Massive dextromethorphan ingestion and abuse

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.

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.

Focus on Over-the-Counter Drugs' Misuse: A Systematic Review on Antihistamines, Cough Medicines, and Decongestants

Background: Over the past 20 years or so, the drug misuse scenario has seen the emergence of both prescription-only and over-the-counter (OTC) medications being reported as ingested for recreational purposes. OTC drugs such as antihistamines, cough/cold medications, and decongestants are reportedly the most popular in being diverted and misused. Objective: While the current related knowledge is limited, the aim here was to examine the published clinical data on OTC misuse, focusing on antihistamines (e.g., diphenhydramine, promethazine, chlorpheniramine, and dimenhydrinate), dextromethorphan (DXM)- and codeine-based cough medicines, and the nasal decongestant pseudoephedrine. Methods: A systematic literature review was carried out with the help of Scopus, Web of Science databases, and the related gray literature. For data gathering purposes, both the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and PROSPERO guidelines were followed (PROSPERO identification code CRD42020209261). Results: After completion of the selection, eligibility, and screening phases, some 92 articles were here taken into consideration; case reports, surveys, and retrospective case series analyses were included. Findings were organized according to the specific OTC recorded. Most articles focused here on DXM (n = 54) and diphenhydramine (n = 12). When specified, dosages, route(s) of administration, toxicity symptoms (including both physical and psychiatric ones), and outcomes were here reported. Conclusion: Results from the systematic review showed that the OTC misusing issues are both widespread worldwide and popular; vulnerable categories include adolescents and young adults, although real prevalence figures remain unknown, due to a lack of appropriate monitoring systems. Considering the potential, and at times serious, adverse effects associated with OTC misusing issues, healthcare professionals should be vigilant, and ad hoc preventative actions should be designed and implemented.

How experimental neuroscientists can fix the hard problem of consciousness

For the materialist, the hard problem is fundamentally an explanatory problem. Solving it requires explaining why the relationship between brain and experience is the way it is and not some other way. We use the tools of the interventionist theory of explanation to show how a systematic experimental project could help move beyond the hard problem. Key to this project is the development of second-order interventions and invariant generalizations. Such interventions played a crucial scientific role in untangling other scientific mysteries, and we suggest that the same will be true of consciousness. We further suggest that the capacity for safe and reliable self-intervention will play a key role in overcoming both the hard and meta-problems of consciousness. Finally, we evaluate current strategies for intervention, with an eye to how they might be improved.

When good times go bad: managing 'legal high' complications in the emergency department

Patients can use numerous drugs that exist outside of existing regulatory statutes in order to get "legal highs." Legal psychoactive substances represent a challenge to the emergency medicine physician due to the sheer number of available agents, their multiple toxidromes and presentations, their escaping traditional methods of analysis, and the reluctance of patients to divulge their use of these agents. This paper endeavors to cover a wide variety of "legal highs," or uncontrolled psychoactive substances that may have abuse potential and may result in serious toxicity. These agents include not only some novel psychoactive substances aka "designer drugs," but also a wide variety of over-the-counter medications, herbal supplements, and even a household culinary spice. The care of patients in the emergency department who have used "legal high" substances is challenging. Patients may misunderstand the substance they have been exposed to, there are rarely any readily available laboratory confirmatory tests for these substances, and the exact substances being abused may change on a near-daily basis. This review will attempt to group legal agents into expected toxidromes and discuss associated common clinical manifestations and management. A focus on aggressive symptom-based supportive care as well as management of end-organ dysfunction is the mainstay of treatment for these patients in the emergency department.

Misuse of OTC drugs in Poland

INTRODUCTION

The misuse of over-the-counter (OTC) drugs became a global public health concern. Although abuse with dextrometorphan (DXM), pseudoefedrine (PSD), codeine (COD) or benzydamine (BND) may lead even to psychosis, drugs containing these substances are relatively cheap and freely available. In Poland the Act on Counteracting Drug Addiction was amended in 2015, however it seems that there are still some points which could be improved.

METHODS

Study was conducted between October 2014 and June 2015 using a specially designed questionnaire delivered to pharmacists from the Greater Poland region. Questionnaire consisting of 11 closed questions was distributed by direct contact and via the Internet. From over 2500 distributed questionnaires, we received 761 sheets and 680 were included.

RESULTS

The misuse of OTC drugs is increasing in Poland from pharmacists point of view. The most popular substance was PSD followed by COD and DXM. The main reason of misuse of these drugs could be related to the use of Internet and free access to these medications. In respondents (58.2%) opinion OTC drugs containing analyzed substances should be moved into the prescription status.

CONCLUSIONS

The misuse of OTC drugs should be considered as a very dangerous phenomenon. Although the Act on Counteracting Drug Addiction was amended in Poland in 2015, there are some facets requiring improvement. Social education may play a key role in the limitation of misuse of OTC drugs.

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.

Dextromethorphan: An update on its utility for neurological and neuropsychiatric disorders

Dextromethorphan (DM) is a commonly used antitussive and is currently the only FDA-approved pharmaceutical treatment for pseudobulbar affect. Its safety profile and diverse pharmacologic actions in the central nervous system have stimulated new interest for repurposing it. Numerous preclinical investigations and many open-label or blinded clinical studies have demonstrated its beneficial effects across a variety of neurological and psychiatric disorders. However, the optimal dose and safety of chronic dosing are not fully known. This review summarizes the preclinical and clinical effects of DM and its putative mechanisms of action, focusing on depression, stroke, traumatic brain injury, seizure, pain, methotrexate neurotoxicity, Parkinson's disease and autism. Moreover, we offer suggestions for future research with DM to advance the treatment for these and other neurological and psychiatric disorders.

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.

Antitussives and substance abuse

Abuse of antitussive preparations is a continuing problem in the United States and throughout the world. Illicit, exploratory, or recreational use of dextromethorphan and codeine/promethazine cough syrups is widely described. This review describes the pharmacology, clinical effects, and management of toxicity from commonly abused antitussive formulations.

Dextromethorphan-induced psychotoxic behaviors cause sexual dysfunction in male mice via stimulation of σ-1 receptors

Dextromethorphan (DM) is a well-known antitussive dextrorotatory morphinan. We and others have demonstrated that sigma (σ) receptors may be important for DM-mediated neuromodulation. Because an earlier report suggested that DM might affect sexual function and that σ receptor ligands affect signaling pathways in the periphery, we examined whether DM-induced psychotoxic burden affected male reproductive function. We observed that DM had a high affinity at σ-1 receptors in the brain and testis but relatively low affinity at σ-2 receptors. Prolonged treatment with DM resulted in conditioned place preference and hyperlocomotion, followed by an increase in Fos-related antigen expression in the nucleus accumbens in male mice. Simultaneously, DM induced significant reductions in gonadotropin-releasing-hormone immunoreactivity in the hypothalamus. Moreover, we observed that DM induced increased sperm abnormalities and decreased sperm viability and sexual behavior. These phenomena were significantly attenuated by combined treatment with BD1047, a σ-1 receptor antagonist, but not by SM-21, a σ-2 receptor antagonist. Thus, these results suggest that DM psychotoxicity might lead to reproductive stress in male mice by activating σ-1 receptors.

Effect of a single dose of dextromethorphan on psychomotor performance and working memory capacity

BACKGROUND

Previous studies show that the prolonged use of dextromethorphan produces cognitive deterioration in humans.

AIM

The aim of this study was to investigate the effect of a single dose of dextroemthrophan on psychomotor performance and working memory capacity.

MATERIALS AND METHODS

This is a randomized, double-blind, controlled, and prospective study. Thirty-six (17 women, 19 men) medical students enrolled in the study; half of them (7 women, 11 men) were given placebo, while the other half (10 women, 8 men) received dextromethorphan. The choice reaction time, critical flicker fusion threshold, and N-back working memory task were measured before and after 2 h of taking the drugs.

RESULTS

Dextromethorphan showed a significant deterioration in the 3-back working memory task (P<0.05). No significant changes were seen as regards the choice reaction time components (total, recognition, motor) and critical flicker fusion threshold (P>0.05). On the other hand, placebo showed no significant changes as regards the choice reaction time, critical flicker fusion threshold, and N-back working memory task (P>0.05).

CONCLUSION

A single dose of dextromethorphan has no effect on attention and arousal but may significantly impair the working memory capacity.

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 metabolic blockade on the psychoactive effects of dextromethorphan

OBJECTIVE

Variation in the activity of cytochrome P450 2D6 (CYP2D6) affects the pharmacokinetics and effectiveness of dextromethorphan (DM), because it controls the production of dextrorphan, an active metabolite, with higher affinity for the NMDA receptor than the parent compound. This study examined whether pharmacological inhibition of CYP2D6 activity with quinidine would mimic the genetic mutation and thus also alter the psychoactive effects of DM.

METHODS

In a single-blind, within-subjects study, eight healthy volunteers (all homozygous for the wild type allele for CYP2D6) received placebo and varying doses of DM, both with and without quinidine pre-treatment. Pharmacokinetic and pharmacodynamic measures were assessed at baseline and every hour post-drug for 6 h.

RESULTS

Compared to the no quinidine condition, quinidine pre-treatment decreased the area under the dose-response curve on subjective measures of positively reinforcing effects (e.g., euphoria, p < 0.04; drug liking, p < 0.05), and was significantly greater for measures of dysphoria (e.g., unpleasantness, p < 0.02). These changes corresponded to increased DM and decreased dextrorphan plasma concentrations.

CONCLUSIONS

Compared to DM alone, quinidine pre-treatment inhibited DM metabolism and changed its subjective effects, demonstrating that the psychoactive properties of DM are a function of drug metabolism. These results demonstrate the relationship between CYP2D6 activity, plasma drug levels, and psychoactive drug effects, and have implications for both the abuse liability and therapeutic utility of DM.

REPETITIVE DEXTROMETHORPHAN AT ADOLESCENCE AFFECTS WATER MAZE LEARNING IN FEMALE RATS

Effects of repetitive dextromethorphan at adolescence on a spatial learning of rats were investigated. Rats received 10 daily injections of dextromethorphan (40 mg/kg) from postnatal day 28 thru 37, and were then subjected to the Morris water maze task from day 38. Significant impairments were found in the probe trial and the reversal training of the maze learning in the female rats, but not in males, treated with dextromethorphan. This result suggests that repetitive dextromethorphan, that is, abuse of dextromethorphan, at adolescence may induce deficits in the hippocampus-based memory function, perhaps more obviously in females.

Dextromethorphan abuse: clinical effects and management

OBJECTIVE

To describe the epidemiology, patient presentation, and clinical management associated with dextromethorphan (DM) abuse.

DATA SOURCES

PubMed/Medline search using terms dextromethorphan and abuse through July 2008, bibliographies of selected publications, epidemiology tracking databases.

STUDY SELECTION

By the authors.

DATA EXTRACTION

English language-published review articles, clinical trials, and case reports that described the epidemiologic and toxicologic profile of DM were included.

DATA SYNTHESIS

DM is a relatively inexpensive and easily accessible over-the-counter (OTC) medication intended for use as an antitussive. Increasingly, illicit use of the drug has been reported. At clinical doses, the drug produces few adverse effects. However, when abused in large quantities (>2 mg/kg), the drug has been associated with a dissociative effect similar to those described by ketamine and phencyclidine abusers. Massive ingestions of the drug may be associated with untoward effects, including tachycardia, hypertension, and respiratory depression. Overdose symptoms may also be associated with coformulated products such as antihistamines and sympathomimetic amines. Management is primarily supportive. Naloxone has been used to manage DM toxicity but with conflicting reports of effectiveness.

CONCLUSION

Recent reports indicate that DM is often abused by individuals seeking its dissociative effects. Clinicians should be aware of the abuse potential of DM. Pharmacists might be particularly cognizant of the risks involved with DM abuse as they control OTC access to the drug.

Dextromethorphan-induced serotonin syndrome

INTRODUCTION

The ability of dextromethorphan to potentiate serotonin levels and lead to serotonin syndrome is well known but few case reports are published. The lack of published cases suggests therapeutic doses of these drugs are not enough to cause serotonin syndrome. We present two cases of serotonin syndrome associated with supra-therapeutic doses of dextromethorphan and therapeutic levels of a selective serotonin reuptake inhibitors (SSRI).

CASE SERIES

In case one, serum drug levels from admission revealed a dextromethorphan level of 950 ng/mL (normal < 5), escitalopram of 23 ng/mL (normal < 200), chlorpheniramine of 430 ng/mL (normal < 20) and undetectable levels of aripiprazole and benztropine. In case two, serum drug levels from admission revealed a dextromethorphan level of 2820 ng/mL, sertraline of 12.5 ng/mL (normal < 200), and caffeine of 1.4 microg/mL (normal < or = 9 microg/mL).

DISCUSSION

To our knowledge, these are the first cases to use serum levels of dextromethorphan and a SSRI to confirm dextromethorphan-induced serotonin syndrome.

CONCLUSION

Our cases suggest supra-therapeutic dextromethorphan doses with a therapeutic amount of a SSRI are required for serotonin syndrome. More work is needed to answer this question more completely.

Accidental dextromethorphan ingestions in children less than 5 years old

INTRODUCTION

The purpose of this study is to evaluate the clinical presentation of accidental dextromethorphan (DXM) ingestions in children <5 years old. Two consecutive years of poison center patient encounters were reviewed. Data including age, outcomes, amount of DXM ingested, co-ingestions, vital signs, clinical manifestations, hospital admissions, and mortality were abstracted. Data were analyzed using descriptive statistics.

DISCUSSION

A total of 304 cases were identified with a mean age of 28.2 months (72% were > or =23 months). All cases co-ingested other products of over-the-counter cough and cold medications (i.e., acetaminophen, pseudoephedrine, guaifenesin, ibuprofen, various H1 receptor antagonists, and very infrequently ethanol). The mean DXM dose ingested was 35.0 mg (2.64 mg/kg). Of the patients, 62 (20.4%) experienced lethargy as the sole neurological sign and no patient had any cardiovascular abnormalities. Only 1 (13-monthold) patient, who ingested 3.2 mg/kg and presented with lethargy, was hospitalized and subsequently discharged 14 hours later. No deaths were recorded.

CONCLUSION

As demonstrated in our patient population, accidental ingestions of DXM in the pediatric patient did well with supportive care alone and rarely required inpatient treatment.

Dextromethorphan poisoning: An evidence-based consensus guideline for out-of-hospital management

The objective of this guideline is to assist poison center personnel in the appropriate out-of-hospital triage and initial out-of-hospital management of patients with a suspected ingestion of dextromethorphan by 1) describing the process by which an ingestion of dextromethorphan might be managed, 2) identifying the key decision elements in managing cases of dextromethorphan ingestion, 3) providing clear and practical recommendations that reflect the current state of knowledge, and 4) identifying needs for research. This guideline applies to the ingestion of dextromethorphan alone. Co-ingestion of additional substances could require different referral and management recommendations depending on the combined toxicities of the substances. This guideline is based on an assessment of current scientific and clinical information. The expert consensus panel recognizes that specific patient care decisions might be at variance with this guideline and are the prerogative of the patient and the health professionals providing care, considering all of the circumstances involved. This guideline does not substitute for clinical judgment. The grade of recommendation is in parentheses. 1) All patients with suicidal intent, intentional abuse, or in cases in which a malicious intent is suspected (e.g., child abuse or neglect) should be referred to an emergency department (Grade D). 2) Patients who exhibit more than mild effects (e.g., infrequent vomiting or somnolence [lightly sedated and arousable with speaking voice or light touch]) after an acute dextromethorphan ingestion should be referred to an emergency department (Grade C). 3) Patients who have ingested 5-7.5 mg/kg should receive poison center-initiated follow-up approximately every 2 hours for up to 4 hours after ingestion. Refer to an emergency department if more than mild symptoms develop (Grade D). 4) Patients who have ingested more than 7.5 mg/kg should be referred to an emergency department for evaluation (Grade C). 5) If the patient is taking other medications likely to interact with dextromethorphan and cause serotonin syndrome, such as monoamine oxidase inhibitors or selective serotonin reuptake inhibitors, poison center-initiated follow-up every 2 hours for 8 hours is recommended (Grade D). 6) Patients who are asymptomatic and more than 4 hours have elapsed since the time of ingestion can be observed at home (Grade C). 7) Do not induce emesis (Grade D). 8) Do not use activated charcoal at home. Activated charcoal can be administered to asymptomatic patients who have ingested overdoses of dextromethorphan within the preceding hour. Its administration, if available, should only be carried out by health professionals and only if no contraindications are present. Do not delay transportation in order to administer activated charcoal (Grade D). 9) For patients who have ingested dextromethorphan and are sedated or comatose, naloxone, in the usual doses for treatment of opioid overdose, can be considered for prehospital administration, particularly if the patient has respiratory depression (Grade C). 10) Use intravenous benzodiazepines for seizures and benzodiazepines and external cooling measures for hyperthermia (>104 degrees F, >40 degrees C) for serotonin syndrome. This should be done in consultation with and authorized by EMS medical direction, by a written treatment protocol or policy, or with direct medical oversight (Grade C). 11) Carefully ascertain by history whether other drugs, such as acetaminophen, were involved in the incident and assess the risk for toxicity or for a drug interaction.

“Crystal Dex:” Free-Base Dextromethorphan

Dextromethorphan (DXM) is a common component of combination cold medications that has become a popular drug of abuse for young adults. Abusers of DXM have developed a simple acid-base extraction technique to "free-base," or extract, the DXM from the unwanted guaifenesin, coloring agents, sweeteners, and alcohol that are typically included in combination cold preparations. We report a case of DXM overdose after ingestion of this purified "Crystal Dex" and discuss the "Agent Lemon" and single-phase extraction techniques that are used to free-base the dextromethorphan.

Impairments in water maze learning of aged rats that received dextromethorphan repeatedly during adolescent period

RATIONALE

Dextromethorphan (DM), an over-the-counter cough suppressant, has been recently used as a drug of abuse by teenage groups in some countries, such as the United States, Canada, and Korea. We previously showed that repeated administration of DM, a noncompetitive antagonist of N-methyl-D-aspartate (NMDA) receptors, impairs spatial learning performance in adolescent rats.

OBJECTIVES

In the present study, long-term adverse effects of repetitive DM use at adolescence were examined in rats.

METHODS

Male and female Sprague-Dawley rat pups received either intraperitoneal DM (40 mg/kg) or saline daily during postnatal days 28-37, and were then subjected to the Morris water maze task at the age of 18 months. Expression levels of NMDAR1, functional subunit of NMDA receptors, in the prefrontal cortex and the hippocampus were examined by Western blot analysis. Changes in plasma corticosterone levels responding to stress were determined by radioimmunoassay.

RESULTS

DM-experienced male rats exhibited deficits in the probe trial, and female rats in the initial learning and the reversal training, in water maze performance. Expression levels of NMDAR1 in the brain regions were significantly increased in DM-experienced rats, compared to control rats. Stress-induced increases in plasma corticosterone levels were blunted both in male and female DM rats.

CONCLUSIONS

The results suggest that repeated administration of DM at high doses during adolescent period may induce permanent deficits in cognitive function and that increased expression of NMDAR1 in the prefrontal cortex and the hippocampus may take a role in DM-induced memory deficits.

Dextromethorphan abuse in adolescence: an increasing trend: 1999-2004

OBJECTIVES

To analyze the trend of dextromethorphan abuse in California and to compare these findings with national trends.

DESIGN

A 6-year retrospective review.

SETTING

California Poison Control System (CPCS), American Association of Poison Control Centers (AAPCC), and Drug Abuse Warning Network (DAWN) databases from January 1, 1999, to December 31, 2004.

PARTICIPANTS

All dextromethorphan abuse cases reported to the CPCS, AAPCC, and DAWN. The main exposures of dextromethorphan abuse cases included date of exposure, age, acute vs long-term use, coingestants, product formulation, and clinical outcome. Main Outcome Measure The annual proportion of dextromethorphan abuse cases among all exposures reported to the CPCS, AAPCC, and DAWN databases.

RESULTS

A total of 1382 CPCS cases were included in the study. A 10-fold increase in CPCS dextromethorphan abuse cases from 1999 (0.23 cases per 1000 calls) to 2004 (2.15 cases per 1000 calls) (odds ratio, 1.48; 95% confidence interval, 1.43-1.54) was identified. Of all CPCS dextromethorphan abuse cases, 74.5% were aged 9 to 17 years; the frequency of cases among this age group increased more than 15-fold during the study (from 0.11 to 1.68 cases per 1000 calls). Similar trends were seen in the AAPCC and DAWN databases. The highest frequency of dextromethorphan abuse occurred among adolescents aged 15 and 16 years. The most commonly abused product was Coricidin HBP Cough & Cold Tablets.

CONCLUSIONS

Our study revealed an increasing trend of dextromethorphan abuse cases reported to the CPCS that is paralleled nationally as reported to the AAPCC and DAWN. This increase was most evident in the adolescent population.

Ovariectomy ameliorates dextromethorphan--induced memory impairment in young female rats

We have previously found that dextromethorphan (DM), over-the-counter cough suppressant, impairs memory retention in water maze task, when it is repeatedly administrated to adolescent female rats at high doses. In this study we examined first if ovariectomy ameliorates the DM-induced memory impairment in female rats, and then whether or not the DM effect is revived by estrogen replacement in ovariectomized female rats. Female rat pups received bilateral ovariectomy or sham operation on postnatal day (PND) 21, and then intraperitoneal DM (40 mg/kg) daily during PND 28-37. Rats were subjected to the Morris water maze task from PND 38, approximately 24 h after the last DM injection. In probe trial, goal quadrant dwell time was significantly reduced by DM in the sham operated group, however, the reduction by DM did not occur in the ovariectomy group. When 17beta-estradiol was supplied to ovariectomized females during DM treatment, the goal quadrant dwell time was significantly decreased, compared to the vehicle control group. Furthermore, a major effect of estrogen replacement was found in the escape latency during the last 3 days of initial learning trials. These results suggest that ovariectomy may ameliorate the adverse effect of DM treatment on memory retention in young female rats, and that estrogen replacement may revive it, i.e. estrogen may take a major role in DM-induced memory impairment in female rats.

Simultaneous analysis of d-3-methoxy-17-methylmorphinan and l-3-methoxy-17-methylmorphinan by high pressure liquid chromatography equipped with PDA

d-3-Methoxy-17-methylmorphinan (Dextromethorphan, DXM), which is a structural analog of morphine and codeine, has been widely used as a non-narcotic antitussive agent. It is a safe drug in therapeutic dose and does not produce analgesic effects, while its enantiomer, l-3-methoxy-17-methylmorphinan called levomethorphan (LXM) is a potent narcotic analgesic. DXM has been widely abused in Korea due to its hallucinogenic effect in large doses; therefore, the health authorities have regulated its use as a psychotropic agent since 2003. As its abuse has been serious, a possibility that DXM would be smuggled into Korea has also increased. Moreover, it has been suspected that there was the possibility of the adulteration or substitution of DXM with LXM due to their chemical similarities. Therefore, it was necessary for us to establish the enantiomeric separation of DXM and LXM. In this study, a liquid chromatographic method using a chiral column capable of separating stereoisomers of DXM as well as analyzing the major metabolites of DXM, 3-methoxymorphinan, 3-hydroxymorphinan, and 17-hydroxymethylmorphinan was developed. The validation of a method was studied through repeatability of retention times. Using this method, 32 confiscated DXM samples were analyzed to identify the enantiomers of DXM. As a result, DXM was detected in all samples and there was no evidence of the adulteration or substitution of DXM with LXM. Nevertheless, the stereochemical analysis of DXM and LXM is important not only to identify starting materials for illegal drug manufacture but also to understand the trends of abused drugs.

New Drugs of Abuse in North America

The term "drugs of abuse" usually brings to mind traditional street drugs, such as cocaine, heroin, marijuana, and methamphetamine. The drug scene, however, is constantly evolving. As various law enforcement agencies pursue and dismantle distribution and pro-duction organizations of the usual drugs of abuse, dealers and users are turning to less known, more accessible, and often currently licit substances. The widespread growth of the Internet with its vast distribution of information has increased the accessibility ofa host of substances and facilitated synthesis and production of various substances by individuals. This article discusses several new and emerging abused substances, including new synthetic variations, plants, and pharmaceuticals diverted for abuse.

Effects of dextromethorphan on in vitro contractile responses of mouse and rat urinary bladders

PURPOSE

Dextromethorphan (DXM) is a cough-suppressing ingredient in a variety of over-the-counter cough and cold medications. Dextromethorphan elevates the threshold for coughing primarily through a central mechanism. At doses recommended for treating coughs the drug is safe and effective. At much higher doses, DXM produces dissociative effects similar to those of phencyclidine and ketamine. Opioid analgesics structurally related to DXM also inhibit bladder contractions and produce urinary retention through a non-opioid mechanism. This study evaluated the direct effects of DXM on in vitro contractile responses of rat and mouse urinary bladders.

METHODS

Male rats and mice were anaesthetized and their bladders removed. Bladder strips were suspended in 15 ml oxygenated Tyrode's solution containing glucose. Bladder strip contractions were evoked by field stimulation (FS), carbachol or elevated KCl concentrations and contractile responses recorded. The strips were then exposed to 3 microM (DXM) for 30 min and re-stimulated. This sequence was repeated at 10, 30, and 100 microM DXM.

RESULTS

(a) The rat bladder generated significantly greater tension than the mouse bladder. (b) Dextromethorphan produced a dose-dependent inhibition of the response to FS that was approximately equal for rat and mouse bladders. FS at 8 or 32 Hz was significantly more sensitive to DXM inhibition than 2 Hz. (c) The response to carbachol was more sensitive to inhibition by DXM than the responses to FS or KCl.

CONCLUSIONS

These results demonstrate that DXM inhibits bladder contractions in vitro and that mouse and rat bladders are affected to approximately the same extent.

Emerging drugs of abuse

Several new and emerging substances are being diverted for abuse. Most of these emerging abused substances do not cause traditional drug screens to turn positive. The health effects of these substances have not yet been fully elucidated. Health care providers should be aware of the existence of these new abused substances.

Adolescent abuse of dextromethorphan

Dextromethorphan hydrobromide (DXM), a constituent of more than 125 patent cough/cold remedies, is the most popular antitussive medication in the United States. Cough syrups or capsules also contain additional ingredients such as acetaminophen, chlorpheniramine maleate, guaifenesin, and/or pseudoephedrine, and toxicity with overdosage is additive to that of dextromethorphan alone. An unknown number of adolescents in the United States and Europe intoxicate themselves with acute megadoses of dextromethorphan. A megadose of DXM is defined as 5 to 10 times the dose recommended for control of annoying nonproductive coughs. Although a moderate overdose of pure DXM hydrobromide is free of serious adverse effects, approximately 5% of persons of European ethnicity lack the ability to metabolize the drug normally, leading to rapid acute toxic levels. Variable quantities of pure dextromethorphan powder in multiples of 1 gram are easily available from the worldwide web, including e-Bay. Recipe-like extraction procedures are quickly available on the Internet for seemingly simple and inexpensive home manufacture of concentrated dextromethorphan powder from Coricidin HBP Cough & Cold tablets (street name triple C). Adolescents intoxicate themselves at parties and even before or after school since the drug is legal, relatively inexpensive, and easily purchased or shoplifted at drug or convenient stores. Acute megadoses of the drug have profound psychological and physiological effects similar to those of phencyclidine (PCP). Megadoses of dextromethorphan used to self-intoxicate, can produce a false-positive screening test for phencyclidine in a urine specimen.

Side effects of dextromethorphan abuse, a case series

The aim of this study was to investigate the Dextromethorphan (DXM) abuse side effects. Subjects were 53 volunteers who had consumed DXM with mean age 23.4 years. The mean of side effects during first day was 12.49 and during first week was 5.57. The causes of repeated DXM abuse were psychological dependency 46.5%, recreational abuse in 32.6%. Neurological and psychological symptoms were the most common of side effects in DXM abusers.

Dextromethorphan abuse

Dextromethorphan is an over-the-counter dissociative agent of increasing popularity as a drug of abuse among younger adolescents. The drug produces a range of toxicities depending upon either the dose or the components of the specific formulation that was ingested. Most cases improve with supportive care alone, but severely intoxicated patients may require significant attention. Because dextromethorphan is misused primarily by younger adolescents, the early identification and treatment of dextromethorphan abuse may be important in preventing broader substance abuse in these children. Consequently, it is important for clinicians to recognize, treat, and appropriately refer those who present with intoxication from this drug.

The association of gastroesophageal reflux disease with asthma and chronic cough in the adult

Gastroesophageal reflux disease (GERD) is a common condition which is particularly prevalent in patients with asthma and chronic cough. Physiologic changes caused by asthma and chronic cough promote acid reflux. GERD is also considered by many investigators as a factor contributing to airway inflammation. An etiological relationship between GERD and asthma/chronic cough and vice versa has been supported by a large number of experimental and clinical findings and refuted by others. Although further controlled studies are needed to clarify this relationship, GERD and asthma/chronic cough appear to be linked to each other. The association of GERD with asthma and chronic cough involves nerve reflexes, cytokines, inflammatory and neuroendocrine cells and, in some patients, tracheal aspiration of refluxing gastric fluids. GERD may present with typical symptoms but can also be asymptomatic. Sensitive methods for diagnosing GERD are available, which include esophageal pH monitoring, acid provocative tests, modified barium swallow and endoscopy. Consideration of the association of GERD with asthma and chronic cough is of practical value in the management of chronic cough or asthma resistant to treatment. Treatment of GERD in patients with asthma has been consistently shown to improve respiratory symptoms but not necessarily pulmonary function tests. Surgical treatment can be a useful and cost-effective approach in selected patients with asthma and GERD.

The role of pharmacogenetically-variable cytochrome P450 enzymes in drug abuse and dependence

The risk of drug dependence is determined by the interaction of drug, individual and environment. 'Pharmacogenetics' is the study of the influence of heredity on the response to drugs and their fate in the body; these studies aim to improve the understanding of inter-individual variability in drug response. The authors have applied this research approach to the study of drug metabolism and dependence. Specifically the interaction of genetically variable hepatic cytochrome P450 (CYP) enzymes and their effect on self-administration of drugs has been examined. Many drugs of abuse are substrates (e.g., amphetamines, codeine, nicotine) or inhibitors (e.g., (-)-cocaine) of polymorphic CYPs. Drug metabolism by genetically polymorphic enzymes can have significant clinical implications relating to drug toxicity, therapeutic failure, drug-drug interactions, disease susceptibility and abuse liability. There is good evidence that drug metabolism by genetically variable CYPs can influence the risk of drug dependence, the amount of drug consumed by dependent individuals and some of the toxicities associated with drug-taking behavior. It is anticipated that pharmacogenetics will be used to identify individuals at a greater risk for specific drug dependencies, provide information that can lead to novel treatment and prevention approaches as well as provide guidance for individualization of treatment choice.

Discrepancy between CYP2D6 phenotype and genotype derived from post-mortem dextromethorphan blood level

OBJECTIVE

To describe the death of a toddler after a therapeutic dose of dextromethorphan and its investigation.

STUDY DESIGN

Case report, cytochrome P450 phenotype and genotype determination in the victim and post-mortem drug redistribution study performed in rats.

RESULTS

A 20-month Asian male who received 3 mg of dextromethorphan once at 09:00 h and again at 22:00 h was found dead at 04:35 h. Post-mortem examination showed signs of early bronchopneumonia (bacterial cultures were negative); dextromethorphan and dextrorphan blood concentrations taken from the heart cavity were 500 ng/ml (1. 84 micromol/l) and 200 ng/ml (0.78 micromol/l), respectively. Despite the dextromethorphan level being almost 100-fold higher than expected after therapeutic doses, intentional or unintentional overdose was extremely unlikely; other potential causes were investigated. Post-mortem drug redistribution study performed in rats showed that dextromethorphan does not undergo extensive redistribution after death (6+/-5-fold increase) and could not explain the observed dextromethorphan level. The dextromethorphan/dextrorphan concentration ratio of 2.5 found in this toddler was compatible with a slow CYP2D6 metabolizer phenotype. However, the toddler exhibited a fast metabolizer genotype. Potential reasons for this discrepancy are discussed.

CONCLUSION

CYP450 phenotypes derived from post-mortem blood levels should be interpreted with caution and preferably confirmed by a genotype analysis.