Prescription opioid abuse based on representative postmortem toxicology

Patient-reported pain, satisfaction, adverse effects, and deviations from ambulatory surgery pain medication

OBJECTIVES

Addressing the challenges of ambulatory surgery involves balancing effective pain relief with minimizing the side effects of pain medication. Due to the heightened risk of opioid abuse, Helsinki University Hospital (Finland) has had a stringent oxycodone prescription policy. This policy prompts an exploration into whether ambulatory surgery patients experience severe post-surgical pain and whether an increase in prescribed opioids would cause elevation in adverse effects.

METHODS

This prospective cohort study, with a 1-week follow-up, included 111 adult ambulatory surgery patients (orthopaedics, urology). The patients documented their pain levels within the first postoperative week (using a numerical rating scale [NRS] of 0-10) and pain medication intake up to two days postoperatively. Furthermore, they completed a questionnaire assessing their satisfaction with pain relief, medication-related adverse effects, and adherence to instructions. Medication intake was cross-referenced with the provided instructions and prescriptions.

RESULTS

A notable 56% of patients reported experiencing intense pain (NRS ≥5) within a week following surgery. Of these, 52% received a single dose of slow-release oxycodone (5-20 mg) at discharge for use on the night of surgery. Predominantly prescribed pain medications included a combination of paracetamol and codeine (64%) or ibuprofen (62%). Satisfaction rates were high, with 87% expressing satisfaction with pain medication given at hospital discharge and 90% expressing contentment with the prescribed medication. The most common adverse effects were tiredness/grogginess (45%), sleep disturbances (38%), nausea (37%), and constipation (27%). Also, 24% of patients self-reported deviations from medication instructions. A comparison of self-reported and instructed medications revealed that 14% exceeded prescribed dosages, and 28% opted for preparations different from those prescribed. Notably, patients who self-reported deviations from instructions differed from those objectively deviating from instructions.

CONCLUSIONS

Although 56% of patients had intense pain, the majority expressed satisfaction with the provided pain relief. Instances of non-adherence to medication instructions were prevalent, often going unnoticed by the patients themselves.

Adverse Drug Reactions to Opioids: A Study in a National Pharmacovigilance Database

INTRODUCTION

Opioids are commonly used as analgesics; however, like any medicine, they can produce adverse drug reactions (ADRs), including nausea, constipation, dependence, and respiratory depression, that result in harmful and fatal events. Therefore, it is essential to monitor the safety of these drugs in clinical practice.

OBJECTIVE

This study aimed to characterize the safety profile of opioids by conducting a descriptive study based on a spontaneous reporting system (SRS) for ADRs in The Netherlands, focusing on abuse, misuse, medication errors, and differences between sexes.

METHODS

Reports submitted to the Netherlands Pharmacovigilance Centre Lareb from January 2003 to December 2021 with an opioid drug as the suspected/interacting medicine were analyzed. Reporting odds ratios (RORs) for drug-ADR combinations were calculated, analyzed, and corrected for sex and drug utilization (expenditure) for the Dutch population.

RESULTS

A total of 8769 reports were analyzed. Tramadol was the opioid with the most reports during the period (n = 2746), while oxycodone or tramadol had the highest number of reports per year in the study period. The most reported ADRs from opioid use were nausea, followed by dizziness and vomiting, independent of sex, and all of them were more often reported in women. Vomiting associated with tramadol (ROR females/males = 2.17) was significantly higher in women. Buprenorphine was responsible for most ADRs when corrected for expenditure, with high RORs observed with application site hypersensitivity, application site reaction, and application site rash. Fentanyl gave rise to most of the reports of ADRs concerning abuse, misuse, and medication errors.

CONCLUSION

Patients treated with opioids experienced ADRs, primarily nausea, dizziness, and vomiting. For those groups of drugs, no significant differences were found between the sexes, except for the vomiting associated with tramadol. In general, ADRs related to opioids presented higher RORs when uncorrected and corrected for sexes and expenditure than other drugs. There was more disproportionate reporting for ADRs concerning abuse, misuse, and medication errors for opioids than other drugs in the Dutch SRS.

"You get stuck in it": Young people's accounts of attempting to quit non-medical tramadol use

Aim: Non-medical use of tramadol and other prescription opioid use has become a great concern in many countries, including Sweden. This study examines key components in young people's accounts of attempting to quit drugs, focusing on non-medical use of tramadol. Methods: Repeated qualitative interviews were conducted with 12 individuals aged 19-24 years with experiences of problems related to non-medical tramadol use. The analysis used the concepts of autonomy, competence, and relatedness from self-determination theory. Results: Three themes emerged from the young people's accounts: (1) quitting initiated by parents and professionals; (2) being willing, but unable; and (3) between ambivalence and determination. These themes demonstrate conflicting emotions towards drug use along with a significant external pressure to quit, but also difficulties in quitting due to experiences of dependence, withdrawal symptoms, and mental health issues. For most participants, however, an increasing autonomous will and ability to abstain from drugs gradually developed, with the support from trusted relationships with professionals, family, and friends playing a crucial role. Conclusion: The process of trying to quit non-medical tramadol use can be challenging and involve a complex interaction between willingness and capability, where external influence can be either facilitating or hindering. This study highlights the importance of taking into account young people's own perspectives in treatment efforts, where trust is a key component.

Multiple suicide attempts associated with addiction to tramadol

BACKGROUND

The opioid tramadol is used as analgesic drug, and more recently was also proposed for the management of major depressive disorder. However, growing evidence suggests a link between opioid system dysfunction and suicidal behaviors, raising the question of tramadol use in view of the high addictive and suicidal risk. Here, we present the case of a young adult woman with multiple suicide attempts related to tramadol addiction.

CASE PRESENTATION

A 25-year-old woman was admitted for suicide attempt by phlebotomy in the Department of Psychiatric Emergency and Acute Care, Montpellier (France), in March 2020. The suicide attempt occurred 3 days after an abrupt tramadol withdrawal. In 2018, due to spinal disc herniation, she had a first prescription of tramadol to which she became addicted. The patient described an effect on psychological pain and suicidal ideation. However, she had to increase tramadol dose to obtain the desired effects, and for several months her intake was 2 000 mg per day. When she could not obtain tramadol any longer, suicidal ideation and psychological pain increased, leading to the suicide attempt. At the time of a worldwide opioid crisis that contributes to increasing suicidal behaviors, this case raises questions about tramadol prescription (often considered to be less addictive and with lower abuse potential) to individuals at risk of suicide.

In-hospital postoperative opioid use and its trends in neurosurgery between 2007 and 2018

Background

Postoperative opioid use plays an important role in the global opioid crisis, but little is known about in-hospital opioid use trends of large surgical units. We investigated whether postoperative in-hospital opioid consumption changed in a large academic neurosurgical unit between 2007 and 2018.

Methods

We extracted the data of consumed opioids in the neurosurgical intensive care unit and two bed wards between 2007 and 2018. Besides overall consumption, we analyzed the trends for weak (tramadol and codeine), strong, and the most commonly used opioids. The use of various opioids was standardized using the defined daily doses (DDDs) of each opioid agent. A linear regression analysis was performed to estimate annual treatment day-adjusted changes with 95% confidence intervals.

Results

Overall, 121 361 opioid DDDs were consumed during the 196 199 treatment days. Oxycodone was the most commonly used postoperative opioid (49% of all used opioids) in neurosurgery. In the bed wards, the use of oral oxycodone increased 375% (on average 13% (9–17%) per year), and the use of transdermal buprenorphine 930% (on average 26% (9–45%) per year) over the 12-year period. Despite the increased use of strong opioids in the bed wards (on average 3% (1–4%) per year), overall opioid use decreased 39% (on average 6% (4–7%) per year) between 2007 and 2018.

Conclusions

Due to the increase of strong opioid use in the surgical bed wards, we encourage other large teaching hospitals and surgical units to investigate whether their opioid use trends are similarly worrisome and whether the opioid consumption changes in the hospital setting are transferred to opioid use patterns or opioid-related harms after discharge.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00701-021-05021-9.

Current attention-deficit/hyperactivity disorder and nonmedical prescription opioid use attributed to tramadol among male adolescents without conduct disorder in Egypt

Background: Evidence for the association between attention-deficit/hyperactivity disorder (ADHD) and substance use disorders (SUDs) is common. However, little research has investigated this relationship among adolescents using nonmedical prescription opioids, particularly tramadol.Objective: To estimate the prevalence and correlates of ADHD among adolescents with tramadol misuse and without conduct disorder (CD).Methods: This study included 122 Egyptian adolescents (100% male) with opioid use disorders attributed to tramadol. The diagnosis of SUDs, ADHD, and CD (to exclude) was based on the SCID-I criteria of the DSM-IV-TR. Drug-related problems were assessed using the Drug Use Disorders Identification Test (DUDIT). All adolescents were screened for drugs by urinalysis.Results: Thirty-eight percent of adolescents with tramadol misuse had ADHD. Adolescents with tramadol misuse and ADHD were more likely to have a younger age of onset of smoking, substance use, and tramadol misuse than adolescents without ADHD.Conclusions: ADHD is common among adolescents with tramadol misuse. There is an association between ADHD and young age of onset of tramadol misuse and drug-related problems.

A review on tramadol toxicity: mechanism of action, clinical presentation, and treatment

Aims

As an analgesic that acts upon the central nervous system (CNS), tramadol has gained popularity in treating moderate to severe pain. Recently, it has been increasingly reported as a drug of misuse with intentional overdoses or intoxications. This review focuses on tramadol intoxication in humans and its effects on different systems.

Subject and method

This narrative review provides a comprehensive view of the pharmacokinetics, mechanism of action, and incidence of tramadol toxicity with an in-depth look at its side effects. In addition, the main approaches to the management of tramadol poisoning are described.

Results

Tramadol poisoning can affect multiple organ systems: gastrointestinal, central nervous system (seizure, CNS depression, low-grade coma, anxiety, and over time anoxic brain damage), cardiovascular system (palpitation, mild hypertension to life-threatening complications such as cardiopulmonary arrest), respiratory system, renal system (renal failure with higher doses of tramadol intoxication), musculoskeletal system (rhabdomyolysis), endocrine system (hypoglycemia), as well as, cause serotonin syndrome. Seizure, a serious nervous disturbance, is more common in tramadol intoxication than with other opioids. Fatal tramadol intoxications are uncommon, except in ingestion cases concurrent with other medications, particularly CNS depressants, most commonly benzodiazepines, and ethanol.

Conclusion

With the increasing popularity of tramadol, physicians must be aware of its adverse effects, substantial abuse potential, and drug interactions, to weigh its risk–benefit ratio for pain management. Alternative therapies might be considered in patients with a previous overdose history to reduce risks for adverse outcomes.

The Role of Risk or Contributory Death Factors in Methadone-Related Fatalities: A Review and Pooled Analysis

Methadone-related deaths are characterized by a wide range of post-mortem blood concentrations, due to the high pharmacokinetic/dynamic inter-individual variability, the potential subjective tolerance state and to other risk factors or comorbidities, which might enhance methadone acute toxicity. In the present study, the association among pre-existing and external conditions and diseases and the resultant methadone death capacity have been investigated. Beside a systematic literature review, a retrospective case-control study was done, dividing cases in which methadone was the only cause of death (controls), and those with associated clinical-circumstantial (naive/non-tolerant state), pathological (pulmonary or cardiovascular diseases) or toxicological (other drugs detected) conditions. Methadone concentrations were compared between the two groups and the association with conditions/diseases was assessed by multiple linear and binomial logistic regressions. Literature cases were 139, in house 35, consisting of 22 controls and 152 cases with associated conditions/diseases. Mean methadone concentrations were 2122 ng/mL and 715 ng/mL in controls and cases respectively, with a statistically significant difference (p < 0.05). Lower methadone concentrations (by 24, 19 and 33% respectively) were detected in association with naive/non-tolerant state, pulmonary diseases and presence of other drugs, and low levels of methadone (<600 ng/mL) might lead to death in the presence of the above conditions/diseases.

Mortality of treatment-seeking men and women with alcohol, opioid or other substance use disorders - A register-based follow-up study

BACKGROUND

Alcohol (AUD), opioid (OUD) and other substance use disorders (SUD) are associated with an increased risk of premature death. The aim of this register-based follow-up study was to compare the risk of death between individuals who had sought treatment for AUDs, OUDs and other SUDs in Finland.

DESIGN, SETTING, PARTICIPANTS

Data included 10,888 individuals who had sought help from three clinics at some point between 1990 and 2009. Treatment data were linked to national register data concerning education, hospitalizations and death by the year 2018.

MEASUREMENTS

Individuals were categorized into four groups: only alcohol (AUD-only), all OUDs (OUD-all), other or multiple SUDs (SUD-other) and outpatients without substance-related diagnoses or hospitalizations (SU-NAS); in mortality analyses, those who had started in opioid substitution treatment (OST) were analyzed separately. COX regression analyses were used to calculate the risk of death by the year 2018 or up to 15 years after seeking treatment.

RESULTS

Among the 10,888 treatment-seeking individuals the cumulative mortality rates during 1-, 5- and 15-year follow-up were 2.5% (n = 271), 10.9% (n = 1191) and 28.4% (n = 3096), respectively. The mean age at death varied according to substance of use (55.0 years for AUD-only, 35.8 OUD-all, 45.8 SUD-other and 55.6 SU-NAS). The patients who had started in OST had a lower risk of death compared to the other groups, as did the SU-NAS group that likely included individuals with a less severe course of AUDs/SUDs. There were no differences between the AUD-only, OUD-other and SUD-other groups for the risk of death during the 15-year follow-up period when gender and year of birth were included as covariates.

CONCLUSIONS

The mortality rates were very high; however, most of the deaths occurred several years after seeking treatment. The lower mortality amongst the patients who had initiated OST solidifies previous knowledge on the benefits of OST and efforts should be made to improve access to treatment. These results show that treatment plays a role in lowering the risk of death among individuals with AUDs/SUDs.

Wisdom of the CROUD: Development and validation of a patient-level prediction model for opioid use disorder using population-level claims data

OBJECTIVE

Some patients who are given opioids for pain could develop opioid use disorder. If it was possible to identify patients who are at a higher risk of opioid use disorder, then clinicians could spend more time educating these patients about the risks. We develop and validate a model to predict a person's future risk of opioid use disorder at the point before being dispensed their first opioid.

METHODS

A cohort study patient-level prediction using four US claims databases with target populations ranging between 343,552 and 384,424 patients. The outcome was recorded diagnosis of opioid abuse, dependency or unspecified drug abuse as a proxy for opioid use disorder from 1 day until 365 days after the first opioid is dispensed. We trained a regularized logistic regression using candidate predictors consisting of demographics and any conditions, drugs, procedures or visits prior to the first opioid. We then selected the top predictors and created a simple 8 variable score model.

RESULTS

We estimated the percentage of new users of opioids with reported opioid use disorder within a year to range between 0.04%-0.26% across US claims data. We developed an 8 variable Calculator of Risk for Opioid Use Disorder (CROUD) score, derived from the prediction models to stratify patients into higher and lower risk groups. The 8 baseline variables were age 15-29, medical history of substance abuse, mood disorder, anxiety disorder, low back pain, renal impairment, painful neuropathy and recent ER visit. 1.8% of people were in the high risk group for opioid use disorder and had a score > = 23 with the model obtaining a sensitivity of 13%, specificity of 98% and PPV of 1.14% for predicting opioid use disorder.

CONCLUSIONS

CROUD could be used by clinicians to obtain personalized risk scores. CROUD could be used to further educate those at higher risk and to personalize new opioid dispensing guidelines such as urine testing. Due to the high false positive rate, it should not be used for contraindication or to restrict utilization.

Substance Dependence and Hepatitis among Tramadol Prescription Users: A Study of Former Adolescent Psychiatric Inpatients in Northern Finland

We investigated the association between tramadol use, co-morbid substance use disorders and hepatitis in former adolescent psychiatric inpatients. The study sample consisted of 508 adolescents, admitted to psychiatric inpatient care between 13 and 17 years of age. Follow-up information of tramadol prescriptions, substance use disorders and hepatitis were obtained from the Finnish national health care registers. The users of prescription tramadol were categorized as follows: single users (one tramadol purchase), mild users (2-5 purchases) and heavy users (≥6 purchases). About one tenth (11.0%, n = 56) of study participants were tramadol users. Heavy users of tramadol had mothers with psychiatric problems (p = .039), and a diagnosis of substance use disorder (p < .001) in adolescence. Heavy use of tramadol was predicted with adolescent substance use disorder (OR = 8.31, 95%Cl 2.10-32.91, p = .003) and with mother´s psychiatric problems (OR = 5.85, p = .003). Hepatitis C (n = 54, 10.6%) associated with mild and heavy tramadol use (p < .001). Comorbid diagnosis of opioid dependence prevailed among heavy tramadol users (p <.001). Tramadol should only be prescribed to adolescents after careful evaluation. Particular caution is required in adolescents with a history of substance use disorders.

Fatal poisonings in Northern Finland: causes, incidence, and rural-urban differences

Background

In this study we evaluate differences between rural and urban areas in the causes and incidence of fatal poisonings.

Methods

Data from all fatal poisonings that occurred in Northern Finland from 2007 to 2011 were retrieved from Cause of Death Registry death certificates provided by Statistics Finland. The demographics and causes of fatalities were compared between rural and urban areas. Incidences were calculated based on the population data.

Results

There were a total of 684 fatal poisonings during the study period and 57.9% (n = 396) occurred in the urban population. Ethanol was the most common primary poisoning agent in cases of fatal poisoning, accounting for 47.5% of cases in urban areas and 68.1% in rural areas (P < 0.001). Fatal poisonings caused by psychoactive pharmaceutical products and opioids were more common in urban areas (28.3% compared to 18.0%, P < 0.001).

The crude incidence of fatal poisonings in the study area was 18.8 (17.4–20.2) per 100,000 inhabitants per year and there was no difference in incidence between urban and rural areas. In the youngest age group (15 to 24 years), the incidence of fatal poisonings observed in urban areas was two times higher than that in rural areas.

Discussion

Higher rate of fatal ethanol poisonings in rural areas could be linked to higher alcohol consumption in rural areas and also differences in drinking behaviour. Higher incidence of poisoning suicides in urban areas could be due to availability of different toxic agents as a suicidal method. Preventive measures could be key in reducing the number of fatal poisonings in both areas, as most of the fatal poisonings still occur outside hospital.

Conclusion

There was a higher rate of fatal ethanol poisoning in rural areas and higher rate of fatal poisoning related to psychoactive pharmaceutical products and opioids in urban areas. There were twice as many fatal poisonings in the youngest age group (15–24 years) in urban areas compared to rural areas, and suicide was more common in urban areas.

High Concomitant Misuse of Fentanyl in Subjects on Opioid Maintenance Treatment

BACKGROUND

Concomitant opioid misuse is an increasing problem in opioid maintenance treatment as it interferes with treatment success.

OBJECTIVE

Therefore, the rates of concomitant fentanyl misuse in opioid maintained patients were investigated.

METHODS

We conducted a cross-sectional study which consisted in collecting data via urine samples and questionnaires in Germany. Urine samples of patients on opioid maintenance treatment were gathered and fentanyl concentrations were measured from 2008 to 2012. An anonymous questionnaire provided data on the consumption of fentanyl as concomitant drug. Data were analyzed with descriptive statistics and group differences were calculated using the Chi-Square test.

RESULTS

Among the total sample (urine probes of 960 patients), 6.8% opioid maintained patients had positive urine samples for fentanyl and 37.9% reported concomitant fentanyl misuse (401 of these patients filled out the questionnaire). A significant age-related association of concomitant fentanyl misuse was identified in the urine analyses (χ² = 7.489; p = .024) and also in the questionnaire data (χ² = 11.899, p = .003), indicating that young age increased the probability of fentanyl consumption. Patients receiving methadone had the highest rates of concomitant fentanyl misuse with 18.4% according to urine analysis. In addition, the results show that patients who are on diamorphine are significantly less likely to misuse fentanyl.

CONCLUSIONS

Fentanyl is a frequently used concomitant drug. Especially young patients and patients taking methadone are at high risk. Because of the life-threatening consequences of fentanyl overdose, patients taking fentanyl should be intensively medically surveilled.

How Resistant to Tampering are Codeine Containing Analgesics on the Market? Assessing the Potential for Opioid Extraction

Introduction

Misuse of opioid analgesics, in combination with diversion, dependence, and fatal overdoses, presents a serious problem for public health, which affects many countries worldwide. Within this context, tampering with opioids has been associated with serious harm. The aim of the present study was to assess the tampering potential of codeine combination analgesics on the market (containing codeine/non-opioid analgesics) by the extraction of codeine.

Methods

Codeine was extracted from three combination formulations sold lawfully from licensed pharmacies without a medical prescription in Denmark and the UK. Extraction of codeine followed tampering procedures available on the Internet. The amounts of codeine and accompanying non-opioid analgesics in tampering products were analysed with liquid chromatography and tandem mass spectrometry (LC–MS/MS).

Results

LC–MS/MS showed recoveries of the total amounts of codeine in tampering products of 81–84% from Product 1 (codeine/acetylsalicylic acid); 61–67% from Product 2 (codeine/ibuprofen); and 42–71% from Product 3 (codeine/paracetamol). Recoveries of non-opioid analgesics ranged between: 57–73% acetylsalicylic acid; 5.5–8.5% ibuprofen, and 5.0–9.2% paracetamol.

Conclusion

With the tampering procedures used, high amounts of codeine were separated from the accompanying analgesics in some, but not in all of the codeine containing formulations. Evidence-based medicine regulation, treatment for opioid dependence, and information to minimise risks to the public are essential components of an effective public health strategy to address the harms of tampering and misuse.

Funding

Marie Pedersen and Jensine Heiberg Foundation.

Demographics and post-mortem toxicology findings in deaths among people arrested multiple times for use of illicit drugs and/or impaired driving

BACKGROUND

Multiple arrests for use of illicit drugs and/or impaired driving strongly suggests the existence of a personality disorder and/or a substance abuse problem.

METHODS

This retrospective study (1993-2010) used a national forensic toxicology database (TOXBASE), and we identified 3943 individuals with two or more arrests for use of illicit drugs and/or impaired driving. These individuals had subsequently died from a fatal drug poisoning or some other cause of death, such as trauma.

RESULTS

Of the 3943 repeat offenders 1807 (46%) died from a fatal drug overdose and 2136 (54%) died from other causes (p<0.001). The repeat offenders were predominantly male (90% vs 10%) and mean age of drug poisoning deaths was 5 y younger (mean 35 y) than other causes of death (mean 40 y). Significantly more repeat offenders (46%) died from drug overdose compared with all other forensic autopsies (14%) (p<0.001). Four or more drugs were identified in femoral blood in 44% of deaths from poisoning (drug overdose) compared with 18% of deaths by other causes (p<0.001). The manner of death was considered accidental in 54% of deaths among repeat offenders compared with 28% for other suspicious deaths (p<0.001). The psychoactive substances most commonly identified in autopsy blood from repeat offenders were ethanol, morphine (from heroin), diazepam, amphetamines, cannabis, and various opioids.

CONCLUSIONS

This study shows that people arrested multiple times for use of illicit drugs and/or impaired driving are more likely to die by accidentally overdosing with drugs. Lives might be saved if repeat offenders were sentenced to treatment and rehabilitation for their drug abuse problem instead of conventional penalties for drug-related crimes.

Buprenorphine infrequently found in fatal overdose in New York City

BACKGROUND

Buprenorphine is an opioid agonist medication that is both safe and effective in the treatment of opioid use disorders and the prevention of opioid overdoses. Despite this, media coverage has highlighted public concerns about the potential safety consequences of buprenorphine misuse and diversion. To address the possible contribution of buprenorphine to overdose mortality, we systematically tested post mortem blood specimens from decedents who had died of an unintentional drug overdoses in 2013.

METHODS

We retrospectively tested consecutive drug overdose cases that occurred from June through October 2013. Cases with available blood specimens were tested for buprenorphine and norbuprenorphine using liquid chromatography-tandem mass spectrometry. Toxicology results were linked to death certificates and case files from New York City Vital Statistics and New York City Office of the Chief Medical Examiner.

RESULTS

Of the 98 unintentional drug overdose fatalities tested, only 2 (2.0%) tested positive for buprenorphine metabolites. All 98 unintentional fatalities involved multiple substances.

CONCLUSIONS

Buprenorphine was infrequently found in drug overdose deaths in New York City. Since the safety and efficacy of buprenorphine are well documented, and overdoses resulting from buprenorphine treatment or diversion are very rare, facilitating access to buprenorphine treatment is strongly recommended.

Patterns of drug abuse among drug users with regular and irregular attendance for treatment as detected by comprehensive UHPLC-HR-TOF-MS

The most severe consequences of drug abuse include infectious diseases, overdoses, and drug-related deaths. As the range of toxicologically relevant compounds is continually changing due to the emergence of new psychoactive substances (NPS), laboratories are encountering analytical challenges. Current immunoassays are insufficient for determining the whole range of the drugs abused, and a broad-spectrum screening method is therefore needed. Here, the patterns of drug abuse in two groups of drug users were studied from urine samples using a comprehensive screening method based on high-resolution time-of-flight mass spectrometry. The two groups comprised drug abusers undergoing opioid maintenance treatment (OMT) or drug withdrawal therapy and routinely visiting a rehabilitation clinic, and drug abusers with irregular attendance at a harm reduction unit (HRU) and suspected of potential NPS abuse. Polydrug abuse was observed in both groups, but was more pronounced among the HRU subjects with a mean number of concurrent drugs per sample of 3.9, whereas among the regularly treated subjects the corresponding number was 2.1. NPS and pregabalin were more frequent among HRU subjects, and their abuse was always related to drug co-use. The most common drug combination for an HRU subject included amphetamine, cannabis, buprenorphine, benzodiazepine, and alpha-pyrrolidinovalerophenone. A typical set of drugs for treated subjects was buprenorphine, benzodiazepine, and occasionally amphetamine. Abuse of several concurrent drugs poses a higher risk of drug intoxication and a threat of premature termination of OMT. Since the subjects attending treatment used fewer concurrent drugs, this treatment could be valuable in reducing polydrug abuse.