandem triple-quadrupole mass spectrometry.

A rapid and sensitive ultra performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) method has been developed and validated for the simultaneous quantitative determination of dextromethorphan (DM) and its metabolites dextrorphan (DX), 3-methoxymorphinan (3MM) and 3-hydroxymorphinan (3HM), in human lithium heparinized plasma. The extraction involved a simple liquid-liquid extraction with 1 ml n-butylchloride from 200µl aliquots of plasma, after the addition of 20 µl 4% (v/v) ammonium hydroxide and 100 µl stable labeled isotopic internal standards in acetonitrile. Chromatographic separations were achieved on an Aquity UPLC(®) BEH C(18) 1.7 µm 2.1 mm x 100mm column eluted at a flow-rate of 0.250 ml/min on a gradient of acetonitrile. The overall cycle time of the method was 7 min, with elution times of 1.3min for DX and 3HM, 2.8 min for 3MM and 2.9min for DM. The multiple reaction monitoring transitions were set at 272>215 (m/z), at 258>133 (m/z), at 258>213 (m/z) and at 244>157 (m/z) for DM, DX, 3MM and 3HM, respectively. The calibration curves were linear (r²≥0.995) over the range of 0.500-100 nM with the lower limit of quantitation validated at 0.500 nM for all compounds, which is equivalent to 136, 129, 129 and 122 pg/ml for DM, DX, 3MM and 3HM, respectively. Extraction recoveries were constant, but ranged from 39% for DM to 83% for DX. The within-run and between-run precisions were within 11.6%, while the accuracy ranged from 92.7 to 110.6%. The applicability of the bioanalytical method was demonstrated and is currently implemented in a clinical trial to study DM as probe-drug for individualized tamoxifen treatment in breast cancer patients.

Neuropsychopharmacological understanding for therapeutic application of morphinans.

Morphinans are a class of compounds containing the basic structure of morphine. It is well-known that morphinans possess diverse pharmacological effects on the central nervous system. This review will demonstrate novel neuroprotective effects of several morphinans such as, dextromethorphan, its analogs and naloxone on the models of multiple neurodegenerative disease by modulating glial activation associated with the production of a host of proinflammatory and neurotoxic factors, although dextromethorphan possesses neuropsychotoxic potentials. The neuroprotective effects and the therapeutic potential for the treatment of excitotoxic and inflammatory neurodegenerative diseases, and underlying mechanism of morphinans are discussed.

Effect of black seed on dextromethorphan O- and N-demethylation in human liver microsomes and healthy human subjects.

OBJECTIVE: To investigate the effects of black seed on the metabolic activities of CYP3A4 and CYP2D6 in human liver microsomes and in human subjects using dextromethorphan as a probe drug. METHODS: CYP2D6-mediated O-demethylation and CYP3A4-mediated N-demethylation of dextromethorphan (DEX) to dextrorphan (DOR) and 3-methoxymorphinan (3-MM), respectively, were utilized to assess the metabolic activities of the two enzymatic pathways. In the in vitro experiments, DEX was incubated with microsomes and NADPH in absence or presence of black seed extract (10-100 microg/ml) and the formation of the metabolites were measured by HPLC. In the clinical study, four healthy volunteers received a single oral dose of DEX 30 mg alone in phase I, and along with last dose of black seed (2.5 g twice daily for seven days) in phase II. Activities of the two enzymes were evaluated based on the urinary metabolic ratios (MRs), which were calculated from eight-hour urine collections. DEX and its metabolites were assayed in urine samples by HPLC following a liquid-liquid extraction. RESULTS: Black seed extracts significantly inhibited the formation of both metabolites in microsomes. The maximum inhibition was observed at the highest extract concentration (i.e., 100 microg/ml), which was about 80% and 60% for DOR and 3-MM, respectively. In the clinical study, the urinary MRs of DEX/DOR and DEX/3-MM increased by factors of 127 and 1.6-fold, respectively, after consumption of black seed. CONCLUSION: Black seed significantly inhibited CYP2D6 and CYP3A4 mediated metabolism of DEX in human liver microsomes and healthy human volunteers indicating that it has the potential to interact with CYP2D6 and CYP3A4 substrates.

A validated SIM GC/MS method for the simultaneous determination of dextromethorphan and its metabolites dextrorphan, 3-methoxymorphinan and 3-hydroxymorphinan in biological matrices and its application to in vitro CYP2D6 and CYP3A4 inhibition study.

Dextromethorphan is used as a probe drug for assessing CYP2D6 and CYP3A4 activity in vivo and in vitro. A SIM GC/MS method without derivatization for the simultaneous determination of dextromethorphan and its metabolites, dextrorphan, 3-methoxymorphinan and 3-hydroxymorphinan, in human plasma, urine and in vitro incubation matrix was developed and validated. Calibration curves indicated good linearity with a coefficient of variation (r) better than 0.995. The lower limit of quantitation was found to be 10 ng/mL for all analytes in all matrices. Intra-day and inter-day precision for dextromethorphan and its metabolites was better than 9.02 and 9.91%, respectively and accuracy ranged between 91.76 and 106.27%. Recovery for dextromethorphan, its metabolites and internal standard levallorphan was greater than 72.68%. The method has been successfully applied for the in vitro inhibition of metabolism of dextromethorphan by CYP2D6 and CYP3A4 using known inhibitors of CYPs such as quinidine and verapamil.

Inhibitory effect of glutamate release from rat cerebrocortical synaptosomes by dextromethorphan and its metabolite 3-hydroxymorphinan.

Dextromethorphan (DM), a widely used antitussive, has demonstrated an effective neuroprotective effect. Excessive release of glutamate is considered to be an underlying cause of neuronal damage in several neurological diseases. In the present study, we investigated whether DM or its metabolite 3-hydroxymorphinan (3-HM) could affect glutamate release in rat cerebral cortex nerve terminals (synaptosomes). DM or 3-HM inhibited the Ca(2+)-dependent release of glutamate that was evoked by exposing synaptosomes to the K(+) channel blocker 4-aminopyridine (4-AP), and this presynaptic inhibition was concentration-dependent. Inhibition of glutamate release by DM or 3-HM was resulted from a reduction of vesicular exocytosis, because the vesicular transporter inhibitor bafilomycin A1 completely blocked DM or 3-HM-mediated inhibition of 4-AP-evoked glutamate release. DM or 3-HM did not alter the resting synaptosomal membrane potential or 4-AP-mediated depolarization, but significantly reduced depolarization-induced increase in [Ca(2+)](C). DM or 3-HM-mediated inhibition of 4-AP-evoked glutamate release was blocked by omega-conotoxin MVIIC, an antagonist of N- and P/Q-type Ca(2+) channel, not by dantrolene, an intracellular Ca(2+) release inhibitor. DM or 3-HM modulation of 4-AP-evoked glutamate release appeared to involve a protein kinase C (PKC) signaling cascade, insofar as pretreatment of synaptosomes with the PKC inhibitors GF109203X or Ro318220 all effectively occluded the inhibitory effect of DM or 3-HM. Furthermore, 4-AP-induced phosphorylation of PKC was reduced by DM or 3-HM. These results suggest that DM or 3-HM inhibits glutamate release from rat cortical synaptosomes through the suppression of presynaptic voltage-dependent Ca(2+) entry and PKC activity. This may explain the neuroprotective effects of DM against neurotoxicity.

Metabolism of dextrorphan by CYP2D6 in different recombinantly expressed systems and its implications for the in vitro assessment of dextromethorphan metabolism.

Cytochrome P450 2D6 (CYP2D6) mediated formation of dextrorphan (DOR) from dextromethorphan (DEX) is widely used as a marker to assess the activity of this enzyme both in vitro and in vivo. The sequential metabolism of DOR during in vitro studies, particularly using recombinant systems (rCYPs) expressing human CYP2D6, is assumed to be negligible. The extent of metabolism was investigated for a range of DEX and DOR concentrations in microsomal preparations from three different rCYPs expressing human CYP2D6 (yeast, Supersomes and Bactosomes) containing 10 pmol of the enzyme. Bactosomes and Supersomes, but not yeast rCYP microsomes, were capable of metabolising DOR to 3-hydroxymorphinan (HYM). Two novel CYP2D6 related metabolites were identified in Bactosomes, and assigned as single hydroxylations in the phenyl rings of DOR and HYM using ion-trap mass spectrometry. Therefore, in rCYP systems with high turn over rate (e.g. Bactosomes) DOR may not be considered as an end product particularly at low concentrations of DEX; leading to an underestimation of true metabolic rate. The results also put further emphasis on the necessity of optimising study conditions when switching between rCYP sources.

Concise synthesis of dimemorfan (DF) starting from 3-hydroxymorphinan (3-HM).

Dimemorfan (DF) has been known to possess neuroprotective properties. While this promising compound deserves further biological evaluation, synthetic methods have not improved since Murakami group unveiled the synthetic efforts in 1972. Herein a succinct synthesis toward DF from commercially available 3-hydroxymorphinan (3-HM) is disclosed. Other morphinan analogs have been effectively prepared by adopting the similar methodology.

Isobolographic analysis of epinephrine with bupivacaine, dextromethorphan, 3-methoxymorphinan, or dextrorphan on infiltrative anesthesia in rats: dose-response studies.

BACKGROUND AND OBJECTIVES: The aims of this study were to establish the potencies of epinephrine, bupivacaine, dextromethorphan, 3-methoxymorphinan, and dextrorphan and evaluate interactions of epinephrine with bupivacaine, dextromethorphan, 3-methoxymorphinan, or dextrorphan as an infiltrative anesthetic. Bupivacaine, a common and long-acting local anesthetic, was used as control. METHODS: Dose-dependent responses of epinephrine, dextromethorphan, 3-methoxymorphinan, and dextrorphan on cutaneous analgesia were compared with bupivacaine in rats. The interactions of drugs were evaluated via an isobolographic analysis. RESULTS: We found that epinephrine, bupivacaine, dextromethorphan, 3-methoxymorphinan, and dextrorphan produced a dose-dependent local anesthetic effect as infiltrative cutaneous analgesia. Relative potencies were epinephrine > bupivacaine > dextromethorphan > 3-methoxymorphinan > dextrorphan (P < .01 for each comparison). Coadministration of bupivacaine with epinephrine produced a synergistic effect, and coadministration of dextromethorphan, 3-methoxymorphinan, or dextrorphan with epinephrine produced an additive effect. CONCLUSIONS: Epinephrine, dextromethorphan, 3-methoxymorphinan, and dextrorphan are known to have local anesthetic effects as infiltrative cutaneous analgesia in rats. Epinephrine increased the potency of bupivacaine, but not dextromethorphan, 3-methoxymorphinan, or dextrorphan as an infiltrative anesthetic. The cutaneous analgesic effects of adding epinephrine to dextromethorphan, 3-methoxymorphinan, or dextrorphan, are similar to combinations of 2 local anesthetics.

Neuropsychotoxicity of abused drugs: potential of dextromethorphan and novel neuroprotective analogs of dextromethorphan with improved safety profiles in terms of abuse and neuroprotective effects.

Drug abuse involving dextromethorphan, an antitussive, has been a social problem in various geographic locations since the 1960s. Ironically, high doses of the drug confer neuroprotective activity with central nervous system and behavioral effects. Accumulating evidence suggests that metabolism to phencyclidine-like dextrorphan is not essential for the neuroprotective activity of dextromethorphan. Here, we review the neuroprotective properties of dextromethorphan and its potential for abuse and the potential neuroprotective effects of the drug's analogs and 3-hydroxymorphinan, a metabolite of dextromethorphan. These compounds may provide a novel therapeutic direction for the treatment of neurodegenerative diseases such as convulsive or parkinsonian-like disorders.

Anti-inflammatory effects of LK-3, on LPS-induced sepsis in rats.

Dextromethorphan (DM), an antitussive agent, has been shown to have anti-inflammatory and immunomodulatory effects in vitro. Thus, the aim of this study was to evaluate the effects of LK-3, an analog of DM, on sepsis induced by intravenous (i.v.) administration of lipopolysaccharide (LPS; 10 mg/ kg) in anesthetized Wistar rats. Results demonstrated that post-treatment with LK-3 (4 mg/kg, i.v.) significantly attenuated the deleterious hemodynamic changes (e.g., hypotension and bradycardia) in rats treated with LPS. Meanwhile, LK-3 (4 mg/kg) significantly inhibited the elevation of plasma tumor necrosis factor-alpha, as well as values of glutamate-oxalacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) caused by LPS. The induction of inducible NO synthase and the overproduction of NO and superoxide anions by LPS were also reduced by post-treatment of LK-3. Moreover, infiltration of neutrophils into the lungs and liver of rats 8 h after treatment with LPS was also reduced by post-treatment with LK-3. In conclusion, the beneficial effects of LK-3 on LPS-induced sepsis resulted from its anti-inflammatory and antioxidant effects.