Sensitive detection of dextromethorphan hydrobromide based on portable Raman spectrometer and CuO@AgNPs nano composite SERS substrate

A highly sensitive surface-enhanced Raman spectroscopy approach was established for the detection of dextromethorphan hydrobromide (DXM) utilizing nano CuO modified silver nanoparticles (CuO@AgNPs) as substrate. Ultraviolet visible spectra (UV-vis), X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterized the synthesized CuO@AgNPs. UV-vis and fourier transform infrared (FT-IR) were adopted to investigate the interaction between DXM and CuO@AgNPs. The optimal experimental conditions (the dosages of CuO@AgNPs and NaCl as well as mixing time) were explored. The enhancement factor (EF) was 1.71 × 106. The linear relationship between SERS intensity and the concentration of DXM in the range of 67 - 1000 nmol L-1 was obtained as ISERS = 25.81 c + 40398.77, and the limit of detection (LOD) was 2.12 nmol L-1 (S/N = 3). The interference of K+, Mg2+, Zn2+, Ca2+, Cu2+, Fe3+, glucose, HSA, L-tryptophan, soluble starch and ibuprofen were investigated. The method was successfully applied to test DXM in serum samples. The recovery was 99.06% - 101.51% with the relative standard deviation (RSD) of 0.74% - 3.87%.

Development of a novel enantioselective high-performance liquid chromatography-mass spectrometry method for the differentiation of dextro- and levo-methorphan and their O-demethylated metabolites in human blood and its application to post-mortem samples

Recently we proposed an isocratic enantioselective high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the separation and quantitative determination of dextro- (DXM) and levo-methorphan (LVM) and their pharmacologically relevant metabolites, dextrorphan and levorphanol, respectively, in human blood samples. This method was based on the polysaccharide-based chiral column Lux AMP, a specialty column characterized with high stability in mobile phases of pH 11.0 and above. The use of a single-source column is a limitation for any analytical method. Therefore, the major goal of the present study was to develop an enantioselective method for the differentiation of dextro- and levo-methorphan, as well as their metabolites dextrorphan and levorphanol, using Lux Cellulose-3 as alternative chiral column with methanol containing 0.1 % diethylamine mobile phase. A newly developed method uses a chiral selector part of HPLC columns available from multiple manufacturers and a fairly common mobile phase. The method was validated and applied to post-mortem blood samples. Out of 50 analyzed new samples, dextromethorphan (DXM) was detected in 17 samples. Of these 17 cases DXM was accompanied with LVM in 7 samples. The proposed analytical method is relatively simple, accurate and fast and can be adopted for routine use in forensic and clinical toxicology laboratories.

Classics in Chemical Neuroscience: Dextromethorphan (DXM)

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

Development of an enantioselective high-performance liquid chromatography-tandem mass spectrometry method for the quantitative determination of methorphan and its O-demethylated metabolite in human blood and its application to post-mortem samples

In the present work an isocratic enantioselective high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the separation and quantitative determination of dextro - and levo -methorphan and their pharmacologically relevant metabolites, dextrorphan and levorphanol, respectively, in human blood samples. The separation of enantiomers of methorphan and metabolites was performed on the polysaccharide-based chiral column Lux AMP in combination with acetonitrile and 5 mM aqueous ammonium bicarbonate pH 11 in the ratio 50:50 (%, v/v) as mobile phase with the flow rate 1 mL/min. The mass spectrometer was operated in scheduled multiple reaction monitoring (MRM) mode, with four transitions for each dextromethorpan, levomethorphan, dextrorphan and dextromethorphan-d3 and two transitions for each levorphanol, levorphanol-d3 and dextrorphan-d3. Application of this method to human post-mortem blood samples confirmed cases of severe overdosing with dextromethorphan, levomethorphan, and less commonly with both.

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).

Chiral analysis of dextromethorphan and levomethorphan in human hair by liquid chromatography-tandem mass spectrometry

PURPOSE

Methorphan exists in two enantiomeric forms including dextromethorphan and levomethorphan. Dextromethorphan is an over-the-counter antitussive drug, whereas levomethorphan is strictly controlled as a narcotic drug. Chiral analysis of methorphan could, therefore, assist clinicians and forensic experts in differentiating between illicit and therapeutic use and in tracing the source of the drug.

METHODS

A method for enantiomeric separation and quantification of levomethorphan and dextromethorphan in human hair was developed and validated using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Hair was extracted in hydrochloric acid/methanol (1:20, v/v). The supernatant were separated using a Supelco Astec Chirobiotic™ V2 column (250 × 2.1 mm, i.d., 5 μm particle size) and analyzed on a triple quadrupole linear ion trap mass spectrometer in multiple reaction monitoring mode.

RESULTS

The limits of detection for dextromethorphan and levomethorphan were 2 and 1 pg/mg, respectively; the lower limit of quantification was 2 pg/mg for both drugs. Good linearity (r > 0.995) was observed for both analytes over the linear range. Precision values were below 10% for both analytes; accuracy values ranged from 87.5 to 101%. The extraction recoveries were 78.3-98.4%, and matrix effects were 70.5-88.6%. This method was applied to human hair samples from 120 people suspected of methorphan use to further distinguish the drug chirality. Dextromethorphan was detected in all 120 samples at a concentration range of 2.7-19,100 pg/mg, whereas levomethorphan was not detected in any sample.

CONCLUSIONS

A sensitive quantitative method was established for the enantiomeric separation of dextromethorphan and levomethorphan in hair. This is the first study to achieve chiral analysis of methorphan in human hair.

Fatal cold medication poisoning in an adolescent

BACKGROUND

Toxicity from the intentional misuse of over-the-counter (OTC) combination cold products has been widely recognized. Adolescents are most frequently involved and dextromethorphan containing products are the most popular. Desired symptoms include stimulatory effects, euphoria, hallucinations, and dissociation. Potential adverse effects include tachycardia, agitation, hyperthermia, acidosis, and coma. However, mortality is rare [ 1-3]. Co-formulated ingredients such as acetaminophen, pseudoephedrine, and antihistamines may also be present and potentiate dangerous effects. We report a case of an adolescent decedent with markedly elevated postmortem chlorpheniramine (CPA) and dextromethorphan (DXM) blood concentrations and no other identifiable cause of death.

Dextromethorphan Abuse Among Opioid-Dependent Patients

BACKGROUND

Among opioid-dependent patients on maintenance therapy, concomitant drug abuse is a serious problem. Dextromethorphan, an over-the-counter antitussive agent that can be purchased without prescription, is a drug with a high potential for misuse, especially when consumed in high doses.The objective of this study was to investigate possible abuse of dextromethorphan among substituted opioid-dependent patients and comparison of subjective and objective findings.Due to its ability to increase serotonin levels, opioid-dependent patients may be particularly susceptible to dextromethorphan misuse. Dextromethorphan misuse may have side effects, including psychiatric symptoms and serotonin syndrome, and may induce assault, suicide, or homicide.

METHODS

A total of 104 opioid-dependent patients in maintenance treatment were included in this cross-sectional study conducted in the outpatient department of the Psychiatric Hospital, University of Zurich. Study participants were divided into 2 groups based on laboratory results: dextromethorphan abusers (n = 12) and nonabusers (n = 92). The objective use and concentrations of dextromethorphan was detected using 3-month hair toxicology analysis.Statistical analysis was performed by using χ test, Student t test, Mann-Whitney U test, and Barnard exact test.

RESULTS

Dextromethorphan was abused by 12 (11.5%) patients, 11 (91.7%) of whom did not report concomitant abuse of dextromethorphan but were identified through hair analysis. In general, there were significant differences among patients abusing dextromethorphan compared with nondextromethorphan consumers in terms of trauma due to sexual maltreatment/violence, multiple traumas, or harmful use of hallucinogenic drugs.

CONCLUSIONS

Further studies are necessary to examine dextromethorphan and its impact on patients with psychiatric comorbidities and psychiatric medication. According to literature, there is a significant drug interaction risk due to the impact of dextromethorphan misuse on serotonin syndrome and psychiatric symptoms.1-3 We recommend active inquiry into and testing for concomitant drug abuse among substituted opioid-dependent patients to reduce the risk of drug interactions and side effects in this especially vulnerable group of patients.

Alterations in the biochemical indices in Wistar rats exposed to an overdose of codeine and dextromethorphan

OBJECTIVE

This study investigates the impact of repeated oral exposure to two cough syrups containing codeine and dextromethorphan (DXM) on male Wistar rats.

METHODS

We divided 35 rats into seven groups of five rats each. Group A was given 0.5 mL of distilled water, Groups B, C, and D were given 0.1, 0.2 and 0.4 mL/kg body weight (b. w) of cough syrup containing codeine (CSC), respectively, and Groups E, F, and G were administered 0.1, 0.2 and 0.4 mL/kg b. w of cough syrup containing DXM, respectively. The treatment was continued for 28 days. The rats were euthanised under mild diethyl ether anaesthesia. The kidney, liver, and blood of the rats were examined for further analyses.

RESULTS

Significant (p < 0.05) alterations were observed in the liver function tests: ALT, AST, ALP, albumin, and total bilirubin. All doses of CSC and DXM significantly increased the ALT levels (p < 0.05). Furthermore, similar significant alterations were observed for the kidney function parameters such as creatinine, urea, and uric acid (p < 0.05). All doses of DXM caused significant elevations in the levels of urea (p < 0.05). The histopathological evaluations also showed slight changes in the architecture of the liver, kidney, and brain tissues.

CONCLUSION

The findings of this study suggest that overdose of these cough syrups may predispose the consumer to hepatic and renal injuries.

Dextromethorphan Analgesia in a Human Experimental Model of Hyperalgesia

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Background

Central pain sensitization is often refractory to drug treatment. Dextromethorphan, an N-methyl-d-aspartate receptor antagonist, is antihyperalgesic in preclinical pain models. The hypothesis is that dextromethorphan is also antihyperalgesic in humans.

Methods

This randomized, double-blind, placebo-controlled, crossover study explores the antihyperalgesic effect of single and repeated 30-mg dose of oral dextromethorphan in 20 volunteers, using the freeze-injury pain model. This model leads to development of primary and secondary hyperalgesia, which develops away from the site of injury and is associated with central sensitization and activation of N-methyl-d-aspartate receptor in the spinal cord. The primary outcome was antihyperalgesia calculated with the area under the curve of the percentage change in mechanical pain threshold (electronic von Frey) on the area of secondary hyperalgesia. The secondary outcomes were mechanical pain threshold on the area of primary hyperalgesia and cognitive (reaction time) effect.

Results

Single 30-mg results are reported. Antihyperalgesia (% · min) is significantly higher on the area of secondary hyperalgesia with dextromethorphan than placebo (median [interquartile range]: 3,029 [746; 6,195] vs. 710 [–3,248; 4,439], P = 0.009, Hedge’s g = 0.8, 95% CI [0.1; 1.4]). On primary hyperalgesia area, mechanical pain threshold 2 h after drug intake is significantly higher with dextromethorphan (P = 0.011, Hedge’s g = 0.63, 95% CI [0.01; 1.25]). No difference in antinociception is observed after thermal painful stimuli on healthy skin between groups. Reaction time (ms) is shorter with placebo than with dextromethorphan (median [interquartile range]: 21.6 [–37.4; 0.1] vs. –1.2 [–24.3; 15.4], P = 0.015, Hedge’s g = 0.75, 95% CI [0.12; 1.39]). Nonserious adverse events occurrence (15%, 3 of 20 volunteers) was similar in both groups.

Conclusions

This study shows that low-dose (30-mg) dextromethorphan is antihyperalgesic in humans on the areas of primary and secondary hyperalgesia and reverses peripheral and central neuronal sensitization. Because dextromethorphan had no intrinsic antinociceptive effect in acute pain on healthy skin, N-methyl-d-aspartate receptor may need to be sensitized by pain for dextromethorphan to be effective.

A novel and simple LC–MS/MS quantitative method for dextromethorphan and dextrorphan in oral fluid

Aim: To develop and validate a simple method using LC–MS/MS for determination of dextromethorphan (DXM) and dextrorphan (DT) in human oral fluid. Results: Following protein precipitation, chromatographic separation used a phenyl column with isocratic elution (1 ml/min) of 10 mM ammonium-formate buffer and acetonitrile (65:35; v/v) with 0.1% formic acid. Retention times were 2.6 min for DT and 5 min for DXM. Total run time was 7 min. The intra- and inter-assay deviations (accuracy) for DT (1–100 ng/ml) and DXM (5–1000 ng/ml) ranged from -13.6 to 8.8% and -9.6 to 5.7%, respectively. Precision variations were ≤7.5%. Matrix effect was ≤11.8%. Conclusion: This method may prove helpful for quantification of DT and DXM in oral fluid for either clinical or toxicological purposes.

Identifying and treating patients with synthetic psychoactive drug intoxication

Tens of thousands of ED visits each year are related to synthetic psychoactive drug intoxication. Signs, symptoms, and treatment of toxicity with synthetic cathinones, synthetic cannabinoids, or dextromethorphan overlap greatly and can be challenging. This article describes signs and symptoms of psychoactive drug abuse and how to properly manage these symptoms.

MK-801, but not naloxone, attenuates high-dose dextromethorphan-induced convulsive behavior: Possible involvement of the GluN2B receptor

Dextromethorphan (DM) is a dextrorotatory isomer of levorphanol, a typical morphine-like opioid. When administered at supra-antitussive doses, DM produces psychotoxic and neurotoxic effects in humans. Although DM abuse has been well-documented, few studies have examined the effects of high-dose DM. The present study aimed to explore the effects of a single high dose of DM on mortality and seizure occurrence. After intraperitoneal administration with a high dose of DM (80mg/kg), Sprague-Dawley rats showed increased seizure occurrence and intensity. Hippocampal expression levels of N-methyl-d-aspartate (NMDA) receptor subunits (GluN1<GluN2A<GluN2B), c-Fos and pro-apoptotic factors (Bax and cleaved caspase-3) were upregulated by DM treatment; while levels of anti-apoptotic factors (Bcl-2 and Bcl-xL) were downregulated. Consistently, DM also induced ultrastructural degeneration in the hippocampus. A non-competitive NMDA receptor antagonist, MK-801, attenuated these effects of high-dose DM, whereas an opioid antagonist, naloxone, did not affect DM-induced neurotoxicity. Moreover, pretreatment with a highly specific GluN2B subunit inhibitor, traxoprodil, was selectively effective in preventing DM-induced c-Fos expression and apoptotic changes. These results suggest that high-dose DM produces convulsive behaviors by activating GluN2B/NMDA signaling that leads to pro-apoptotic changes.

Drug Misuse in Adolescents Presenting to the Emergency Department

OBJECTIVES

Drug misuse is a disturbing, common practice among youth. One in 4 American adolescents reports consuming prescription medications without a clinical indication. We sought to explore current trends of drug misuse in adolescents.

METHODS

Using the 37 participating sites of the ToxIC (Toxicology Investigators Consortium) Case Registry, a cross-country surveillance tool, we conducted an observational cohort study of all adolescents (aged 13-18 years) who presented to emergency departments with drug misuse and required a bedside medical toxicology consultation between January 2010 and June 2013.

RESULTS

Of 3043 poisonings, 202 (7%) involved drug misuse (139 [69%] were males). Illicit drugs (primarily synthetic cannabinoids and "bath salts") were encountered in 101 (50%), followed by prescription medications (56 [28%]) and over-the-counter (OTC) drugs (51 [25%]). Dextromethorphan was the most commonly misused legal medication (24 [12%]). Polypharmacy exposure was documented in 74 (37%). One hundred sixty-three adolescents (81%) were symptomatic; of these, 81% had central nervous system impairments: psychosis (38%), agitation (30%), coma (26%), myoclonus (11%), and seizures (10%); and 66 (41%) displayed a specific toxidrome, most commonly sedative-hypnotic. Benzodiazepines were the most frequently administered medications (46%). Antidotes were administered to 28% of adolescents, primarily naloxone, physostigmine, N-acetyl-cysteine, and flumazenil. No deaths were recorded.

CONCLUSIONS

Adolescents presenting with drug misuse may be exposed to a wide range and combinations of therapeutics or illicit substances and frequently display central nervous system abnormalities, compromising the ability to obtain a reliable history. Frontline clinicians should maintain a high index of suspicion, as routine toxicology screenings fail to detect most contemporary misused legal and designer drugs.

High-dose dextromethorphan produces myelinoid bodies in the hippocampus of rats

Dextromethorphan (DM) administered at supra-antitussive doses produce psychotoxic and neurotoxic effects in humans. We administered DM (80 mg/kg) to rats intraperitoneally to determine the ultrastructural change induced by DM, because intraperitoneal route is sensitive for the behavioral responses. Treatment with DM resulted in mitochondrial dysfunction and formation of myelinoid bodies in the hippocampus. MK-801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate] attenuated DM-induced cytosolic oxidative burdens. However, neither MK-801 nor naloxone affected DM-induced mitochondrial dysfunction and formation of myelinoid bodies, indicating that the neurotoxic mechanism needs to be further elucidated. Therefore, the spectrum of toxicological effects associated with DM need to be reassessed.

Determination of Dextromethorphan in Oral Fluid by LC-MS-MS

Dextromethorphan (DXM) is an antitussive drug found in commonly used nonprescription cold and cough medications. At low doses, DXM is a safe drug that does not produce adverse reactions. However, abuse of DXM has been reported among adolescents and young adults using the drug at higher doses. DXM is not a scheduled drug in the USA, and the primary reason for its abuse is the ease of availability. DXM is available to purchase in the form of over-the-counter cough medications, such as Robitussin(®) and Coricidin(®), or it can be purchased over the Internet in the form of a powder. In this research work, we developed an LC-MS-MS method that can quantify DXM and dextrorphan (DXO) in oral fluid in a high-throughput toxicology laboratory setting. The developed method was validated according to the Scientific Working Group for Forensic Toxicology guidelines. The linear dynamic range was 5-100 ng/mL with a lowest limit of quantitation (LLOQ) of 5.0 ng/mL for DXM and DXO. Overall, the results of the accuracy and the precision values were within the acceptance criteria for both drugs. In addition, selectivity, matrix effect and recovery were calculated for the LC-MS-MS method. Authentic samples (n = 59) were tested to evaluate the applicability of the method. Thirty samples were found to be positive for DXM and DXO and two samples were found to be positive for DXM only.

Levorphanol use: past, present and future

Levorphanol is a potent opioid analgesic that was first approved for use in the United States in 1953. Levorphanol is approved for use in moderate to severe pain where an opioid analgesic is appropriate. Levorphanol has a wide range of activities including mu opioid agonism, delta agonism, kappa1 and kappa3 receptor agonism, N-methyl-d-aspartate receptor antagonism and reuptake inhibition of both norepinephrine and serotonin. This multimodal profile might prove effective for pain syndromes that are refractory to other opioid analgesics, such as central and neuropathic pain and opioid-induced hyperalgesia. Levorphanol is well suited as a first-line opioid and can also be used during opioid rotation. It has no known effect on the cardiac QT interval or drug-drug interactions involving hepatic cytochrome P450s enzymes. In these regards, levorphanol may offer a superior safety profile over methadone and other long-acting opioids. Despite its prospective value of multiple mechanisms of action and the potential for treating various types of pain, levorphanol use has been largely supplanted by other recently approved opioids. Its waning use over the years has caused it to be referred to as the "Forgotten Opioid" and resulted in what some consider its underutilization. In fact, levorphanol is relatively unfamiliar to most prescribers. The purpose of this review is to inform practitioners about the attributes of this opioid and reintroduce it to clinicians as an option for treating moderate to severe pain when alternative treatment options are inadequate, not indicated or contraindicated.

Cough, codeine and confusion

Codeine is widely prescribed in clinical practice with over the counter (OTC) preparations of codeine freely available for consumption typically as a component of remedies for the common cold/cough. We describe the first reported case of acute confusional state in a previously healthy 14-year-old girl ultimately attributed to inappropriate codeine use. The usage of codeine in the paediatric setting has been highlighted in recent years with many reported deaths--mostly due to respiratory depression. The risks associated with codeine usage may be particularly unnecessary with OTC cough suppressants as evidence of efficacy is absent. Finally, codeine dependence is a common problem among adults and has been reported locally and internationally among adolescents. The combination of lack of efficacy, risk of acute intoxication and dependence, suggests that the use of OTC codeine preparations may be unwarranted.

Patterns and Perceptions of Dextromethorphan Use in Adult Members of an Online Dextromethorphan Community

Dextromethorphan (DXM) is a widely available antitussive that has, at elevated dose levels, euphoric and dissociative effects. This article presents the reported patterns and preferences of DXM use, and perceptions of DXM use among adult members of an online DXM community. Analyses were conducted of quantitative and qualitative responses from nine female and 43 male individuals, aged 18-63 years old. All respondents reported illegal and DXM drug use, beginning, on average, at 15.7 and 17.1 years of age, respectively. The majority of respondents first heard about DXM online or from a friend, preferred to use DXM alone, ingested substances concurrently with DXM to modify its effects, had not been to an emergency room or arrested because of their DXM use, and used DXM for its dissociative and mind-altering effects. DXM was perceived as safe and in no need of further regulation with only 14% of respondents mentioning DXM's addictive qualities. Findings from this sample of adult DXM users reveal a sophisticated subculture in which users report using DXM specifically to induce changes to their mental state and use a variety of substances to modify or enhance DXM's effects.

"Robo-tripping": dextromethorphan abuse and its anesthetic implications

Introduction:

We describe a patient scheduled for elective surgery who regularly consumed approximately 12 to 15 times the maximum recommended daily dose of dextromethorphan. We describe the clinical pharmacology of dextromethorphan and discuss its anesthetic implications.

Case Presentation:

A 30-year-old man with a history of a nasal fracture was scheduled to undergo an elective septorhinoplasty. He reported daily consumption of large quantities (1440 to 1800 mg) of dextromethorphan for six years. He was previously treated for dextromethorphan dependency on several occasions with urine dextromethorphan levels exceeding 2000 ng/mL. He described marked dissociative effects when abusing the drug, but had abstained from use for 48 hours before his elective surgery. Considering that dextromethorphan has a relatively short half-life and that the patient did not suffer major withdrawal symptoms after voluntarily discontinuing the drug, the authors proceeded with the case while recognizing that the drug has significant neuropsychiatric and sympathetic nervous system stimulant effects resulting from its actions as a N-methyl-D-aspartate receptor antagonist.

Conclusions:

Anesthesiologists need to be aware of dextromethorphan’s clinical pharmacology because recreational abuse of the drug has become increasingly common in adolescents and young adults.

Evaluating the safety and efficacy of dextromethorphan/quinidine in the treatment of pseudobulbar affect

Pseudobulbar affect (PBA) is a common manifestation of brain pathology associated with many neurological diseases, including amyotrophic lateral sclerosis, Alzheimer's disease, stroke, multiple sclerosis, Parkinson's disease, and traumatic brain injury. PBA is defined by involuntary and uncontrollable expressed emotion that is exaggerated and inappropriate, and also incongruent with the underlying emotional state. Dextromethorphan/quinidine (DM/Q) is a combination product indicated for the treatment of PBA. The quinidine component of DM/Q inhibits the cytochrome P450 2D6-mediated metabolic conversion of dextromethorphan to its active metabolite dextrorphan, thereby increasing dextromethorphan systemic bioavailability and driving the pharmacology toward that of the parent drug and away from adverse effects of the dextrorphan metabolite. Three published efficacy and safety studies support the use of DM/Q in the treatment of PBA; significant effects were seen on the primary end point, the Center for Neurologic Study-Lability Scale, as well as secondary efficacy end points and quality of life. While concentration-effect relationships appear relatively weak for efficacy parameters, concentrations of DM/Q may have an impact on safety. Some special safety concerns exist with DM/Q, primarily because of the drug interaction and QT prolongation potential of the quinidine component. However, because concentrations of dextrorphan (which is responsible for many of the parent drug's side effects) and quinidine are lower than those observed in clinical practice with these drugs administered alone, some of the perceived safety issues may not be as relevant with this low dose combination product. However, since patients with PBA have a variety of other medical problems and are on numerous other medications, they may not tolerate DM/Q adverse effects, or may be at risk for drug interactions. Some caution is warranted when initiating DM/Q treatment, particularly in patients with underlying risk factors for torsade de pointes and in those receiving medications that may interact with DM/Q.

Dextromethorphan Abuse: A Literature Review

Objective:

To review dextromethorphan abuse patterns from 2002–2012 and emphasize the pharmacist's role in prevention, education, and sales surveillance.

Data Sources:

A literature search was conducted through PubMed (2002-November 2012), EMBASE (2002-November 2012), and International Pharmaceutical Abstracts (2002-November 2012), using the search term dextromethorphan abuse. The Drug Enforcement Administration and National Association of Boards of Pharmacy websites were searched for dextromethorphan abuse and legislative updates. The search was limited to a 10-year period to identify the most current case reports and studies.

Study Selection and Data Extraction:

The limits used were studies/case reports evaluating humans and published in the English language. Only studies and case reports that assessed dextromethorphan abuse were included in the review. Eight studies and 9 case reports met the inclusion criteria.

Data Synthesis:

Case reports and studies demonstrate that there are patterns associated with dextromethor phan abuse. A study using data reported to the National Poison Data System identified Coricidin as the most (65.5%) commonly abused dextromethorphan product until 2006; its abuse has decreased since that time (p < 0.0001). The most common abuse effects and toxicities cited in studies and case reports include agitation, confusion, central nervous system depression, tachycardia, hypertension, lethargy, psychosis, hallucinations, mydriasis, dizziness, and cardiotoxicity. One study identified that 96% of samples tested positive for other substances in addition to dextromethorphan. Coingestion of other substances is also common among dextromethorphan abusers.

Conclusions:

Case reports and studies demonstrate that there are patterns associated with dextromethorphan abuse. It is difficult to identify dextromethorphan as the causative agent of abuse effects because of coingestion of other substances. Studies should examine the pharmacist's role and the association between dextromethorphan sales restrictions and abuse patterns.

Nonprescription drug abuse

Nonprescription drug, also referred to as over-the-counter (OTC) abuse, is a serious and growing global health challenge. Drugs from many different therapeutic classes and numerous dosage forms and drug delivery systems are implicated in nonprescription drug abuse. Individuals who commonly abuse certain nonprescription medications are likewise diverse, varying in age, demographics, and overall health status. The clinician is in a unique position to assist in identifying those patients at risk for nonprescription drug abuse and those who are abusers, and may play an important role in intervention, patient care, and in the treatment of nonprescription drug abuse. A concise review of nonprescription drug abuse may be of use to the clinician in this regard.

Quality of online pharmacies and websites selling prescription drugs: a systematic review

BACKGROUND

Online pharmacies are companies that sell pharmaceutical preparations, including prescription-only drugs, on the Internet. Very little is known about this phenomenon because many online pharmacies operate from remote countries, where legal bases and business practices are largely inaccessible to international research.

OBJECTIVE

The aim of the study was to perform an up-to-date and comprehensive review of the scientific literature focusing on the broader picture of online pharmacies by scanning several scientific and institutional databases, with no publication time limits.

METHODS

We searched 4 electronic databases up to January 2011 and the gray literature on the Internet using the Google search engine and its tool Google Scholar. We also investigated the official websites of institutional agencies (World Health Organization, and US and European centers for disease control and drug regulation authorities). We focused specifically on online pharmacies offering prescription-only drugs. We decided to analyze and report only articles with original data, in order to review all the available data regarding online pharmacies and their usage.

RESULTS

We selected 193 relevant articles: 76 articles with original data, and 117 articles without original data (editorials, regulation articles, or the like) including 5 reviews. The articles with original data cover samples of online pharmacies in 47 cases, online drug purchases in 13, consumer characteristics in 15, and case reports on adverse effects of online drugs in 12. The studies show that random samples with no specific limits to prescription requirements found that at least some websites sold drugs without a prescription and that an online questionnaire was a frequent tool to replace prescription. Data about geographical characteristics show that this information can be concealed in many websites. The analysis of drug offer showed that online a consumer can get virtually everything. Regarding quality of drugs, researchers very often found inappropriate packaging and labeling, whereas the chemical composition usually was not as expected in a minority of the studies' samples. Regarding consumers, the majority of studies found that not more than 6% of the samples had bought drugs online.

CONCLUSIONS

Online pharmacies are an important phenomenon that is continuing to spread, despite partial regulation, due to intrinsic difficulties linked to the impalpable and evanescent nature of the Web and its global dimension. To enhance the benefits and minimize the risks of online pharmacies, a 2-level approach could be adopted. The first level should focus on policy, with laws regulating the phenomenon at an international level. The second level needs to focus on the individual. This approach should aim to increase health literacy, required for making appropriate health choices, recognizing risks and making the most of the multitude of opportunities offered by the world of medicine 2.0.

Intentional Coricidin product exposures among Illinois adolescents

OBJECTIVES

We sought to describe the demographics and trends of Coricidin product abuse in children in Illinois and to calculate an approximate total charge to the health-care system.

METHODS

In this retrospective database review, we identified 652 cases of intentional exposure to Coricidin products among children < 18 years old in the Illinois Poison Center database from 2001 to 2006. Demographic, historical, clinical, and outcome data were recorded.

RESULTS

The mean (standard deviation) age was 15.7 (1.58) years. A significant increase in exposures occurred during the study period which showed a cyclic nature with peaks in the fall months. Of the patients with disposition data available, 28.6% were admitted to a critical care unit, 15.2% to a noncritical care hospital unit, 6.3% were admitted for inpatient psychiatric care, and 46.4% were evaluated in the emergency department and discharged home. Moderate or major outcomes were reported in 42.7% of cases in which data were available. No deaths were reported. The total approximate hospital charge was $2,119,881.90 or $353,313.65/year.

CONCLUSIONS

Intentional abuse of Coricidin products reported to the poison center occurred primarily among adolescents and was often associated with significant short-term clinical effects and a clear financial burden to the health-care system.

SCIENTIFIC SIGNIFICANCE

This investigation demonstrates that Coricidin product abuse continues to be a problem particularly among adolescents. Parents and clinicians need to continue to be aware of these substances as drugs of abuse and curbing sales to adolescents should be considered.

Chiral analyses of dextromethorphan/levomethorphan and their metabolites in rat and human samples using LC-MS/MS

In order to develop an analytical method for the discrimination of dextromethorphan (an antitussive medicine) from its enantiomer, levomethorphan (a narcotic) in biological samples, chiral analyses of these drugs and their O-demethyl and/or N-demethyl metabolites in rat plasma, urine, and hair were carried out using LC-MS/MS. After the i.p. administration of dextromethorphan or levomethorphan to pigmented hairy male DA rats (5 mg/kg/day, 10 days), the parent compounds and their three metabolites in plasma, urine and hair were determined using LC-MS/MS. Complete chiral separation was achieved in 12 min on a Chiral CD-Ph column in 0.1% formic acid-acetonitrile by a linear gradient program. Most of the metabolites were detected as being the corresponding O-demethyl and N, O-didemethyl metabolites in the rat plasma and urine after the hydrolysis of O-glucuronides, although obvious differences in the amounts of these metabolites were found between the dextro and levo forms. No racemation was observed through O- and/or N-demethylation. In the rat hair samples collected 4 weeks after the first administration, those differences were more clearly detected and the concentrations of the parent compounds, their O-demethyl, N-demethyl, and N, O-didemethyl metabolites were 63.4, 2.7, 25.1, and 0.7 ng/mg for the dextro forms and 24.5, 24.6, 2.6, and 0.5 ng/mg for the levo forms, respectively. In order to fully investigate the differences of their metabolic properties between dextromethorphan and levomethorphan, DA rat and human liver microsomes were studied. The results suggested that there might be an enantioselective metabolism of levomethorphan, especially with regard to the O-demethylation, not only in DA rat but human liver microsomes as well. The proposed chiral analyses might be applied to human samples and could be useful for discriminating dextromethorphan use from levomethorphan use in the field of forensic toxicology, although further studies should be carried out using authentic human samples.

Combined dextromethorphan and chlorpheniramine intoxication in impaired drivers

Dextromethorphan is a nonprescription antitussive which has been gaining in popularity as an abused drug, because of the hallucinogenic, dissociative, and intoxicating effects it produces at high doses. This report describes a series of eight drivers arrested for driving under the influence of the combined effects of dextromethorphan and chlorpheniramine, and a further four drivers under the influence of dextromethorphan alone. In the combined dextromethorphan/chlorpheniramine cases, blood dextromethorphan concentrations ranged from 150 to 1220 ng/mL (n = 8; mean 676 ng/mL, median 670 ng/mL), and chlorpheniramine concentrations ranged from 70 to 270 ng/mL (n = 8; mean 200 ng/mL, median 180 ng/mL). The four cases without chlorpheniramine present had blood dextromethorphan concentrations between 190 and 1000 ng/mL (mean 570 ng/mL, median 545 ng/mL). Some drivers had therapeutic concentrations of other drugs present. Drivers generally displayed symptoms of central nervous system (CNS) depressant intoxication, and there was gross evidence of impairment in their driving, including weaving, leaving the lane of travel, failing to obey traffic signals, and involvement in collisions. Drug Recognition Expert opinions confirmed that the subjects were under the influence of a drug in the CNS-depressant category.