Traumatic experiences, ICD-11 PTSD, ICD-11 complex PTSD, and the overlap with ICD-10 diagnoses

OBJECTIVES

This study investigated the frequency of traumatic experiences, prevalence rates of ICD-11 post-traumatic stress disorder (PTSD) and complex PTSD (CPTSD), and overlap with ICD-10 classified disorders in outpatient psychiatry.

METHOD

Overall, 165 Danish psychiatric outpatients answered the International Trauma Questionnaire, the Life Event Checklist, and the World Health Organization Well-being Index. ICD-10 diagnoses were extracted from the hospital record. Chi-square analysis, t-tests, and conditional probability analysis were used for statistical analysis.

RESULTS

Nearly, all patients (94%) had experienced at least one traumatic event. CPTSD (36%) was more common than PTSD (8%) and had considerable overlap with ICD-10 affective, anxiety, PTSD, personality, adjustment and stress-reaction disorders, and behavioural and emotional disorders with onset usually occurring in childhood and adolescence. ICD-11 PTSD overlapped with ICD-10 anxiety, PTSD, adjustment and stress-reaction disorders, and behavioural and emotional disorders with onset usually occurring in childhood and adolescence. A subgroup of patients with ICD-10 PTSD (23%) did not meet criteria for ICD-11 PTSD or CPTSD.

CONCLUSION

Traumatic experiences are common. ICD-11 CPTSD is a highly prevalent disorder in psychiatric outpatients. One quarter with ICD-10 PTSD did not meet criteria for either ICD-11 PTSD or CPTSD. PTSD and CPTSD had considerable overlap with ICD-10 disorders.

Separation of blood microsamples by exploiting sedimentation at the microscale

Microsample analysis is highly beneficial in blood-based testing where cutting-edge bioanalytical technologies enable the analysis of volumes down to a few tens of microliters. Despite the availability of analytical methods, the difficulty in obtaining high-quality and standardized microsamples at the point of collection remains a major limitation of the process. Here, we detail and model a blood separation principle which exploits discrete viscosity differences caused by blood particle sedimentation in a laminar flow. Based on this phenomenon, we developed a portable capillary-driven microfluidic device that separates blood microsamples collected from finger-pricks and delivers 2 µL of metered serum for bench-top analysis. Flow cytometric analysis demonstrated the high purity of generated microsamples. Proteomic and metabolomic analyses of the microsamples of 283 proteins and 1351 metabolite features was consistent with samples generated via a conventional centrifugation method. These results were confirmed by a clinical study scrutinising 8 blood markers in obese patients.

Indirect hydrogen analysis by gas chromatography coupled to mass spectrometry (GC-MS)

Gas chromatography (GC) is an analytical tool very useful to investigate the composition of gaseous mixtures. The different gases are separated by specific columns but, if hydrogen (H2 ) is present in the sample, its detection can be performed by a thermal conductivity detector or a helium ionization detector. Indeed, coupled to GC, no other detector can perform this detection except the expensive atomic emission detector. Based on the detection and analysis of H2 isotopes by low-pressure chemical ionization mass spectrometry (MS), a new method for H2 detection by GC coupled to MS with an electron ionization ion source and a quadrupole analyser is presented. The presence of H2 in a gaseous mixture could easily be put in evidence by the monitoring of the molecular ion of the protonated carrier gas.

Innovative method for carbon dioxide determination in human postmortem cardiac gas samples using headspace-gas chromatography-mass spectrometry and stable labeled isotope as internal standard

A novel approach to measure carbon dioxide (CO2) in gaseous samples, based on a precise and accurate quantification by (13)CO2 internal standard generated in situ is presented. The main goal of this study was to provide an innovative headspace-gas chromatography-mass spectrometry (HS-GC-MS) method applicable in the routine determination of CO2. The main drawback of the GC methods discussed in the literature for CO2 measurement is the lack of a specific internal standard necessary to perform quantification. CO2 measurement is still quantified by external calibration without taking into account analytical problems which can often occur considering gaseous samples. To avoid the manipulation of a stable isotope-labeled gas, we have chosen to generate in situ an internal labeled standard gas ((13)CO2) on the basis of the stoichiometric formation of CO2 by the reaction of hydrochloric acid (HCl) with sodium hydrogen carbonate (NaH(13)CO3). This method allows a precise measurement of CO2 concentration and was validated on various human postmortem gas samples in order to study its efficiency.

Monitoring of aglycons of yew glycosides (3,5-dimethoxyphenol, myrtenol and 1-octen-3-ol) as first indicator of yew presence

The toxicity of yew (Taxus spp) is well known from ancient times and is mainly due to taxins acting as inhibitors of calcium and sodium transport across the cell membrane of cardiac myocytes. The confirmation of yew taxins in body fluids can be carried out by liquid chromatography-tandem mass spectrometry (LC-MS/MS). However, before selecting this precise but expensive technique, an orientation test should be done to ascertain yew presence as toxic agent in the organism. As the 3,5-dimethoxyphenol (3,5-DMP), myrtenol and 1-octen-3-ol appear as glycosidically bound volatile compounds and are very yew specific, the detection of 3,5-DMP and the measurement of 1-octen-3-ol / myrtenol concentration ratio constitute reliable indicators of yew presence in forensic cases. The detection of these compounds is easily performed by gas chromatography-mass spectrometry (GC-MS) (SIM) after an enzymatic hydrolysis (β-glucosidase) allowing the release of volatile compounds from yew glycosides.

[Ethyl glucuronide: a biomarker of alcohol consumption]

Excessive alcohol consumption represents a major risk factor for morbidity and mortality. It is therefore indispensable to be able to detect at-risk drinking. Ethyl glucuronide (EtG) is a specific marker of alcohol consumption. The determination of ethyl glucuronide in urine or blood can be used to prove recent driving under the influence of alcohol, even if ethanol is no longer detectable. The commercialization of an EtG specific immunological assay now allows to obtain preliminary results rapidly and easily with satisfying sensitivity. Moreover, the detection of ethyl glucuronide in hair offers the opportunity to evaluate an alcohol consumption over a long period. The EtG concentration in hair is in correlation with the amount of ingested alcohol. Thus, the analysis of ethyl glucuronide can be used to monitor abstinence, to detect alcohol relapse and to identify at-risk drinkers. However, a cut off allowing to detect chronic alcohol abuser reliably still does not exist. Therefore, it is recommended to perform the analysis of ethyl glucuronide in complement to the existing blood markers. A study financed by the Swiss Foundation for Alcohol Research is actually conducted by the West Switzerland University Center of Legal Medicine in order to establish an objective cut-off.

[Effects of oral cannabis and dronabinol on driving capacity]

Two retrospective epidemiologic studies have shown that cannabis is the main psychoactive substance detected in the blood of drivers suspected of driving under the influence of psychotropic drugs. An oral administration double-blind crossover study was carried out with eight healthy male subjects, aged 22 to 30 years, all occasional cannabis smokers. Three treatments and one placebo were administered to all participants at a two week interval: 20 mg dronabinol, 16.5 mg D9-tétrahydrocannabinol (THC) and 45.7 mg THC as a cannabis milk decoction. Participants were asked to report the subjective drug effects and their willingness to drive under various circumstances on a visual analog scale. Clinical observations, a psychomotor test and a tracking test on a driving simulator were also carried out. Compared to cannabis smoking, THC, 11-OH-THC and THC-COOH blood concentrations remained low through the whole study (<13.1 ng THC/mL,<24.7 ng 11-OH-THC/mL and<99.9 ng THC-COOH/mL). Two subjects experienced deep anxiety symptoms suggesting that this unwanted side-effect may occur when driving under the influence of cannabis or when driving and smoking a joint. No clear association could be found between these adverse reactions and a susceptibility gene to propensity to anxiety and psychotic symptoms (genetic polymorphism of the catechol-O-methyltransferase). The questionnaires have shown that the willingness to drive was lower when the drivers were assigned an insignificant task and was higher when the mission was of crucial importance. The subjects were aware of the effects of cannabis and their performances on the road sign and tracking test were greatly impaired, especially after ingestion of the strongest dose. The Cannabis Influence Factor (CIF) which relies on the molar ratio of active and inactive cannabinoids in blood provided a good estimate of the fitness to drive.

Delta(9)-THC, 11-OH-Delta(9)-THC and Delta(9)-THCCOOH plasma or serum to whole blood concentrations distribution ratios in blood samples taken from living and dead people

The recreational use and abuse of Cannabis is continuously increasing in Switzerland. Cannabinoids are very often detected alone or in combination with other drugs in biological samples taken from drivers suspected of driving under the influence of drugs. Moreover, they are also frequently found in blood specimens from people involved in various medico-legal events, e.g. muggings, murders, rapes and working accidents as well. In order to assess the influence of Cannabis exposure on man behavior and performances, it is often needed to estimate the time of Cannabis use. For that purpose two mathematical models have been set up by Huestis and coworkers. These models are based on cannabinoids concentrations in plasma. Because plasma samples are rarely available for forensic determinations in our laboratory, it could be useful to assess the time-laps since Cannabis use through these models from whole blood values. One prerequisite to the use of these models from whole blood values is the knowledge of the plasma to whole blood concentrations distribution ratios of cannabinoids. In this respect, the Delta(9)-THC, 11-OH-Delta(9)-THC and Delta(9)-THCCOOH concentrations were measured in plasma and whole blood taken from eight volunteers who smoke Cannabis on a regular basis. Cannabinoids levels were also determined in "serum" and whole blood samples taken from six corpses. The values of the plasma to whole blood distribution ratios were found to be very similar and their individual coefficient of variation relatively low suggesting that plasma levels could be calculated from whole blood concentrations taken into account a multiplying factor of 1.6. The data obtained postmortem suggest that the distribution of cannabinoids between whole blood and "serum" is scattered over a larger range of values than those determined from living people and that more cannabinoids (mean value of the serum/whole blood concentrations ratios=2.4) can be recovered from the "serum" fraction. The successful use of the mathematical models of Huestis and coworkers may, therefore, rely in part upon the selection of the appropriate blood sample, i.e. plasma. When plasma is not available, whole blood values could be considered with some caution taken into account a multiplying factor of 1.6 to calculate plasma concentrations from blood values. In the case of blood samples taken after death, the use of these models to assess the time of Cannabis use is not recommended.

[Cannabis and automobile driving]

Cannabis use has increased considerably during the last 15 years. One of the major problems dealing with cannabis use is driving under the influence of drugs. With the exception of ethyl alcohol, the majority of the epidemiological studies have shown that cannabis is the most frequently detected substance in people suspected of driving under the influence of drugs. Experimental studies are therefore needed to assess cannabis effects on driving capability. Many studies indicate that cannabis impairs psychomotor performance. This impairment becomes obvious when high doses of cannabis are taken, when ethyl alcohol or other drugs are simultaneously ingested, or when sustained attention is needed. Moreover, cannabis effects are qualitatively different from those observed after ethyl alcohol consumption. In forensic practice, cannabis impairment of driving performance must be related to cannabinoids blood concentrations. To facilitate the interpretation of cannabinoids blood levels, several models were set up recently. These models must be further improved in order to fit in with all circumstances of cannabis use.

Performance of a new implantable cardiac assist centrifugal pump

The AB-180 is a new implantable centrifugal pump with a low volume dome (10 ml) and a local heparin delivery system which avoids systemic heparinization. This study focuses on its hemodynamic performance. We analyzed 3 anesthetized calves (71.0 +/- 2.5 kg), equipped with arterial pressure (AP), and Swan-Ganz and left atrial pressure (LAP) catheters. The AB-180 pump was installed through a left thoracotomy, with a transmitral left ventricular (LV) inflow cannula inserted via the left appendage and an outflow tract sutured to the descending aorta. LAP, AP, and blood flow across the pump were recorded for various pump speed and in different preload conditions (right atrial pressure = 4, 7, and 10 mm Hg, respectively). The pump significantly unloaded the left heart cavities and was able to increase the mean AP. For an RAP of 10 mm Hg, running the pump at 4,500 rpm decreased the LAP from 11.0 +/- 0.8 mm Hg to 3.0 +/- 0.8 mm Hg (p < 0.001) and augmented the mean AP from 48.2 +/- 6.4 mm Hg to 80.8 +/- 12.1 mm Hg (p < 0.001). A maximal pump flow of 5.6 +/- 0.2 L/min was obtained under these conditions. In addition to the advantage of its particular design, the AB-180 can be considered as an efficient left ventricular assist device (LVAD). It significantly unloads the left heart cavities and ensures efficient systemic AP and blood flow.

Salvia divinorum: an hallucinogenic mint which might become a new recreational drug in Switzerland

Salvia divinorum Epling & Jativa is an hallucinogenic mint traditionally used for curing and divination by the Mazatec Indians of Oaxaca, Mexico. Young people from Mexican cities were reported to smoke dried leaves of S. divinorum as a marijuana substitute. Recently, two S. divinorum specimens were seized in a large-scale illicit in-door and out-door hemp plantation. Salvinorin A also called divinorin A, a trans-neoclerodane diterpene, was identified in several organic solvent extracts by gas chromatography-mass spectrometry. The botanical identity of the plant was confirmed by comparing it to an authentic herbarium specimen. More plants were then discovered in Swiss horticulturists greenhouses. All these data taken together suggest that many attempts exist in Switzerland to use S. divinorum as a recreational drug. This phenomenon may be enhanced because neither the magic mint, nor its active compound are banned substances listed in the Swiss narcotic law.

First direct observation of coulomb explosion during the formation of exotic atoms

A Doppler broadening of x-ray transitions from pionic nitrogen and muonic oxygen, which is attributed to Coulomb explosion of the molecules, has been observed by using a crystal spectrometer. Large linewidths indicate fast ionization of the molecules and a charge of (3-4)e for the accelerated fragments.

Fatal flecainide intoxication

A fatal case attributed to flecainide acetate (Tambocor), a class Ic antiarrythmic drug, is presented. Flecainide was detected by GC/MS in gastric contents, blood and liver as well. The urine analysis revealed the presence of its dealkylated metabolite. Body fluids and tissue concentrations determined by GC/ECD were 7.7 mg/kg in femoral blood, 0.26 mg/kg in bile, 18 mg/kg in liver, 0.17 mg/kg in cerebrospinal fluid, 0.22 mg/kg in brain cortex and 28.9 mg/kg in urine. The total amount of flecainide in gastric contents was about 43 mg. Even taking into account the postmortem redistribution of flecainide, its blood level still remains in the toxic range.

Fatal overdose of tramadol and alprazolam

A 30-year-old woman, with history of depression, was found dead after the ingestion of an unknown quantity of Xanax (alprazolam), Tramal (tramadol) and alcohol. At the autopsy only a slight decomposition and a diffuse visceral congestion were noticed. Biological samples obtained at autopsy were analysed to detect the presence of alprazolam, tramadol and alcohol. Blood concentrations of alprazolam, alcohol and tramadol were 0.21 mg/l, 1.29 g/kg and 38.3 mg/l, respectively.

Optimization of the pump driven venous return for minimally invasive open heart surgery

Blood return into the cardiotomy reservoir is usually reduced when a cardiopulmonary bypass (CPB) is initiated through a peripheral access, even if the tip of the venous cannula is pushed into the right atrium. A centrifugal pump can be placed on the venous line to increase the negative pressure. Surgery involving the right atrium requires selective cannulation of both vena cavae. Because of the small diameter of the vena cava as compared to the right atrium, the benefit of the centrifugal pump may have limitations. We analyze the factors influencing the active venous return when the cannula is maintained into the vena cava. In 4 calves (83.0+/-14.9 Kg) a CPB was initiated through carotid and jugular access, with the tip of the venous cannula placed into the superior vena cava, before ventricular fibrillation was provoked. Venous drainage was progressively increased thanks to the centrifugal pump. Considering the negative pressure induced on the venous line, we analyzed the performance expressed in l/min of blood drained, of four one stage cannulae ("lighthouse" tip 24F, 28F or 32F, and percutaneous 28F). The performance of all cannulae were highly dependent on the central venous pressure (CVP) with better drainage for higher CVP. The size and type of cannula also significantly affected blood drainage. Active drainage was best with the percutaneous 28F cannula. This cannula was specially attractive at low CVP conditions.

Method for quantification of morphine and its 3- and 6- glucuronides, codeine, codeine glucuronide and 6-monoacetylmorphine in human blood by liquid chromatography-electrospray mass spectrometry for routine analysis in forensic toxicology

Simultaneous determination of opiates and their glucuronides in body fluids has a great practical interest in the forensic assessment of heroin intoxication. A selective and sensitive method for quantification of morphine and its 3- and 6-glucuronides, codeine, codeine glucuronide and 6-monoacetylmorphine (6-MAM) based on liquid chromatography-electrospray ionisation mass spectrometry is described. The drugs were analysed in human autopsy whole blood after solid-phase extraction on a C8 cartridge. The separation was performed on an ODS column in acetonitrile (analysis time 15 min). For the quantitative analysis, deuterated analogues of each compound were used as internal standards. Selected-ion monitoring was applied where the molecular ion was chosen for quantification. The limits of quantification were 0.5 ng/ml for morphine and 6-MAM and 1 ng/ml for the 6-glucuronide of morphine, codeine-6-glucuronide and codeine and 5 ng/ml for the 3-glucuronide of morphine.

Exit association-mediated suicide: toxicologic and forensic aspects

The Swiss German chapter of the Exit Association provides conditional assistance to individuals wishing to end their own lives. The Exit Association advocates death with dignity and fights for the right to freely choose the timing of one's own death. According to the Swiss criminal code (articles 114 and 115), altruistic assistance to suicide is not punishable. Active euthanasia is punished by imprisonment. An individual commits active euthanasia if he or she is driven by honorable motives (e.g., pity) and causes the death of another person wishing to die who seriously and insistently requests such action. Based on our information, the preparation for suicide and its completion relies on a well-defined protocol. First, the candidate's eligibility for Exit Association assistance is verified. The candidate then writes a farewell declaration that explicitly confirms the will to terminate his or her own life. A written report describes the events during the suicide procedure. Depending on the circumstances, the investigative judge requests a forensic autopsy and toxicologic analyses. The results of the forensic investigations conducted in the cases presented here are in agreement with the scenario described in the reports of the Exit Association, namely, suicide by massive ingestion of pentobarbital.

[Brief history of recent hemp cultivation in Switzerland and subsequent medico-legal problems resulting from hemp cultivation]

In March 1995, a decision about cultivation of cannabis was issued by the Swiss Federal Offices of Public Health, Police and Agriculture in order to satisfy the growing interest of farmers and other people in hemp farming. It pointed out that 1)... each hemp plant contains THC and must be therefore considered a drug, 2)... no permission is required for those who grow hemp without the intention to produce drugs ... meaning that the choice of the plant variety was not restricted to those which are characterized by a low THC concentration and grown in a few countries belonging to the European Union. Claiming that natural hemp must contain significant amounts of THC and thanks to the Swiss legislation, areas dedicated to hemp cultivation develop considerably. Most hemp plants which are submitted to our laboratories by the police for THC quantification belong to the drug-type. Nowadays, a great deal of goods (food and beverages, cosmetics, drugs) made of hemp are marketed in Switzerland. Strong suspicions exist however that several of these products could be used as a screen for the illegal market of cannabis. For instance, despite financial support from the state, fiber hemp cultivation remains unsuccessful. No advantage with regard to seed productivity, edible seed and essential oils qualities and yields have been found for drug hemp over fiber hemp by agricultural research stations up to now. Several clues about the possible illicit use of hemp goods rich in THC, especially hemp tea made of flower tops and "therapeutic" pillows filled with cannabis exist. Recently, two Federal edits were issued in order to restrict the selling of hemp seedlings and of hemp foods and beverages to those containing only low amounts of THC. However, the marketing of hemp plants used for decorating remains free partly explaining the recent success of these "beautiful" plants. Broadly speaking, the Swiss and European legislations about hemp have approached mutually during the last years.

Comparison of different immunoassays and GC-MS screening of benzodiazepines in urine

A total of 53 urine samples were tested by different immunoassay methods and by gas chromatography/mass spectrometry to determine repeatability of the different methods and to assess whether the immunoassays performed on samples obtained from elderly patients of the emergency section could be considered as reliable enough for identifying a benzodiazepine consumption. Repeatability was excellent for GC/MS and good for immunoassays. The specificity was not different for the three immunoassays (96%). The sensitivity varied from 36, 64 to 75% for OnLine, RIA Immunalysis and RIA DPC, respectively. An other difference between immunoassays and GC/MS was the ability of GC/MS to detect lorazepam and low concentrations of benzodiazepines whereas immunoassays did not.

2C-B: a new psychoactive phenylethylamine recently discovered in Ecstasy tablets sold on the Swiss black market

This study sought to identify, by means of several analytical methods (GC-MS, HPLC-DAD, CE-DAD, FTIR, and NMR), 4-bromo-2,5-dimethoxyphenethylamine (2C-B), which was found in two sets of tablets obtained from the Swiss black market. Unequivocal identification of 2C-B was only achieved by a combination of mass spectrometric and NMR analysis. Quantitation of 2C-B was performed by HPLC-DAD and CE-DAD. The amounts of 2C-B found in the tablets (3-8 mg) were in the range of the minimum quantity required to induce the effects characteristic of this drug.

Car crash after massive ingestion of digoxin and midazolam

In a case where a 32-year-old man lost control of his vehicle, urine and blood samples were taken 6 h after the crash for toxicological investigations. In the hospital, the driver admitted consumption of some drugs, in particular digoxin and midazolam just before the crash which corresponded to the results of blood analyses. Toxicological findings indicated the presence of digoxin at 12.9 ng/ml and midazolam at 7 ng/ml in the blood. These results suggested that at the moment of the crash digoxin and midazolam blood levels were in the range of toxic and therapeutic concentrations, respectively. Therefore the respective roles of the drugs in the impairment of the ability to drive at the moment of the crash is discussed.

[Ecstasy--the status in French-speaking Switzerland. Composition of seized drugs, analysis of biological specimens and short review of its pharmacological action and toxicity]

Methylenedioxy-N-methylamphetamine (MDMA, "Ecstasy") and other related phenylethylamines are nowadays used extensively in Western Switzerland at dance clubs and raves. There is a widely held belief among teenagers and misusers that ecstasy is safe. In the last years however, an increasing number of reports of MDMA-related deaths has been reported. Acute clinical toxicity problems following MDMA ingestion include hyperthermia, convulsions and arrhythmias. There is also growing concern that these phenylethylamines are neurotoxic and cause long-term damage to serotonineric nerve terminals in animal brains. Qualitative analyses by GC-MS of street samples of ecstasy showed that only a part of them contain MDMA or related phenylethylamines (MDA, MDEA, MBDB and 2C-B). Most of them were mixed with caffeine and an excipient (sugars or polyols [e.g. mannitol]). Amphetamine cut with caffeine and other drugs (e.g. testosterone), stimulants (e.g. pseudoephedrine) and other drugs unrelated to stimulants and phenylethylamines (e.g. LSD, chloroquine, vasodilators) were also detected. Quantitative determinations performed by HPLC-DAD or EC-DAD reveal huge fluctuations in the amount of active substance(s) per tablet. MDMA and related compounds display unique psychoactive properties, acting as a stimulant and inducing feelings of empathy. The effects of MDMA intake are very likely the results of the large release of serotonin (5-HT) in the synaptic cleft, of the inhibition of the re-uptake inactivation of 5-HT and of the inhibition of a key-enzyme involved in the biosynthesis of 5-HT. Forensic investigations performed at our institute showed significant blood levels of MDMA, MDEA and MDA in samples drawn from people suspected of driving under the influence of psychoactive drugs. Up to now, no death could be attributed to MDMA intoxication only because our analyses always revealed the additional presence of toxic amounts of other psychoactive drugs (e.g. opiates, cocaine). Our study shows that because of the variable composition of ecstasy tablets, unpredictable types and amounts of drugs may be taken by MDMA misusers. Moreover, there is considerable concern that traffic accidents may be caused by MDMA-abusers. MDMA intake could result in severe intoxication and even death, especially when combined with other types of drugs.

Drugs and alcohol among suspected impaired drivers in Canton de Vaud (Switzerland)

Epidemiological and analytical laboratory records concerning living drivers suspected of driving under the influence of drug (DUID) during the 13 years period ranging from 1982 to 1994 were examined. This study included 641 records. 551 men (86%) and 90 women (14%). The average age of the drivers was 27 +/- 7 years (n = 636, minimum 18 and maximum 74) and the 18-30 interval age range was overrepresented (80%) in this population sample. A traffic accident had occurred in 254 (40%) of the records, 273 (43%) drivers were suspected of DUID during police controls and 95 (15%) drivers were suspected of DUID because of their erratic driving. One or more psychoactive drugs were found in 92.8% of the samples. In these records, cannabinoids were found in 57%, opiates in 36%, ethanol in 36%, benzodiazepines in 15%, cocaine in 11%, methadone in 10% and amphetamines in 4%. The majority (58%) of cases presented two or more drugs in biological samples, thus indicating a high incidence of potential interactions between drugs. This observation was specially relevant for methadone and methaqualone. We conclude that police suspicion about drivers under influence highly correlated with positive results for drug analyses in biological samples.