An increased risk of motor vehicle accidents after prescription of methadone

AIMS

To investigate whether exposure to methadone affects the risk of motor vehicle accident with personal injury.

DESIGN

Cohort study linking three Norwegian administrative registries using unique person identifiers.

SETTING

Information was retrieved from the Norwegian Prescription Database on any prescriptions ever received by the individuals for methadone and all prescriptions for benzodiazepines. The Norwegian Road Accident Registry provided information about motor vehicle accidents involving personal injuries on Norwegian roads. The Central Population Registry provided demographic information on all residents in Norway.

PARTICIPANTS

All Norwegian adults aged 18-69 years were observed for 2.5 years.

MEASUREMENTS

Standardized incidence ratio (SIR) was calculated by comparing the incidence of traffic accidents with personal injuries in patients exposed to methadone with the incidence in those not exposed.

FINDINGS

During the 4626 person-years observed in patients exposed to methadone, there were 26 motor vehicle accidents. There were very few accidents among the females who received methadone and they had no increased risk of being involved in motor vehicle accidents (SIR 1.1; 95% CI 0.2-3.1). We observed an increased risk of involvement in accidents among males (SIR 2.4; 95% CI 1.5-3.6). This figure did not change significantly when exposure to benzodiazepines was excluded.

CONCLUSIONS

Men exposed to methadone appear to have an increased risk of being involved in motor vehicle accidents involving personal injuries. This increased risk could not be explained by exposure of benzodiazepines.

Long-term methadone treatment reduces phosphorylation of CaMKII in rat brain

Objectives

To reveal a possible relationship between a previously reported impairment of novelty seeking in rats exposed to methadone and changes in intracellular molecules related to learning and memory.

Methods

Expression of phosphorylated Ca2+-calmodulin kinase II (pCaMKII), extracellular-signal-regulated kinase 2 (pERK2) and cAMP-responsive element binding protein (pCREB), as well as protein kinase A (PKA), was investigated in rat hippocampus one hour, one day and one week after a three-week methadone administration regime. Studies after an equivalent exposure to morphine, and in the frontal pole, were included for comparison.

Key findings

One day after the last methadone injection the hippocampal level of pCaMKII was significantly reduced. This coincides with a previously reported impairment of novelty seeking. At one hour and one week no significant changes were seen. There was no effect on the other proteins. Morphine affected pCaMKII similarly to methadone. Also in the frontal pole the two drugs reduced pCaMKII one day after the last injection.

Conclusion

The impaired novelty seeking previously found in rats administered methadone for three weeks coincides with a reduced level of pCaMKII in the brain. This finding implies that methadone treatment may affect learning and memory processes, and should stimulate further studies in a field with important knowledge gaps.

The PMMA epidemic in Norway: comparison of fatal and non-fatal intoxications

During a 6 month period (July 2010-January 2011) we observed 12 fatal intoxications and 22 non-fatal cases related to the drug paramethoxymethamphetamine (PMMA) in Norway (4.8 mill inhabitants). This toxic designer drug, also known as "Death", is occasionally found in street drugs offered as "ecstasy" or "amphetamine". The present study aimed to evaluate the cause of death, and to compare the PMMA blood concentrations in fatal and non-fatal cases. Methods for identification and quantification of PMMA are presented. The median age of fatalities was 30 years (range 15-50) with 67% males; in non-fatal cases 27 years (20-47) with 86% males. In the 12 fatalities, the median PMMA blood concentration was 1.92 mg/L (range 0.17-3.30), which is in the reported lethal range of 0.6-3.1 mg/L in peripheral blood and 1.2-15.8 mg/L in heart blood. In the 22 non-fatal cases, the median PMMA concentration was 0.07 mg/L (range 0.01-0.65). Poly-drug use was frequent both in fatal and non-fatal cases. The PMA concentrations ranging from 0.00 to 0.26 mg/L in both groups likely represented a PMMA metabolite. Three fatalities were attributed to PMMA only, six to PMMA and other psychostimulant drugs, and three to PMMA and CNS depressant drugs, with median PMMA concentrations of 3.05 mg/L (range 1.58-3.30), 2.56 (1.52-3.23) and 0.52 mg/L (0.17-1.24), respectively. Eight victims were found dead, while death was witnessed in four cases, with symptoms of acute respiratory distress, hyperthermia, cardiac arrest, convulsions, sudden collapse and/or multiple organ failure. In summary, all fatalities attributed to PMMA had high PMMA blood concentrations compared to non-fatal cases. Our sample size was too small to evaluate a possible impact of poly-drug use. A public warning is warranted against use and overdose with illegal "ecstasy" or "speed" drugs.

Analysis of alcohol and drugs in oral fluid from truck drivers in Norway

OBJECTIVE

To examine alcohol and drug use among truck drivers compared to car or van drivers in Norway by analyzing samples of oral fluid.

METHODS

Drivers were selected for a voluntary and anonymous study using a stratified multistage cluster sampling procedure. Drivers of trucks were recruited at two control stations for heavy vehicles in southeastern Norway in collaboration with the Norwegian Roads Administration, and drivers of cars and vans were recruited in a roadside survey in collaboration with the mobile police service. Samples of oral fluid were taken by using the Statsure Saliva Sampler (Statsure Diagnostic Systems, Framingham, MA), and the drivers' gender, age, and nationality were recorded. Samples of oral fluid were analyzed for alcohol or drugs, in total 28 psychoactive substances.

RESULTS

About 97 percent of the truck drivers and 94 percent of the car or van drivers agreed to participate in the study. Of the 882 studied truck drivers studied, 1.4 percent were female and 29.1 percent were Norwegian; of the 5305 car or van drivers, 27.6 percent were female and 90.9 percent were Norwegian. Alcohol or drugs were found in 1.9 and 6.6 percent of the samples from truck drivers and car/van drivers, respectively. The adjusted odds ratio (OR) for the detection of a psychoactive substance in a sample from a truck driver compared to car or van driver was 0.29; the 95 percent confidence interval (95% CI) was 0.17 to 0.53. The adjusted OR for the detection of an illegal drug was 0.42 (95% CI: 0.18-0.82), the adjusted OR for the detection of a psychoactive medicinal drug was 0.29 (95% CI: 0.13-0.68), and the adjusted OR for the detection of alcohol was 0.13 (95% CI: 0.02-1.10).

CONCLUSIONS

The proportion of oral fluid samples containing psychoactive substances was lower for truck drivers than for car or van drivers.

Surveillance of abused drugs in forensic autopsy cases in Norway

High drug related mortality has been registered in Norway. Although comparison between countries relies on a standard international coding system of diseases, different practices in verifying cause of death and applying codes could lead to variation. The comparison gives no information on drug findings or drug patterns underlying the cause of deaths. To evaluate deaths involving illicit drugs in Norway, we examined drug patterns in 2735 forensically examined post-mortem samples collected from 15-64 year-old individuals from 2000 to 2009. There were four times as many men as women among the deceased illicit drug users, and the majority were in the age group 25-44 years. The number of deceased showing signs of illicit drug use has gradually declined during the study period. The decline was found among younger individuals, while a larger proportion of the deceased were above 45 years of age in 2009, compared to 2000. Cases positive for heroin, ethanol, ecstasy and flunitrazepam were fewer in 2009, while the prevalence of amphetamine, cannabis, methadone and other opioids has increased. The prevalence of methamphetamine has increased ten fold, and the prevalence of benzodiazepines doubled. Thus, the drug pattern and age of the deceased has changed markedly during the last 10 years. Heroin and ethanol use has partly been substituted by use of amphetamines, cannabis, benzodiazepines and other opioids. This change could possibly be explained by the prolonged survival of drug users on substitution treatment and by the reduced toxicity of consumed drugs.

Can the use of psychoactive drugs in the general adult population be estimated based on data from a roadside survey of drugs and driving?

A roadside survey of drugs and driving was performed in south-eastern Norway in 2005-6. Samples of saliva from a total of 10,503 drivers above 20 years of age were analysed, and the results were weighted for under- and over-sampling compared to the population distribution in the study area. Weighted results were compared with data on dispensed prescriptions of zopiclone, codeine and diazepam at Norwegian pharmacies in the same area and with self-reported use of cannabis. When using roadside data to estimate drug use, the use of medicinal drugs was under-estimated by 17-59% compared to amounts dispensed. One of the main reasons for the under-estimation may be that a large proportion of the users of psychoactive medicinal drugs are not frequent drivers. For cannabis, self-reported data corresponded approximately to the estimated prevalence range. The results indicate that roadside surveys cannot be used for accurate estima tions of drug use in the population, but may provide minimum figures.

Quantitative assessment of time dependent drug-use trends by the analysis of drugs and related metabolites in raw sewage

BACKGROUND

Accurate and timely information on the scale and dynamics of drug consumption is important for assessing the needs of law enforcement and public health services in a community.

AIMS

This paper presents a detailed examination of a comprehensive sewage-sampling campaign for the purposes of increasing an understanding of the dynamics of drug-flows in sewage streams, and developing new methodology by which this technique can support traditional drug-use surveys.

METHODS

A total of 104 sewage samples were collected from a treatment plant servicing approximately 500000 people and analysed for levels of methamphetamine, cocaine and cocaine metabolites. Careful examination of the kinetics of drug-flow profiles was then performed in order to identify trends or patterns of use within the community.

RESULTS

Results were validated against identical measurements of pharmaceutical reference compounds. Consumption profiles for cocaine and methamphetamine were found to differ in terms of frequency and timing of use. The majority of cocaine consumption occurs during the evening hours and 45% of consumption of this drug occurs in weekend periods. The flow of methamphetamine in the sewage system appears more evenly spread throughout the week.

CONCLUSIONS

This result is consistent with both an extended excretion half-life and a pattern of use that is more evenly balanced across all days of the week. Comprehensive investigation in to the scale and kinetics of drug flow in a sewage stream can therefore provide valuable information, not only in terms of the volume of drug consumed, but also in terms of identifying differing usage-patterns over daily and weekly time-scales.

Controlling for High-Density Lipoprotein Cholesterol Does Not Affect the Magnitude of the Relationship Between Alcohol and Coronary Heart Disease

Background—

This study tested the hypothesis that moderate alcohol intake exerts its cardioprotective effect mainly through an increase in the serum level of high-density lipoprotein cholesterol.

Methods and Results—

In the Cohort of Norway (CONOR) study, 149 729 adult participants, recruited from 1994 to 2003, were followed by linkage to the Cause of Death Registry until 2006. At recruitment, questionnaire data on alcohol intake were collected, and the concentration of high-density lipoprotein cholesterol in serum was measured. Using Cox regression, we found that the adjusted hazard ratio for men for dying from coronary heart disease was 0.52 (95% confidence interval, 0.39–0.69) when consuming alcohol more than once a week compared with never or rarely. The ratio changed only slightly, to 0.55 (0.41–0.73), after the regression model included the serum level of high-density cholesterol. For women, the corresponding hazard ratios were 0.62 (0.32–1.23) and 0.68 (0.34–1.34), respectively.

Conclusions—

Alcohol intake is related to a reduced risk of death from coronary heart disease in the follow-up of a large, population-based Norwegian cohort study with extensive control for confounding factors. Our findings suggest that the serum level of high-density cholesterol is not an important intermediate variable in the possible causal pathway between moderate alcohol intake and coronary heart disease.

Drugs related to motor vehicle crashes in northern European countries: a study of fatally injured drivers

The aim of this study was to find which drugs and drug combinations were most common in drivers who died, in particular, in single vehicle crashes where the responsibility for the crash would be referred to the driver killed. The study included all available blood samples from drivers, who died within 24h of the accident, in the years 2001 and 2002 in the five Nordic countries (total population about 24 million inhabitants). The samples were analysed for more than 200 different drugs in addition to alcohol, using a similar analytical programme and cut-off limits in all countries. In three countries (Finland, Norway and Sweden) blood samples were available for more than 70% of the drivers, allowing representative prevalence data to be collected. 60% of the drivers in single vehicle crashes had alcohol and/or drug in their blood samples, compared with 30% of drivers killed in collisions with other vehicles. In single vehicle accidents, 66% of the drivers under 30 years of age had alcohol and/or drugs in their blood (alcohol only - 40%; drugs only - 12%; alcohol and drugs - 14%). The drugs found were mostly illicit drugs and psychoactive medicinal drugs with warning labels (in 57% and 58% respectively of the drivers under 30 with drugs present). Similar findings were obtained for drivers 30-49 years of age (63% with alcohol and/or drugs). In drivers aged 50 years and above, killed in single vehicle crashes (48% with alcohol and/or drugs) illicit drugs were found in only one case, and psychoactive medicinal drugs were detected less frequently than in younger age groups. In 75% of single vehicle crashes, the driver was under 50 years. Thus, the majority of accidents where the drivers must be considered responsible, occurred with drivers who had recently used alcohol, or drugs, alone or in combination. The drugs involved were often illicit and/or psychoactive drugs with warning labels. Therefore a large proportion of single vehicle accidents appear to be preventable, if more effective measures against driving after intake of alcohol and drugs can be implemented.

Prevalence of alcohol and other substances of abuse among injured patients in a Norwegian emergency department

BACKGROUND

Studies have found a high prevalence of both alcohol and other impairing psychoactive drugs in injured patient populations. The aim of this study was to assess the prevalence of potentially impairing psychoactive substances in all patients admitted to a hospital emergency department with injuries from accidents, assault or deliberate self harm.

METHODS

A total of 1272 patients over 18 years of age, admitted to the hospital within 12h of injury, were included. Presence of alcohol was determined by an enzymatic method and other drugs by liquid chromatography-mass spectrometry (LC-MS) or gas chromatography-mass spectrometry (GC-MS), both highly specific analytical methods for determining recent intake.

RESULTS

There were 510 (40%) women in the sample. Of the patients, 38% of the women and 48% of the men had a positive blood sample for psychoactive substances on admission. The most prevalent psychoactive substance was alcohol (27%) with an average concentration of 1.5 g/kg. A further 21% of patients tested showed use of medicinal drugs, and 9% showed use of illicit substances. Cannabis was the most prevalent illicit drug (6.2%). Diazepam (7.4%) and zopiclone (5.3%) were the most prevalent medicinal drugs. In road traffic accidents, 25% of the car drivers had positive findings, about half of them for alcohol.

CONCLUSION

Psychoactive substances were found in nearly half the patients admitted with injuries. The most common substance was alcohol. Alcohol was particularly related to violence, whereas medicinal drugs were most prevalent in accidents at home.

Analysis and interpretation of specific ethanol metabolites, ethyl sulfate, and ethyl glucuronide in sewage effluent for the quantitative measurement of regional alcohol consumption

BACKGROUND

The quantitative measurement of urinary metabolites in sewage streams and the subsequent estimation of consumption rates of the parent compounds have previously been demonstrated for pharmaceuticals and narcotics. Ethyl sulfate and ethyl glucuronide are excreted in urine following the ingestion of alcohol, and are useful biomarkers for the identification of acute alcohol consumption. This study reports a novel ion-exchange-mediated chromatographic method for the quantitative measurement of ethyl sulfate and ethyl glucuronide in sewage effluent, and presents a novel calculation method for the purposes of relating the resulting sewage concentrations with rates of alcohol consumption in the region.

METHODS

A total of 100 sewage samples covering a 25-day period were collected from a treatment plant servicing approximately 500,000 people, and analyzed for levels of ethyl sulfate and ethyl glucuronide. The resulting data were then used to estimate combined alcohol consumption rates for the region, and the results were compared with alcohol related sales statistics for the same region.

RESULTS

Ethyl glucuronide was found to be unstable in sewage effluent. Ethyl sulfate was stable and measurable in all samples at concentrations ranging from 16 to 246 nM. The highest concentrations of the alcohol biomarker were observed during weekend periods. Sixty one percent of the total mass of ethyl sulfate in sewage effluent corresponds to alcohol consumption on Friday and Saturday. Sales statistics for alcohol show that consumption in the region is approximately 6,750 kg/d. The quantity of ethyl sulfate passing through the sewage system is consistent with consumption of 4,900 to 7,800 kg/d.

CONCLUSIONS

  Sewage epidemiology assessments of ethyl sulfate can provide accurate estimates of community alcohol consumption, and detailed examination of the kinetics of this biomarker in sewage streams can also identify time-dependent trends in alcohol consumption patterns.

Toxicological investigations of drivers killed in road traffic accidents in Norway during 2006-2008

AIM

To study the results from the toxicological investigations of drivers of cars and vans who were fatally injured in road traffic accidents in 2006-2008 and discuss the findings in relation to the proposed legal limits and impairment thresholds for drugs.

METHODS

Analyses for alcohol, illegal drugs and psychoactive medicinal drugs were performed by the Norwegian Institute of Public Health. Information on type of accident (single or multiple vehicles) and type of road (urban or rural) was obtained from Statistics Norway.

RESULTS

Toxicological analyses were requested for 59% of the fatally injured drivers. Drivers involved in single vehicle accidents were more often subject to toxicological investigations, so were also young male drivers and drivers killed on urban roads. Alcohol or drugs were found in concentrations above the current (for alcohol) or proposed (for drugs) legal limits in samples from 37.8% of the drivers; from 64.3% those killed in single-vehicle accidents and 17.9% of those killed in multiple-vehicle accidents. In total, alcohol was found in 25.0%, illicit drugs in 10.2%, and psychoactive medicinal drugs in 13.8% of the samples. Combinations of alcohol and drugs were found in 5.1% and multiple drugs without alcohol in 6.1% of the samples. The prevalence of alcohol or drugs was higher in samples from males than females, higher in samples from young drivers, and higher in samples from drivers killed during weekends. Two thirds of the drivers with alcohol or drug concentrations above the current or proposed legal limits had concentrations above the proposed high impairment threshold. About 60% of the latter ones were impaired by alcohol only, 20% by drugs in combination with alcohol, and 20% by drugs only, mainly due to multi-drug use.

CONCLUSION

The use of alcohol or drugs before driving was a significant contributing factor in fatal road traffic accidents, particularly in single vehicle accidents, and particularly among young male drivers. Alcohol was the most significant intoxicant, but multi-substance use was also significantly prevalent. The majority of the drivers with alcohol or drug findings were strongly impaired.

Psychoactive substance use among patients admitted to an acute psychiatric ward: laboratory findings and associations with clinical characteristics

BACKGROUND

Estimates of psychoactive substance use among acutely admitted psychiatric patients vary among studies, and few have used comprehensive laboratory methods.

AIMS

This study used chromatography-based analyses of blood and urine to identify the rates of substance use among acute psychiatric admissions, and to study the associations with socio-demographic variables, clinical characteristics and patients' reports of symptoms, substance use and need for treatment.

METHODS

A cross-sectional study was conducted in 2006/2007 in Oslo, Norway. Blood and urine samples were collected from 298 acute psychiatric admissions and extensively analysed for alcohol, medicinal and illicit drugs. Psychotic symptoms were assessed with the positive subscale of the Positive and Negative Syndrome Scale. Patient self-report questionnaires included the Alcohol and Drug Use Disorder Identification Tests. Patients were also asked if they needed professional help for substance use.

RESULTS

Psychoactive substances were detected in 63% of the 298 admissions, medicinal drugs in 46%, alcohol in 12% and illicit drugs in 28%. Patients using alcohol had a high suicidal risk score at admission and the shortest length of stay (median 1 day). Use of illicit drugs was associated with psychotic symptoms and readmission. Self-report questionnaires indicated harmful use of alcohol for half of the patients and of other substances for one-third. A need for professional help for substance use was reported by one-third of patients.

CONCLUSION

Given the high rates of substance use and the important clinical associations, drug screening seems warranted in acute psychiatric settings. Interventions designed for substance-using patients should be developed and integrated.

Alcohol, psychoactive drugs and fatal road traffic accidents in Norway: a case-control study

A case-control study was conducted on 204 drivers fatally injured in road traffic accidents in south-eastern Norway during the period 2003-2008. Cases from single vehicle accidents (N = 68) were assessed separately. As controls, 10540 drivers selected in a roadside survey in the same geographical area during 2005-2006 were used. Blood samples were collected from the cases and oral fluid (saliva) samples from the controls. Samples were analysed for alcohol, amphetamines, cannabis, cocaine, opioid analgesics, hypnotics, sedatives and a muscle relaxant; altogether 22 psychoactive substances. Equivalent cutoff concentrations for blood and oral fluid were used. The risk for fatal injury in a road traffic accident was estimated using logistic regression adjusting for gender, age, season of the year, and time of the week. The odds for involvement in fatal road traffic accidents for different substances or combination of substances were in increasing order: single drug < multiple drugs < alcohol only < alcohol+drugs. For single substance use: medicinal drug or THC < amphetamine/methamphetamine < alcohol. For most substances, higher ORs were found when studying drivers involved in single vehicle accidents than for those involved in multiple vehicle accidents, but confidence intervals were wider.

Long-term methadone treatment impairs novelty preference in rats both when present and absent in brain tissue

Behavioral consequences of long-term methadone treatment have received little attention either in humans or experimental animals. In this work, we show that methadone (2.5-10 mg/kg) administered (sc) once daily for three weeks with repeated withdrawal on Saturday and Sunday impairs the novelty preference in rats. One hour after the last injection, when methadone was still present in brain tissue, the rats were too affected by the sedative effects of the drug to perform the test. This was confirmed by an almost total lack of locomotor activity or exploratory behavior. One day after the last injection, the methadone treated rats showed a 70% reduction (p < 0.05) in novelty preference compared to rats administered saline. No methadone was detected in the brain tissue at this time. Moreover, there were no differences in locomotor activity or total exploratory behavior between the groups, indicating a specific impairment of cognitive functioning. In brain tissue, the methadone concentration versus time profile was shifted to the left after long-term treatment, indicating a change in uptake and distribution of the drug. The area under the two concentration versus time curves was, however, similar. Methadone disappeared completely from the brain within one day. Together, these results suggest that long-term methadone treatment may have a negative impact on cognitive functioning in rats, regardless of whether methadone is present in brain tissue.

Ethyl glucuronide concentrations in oral fluid, blood, and urine after volunteers drank 0.5 and 1.0 g/kg doses of ethanol

The aim of this study was to investigate the concentrations of ethyl glucuronide (EtG) in oral fluid, blood, and urine after healthy volunteers drank two doses of ethanol, 0.5 (n = 11) and 1.0 g/kg (n = 10), after an overnight fast. Samples of oral fluid, blood, and urine were collected before drinking started and at 1.5, 3.5, 5.5, 8.5, 11.5, and 24 h post-dosing. Following ingestion of low dose of ethanol, the Cmax for EtG was 0.36 mg/L (range 0.28-0.41 mg/L) in blood and 69.8 mg/L (range 47.1-96.5 mg/L) in urine. In oral fluid, the concentrations were < 1% of those in blood, and only three subjects exceeded the limit of quantification for EtG in oral fluid. After ingestion of the high dose of ethanol, the Cmax for EtG was 1.06 mg/L (range 0.8-1.22 mg/L) in blood, 159.9 mg/L (range 97.2-225.5 mg/L) in urine, and 0.032 mg/L (range 0.013-0.059 mg/L) in oral fluid. The median oral fluid/blood ratio was 0.029 (range 0.012-0.054) for EtG. The detection time for EtG was median 11.5 h (range 3.5-11.5 h) in oral fluid. According to this, the detection time for EtG in oral fluid is therefore only a few hours longer than for ethanol itself and represents limited additional value.

Comparison of drug concentrations in blood and oral fluid collected with the Intercept sampling device

The aim of the study was to determine drug concentration ratios between oral fluid collected with the Intercept device and whole blood. Samples of blood and oral fluid were obtained from patients admitted to acute psychiatric treatment and drivers suspected of drugged driving. Samples were analyzed for illegal drugs, benzodiazepines, opioids, carisoprodol, and meprobamate. Drugs were detected in samples of both blood and oral fluid from 59 subjects; altogether, 17 different drugs were found. Concentration ratios between oral fluid and blood were determined for all cases. The distributions of drug concentration ratios were wide for most drugs and do not allow reliable estimations of drug concentrations in blood using concentrations in oral fluid. The median oral fluid/blood drug concentration ratios for the most prevalent drugs were 0.036 diazepam, 0.027 nordiazepam, 7.1 amphetamine, 2.9 methamphetamine, 5.4 codeine, 1.9 morphine, and 4.7 tetrahydrocannabinol. The correlation coefficients between drug concentrations in oral fluid and blood ranged from 0.15 to 0.96 for the six most prevalent drugs.

Use of alcohol and drugs by Norwegian employees: a pilot study using questionnaires and analysis of oral fluid

Background

The use of alcohol and drugs may affect workplace safety and productivity. Little is known about the magnitude of this problem in Norway.

Methods

Employee recruitment methods with or without individual follow-up were compared. The employees filled in a questionnaire and provided a sample of oral fluid. Samples were analysed for alcohol, ethyl glucuronide (EtG; a biological marker of recent large alcohol intake), psychoactive medicinal drugs and illegal drugs.

Results

Participation rates with and without individual follow-up were 96% and 68%, respectively. Alcohol was negative (≤0.1 mg/ml) in all samples, but 21.0% reported the intake of alcohol during the last 24 h. EtG was positive (>2.2 ng/ml) in 2.1% of the samples. In-efficiency or hangover at work during the past year was reported by 24.3%, while 6.2% had been absent from work due to the use of alcohol. The combination of self-report and analytical testing indicated that medicinal or illegal drugs had been used during the last 48 h by 5.1% and 1.7% of the participants, respectively; while only 4.2% and 0.4% admitted the use in the questionnaire.

Conclusions

Self-reported data suggest that hangover after drinking alcohol appears to be the largest substance abuse problem at Norwegian workplaces, resulting in absence and inefficiency at work. Analysis of oral fluid revealed that the use of illegal drugs was more common than drinking alcohol before working or at the workplace. The analysis of oral fluid may be a valuable tool in obtaining additional information on alcohol and drug use compared to using questionnaires alone.

Impairment due to cannabis and ethanol: clinical signs and additive effects

AIMS

Studies have shown that the impairing effects of Delta-9-tetrahydrocannabinol (THC) are dose-related. Cannabis intake increases the risk of traffic accidents. The purpose of this study was to see how different clinical tests and observations were related to blood THC concentrations and to determine whether the combined influence of THC and ethanol was different from either drug alone.

DESIGN

A retrospective cross-sectional forensic database study.

SETTING

Drivers apprehended by the police suspected of driving under the influence of alcohol and other drugs.

PARTICIPANTS

We investigated 589 cases positive for THC only. In addition, 894 cases with THC and ethanol were included. A comparison was made with 3480 drivers with only ethanol in their blood and 79 drivers who tested negative.

MEASUREMENTS

Data were analytical results of blood samples and the 27 clinical tests and observations included in the Norwegian clinical test for impairment (CTI).

FINDINGS

No relationship was found between blood THC concentration and most of the CTI tests. Blood THC concentration was, however, related to conjunctival injection, pupil dilation and reaction to light and to the overall risk of being judged impaired. When THC and ethanol were detected together the risk of being judged impaired was increased markedly.

CONCLUSIONS

This study demonstrates that cannabis impairs driving ability in a concentration-related manner. The effect is smaller than for ethanol. The effect of ethanol and cannabis taken simultaneously is additive. Conjunctival injection, dilated pupils and slow pupil reaction are among the few signs to reveal THC influence.