Myeloneuropathy induced by recreational nitrous oxide use with variable exposure levels.

BACKGROUND AND PURPOSE: Although several case series have described nitrous-oxide-associated neurological disorders, a comprehensive assessment of exposure characteristics (e.g., time to onset, level of exposure) in substance abusers has not been performed. The aim of this study was to describe the onset patterns of recreational use of nitrous-oxide-induced neurological disorders. METHODS: All cases of neurological disorders related to nitrous oxide recreational use reported to the Hauts-de-France addictovigilance center between January 2019 and August 2020 were selected. Only cases requiring hospitalization with informative data to perform the nitrous oxide causality assessment were included. RESULTS: A total of 20 cases from five hospitals were included. The male-to-female ratio was 6:1 and the median age was 19 years (range 16-34). The neurological presentation (myeloneuropathy 64%, 7/11; sensorimotor neuropathy 36%, 4/11) included for all patients gait disorders due to proprioceptive ataxia and limb hypoesthesia. The median dose used per occasion was 100 cartridges (range 5-960; n = 19). The median time from the start of nitrous oxide use to the onset of neurological symptoms was 6 months (range 0.7-54; n = 16). The cumulative dose was significantly higher in patients with damage to all four limbs than in patients with lower limb symptoms only (p = 0.042). CONCLUSIONS: A low intermittent exposure may be sufficient to cause neurological damage in some subjects, suggesting that, at the population level, there is no safe exposure to nitrous oxide in recreational settings. The severity of neurological impairment could increase once used at high doses and for prolonged durations of nitrous oxide.

Detecting the diverted use of psychoactive drugs by adolescents and young adults: A pilot study.

PURPOSE: The increasing trend of diversion of nonprescription drugs (NPDs) by adolescents or young adults is worrying. We implemented this pilot study before a national investigation to identify requests for suspected recreational use of psychoactive drugs made by young subjects to community pharmacies. METHODS: Thirty-eight French community pharmacies were asked to complete questionnaire (with age, gender of subjects; name, form, quantity of drugs) for each suspect request formulated by subjects under 26. Besides, pharmacists were asked about the regulatory measures they thought useful to decrease this diverted use by young people. Nineteen pharmacies participated. The study covered from December 12, 2016 to January 23, 2017. RESULTS: Forty-one requests mentioning 51 drugs were reported. They concerned males (85%) aged 20 years old on average, including 6 minors. The most frequent age class was that comprised between 18 and 20 years old. Codeine-containing drugs (29 reports) and promethazine (17 reports), the main components of the popular cocktail "Purple drank," were the most requested, followed by dextromethorphan (3 reports). Fifteen drugs were requested in syrup form. One request concerned the prescription drug ketamine. Pharmacists suggested to schedule the concerned NPDs to prescription-only drugs and to increase the education of students as well as the public. CONCLUSIONS: Codeine and promethazine, the main components of the popular cocktail Purple drank, were the most requested. Suspect requests of psychoactive drugs made by adolescents or young adults in community pharmacies should be carefully surveyed and combined to the monitoring of falsified prescriptions.

[Pharmaceutical cognitive doping in students: a chimeric way to get-a-head?] / Dopage cognitif chez les étudiants : un moyen chim(ér)ique de s'en mettre plein la tête ?

For students, the pressing demands for memorization, top-level performance, and peer competition create an environment favorable for pharmaceutical cognitive doping behavior. We aimed to describe recent practices and the benefit / risk ratio of such behavior and to discuss the issues at stake. The prevalence of pharmaceutical cognitive doping among students has been reported from 1.3% to 33% across studies, with variations depending on country and definition of pharmaceutical cognitive doping. The therapeutic classes most frequently cited as being diverted for doping purposes are psychostimulants and nootropics (methylphenidate, modafinil, piracetam), corticosteroids, sedative drugs and beta-blockers. Some illegal substances such as cannabis, amphetamines and cocaine are also consumed in order to boost mental function. Finally, over-the-counter products, such as caffeine-based tablets or energy drinks, or alcohol, are also widely used by students whose motivations involve enhanced performance, concentration, memory, and staying awake during the revision and exam period. However, the expected (often fantasized) effectiveness of these products does not correspond to the reality of a modest controversial impact on cognitive performance. There appears to be an emerging profile of the student more inclined to doping behavior. Cognitive doping thus raises the question of its regulation, opening a debate opposing, on one hand, individual freedom and supposed collective benefits and, on the other hand, health consequences, educational (in)equality, and the risk of tarnished academic success. Strengthening school and university medicine, through prevention campaigns and the identification of subjects at risk, is essential to limit the extent, risk, and damages associated with such practices.

Pharmaceutical cognitive doping in students: A chimeric way to get-a-head?

For students, the pressing demands for memorization, top-level performance, and peer competition create an environment favorable for pharmaceutical cognitive doping behavior. We aimed to describe recent practices and the benefit/risk ratio of such behavior and to discuss the issues at stake. The prevalence of pharmaceutical cognitive doping among students has been reported from 1.3% to 33% across studies, with variations depending on country and definition of pharmaceutical cognitive doping. The therapeutic classes most frequently cited as being diverted for doping purposes are psychostimulants and nootropics (methylphenidate, modafinil, piracetam), corticosteroids, sedative drugs and beta-blockers. Some illegal substances such as cannabis, amphetamines and cocaine are also consumed in order to boost mental function. Finally, over-the-counter products, such as caffeine-based tablets or energy drinks, or alcohol, are also widely used by students whose motivations involve enhanced performance, concentration, memory, and staying awake during the revision and exam period. However, the expected (often fantasized) effectiveness of these products does not correspond to the reality of a modest controversial impact on cognitive performance. There appears to be an emerging profile of the student more inclined to doping behavior. Cognitive doping thus raises the question of its regulation, opening a debate opposing, on one hand, individual freedom and supposed collective benefits and, on the other hand, health consequences, educational (in)equality, and the risk of tarnished academic success. Strengthening school and university medicine, through prevention campaigns and the identification of subjects at risk, is essential to limit the extent, risk, and damages associated with such practices.

The dose-effect relationship of baclofen in alcohol dependence: A 1-year cohort study.

OBJECTIVE: Our aim is to study the relationship between dose of baclofen and effectiveness in alcohol dependence. METHODS: Two hundred two patients with alcohol dependence, who received baclofen treatment for drinking reduction, were followed up for 1 year. For each patient-month of treatment, the maximum daily dose of baclofen (DDB) and average weekly alcohol consumption (AWAC) were calculated. We defined a favorable drinking outcome as an AWAC under 200 g/w for at least 2 consecutive months. We divided the DDB of each patient-month into 3 categories (low dose: <90 mg/d, medium dose: 90-150 mg/d, and high dose: >150 mg/d) and investigated the relationship between reaching a favorable outcome and the concurrent DDB category in a time-varying Cox regression analysis. Hazard ratios (HRs) were adjusted based on age, sex, and initial AWAC. RESULTS: One hundred forty subjects were followed during at least 1 month. Of these patients, 58 (41%) had a favorable drinking outcome. In comparison to low dose, medium dose was associated with a decreased rate of favorable drinking outcome (HR = 0.42; 95% CI [0.20, 0.88]), whereas no difference was found with high dose (HR = 1.31; 95% CI [0.65, 2.64]). CONCLUSION: The relationship between dose of baclofen and favorable drinking outcome was U-shaped, that is, was increased at low and high doses compared to medium doses.

Catatonia and cannabis withdrawal: A case report.

BACKGROUND: Catatonia is a severe motor syndrome found in approximately 10% of all acute psychiatric hospital admissions. It can occur in various psychiatric diseases. The authors report the first case report of catatonia during cannabis withdrawal. CASE PRESENTATION: Mr. A, a 32-year-old man, reported to have smoked approximately 20 g of cannabis daily since the age of 11. Mr. A was incarcerated and was reported 3 weeks later to the medical department for having completely ceased talking and eating. At admission in the authors' department, the patient presented with classical catatonia symptoms (Bush-Francis Catatonia Rating Scale [BFCRS] score = 39/69). All laboratory results and brain magnetic resonance imaging (MRI) were normal. Six weeks after his admission and treatments by lorazepam and memantine, his BFCRS score was 0/69. DISCUSSION: This single case study highlights the previously underreported emergence of physical and motor symptoms following cannabis withdrawal. Pathophysiological aspects of abrupt cannabis cessation contributing to γ-aminobutyric acid (GABA)/glutamate balance dysregulation and to catatonia are discussed.

[The current aspects of the use of ecstasy/MDMA in France]. / Les aspects actuels de l'usage de l'ecstasy/MDMA en France.

Methylenedioxymethamphetamine (MDMA), the active compound of ecstasy, has been used for several years, especially by young adults to benefit of psychostimulant properties. By raising the level of neuromodulators in the synapsis, MDMA can cause psychiatric and physical injuries. After reduced supplies in 2009 (number of ecstasy seizures equal to 10 percent of those recorded in 2002), judicial authorities now observed an increased availability (a half more part of seizures in 2012 than 2010). From its "Spontaneous Notifications" data base and "deaths in connection with the abuse of medicine and substances (DRAMES)", "observation of illegal drugs and misuse of psychotropic medications" (OPPIDUM), and "observation of drug dependencies in ambulatory medicine" (OPEMA) national inquiries, the French Addictovigilance network (CEIP-A) highlighted the increasing consumption of MDMA. The way of use appeared quite unchanged: users were mainly young men between 25 and 30 years; they favored an occasional use but mainly combined other products such as alcohol, cannabis and other stimulants. Severity of the clinical cases, based on hospital care and forensic data, could be consistent with the higher amounts of MDMA measured in pills.

New synthetic drugs in addictovigilance.

New substances, also known as "designer drugs" or "legal highs" are increasingly available to drug users. Two hundred and fifteen hitherto unlisted substances have been notified by European Union member states since 2005. These synthetic drugs, which have been developed to side-step the legislation on drugs, are analogues or derivatives of existing drugs and medications. The availability of these "legal highs", sold on Internet under various denominations such as bath salt, plant fertilizer, chemical not intended for human use, or spice, is unlimited. The effects felt by users vary, and the substances may be stimulant, entactogenic, hallucinogenic, psychedelic or dissociative. The pharmacological targets also vary, and may be either the increase of extracellular levels of neurotransmitters via different mechanisms (reuptake inhibition, stimulation of intracellular release) or else fixation on specific receptors. Several chemical classes, themselves divided into sub-classes, are involved: phenethylamines, tryptamines, piperazines, cathinones, cannabinoids etc. The toxicity of the main members of these categories is increasingly well known, the most deleterious being behavioural effects, physical manifestations, and cardiovascular consequences. However, small variations in their chemical structure can generate effects that are quantitatively different, thus enhancing their toxicity or addictive potential, and much remains to be achieved in terms of knowledge about these new drugs. These substances are indeed present on the French territory, as shown by data provided by the Observatoire Français des Drogues et Toxicomanies, and notifications by the French Addictovigilance network. Screening in clinical toxicology laboratories is not widespread, since these molecules are not detected by the standard screening tests, so that there is probably an under-estimation of the use of these new drugs. The legislation on these substances changes regularly, with more and more countries classifying them as "narcotics" or illegal psychotropic drugs so as to restrict their use, applying a generic classification when possible.

[Temporary recommendation for use on off-label baclofen: viewpoint of Prescribers of the CAMTEA system]. / La « recommandation temporaire d'utilisation ¼ sur le baclofène : point de vue des prescripteurs du dispositif CAMTEA.

The use of high dose baclofen for alcohol-dependence emerged in France from 2008 based on empirical findings, and is still off-label. However, due to the rapid increase in this prescribing practice, the French health authorities have decided to frame it using an extraordinary regulatory measure named "temporary recommendation for use" (TRU). Baclofen prescribers from CAMTEA, a regional team-based off-label system for supervising baclofen prescribing, which was developed much prior to the TRU, discuss herein the pros and cons of this measure and the applicability of its different aspects in the daily clinical practice.

Assessing alcohol versus baclofen withdrawal syndrome in patients treated with baclofen for alcohol use disorder.

Baclofen is a γ-aminobutyric acid B (GABA-B) receptor agonist that is approved for spasticity. Recently, the off-label use of baclofen for alcohol use disorder (AUD) has increased. However, baclofen is known to induce a neuroadaptation process, which may be identified by the occurrence of a specific baclofen withdrawal syndrome (BWS), that is, confusion, agitation, seizures, and delirium. The same set of symptoms characterizes alcohol withdrawal syndrome (AWS), which could lead to mistaking BWS for AWS in some situations. We report the cases of 3 patients under a chronic baclofen treatment for AUD. The patients emergently presented with a clinical state of confusion that was initially diagnosed and treated as AWS, with limited effect of benzodiazepines. Retrospectively, using a validated algorithm for assessing drug-induced withdrawal, we determined that all of these clinical cases were consistent with BWS. Both AWS and BWS should be considered in the case of acute confusion or delirium occurring in patients treated with baclofen for AUD. Moreover, further research should investigate to what extent GABA-A and GABA-B induce shared or distinct neuroadaptation processes and withdrawal syndromes.

Severe tinnitus induced by off-label baclofen.

OBJECTIVE: The γ-aminobutyric acid type B (GABA-B) receptor agonist baclofen is approved for spasticity up to the dose of 80 mg/d. Recently, off-label use of high-dose baclofen (HDB), up to 400 mg/d, has been increasing for treating alcohol use disorders (AUDs), although the efficacy and safety profiles of HDB are relatively unknown. We report 2 cases of tinnitus in patients treated with HDB for AUD. CASE SUMMARIES: The first case concerns a 60-year-old man who reported tinnitus when he reached a 180 mg/d dose of baclofen after 3 months of treatment. Tinnitus persisted until the dose was reduced to 90 mg/d. The second case concerns a 45-year-old woman who presented with tinnitus when she reached a 210 mg/d dose of baclofen after 4 months of treatment. Tinnitus persisted until the dose was reduced to 60 mg/d. DISCUSSION: Using the Naranjo scale, imputability to baclofen was considered probable in both cases. GABA-B receptors have been reported to be implicated in both the etiology and the treatment of tinnitus. There may be an individual susceptibility to develop tinnitus under baclofen therapy because of some GABA-B genetic polymorphisms that remain to be determined. CONCLUSION: HDB may be responsible for the occurrence of severe tinnitus, possibly in a dose-dependent manner. This appears to be coherent with the previously known involvement of GABA-B receptors in the pathophysiology of tinnitus.

Baclofen-induced manic symptoms: case report and systematic review.

BACKGROUND: The gamma-aminobutyric acid type B receptor agonist baclofen is approved for spasticity and is used off-label for diverse types of addictive disorders, notably alcohol dependence. Baclofen may induce numerous neuropsychiatric adverse drug reactions, including behavioral disinhibition. However, this precise adverse drug reaction has never been assessed using either a validated causality algorithm or a scale for manic symptoms. METHODS: We report a case of a 49-year-old male patient who exhibited de novo mania during treatment with baclofen for alcohol dependence. Symptoms were evaluated using the Young Mania Rating Scale, and the causality of baclofen was determined using the Naranjo algorithm. This case was also compared with other cases of baclofen-induced mania through a systematic literature review. RESULTS: Mr. X, taking 180 mg/d of baclofen, presented with mania and scored 24 of 44 on the Young Mania Rating Scale, and the imputability of baclofen was "probable" using the Naranjo algorithm (8 of 13). In addition, 4 other cases of baclofen-induced mania were reported in the literature; 3 cases had a bipolar I disorder history. Baclofen-induced manic symptoms occurred mostly during the dose-escalation phase. CONCLUSION: Baclofen-induced manic symptoms may appear in patients with or without bipolar disorder. Particular attention is required during the dose-increase phase and in patients with a history of mood disorders.

[Baclofen and liver cirrhosis: literature review and safety precautions implemented within the system CAMTEA]. / Baclofène et cirrhose : analyse de la littérature et précautions d'emploi adoptées au sein du dispositif CAMTEA.

The off-label prescribing of high dose baclofen (HDB) has been recently spreading in France. The impact of HDB on subjects with liver cirrhosis remains poorly known. The main pharmacodynamic and pharmacokinetic data on baclofen result from studies on healthy subjects or using low doses of treatment. The specific biodisponibility and elimination of HDB have not been studied yet in cirrhosis. National pharmacovigilance reports suggest that a careful use of baclofen or even HDB could be possible in compensated cirrhosis. However, theoretical risks of baclofen overdose exist in cases of hepatorenal syndrome or portosystemic shunt. Baclofen could also induce a specific pharmacological potentiation of hepatic encephalopathy and gastropathy. Within CAMTEA, a regional team-based multidisciplinary system for delivering and monitoring off-label medications in alcohol use disorders, a set of predefined precautions for using baclofen in cirrhosis have been implemented, until further information becomes available. These precautions notably consist of a protocolized process for declaring adverse events, and a hepatologic follow-up associated with the usual multidisciplinary care system set up within CAMTEA.

Could psychostimulant drug use among university students be related to ADHD symptoms? A preliminary study.

We aimed to explore if psychostimulant use among student could be linked to attention deficit-hyperactivity disorder (ADHD) symptoms using a self-administered questionnaire sent by email to French students in 2021. Participants were asked about their psychostimulant use and the presence of ADHD symptoms using the Wender Utah Rating Scale and the Adult Self-Report Scale. Among the 4431 respondents, the prevalence of psychostimulant use was concerning and significantly associated with ADHD symptoms. This association could be related to undiagnosed ADHD or to psychobehavioral impairments induced by psychostimulant use underlining the need of ADHD screening and targeted prevention measures.

Factors associated with the use of benzodiazepine and opioid prescription drug in the student population: a cross-sectional study.

The misuse of benzodiazepines and opioid medications is frequent in students. To improve our understanding of this behavior, we aimed to identify factors associated with separate and concomitant use of these substances. Anonymous self-reported questionnaires were e-mailed to students enrolled at a French university between March and July 2021, covering: sociodemographic characteristics, academics, psychoactive substance use, ADHD symptomatology (adulthood and childhood), and psychiatric/psychological or addiction follow-up. Factors associated with the use of benzodiazepines and opioid medications included female sex (OR = 1.41 [1.08; 1.86]) and OR = 1.38 [1.06; 1.79], respectively), older age (OR = 1.65 [1.04; 2.6] and OR = 2.17 [1.4; 3.36], respectively), current psychiatric/psychological follow-up (OR = 6.53 [5.18; 8.24] and OR= 1.5 [1.12; 2.0], respectively), ADHD symptomatology (OR= 2.33 [1.71;3.16] and OR= 1.61 [1.15; 2.24], respectively), polyconsumption (tobacco use for benzodiazepine users, OR = 1.38 [1.04; 1.82]; alcohol use OR = 1.67 [1.17; 2.39] and tobacco use OR = 1.62 [1.23; 2.14] for opioid users). These factors were even more strongly associated with the concomitant use of benzodiazepines and opioid medications: older age (OR = 3.64 [2.22; 5.99]), female sex (OR = 1.54 [1.1; 2.14]), grade repetition (OR = 1.7 [1.14; 2.54]), psychiatric/psychological follow-up (OR = 4.51 [3.35;6.06]), ADHD symptomatology (OR = 5.3 [3.69; 7.63]), polyconsumption (tobacco use OR = 2.05 [1.39; 3] and cannabis use, OR = 2.07 [1.97; 4.16]. The factors associated with the use of benzodiazepines and prescription opioids identified in this study could lead to the development of targeted prevention methods.

Substance use disorder of equimolar oxygen-nitrous oxide mixture in French sickle-cell patients: results of the PHEDRE study.

BACKGROUND: In many countries, nitrous oxide is used in a gas mixture (EMONO) for short-term analgesia. Cases of addiction, with significant misuse, have been reported in hospitalized patients. Patients suffering from sickle cell disease (SCD) could represent a high-risk population for substance use disorder (SUD) due to their significant pain crisis and repeated use of EMONO. The objective of the PHEDRE study was to assess the prevalence of SUD for EMONO in French SCD patients. RESULTS: A total of 993 patients were included. Among 339 EMONO consumers, only 38 (11%) had a SUD, with very few criteria, corresponding mainly to a mild SUD due to a use higher than expected (in quantity or duration) and relational tensions with the care teams. Almost all patients (99.7%) were looking for an analgesic effect, but 68% of patients were also looking for other effects. The independent risks factors associated with at least one SUD criterion were: the feeling of effects different from the expected therapeutic effects of EMONO, at least one hospitalization for vaso occlusive crisis in the past 12 months and the presence of a SUD for at least one other analgesic drug. CONCLUSIONS: The use of EMONO was not problematic for the majority of patients. Manifestations of SUD that led to tensions with healthcare teams should alert and lead to an evaluation, to distinguish a true addiction from a pseudoaddiction which may be linked to an insufficient analgesic treatment related to an underestimation of pain in SCD patients. TRIAL REGISTRATION: Clinical Trials, NCT02580565. Registered 16 October 2015, https://clinicaltrials.gov/.

An overview of the use of psychoactive substances among students at the University of Lille during the COVID-19 health crisis: Results of the PETRA study.

OBJECTIVES: Students represent a population at risk for substance abuse. That risk may have been exacerbated by the COVID-19 pandemic. We aimed to describe substance abuse among students and to compare consumption according to the university field. METHODS: A self-administered questionnaire was sent by email to all students at the University of Lille, France, between March and July 2021. This anonymous questionnaire included questions about sociodemographic characteristics, university courses and the use of psychoactive substances (frequency, reasons, routes of administration) since the first university year. RESULTS: Among the 4431 students who responded (response rate 6.1%), eighty percent declared having used alcohol since the first university year, 34% cannabis, 15.4% benzodiazepines, 14.7% opioid drugs, 7.5% cocaine, 6.8% nitrous oxide and 6.5% MDMA. More than 20% of the users of cannabis, benzodiazepines, amphetamines and cocaine reported having already felt dependent. Recreational use was described by more than 10% of benzodiazepine or opioid drug users. Nitrous oxide use was significantly more frequent in the health and sport field (p < 0.001). Tobacco, benzodiazepine, cannabis and MDMA uses were significantly more frequent in the humanities and social sciences/art, language and literature fields (p < 0.001). CONCLUSION: Prevention measures focusing on alcohol, cannabis, illicit psychostimulants, nitrous oxide and prescription drugs are required in the student population.

Comparison of biomarker for diagnosis of nitrous oxide abuse: challenge of cobalamin metabolic parameters, a retrospective study.

BACKGROUND: Recreational use of nitrous oxide (N2O) leads to neurological disorders including combined subacute degeneration of spinal cord, psychological disorders, and thrombosis. Serum or urine N2O assays could not be routinely performed. Hence, it is necessary to investigate other biological markers such as metabolic markers. We aimed here to challenge the three main biological markers used for the diagnosis of nitrous oxide abuse as total vitamin B12, homocysteine, and methylmalonic acid. METHODS: We retrospectively collected clinical and biological data from 52 patients with known, documented chronic N2O abuse and associated clinical signs (peripheral neuropathy disability score or thrombosis event). Sera and plasma total vitamin B12, methylmalonic acid (MMA), and homocysteine were performed to identify the most specific marker of chronic N2O intoxication and related clinical outcomes. RESULTS: Plasma homocysteine was almost consistently increased in case of N2O chronic consumption, whereas MMA increase and total vitamin B12 decrease are not systematically found. Our results showed that none of the markers are correlated with levels of N2O consumptions. However, homocysteine and MMA are correlated with clinical severity, but MMA seems to be a better marker of clinical severity. CONCLUSION: There is no specific marker of nitrous oxide abuse according to levels of consumption, total vitamin B12 decrease could not be used either as consumption or as severity marker. However, we showed that homocysteine is consistently increased and could be used as marker of recent N2O consumption. On the other hand, we showed that MMA could be used as a marker of clinical gravity.

Rectal bleeding and hemostatic disorders induced by dabigatran etexilate in 2 elderly patients.

OBJECTIVE: To report rectal bleeding associated with hemostatic disorders in 2 elderly patients treated with dabigatran etexilate. CASE SUMMARY: A 79-year-old woman (weight, 69 kg) was hospitalized in a gastroenterology unit for severe rectal bleeding. She had been treated for 2 months with dabigatran etexilate 110 mg twice daily for chronic atrial fibrillation. On admission, her creatinine clearance (CrCl) was 20.7 mL/min/1.73 m(2), prothrombin time (PT) less than 10% (reference range 70-130%), and international normalized ratio (INR) 14.5 (venous blood). Eleven days after admission, hematologic and renal function were normalized and rectal bleeding stopped. An 84-year-old man (weight, 71 kg) was admitted for rectal bleeding with acute renal failure and dehydration that began while he was treated with dabigatran etexilate 110 mg twice daily for atrial fibrillation. On admission, CrCl was 33.5 mL/min/1.73 m(2), PT 13%, and INR 7.53 (venous blood). Dabigatran etexilate was stopped on admission. At the end of the hospitalization, CrCl was 66.5 mL/min/1.73 m(2), PT 54%, and INR 1.53. In both cases, an objective causality assessment revealed that those adverse reactions were probably related to dabigatran etexilate. DISCUSSION: In these 2 cases of rectal bleeding during dabigatran etexilate therapy, coagulation monitoring showed elevated PT and INR; neither patient had been exposed to vitamin K antagonists. These cases indicate the importance of PT and INR monitoring when using dabigatran etexilate, mainly in patients with a high risk of overdose, such as elderly patients or those with renal function impairment. CONCLUSIONS: It is critical to identify and subsequently manage dabigatran etexilate toxicity because there is no specific antidote to reverse the drug's anticoagulant effects.