Which illicit drugs are injected in Oslo? A study based on analysis of drug residues in used injection equipment and self-reported information.

BACKGROUND: People who inject drugs (PWID) have a high risk of premature death due to fatal overdoses. Newly emerged fentanyls, much more potent than heroin and other opioids, may increase this risk further. Therefore, precise information on injected drugs is critical to improving prevention strategies. AIMS: This study aimed to analyse drug residues in used injection equipment in order to determine drug and drug combinations and compare and complement findings with self-reported information. METHODS: Used syringes and needles (n=766) were collected at the supervised drug consumption facilities, the needle exchange service and two low-threshold health services for problem drug users in Oslo, Norway. The material was collected every third month from June 2019 to June 2020 and analysed for 64 substances using highly specific analytical methods (ultra-high performance liquid chromatography tandem mass spectrometry). Additionally, a street-recruited sample of PWID was interviewed from 2017 to 2019 regarding their drug injection habits (n=572). RESULTS: Heroin (65.5%) or amphetamines (59.8%), often in combination (30.5%), were commonly detected in drug residues. Other opioids, stimulants or benzodiazepines were rarely detected (6.1%). Fentanyl was detected in only one syringe. Heroin was the most reported drug (77.6% during the past four weeks, 48.3% daily/almost daily), followed by amphetamines (57.5% during the past four weeks, 23.1% daily or almost daily). Injection of methadone, buprenorphine and dissolved tablets was self-reported more frequently than determined in drug residue findings. CONCLUSIONS: Analysis of the injection equipment proved useful as a non-invasive, rapid and accurate means to obtain detailed information on injected drugs in Oslo and supplement traditional PWID survey information.

Concentrations of psychoactive substances in blood samples from non-fatal and fatal opioid overdoses.

AIM: The primary aim was to compare concentrations of psychoactive substances in blood in non-fatal and fatal opioid overdoses. The secondary aim was to assess the concentration levels of naloxone in blood in non-fatal overdoses and the association between naloxone findings and concomitantly detected drugs. METHOD DESIGN: Case-control study. SETTING: Norway. Fatal overdoses from 2017 and non-fatal overdoses from February 2018 to September 2019. CASES: Thirty-one non-fatal and 160 fatal opioid overdose cases. Data from the non-fatal overdoses were collected from hospital records and blood samples, and data from the fatal overdoses were collected from autopsy reports. Concentrations of psychoactive substances (including ethanol) in blood samples were collected at the time of hospital admission for the non-fatal overdoses and during autopsy for the fatal overdoses. RESULTS: The median number of different substances detected was four for fatal and five for non-fatal overdoses. The fatal overdoses had higher pooled concentrations of opioids (188 vs 57.2 ng/mL, P < .001), benzodiazepines (5467 vs 2051 ng/mL, P = .005) and amphetamines (581 vs 121 ng/mL, P < .001) than the non-fatal overdoses. A linear relationship between naloxone and concomitant pooled opioid concentrations was found (95% confidence interval = 0.002-0.135, P < .05). CONCLUSION: The total load of drug concentrations was associated with the fatal outcome of an overdose, while the number of drugs used, to a lesser extent, differentiated between those who survived and those who died from an overdose. Higher opioid concentrations were associated with treatment with higher naloxone doses.

Deaths associated with MDMA in the period 2000-2019. / Dødsfall assosiert med MDMA i perioden 2000­19.

BACKGROUND: The use of MDMA (3,4-methylenedioxymethamphetamine), also known as ecstasy, has increased in Norway in recent years. Since MDMA has the potential to be toxic and cause death, we studied whether increased availability and use correlates with the increase in MDMA-associated deaths. MATERIAL AND METHOD: The study includes post-mortems with findings of MDMA in blood, linked to information about cause of death from the Norwegian Cause of Death Registry. These data were compared with the number of arrested drug drivers with MDMA detected in their blood as well as annual seizure statistics from Kripos (The National Criminal Investigation Service) in the period 2000-2019. RESULTS: In the period 2000-2019, MDMA was detected in 142 fatalities, and the cause of death was known for 132 of these. The number of annual MDMA-associated deaths varied from 1 to 18. The median MDMA concentration among the fatalities increased from 1.9 µmol/L (interquartile range (IQR) 0.9 to 5.0) in 2000-2004 to 3.8 µmol/L (1.4 to 12.0) in 2015-2019. In 47/132 (36 %) of cases, MDMA and other central nervous system (CNS) stimulant drugs contributed to the death. Among arrested drug drivers with detected MDMA, the annual number of detected cases was 7-262 in this period, but the median concentration remained stable. INTERPRETATION: MDMA may have contributed to numerous deaths in Norway. Increased availability, increased use and increased strength of contents seem to be significant.

Comparison of the Diagnostic Value of Phosphatidylethanol and Carbohydrate-Deficient Transferrin as Biomarkers of Alcohol Consumption.

BACKGROUND: The aim of this study was to compare the results of Phosphatidylethanol (PEth) and carbohydrate-deficient transferrin (CDT) in blood as biomarkers of alcohol consumption in a large clinical cohort and to evaluate concentrations in relation to age and sex. METHODS: Results of PEth 16:0/18:1 in blood and CDT in serum were included, together with information of age and sex, which were extracted from a clinical chemistry database containing samples mostly from patients of primary care physicians and social care institutions. PEth concentrations were determined using Ultra Performance Convergence chromatography mass spectrometer. CDT was quantified by electrophoretic Capillary System. CDT values ≥ 1.7 %-units and PEth values ≥ 0.31 µmol/L were considered to indicate heavy alcohol consumption. RESULTS: Samples from 6705 patients were included. The median age was 54.5 years, and 34 % were females. Only 47 % of the patients with PEth ≥ 0.31 µmol/L had increased CDT ≥ 1.7 %-units examined in the same specimen (Cohen's kappa was 0.43, p < 0.001). Patients above 50 years had significantly higher concentrations for both CDT (1.0 %-units vs. 0.9 %-units, p < 0.001) and PEth (0.340 µmol/L vs. 0.200 µmol/L, p < 0.001) compared with younger patients. Concentrations of CDT were significantly higher in males compared with females (p = 0.002), while no significant sex differences were seen for PEth (p = 0.465). CONCLUSIONS: A high fraction of the patients had PEth values above the suggested cutoff for heavy drinking and normal CDT values, verifying the superior sensitivity of PEth compared with CDT. The effect of age seems to be minor for both markers. Higher concentrations of CDT, but not PEth, were seen in males, indicating that PEth, as opposed to CDT, might be formed equally in men and women. Therefore, the bias due to sex is possibly present only for CDT, not for PEth.

The Association between the Alcohol Biomarker Phosphatidylethanol (PEth) and Self-Reported Alcohol Consumption among Russian and Norwegian Medical Patients.

AIMS: Valid measures to identify harmful alcohol use are important. Alcohol Use Disorders Identification Test (AUDIT) is a validated questionnaire used to self-report harmful drinking in several cultures and settings. Phosphatidylethanol 16:0/18:1 (PEth) is a direct alcohol biomarker measuring alcohol consumption levels. The aim of this study was to investigate how PEth levels correlate with AUDIT-QF and weekly grams of alcohol consumed among patients in two urban hospitals. In addition, we wanted to investigate the predictive value of PEth in identifying harmful alcohol use as defined by AUDIT-QF and weekly grams of alcohol cutoffs. METHODS: A cross-sectional study comprising acute medically ill patients with measurable PEth levels (≥0.030 µM) admitted to two urban hospitals in Oslo, Norway (N = 931) and Moscow, Russia (N = 953) was conducted using PEth concentrations in whole blood, sociodemographic data and AUDIT-QF questionnaires. RESULTS: PEth levels from patients with measurable PEth were found to be positively correlated with AUDIT-QF scores, with PEth cutpoints of 0.128 µM (Oslo) and 0.270 µM (Moscow) providing optimal discrimination for harmful alcohol use defined by AUDIT-QF (the difference between cities probably reflecting different national drinking patterns in QF). When converting AUDIT-QF into weekly grams of alcohol consumed, the predictive value of PEth improved, with optimal PEth cutpoints of 0.327 (Oslo) and 0.396 (Moscow) µM discriminating between harmful and non-harmful alcohol use as defined in grams (≥350 grams/week). CONCLUSIONS: By using PEth levels and converting AUDIT-QF into weekly grams of alcohol it was possible to get an improved rapid and sensitive determination of harmful alcohol use among hospitalized patients.

Psychoactive substances have major impact on injuries in rural arctic Norway - A prospective observational study.

BACKGROUND: Rural areas have increased injury mortality with a high pre-hospital death rate. Knowledge concerning the impact of psychoactive substances on injury occurrence is lacking for rural arctic Norway. These substances are also known to increase pre-, per- and postoperative risk. The aim was by prospective observational design to investigate the prevalence and characteristics of psychoactive substance use among injured patients in Finnmark county. METHODS: From January 2015 to August 2016, patients ≥18 years admitted to hospitals in Finnmark due to injury were approached when competent. Blood was analysed for ethanol, sedatives, opioids, hypnotics and illicit substances in consenting patients, who completed a questionnaire gathering demographic factors, self-reported use/behaviour and incident circumstances. RESULTS: In 684 injured patients who consented to participation (81% consented), psychoactive substances were detected in 35.7%, alcohol being the most prevalent (23%). Patients in whom substances were detected were more often involved in violent incidents (odds ratio 8.92 95% confidence interval 3.24-24.61), indicated harmful use of alcohol (odds ratio 3.56, 95% confidence interval 2.34-5.43), reported the incident being a fall (odds ratio 2.21, 95% confidence interval 1.47-3.33) and presented with a reduced level of consciousness (odds ratio 3.91, 95% confidence interval 1.58-9.67). Subgroup analysis revealed significant associations between testing positive for a psychoactive substance and being diagnosed with a head injury or traumatic brain injury. CONCLUSION: A significant proportion of injured patients had used psychoactive substances prior to admission. Use was associated with violence, falls, at-risk alcohol consumption, decreased level of consciousness on admittance and head injury.

Comparative Neuropharmacology and Pharmacokinetics of Methamphetamine and Its Thiophene Analog Methiopropamine in Rodents.

Methiopropamine is a novel psychoactive substance (NPS) that is associated with several cases of clinical toxicity, yet little information is available regarding its neuropharmacological properties. Here, we employed in vitro and in vivo methods to compare the pharmacokinetics and neurobiological effects of methiopropamine and its structural analog methamphetamine. Methiopropamine was rapidly distributed to the blood and brain after injection in C57BL/6 mice, with a pharmacokinetic profile similar to that of methamphetamine. Methiopropamine induced psychomotor activity, but higher doses were needed (Emax 12.5 mg/kg; i.p.) compared to methamphetamine (Emax 3.75 mg/kg; i.p.). A steep increase in locomotor activity was seen after a modest increase in the methiopropamine dose from 10 to 12.5 mg/kg, suggesting that a small increase in dosage may engender unexpectedly strong effects and heighten the risk of unintended overdose in NPS users. In vitro studies revealed that methiopropamine mediates its effects through inhibition of norepinephrine and dopamine uptake into presynaptic nerve terminals (IC50 = 0.47 and 0.74 µM, respectively), while the plasmalemmal serotonin uptake and vesicular uptake are affected only at high concentrations (IC50 > 25 µM). In summary, methiopropamine closely resembles methamphetamine with regard to its pharmacokinetics, pharmacodynamic effects and mechanism of action, with a potency that is approximately five times lower than that of methamphetamine.

Associations between psychoactive substance use and sensation seeking behavior among drivers in Norway.

BACKGROUND/AIM: Drug use and risky driving is associated with sensation seeking. The aim of this study was to investigate the association between use of psychoactive substances and levels of the sensation seeking personality trait as measured with the Brief Sensation Seeking Scale 4 among drivers in Norway. METHOD: A cross-sectional design was applied to estimate the association between psychoactive substance use and sensation seeking behavior. Drivers in normal traffic were included in two roadside surveys: one in the north (September 2014 - October 2015) and the other in the south-east of Norway (April 2016 - April 2017). Oral fluid was analyzed for alcohol and psychoactive drugs, and data on sex, age and time of participation were recorded. Participants filled in the Brief Sensation Seeking Scale 4 questionnaire. RESULTS: A total of 8053 drivers were included, of which 32% were women and 62% were under 40 years. The prevalence of alcohol was 0.3%, stimulants 0.6%, tetrahydrocannabinol 1.4%, benzodiazepines and/or z-hypnotics 2.0% and polydrug use 0.6%. Associations were found between the use of tetrahydrocannabinol or benzodiazepines and/or z-hypnotics and a low score on the "thrill and adventure seeking" domain of the Brief Sensation Seeking Scale 4 (OR = 1.723, 95% C.I. = 1.001-2.966). Associations were also found between the use of stimulants and the highest scores on the "experience seeking" (OR = 2.085, 95% C.I. = 1.084-4.009) and "disinhibition" (OR = 4.791, 95% C.I. =1.748-13.135) domains of the Brief Sensation Seeking Scale 4. No associations were found between sensation seeking behavior and alcohol or polydrug use. CONCLUSION: A high degree of sensation seeking was found among drivers who had used stimulating drugs, in contrast to drives who had used tetrahydrocannabinol and benzodiazepines and/or z-hypnotics who showed a low degree of sensation seeking. The combination of sensation seeking behavior and the use of stimulants might lead to increased risky behavior and thus traffic crashes.

Pharmacokinetics of Single Doses of Methadone and Buprenorphine in Blood and Oral Fluid in Healthy Volunteers and Correlation With Effects on Psychomotor and Cognitive Functions.

PURPOSE: We aimed to study the pharmacokinetics of methadone and buprenorphine in blood and oral fluid after single-dose administration and investigate correlations between concentrations in blood and neurocognitive functions. METHODS: A 5-way, double-blind, randomized, placebo-controlled, double-dummy, crossover study was performed to study the pharmacokinetics and neurocognitive effects of methadone (5 and 10 mg per oral) and buprenorphine (0.2 and 0.4 mg sublingual) in 22 healthy volunteers. Blood and oral fluid were collected throughout the test days, and drug concentrations in both matrices were analyzed using ultrahigh-performance liquid chromatography-tandem mass spectrometry. On-road driving testing, neurocognitive computerized tests, and subjective questionnaires were performed. RESULTS: Large individual variations in concentrations of methadone and buprenorphine in blood and oral fluid, and accordingly oral fluid/blood drug concentration ratios, were observed. The mean ratio 6.5 hours after drug administration was 2.0 (range, 0.49-7.39) for methadone after both doses. Buprenorphine was not detected above the limit of quantification in blood after 6.5 hours. No significant correlation between methadone concentration in blood and effect was found. Significant correlations were found between buprenorphine concentration in blood and standard deviation of lateral position in the driving test and some measures of reaction time, divided attention, balance, alertness, contentedness. and sleepiness. CONCLUSIONS: Concentrations of methadone and buprenorphine in blood and oral fluid showed large interindividual variations. No concentration-effect correlations were found for methadone, whereas low to moderate correlations were observed between buprenorphine concentration and driving, psychomotor function, and subjective rating of sleep and alertness.

A clinical trial on the acute effects of methadone and buprenorphine on actual driving and cognitive function of healthy volunteers.

AIMS: The present study assessed the acute effects of methadone and buprenorphine on actual on-road driving performance and neurocognitive function. METHODS: Methadone (5 and 10 mg per os) and buprenorphine (0.2 and 0.4 mg sublingual) were administered to 22 healthy volunteers in a five-way, double-blind, randomized, placebo-controlled, double-dummy, cross-over study. Driving performance was assessed with an on-road driving test. The primary outcome measure was standard deviation of lateral position (SDLP), a measure of road tracking control. Laboratory tests were used to measure cognitive function (e.g. reaction time and attention) and questionnaires were used to assess subjective measures of mood and sedation. RESULTS: There was no significant main effect of treatment on SDLP. Yet, analysis of individual drug-placebo contrast data revealed that buprenorphine 0.4 mg significantly increased SDLP. Driving impairment was mild and below the impairment threshold of a blood alcohol concentration of 0.5 mg ml-1 . Four participants stopped their driving test while under the influence of either opioid due to sleepiness. Both opioids produced impairments of cognitive task performance and increased sleepiness particularly at the highest dose. CONCLUSIONS: Analgesic doses of buprenorphine produced mild impairing effects on driving and related cognitive skills, while methadone impaired cognitive task performance but not driving performance. Large individual variations were observed for both drugs. Patients should be informed about the possibility of driving impairment when initiating opioid treatment.

Systematic screening of substance use upon hospitalisation. / Systematisk kartlegging av rusbruk ved innleggelse.

Many people can improve their health by reducing their consumption of alcohol and habit-forming medications. By screening for this in connection with emergency hospital admissions, we can help to reduce use.

Comparison of (+)- and (-)-Naloxone on the Acute Psychomotor-Stimulating Effects of Heroin, 6-Acetylmorphine, and Morphine in Mice.

Toll-like receptor 4 (TLR4) signaling is implied in opioid reinforcement, reward, and withdrawal. Here, we explored whether TLR4 signaling is involved in the acute psychomotor-stimulating effects of heroin, 6-acetylmorphine (6-AM), and morphine as well as whether there are differences between the three opioids regarding TLR4 signaling. To address this, we examined how pretreatment with (+)-naloxone, a TLR4 active but opioid receptor (OR) inactive antagonist, affected the acute increase in locomotor activity induced by heroin, 6-AM, or morphine in mice. We also assessed the effect of pretreatment with (-)-naloxone, a TLR4 and OR active antagonist, as well as the pharmacokinetic profiles of (+) and (-)-naloxone in the blood and brain. We found that (-)-naloxone reduced acute opioid-induced locomotor activity in a dose-dependent manner. By contrast, (+)-naloxone, administered in doses assumed to antagonize TLR4 but not ORs, did not affect acute locomotor activity induced by heroin, 6-AM, or morphine. Both naloxone isomers exhibited similar concentration versus time profiles in the blood and brain, but the brain concentrations of (-)-naloxone reached higher levels than those of (+)-naloxone. However, the discrepancies in their pharmacokinetic properties did not explain the marked difference between the two isomers' ability to affect opioid-induced locomotor activity. Our results underpin the importance of OR activation and do not indicate an apparent role of TLR4 signaling in acute opioid-induced psychomotor stimulation in mice. Furthermore, there were no marked differences between heroin, 6-AM, and morphine regarding involvement of OR or TLR4 signaling.

Extended Detection of Amphetamine and Methamphetamine in Oral Fluid.

BACKGROUND: Amphetamine and methamphetamine are popular drugs of abuse worldwide and are important components of drug monitoring programs. Windows of detection for amphetamine and methamphetamine in oral fluid after high doses have not been investigated. Repeated high-dose ingestions are likely to cause positive samples for extended periods. Common routes of administration of amphetamine/methamphetamine in Norway are oral intake or injection. The aim of this study was to investigate windows of detection for amphetamine and methamphetamine in oral fluid from drug addicts under sustained abstinence during detoxification. METHODS: Twenty-five patients admitted to a closed detoxification unit were included in this study. Oral fluid samples were collected daily in the morning and evening, and urine every morning for 10 days. A blood sample was drawn during the first 5 days after admission if the patient consented. Oral fluid results were compared with urine results to determine whether a new ingestion occurred. Oral fluid was collected with the Intercept oral fluid collection device. In-house cutoff concentrations for amphetamine and methamphetamine were 6.8 and 7.5 mcg/L, respectively, in oral fluid, and 135 and 149 mcg/L, respectively, in urine. RESULTS: Amphetamines were detected in 11 oral fluid, 5 urine, and 2 blood specimens from 25 patients. Patients self-reported amphetamines intake of up to 0.5-2 g daily. Windows of detection for amphetamine and methamphetamine in oral fluid were up to 8 days, longer than in urine at the applied cutoff values. CONCLUSIONS: These data confirm that oral fluid is a viable alternative to urine for monitoring amphetamine abuse, and that these substances might be detected in oral fluid for at least 1 week after ingestion of high doses. Such long detection times were, as far as we are aware, never reported previously for oral fluid amphetamines.

Novel psychoactive substances. / Nye psykoaktive stoffer.

There has been a significant increase in the number of new intoxicants on the illegal drugs market globally, also in Norway. The substances are given the name NPS: Novel Psychoactive Substances, and are mainly sold over the Internet. Uncertain dosage of potent substances entails a risk of accidental overdose, and therefore serious intoxication and death. In this article we provide an overview of current knowledge with regard to these substances.

Detection Times of Diazepam, Clonazepam, and Alprazolam in Oral Fluid Collected From Patients Admitted to Detoxification, After High and Repeated Drug Intake.

BACKGROUND: Clonazepam, diazepam, and alprazolam are benzodiazepines with sedative, anticonvulsant, and anxiolytic effects, but their prevalence in drug abuse and drug overdoses has long been recognized. When detection times for psychoactive drugs in oral fluid are reported, they are most often based on therapeutic doses administered in clinical studies. Repeated ingestions of high doses, as seen after drug abuse, are however likely to cause positive samples for extended time periods. Findings of drugs of abuse in oral fluid collected from imprisoned persons might lead to negative sanctions, and the knowledge of detection times of these drugs is thus important to ensure correct interpretation. The aim of this study was to investigate the time window of detection for diazepam, clonazepam, and alprazolam in oral fluid from drug addicts admitted to detoxification. METHODS: Twenty-five patients with a history of heavy drug abuse admitted to a detoxification ward were included. Oral fluid was collected daily in the morning and the evening and urine samples every morning for 10 days, using the Intercept device. Whole blood samples were collected if the patient accepted. The cutoff levels in oral fluid were 1.3 ng/mL for diazepam, N-desmethyldiazepam, and 7-aminoclonazepam and 1 ng/mL for clonazepam and alprazolam. In urine, the cutoff levels for quantifications were 30 ng/mL for alprazolam, alpha-OH-alprazolam, and 7-aminoclonazepam, 135 ng/mL for N-desmethyldizepam, and 150 ng/mL for 3-OH-diazepam and for all the compounds, the cutoff for the screening analyses were 200 ng/mL. RESULTS: The maximum detection times for diazepam and N-desmethyldiazepam in oral fluid were 7 and 9 days, respectively. For clonazepam and 7-aminoclonazepam, the maximum detection times in oral fluid were 5 and 6 days, respectively. The maximum detection time for alprazolam in oral fluid was 2.5 days. New ingestions were not suspected in any of the cases, because the corresponding concentrations in urine were decreasing. Results from blood samples revealed that high doses of benzodiazepines had been ingested before admission, and explains the longer detection times in oral fluids than reported previously after intake of therapeutic doses of these drugs. CONCLUSIONS: This study has shown that oral fluid might be a viable alternative medium to urine when the abuse of benzodiazepines is suspected.

[Prevalence of injuries associated with the «russ¼ celebration in Norway]. / Forekomst av skader i russetiden.

BACKGROUND: Every year the Norwegian Institute of Public Health receives a number of enquiries from the media regarding the extent to which alcohol intake by upper secondary school leavers celebrating in their final spring term (the traditional Norwegian «russ¼ celebration) is a cause of injuries, and whether there are more injuries during this period. The purpose of this study is to investigate the prevalence of injuries in the «russ¼ celebration period. MATERIAL AND METHOD: Data from the Norwegian patient register (NPR) were used to investigate the prevalence of injuries in 16-, 19- and 21-year-olds from 2007 to 2011. The 19-year-olds represent those who celebrate «russ¼. Injuries recorded using ICD-10 codes were examined. The month of May and the period 20 April to 20 May were compared to the other months of the year. RESULTS: The 19-year-olds have significantly more injuries during the «russ¼ period compared to the 16- and 21-year-olds. In the «russ¼ period, the 19-year-olds accounted for 41.4% of the injuries, the 16-year-olds for 27.7% and the 21-year-olds for 30.9%. The 19-year-olds have more injuries in May compared to other months. There is a particular increase in the prevalence of head injuries. CONCLUSION: An increase was observed in the number of injuries among 19-year-olds associated with the period of the «russ¼ celebration compared to the rest of the year. There are no data available which describe the causes of the injuries. There is a need for better recording of the use of alcohol or intoxicants as a possible cause. Injuries treated by the specialist health services are probably of a more serious nature, and the study may indicate an increase in serious injuries among 19-year-olds during the «russ¼ celebration.

Detection time for THC in oral fluid after frequent cannabis smoking.

BACKGROUND: The use of oral fluid for detecting drugs of abuse has become increasingly more frequent. Few studies have, however, investigated the detection times for drugs of abuse in oral fluid, compared with that of in urine or in blood. Cannabis is the world's most widely used drug of abuse, and the detection times for cannabis, in different types of matrixes, are therefore important information to the laboratories or institutions performing and evaluating drugs of abuse analyses. It is well known that frequent use of high dosages of cannabis, for longer periods of time, might lead to prolonged detection times for THC-COOH in urine. Cannabis intake is detected in oral fluid as THC, and a positive finding is considered to be a result of recent smoking, although some studies have already reported longer detection times. The aim of this study was to investigate the detection time for THC in oral fluid, collected from drug addicts admitted for detoxification. Findings in oral fluid were compared with findings in urine, among 26 patients admitted to a closed detoxification unit. METHODS: The study, being the first in doing so, describes the concentration-time profiles for THC in oral fluid among chronic cannabis users, during monitored abstinence, using the Intercept collection kit. The study also includes the concentration-time profiles for creatinine-corrected THC-COOH ratios in urine samples, included to monitor for the possibility of new intakes. RESULTS: THC was detected in oral fluid collected from 11 of the 26 patients in the study. The elimination curves for THC in oral fluid revealed that negative samples could be interspersed among positive samples several days after cessation, whereas the THC-COOH concentrations in urine were decreasing. THC was, in this study, detected in oral fluid for up to 8 days after admission. CONCLUSIONS: The study shows that frequent use of high dosages of cannabis may lead to prolonged detection times, and that positive samples can be interspersed among negative samples. These results are of great importance when THC results from oral fluid analyses are to be interpreted.