Influence of ethanol on cannabinoid pharmacokinetic parameters in chronic users.

Cannabis is not only the most widely used illicit drug worldwide but is also regularly consumed along with ethanol. In previous studies, it was assumed that cannabis users develop cross-tolerance to ethanol effects. The present study was designed to compare the effects of ethanol in comparison to and in combination with a cannabis joint and investigate changes in pharmacokinetics. In this study, 19 heavy cannabis users participated and received three alcohol dosing conditions that were calculated to achieve steady blood alcohol concentrations (BAC) of about 0, 0.5 and 0.7 g/l during a 5-h time window. Subjects smoked a Δ(9)-tetrahydrocannabinol (THC) cigarette (400 µg/kg) 3 h post-onset of alcohol dosing. Blood samples were taken between 0 and 4 h after smoking. During the first hour, samples were collected every 15 min and every 30 min thereafter. Mean steady-state BACs reached 0, 0.36 and 0.5 g/l. The apparent elimination half-life of THC was slightly prolonged (1.59 vs. 1.93 h, p < 0.05) and the concentration 1 h after smoking was slightly lower (24 vs. 17 ng/ml, p < 0.05) with the higher ethanol dose. The prolonged THC elimination might be explained by a small ethanol-mediated change in distribution to and from deep compartments. Concentrations and pharmacokinetics of 11-hydroxy-THC and 11-nor-9-carboxy-THC (THCA) were not significantly influenced by ethanol. However, THCA concentrations appeared lower in both ethanol conditions, which might also be attributable to changes in distribution. Though not significant in the present study, this might be relevant in the interpretation of cannabinoid concentrations in blood.

Application of LC-TOF MS to analysis of hemoglobin acetaldehyde adducts in alcohol detoxification patients.

Acetaldehyde adducts of hemoglobin have been regarded as potential biochemical markers of alcohol exposure. In this study a novel sensitive method using liquid chromatography coupled to time-of-flight mass spectrometry (LC-TOF MS) has been used to investigate changes in adduct levels in alcohol detoxification patients. Hemoglobin and authentic blood samples from 66 adults with an alcohol-dependence syndrome and from 12 children were analyzed for acetaldehyde modifications with and without trypsin digestion using LC-TOF MS. After in-vitro incubation of hemoglobin with increasing concentrations of acetaldehyde, followed by tryptic digestion, 21 modified peptide fragments could be identified from their accurate mass and retention time shift. Eight of these could also be detected in authentic human blood samples. Trace amounts in children's blood were indicative of an endogenous source. Modified peptide levels in patients' samples with and without ethanol were significantly different, as also were levels in samples from admission and from five days later. Samples obtained 5, 10, or 15 days after admission did not differ in adduct levels. The LC-TOF MS method was sensitive enough to detect acetaldehyde-modified hemoglobin peptides in blood samples from patients with an alcohol-dependence syndrome. However, elevated levels were only observed after recent ethanol consumption and decreased during five days of abstinence, suggesting that acetaldehyde-modified tryptic peptides of hemoglobin are potential biomarkers only for short-term ethanol ingestion.

Comparison of cannabinoid pharmacokinetic properties in occasional and heavy users smoking a marijuana or placebo joint.

Cannabinoid pharmacokinetics in occasional users is well studied, but the interpretation of data from heavy users is difficult. In the present study, blood pharmacokinetic properties were investigated in occasional and heavy users in cannabis and placebo conditions. The results obtained with occasional users were in contrast to those of the heavy users who admitted cannabis use on 4-25 occasions during the previous week. Of the 12 heavy users, 10 exhibited up to 12.3 microg/L Delta(9)-tetrahydrocannabinol (THC) prior to smoking. During the 8 h after smoking, the distribution and elimination patterns were comparable to those of the occasional users and the concentrations returned to 68-196% (median 110%) of the initial values. However, the maximal concentration and the areas under the curves were significantly higher with marked interindividual variation. In contrast to the cannabis conditions, the THC concentrations in the placebo phase decreased more slowly (elimination half-life 17.5-43.5 h vs. 1.0-5.9 h) in accordance with a late elimination phase. The elimination half-lives of 11-hydroxy-THC and 11-nor-9-carboxy-THC in th cannabis conditions (medians 3.1 h and 6.2 h, respectively) were longer than those of THC, which was different in the placebo phase (medians 7.2 h and 13.0 h, respectively). From the results, it must be cautioned that cannabinoid blood concentrations from heavy users in a late elimination phase may be difficult to distinguish from concentrations measured in occasional users after acute cannabis use.

Pharmacokinetic properties of delta9-tetrahydrocannabinol in serum and oral fluid.

In a study on the effects of smoked cannabis (18.2 +/- 2.8 mg as low and 36.5 +/- 5.6 mg as high dose) paired blood and oral fluid samples were collected from 10 study participants up to 6 h after smoking and analyzed for the cannabinoids Delta(9)-tetrahydrocannabinol (THC), 11-hydroxy-THC (THC-OH) and 11-nor-9-carboxy-THC (THCA) using gas chromatography-mass spectrometry. Highest concentrations in serum were 47.8 +/- 35.0 and 79.1 +/- 42.5 microg/L at the end of smoking (low and high dose, respectively) and decreased to less than 1 microg/L during 6 h with elimination half-lives of 1.4 +/- 0.1 h calculated from 1 to 6 h, which is shorter than reported previously. The elimination half-lives of THC-OH (2.0 +/- 0.3 h) and THCA (3.4 +/- 0.9 h) were significantly higher. The THC concentrations in oral fluid were highest with 900 +/- 589 and 1041 +/- 652 microg/L (low and high dose, respectively) in the first sample collected at 0.25 h and decreased to 18 +/- 12 microg/L over 6 h with elimination half-lives of 1.5 +/- 0.6 h. The elimination half-life of THC in serum and oral fluid and between the two doses did not significantly differ. Oral fluid/serum ratios were 46 +/- 27 and 36 +/- 20 (low and high dose, respectively), which are higher than previously reported and might be based on sample collection and/or analytical issues. In conclusion, despite similar elimination rates of THC in serum and oral fluid, which appear incidental, the high differences in oral fluid/serum ratios are not a reliable basis for correlating THC concentrations in oral fluid and serum. The oral compartment and its kinetics for drugs, particularly THC, are not yet satisfactorily understood.

Assay of Delta9-tetrahydrocannabinol (THC) in oral fluid-evaluation of the OraSure oral specimen collection device.

Oral fluid is considered to be an alternative to urine testing for the detection of acute ingestion of drugs. The OraSure Intercept DOA Oral Specimen Collection Device (OSCD) has been used in studies for the quantitation of Delta9-tetrahydrocannabinol (THC), but concerns have been raised. In the present study, we investigated whether the volume of oral fluid can be determined and how much THC remains adsorbed on the device. It was found that THC is markedly adsorbed onto the absorptive pad. The recovery using the standard elution procedure was only 37.8 +/- 9.4% for 10 ng/mL and 55.6 +/- 1.0% for 100 ng/mL of THC in oral fluid (n = 5 each). With an additional methanol wash, a further 25% could be eluted. Therefore, a modification of the procedure was evaluated, consisting of the addition of 2 mL of methanol to the elution buffer. THC could be completely recovered over a range of concentrations (1 to 1000 ng/mL). For the determination of the amount of oral fluid absorbed, a gravimetric approach was evaluated as the weights of the devices vary only by 0.6% relative standard deviation. After application of 0.5 mL oral fluid to pads and evaluation of the weight differences, the applied amount could be estimated with a precision of 7.5% (n = 8) and an accuracy of 6.1%. From these results it can be concluded that the OraSure OSCD is useful to collect oral fluid for reliable quantitative THC assay applying a modified elution procedure and gravimetric determination of the amount of oral fluid.

Driving under the influence of drugs -- evaluation of analytical data of drugs in oral fluid, serum and urine, and correlation with impairment symptoms.

A study was performed to acquire urine, serum and oral fluid samples in cases of suspected driving under the influence of drugs of abuse. Oral fluid was collected using a novel sampling/testing device (Dräger DrugTest System). The aim of the study was to evaluate oral fluid and urine as a predictor of blood samples positive for drugs and impairment symptoms. Analysis for cannabinoids, amphetamine and its derivatives, opiates and cocaine was performed in urine using the Mahsan Kombi/DOA4-test, in serum using immunoassay and gas chromatography-mass spectrometry (GC-MS) confirmation and in oral fluid by GC-MS. Police and medical officer observations of impairment symptoms were rated and evaluated using a threshold value for the classification of driving inability. Accuracy in correlating drug detection in oral fluid and serum were >90% for all substances and also >90% in urine and serum except for THC (71.0%). Of the cases with oral fluid positive for any drug 97.1% of corresponding serum samples were also positive for at least one drug; of drug-positive urine samples this were only 82.4%. In 119 of 146 cases, impairment symptoms above threshold were observed (81.5%). Of the cases with drugs detected in serum, 19.1% appeared not impaired which were the same with drug-positive oral fluid while more persons with drug-positive urine samples appeared uninfluenced (32.7%). The data demonstrate that oral fluid is superior to urine in correlating with serum analytical data and impairment symptoms of drivers under the influence of drugs of abuse.

Screening for drugs of abuse in oral fluid--correlation of analysis results with serum in forensic cases.

The testing of saliva or oral fluid at the roadside could be a powerful tool to detect drivers under the influence of drugs and has several advantages over urine screening. In 177 cases of individuals suspected of driving under the influence of drugs, oral fluid was collected at the roadside and analyzed in parallel to serum samples. The study was performed to investigate the variability of oral fluid analysis results in relation to blood/serum. In 45% of the cases single-drug use was found, and in 50% poly-drug use was found. Cannabis was most prevalent (78%), and 70% of these individuals were also positive for tetrahydrocannabinol in serum. Overall, 97% of oral fluid samples positive for any substance were also positive in serum. Comparing data of oral fluid and serum for amphetamine, MDMA, morphine, benzoylecgonine, and tetrahydrocannabinol, the sensitivities were 100%, 97%, 87%, 87%, and 92%, respectively. Overall specificity and accuracy were in the range of 91-98%. Discrepancies between a negative oral fluid sample and a positive serum sample could be explained by analytical insensitivity in the lower volume of oral fluid analyzed (estimated for 0.1 mL confirmation vs. 1 mL of serum) or a shorter detection window in oral fluid. The low prevalence of discrepancies with positive oral fluid and negative serum results (2-9% of the cases) may be explained by persistent oral contamination especially for orally consumed drugs, like MDMA and cannabis. It is concluded that the detection of a psychoactive substance in oral fluid taken at the roadside is highly predictive for the detection of the corresponding drug or its metabolite in serum. Oral fluid testing is therefore suitable for the efficient confirmation of drug use of drivers suspected of being under the influence of drugs.

Artifact production in the assay of anhydroecgonine methyl ester in serum using gas chromatography-mass spectrometry.

The detection of the pyrolysis product anhydroecgonine methyl ester (AEME, methylecgonidine) after cocaine smoking using gas chromatography-mass spectrometry is hampered by the artifactual production of AEME. The amount of AEME increases with the amount of cocaine used producing false positive values in authentic samples. A method for the correction of quantitative values was established using calibration of pyrolysis and estimation of the artifactual AEME. Authentic AEME in serum was differentiated from the artifact above 3.5 microg/l, 99% prediction limits of the quantitation were +/-3.1 microg/l. In 16 serum samples and five postmortem blood samples, cocaine and AEME were detected, but after application of the correction method only ten were truly positive for AEME.

Determination of naltrexone and 6-beta-naltrexol in human plasma following implantation of naltrexone pellets using gas chromatography-mass spectrometry.

An alternative to detoxification by oral therapy with the narcotic antagonist naltrexone is the subcutaneous implantation of naltrexone pellets. From detoxified patients with naltrexone implants (1g) 26 blood samples were collected up to 73 days after implantation. The assay for naltrexone and 6-beta-naltrexol in plasma was developed using automated mixed-mode solid-phase extraction, catalysed trimethylsilylation and gas chromatography-mass spectrometry in single ion monitoring mode with naloxone as internal standard. The analytical method was very sensitive with limits of detection of 0.1 ng/ml and was linear up to 60 ng/ml for naltrexone and 200 ng/ml for naltrexol. Intra-day precision for naltrexone and naltrexol were 24.3 and 22.9%, respectively, at the LLOQ (accuracy 1.4 and 0.4%, respectively) and less than 10% (2.0, 6.0 and 20.0 ng/ml, n = 6 each) above. Inter-day precision was 7.9% (accuracy -0.6%) for naltrexone and 10.9% (accuracy 1.6%) for naltrexol (20 ng/ml, n = 10). Extraction recoveries were 83% for both analytes (10 ng/ml, n = 6). The concentrations of naltrexone and naltrexol in the plasma samples were in the range of 0.7-13.7 and 0.9-17.0 ng/ml, respectively. The simple analytical procedure described provided good sensitivity for the assay of naltrexone and naltrexol in plasma after naltrexone pellet implantation.

Driving under the influence of khat--alkaloid concentrations and observations in forensic cases.

The use of the herbal stimulant khat (Catha edulis FORSK) is maintained by immigrants from countries where it is part of their cultural life (Arabian Peninsula and eastern Africa). In western countries the drug and its effects are largely unknown and no experience in evaluating impairment symptoms due to the khat-alkaloids, e.g. cathinone, cathine and norephedrine exists. Blood and urine samples from khat users involved in 19 cases of suspected driving under the influence of drugs were analysed and correlated with the results of medical examination and police officer reports. In 3 cases impaired driving and in 10 cases marked impairment of psychophysical functions was observed such as effects on the nervous system (slow pupil reaction to light, dry mouth, increased heart-rate), trembling, restlessness/nervousness, daze/apathy/dullness, impairment of attention, walking and standing on one leg. However, the alkaloid concentrations assayed in blood did not correlate with the impairment symptoms. Apart from an acute phase of indirect sympathomimetic action the development of habituation and withdrawal symptoms must also be considered in explaining the diversity of effects observed. From these results it can be concluded that chewing khat may severely impair driving ability, but may also be without noticeable effects.

Studies on in vitro degradation of anhydroecgonine methyl ester (methylecgonidine) in human plasma.

The presence of the cocaine pyrolysis product anhydroecgonine methyl ester (AEME, methylecgonidine) in plasma indicates the smoking of cocaine. The stability of this analyte in human plasma has not been studied. In the present investigation AEME and its hydrolysis product anhydroecgonine (AE, ecgonidine) were assayed in plasma and buffers using gas chromatography-mass spectrometry. It was found that 50% of AEME in human plasma was hydrolyzed to AE within 5 days at room temperature and within 13 days at 4 degrees C. Addition of esterase inhibitors such as sodium fluoride or echothiophate iodide reduced the hydrolysis significantly. Hydrolysis of AEME also occurred in buffers with pH values above 5, but the hydrolysis rate was significantly lower when compared with plasma and could be markedly increased by the addition of butyrylcholine esterase. The data suggest that AEME is degraded via two mechanisms: chemical hydrolysis at basic pH and enzymatic hydrolysis by butyrylcholine esterase. Therefore, proper storage conditions must be provided for the assay of AEME in plasma.

A fatal human intoxication with the herbicide allyl alcohol (2-propen-1-ol).

Oral ingestion of allyl alcohol by a 55-year-old man resulted in death within 100 min. At autopsy, bloody, reddish fluid was found in mouth, larynx, esophagus, and trachea. The mucous membranes of the trachea, stomach, and duodenum were congested and inflamed. The stomach contained a pungent green-black fluid, and all internal organs exhibited a strong pungent odor. Toxicological analysis of blood identified allyl alcohol using solid-phase microextraction and gas chromatography-mass spectrometry. Quantitative determination of allyl alcohol and its toxic metabolite, acrolein, was performed using headspace gas chromatography with flame-ionization detection. Total amounts of allyl alcohol in gastric content, bile, and urine were 3.6 g, 15 mg, and 0.5 mg, respectively. The concentration in blood was 309 mg/L. Acrolein was not detected in gastric contents and only in small amounts in bile and urine. The concentration of acrolein in blood was 7.2 mg/L. Death was attributed to acrolein-induced acute cardiotoxicity, similar to that previously documented in animal experiments.

Factors leading to the degradation/loss of insulin in postmortem blood samples.

Since lethal insulin injection has been used in murder and suicide cases, its non-ambiguous detection in postmortem, mostly hemolytic blood samples is still a problem. In the present study the stability of insulin and reasons for its loss in those blood samples were examined. When incubated with buffer, serum or with intact blood cell suspensions insulin concentrations were found to remain stable over time, but a significant loss of insulin was observed in hemolyzed blood samples. This was not due to an enzymatic cleavage, but predominantly to the presence of hemoglobin. Incubation of insulin with a hemoglobin solution containing the same hemoglobin content as hemolyzed blood caused a dramatic decrease of the insulin concentration. Degradation of insulin reached its maximum after 23 h of incubation. The charge state of the ferric ion of hemoglobin could not be held accountable for the insulin-loss, but rather the protein part of hemoglobin. Alkylation experiments using iodoacetamide suggested that the thiol groups of the globin molecule are involved in the insulin loss preventing degradation at least partially. The same was observed by lowering the pH to 2.7 in the incubation mixture. Two degradation products of insulin were identified by mass spectrometry such as modified insulin A and B chains with 4 (A chain) and 2 Da (B chain) lower masses. These results suggest that thiol groups of hemoglobin cause splitting of the disulfide bonds of insulin which immediately leads to the formation of new intramolecular disulfide bridges, a reaction which occurs in hemolytic blood and may explain the gradual loss of insulin in postmortem blood samples.

Influence of ethanol on the pharmacokinetic properties of Δ9-tetrahydrocannabinol in oral fluid.

Oral fluid (OF) tests aid in identifying drivers under the influence of drugs. In this study, 17 heavy cannabis users consumed alcohol to achieve steady blood alcohol concentrations of 0 to 0.7 g/L and smoked cannabis 3 h afterward. OF samples were obtained before and up to 4 h after smoking and on-site tests were performed (Dräger DrugTest 5000 and Securetec DrugWipe 5+). Maximum concentrations of tetrahydrocannabinol (THC) immediately after smoking (up to 44,412 ng/g) were below 4,300 (median 377) ng/g 1 h after smoking and less than 312 (median 88) ng/g 3 h later with 5 of 49 samples negative, suggesting that recent cannabis use might occasionally not be detectable. An influence of alcohol was not observed. Drinking 300 mL variably influenced THC concentrations (median only -29.6%), which suggests that drinking does not markedly affect on-site test performance. Many (92%) Dräger tests performed 4 h after smoking were still positive, indicating sufficient sensitivity for recent cannabis use. Differences in the results of a roadside study with DrugTest 5000 (sensitivity 84.8%, specificity 96.0%, accuracy 84.3%) could be explained by a higher number of true negatives, differences between OF and serum and differences between occasional and chronic users.

MDMA (ecstasy) effects on actual driving performance before and after sleep deprivation, as function of dose and concentration in blood and oral fluid.

RATIONALE: Experimental research has shown that 3,4-methylenedioxymethamphetamine (MDMA) can improve some psychomotor driving skills when administered during the day. In real life, however, MDMA is taken during the night, and driving may likely occur early in the morning after a night of "raving" and sleep loss. OBJECTIVES: The present study assessed the effects of MDMA on road-tracking and car-following performance in on-the-road driving tests in normal traffic. METHODS: Sixteen recreational MDMA users participated in a randomized double-blind placebo-controlled four-way cross-over design. They received single, evening doses of 0, 25, 50, and 100 mg MDMA on separate occasions. Actual driving tests were conducted in the evening when MDMA serum concentrations were maximal and in the morning after a night of sleep loss. RESULTS: The primary measure of driving, i.e., standard deviation of lateral position (SDLP, a measure of weaving) was significantly increased during driving tests in the morning in all treatment conditions, irrespective of MDMA dose and concentration. The increments in SDLP were of high clinical relevance and comparable to those observed for alcohol at blood alcohol concentrations >0.8 mg/mL. These impairments were primarily caused by sleep loss. CONCLUSIONS: In general, MDMA did not affect driving performance nor did it change the impairing effects of sleep loss. It is concluded that MDMA cannot compensate for the impairing effects of sleep loss and that drivers who are under the influence of MDMA and sleep deprived are unfit to drive.

Neurophysiological functioning of occasional and heavy cannabis users during THC intoxication.

RATIONALE: Experienced cannabis users demonstrate tolerance to some of the impairing acute effects of cannabis. OBJECTIVES: The present study investigates whether event-related potentials (ERPs) differ between occasional and heavy cannabis users after acute Δ9-tetrahydrocannabinol (THC) administration, as a result of tolerance. METHODS: Twelve occasional and 12 heavy cannabis users participated in a double-blind, placebo-controlled, crossover study. On two separate days, they smoked a joint containing 0 or 500 µg/kg body weight THC. ERPs were measured while subjects performed a divided attention task (DAT) and stop signal task (SST). RESULTS: In the DAT, THC significantly decreased P100 amplitude in occasional but not in heavy cannabis users. P300 amplitude in the DAT was significantly decreased by THC in both groups. The N200 peak in the SST was not affected by treatment in neither of the groups. Performance in the SST was impaired in both groups after THC treatment, whereas performance in the DAT was impaired by THC only in the occasional users group. CONCLUSIONS: The present study confirms that heavy cannabis users develop tolerance to some of the impairing behavioral effects of cannabis. This tolerance was also evident in the underlying ERPs, suggesting that tolerance demonstrated on performance level is not (completely) due to behavioral compensation.

Influence of ethanol on the pharmacokinetics of methylphenidate's metabolites ritalinic acid and ethylphenidate.

In view of the widespread application of methylphenidate for attention-deficit/ hyperactivity disorder (ADHD) therapy its interaction with alcohol was investigated in an in-vitro assay and in a study involving 9 male volunteers. The study conditions were: methylphenidate (20 mg) only, methylphenidate followed by ethanol (0.8 g/kg body weight) and ethanol followed by methylphenidate. Methylphenidate (CAS 113-45-1), ritalinic acid (CAS 19395-41-6) and ethylphenidate (CAS 57413-43-1) were assayed in blood samples collected up to 7 h after ingestion using liquid chromatography-mass spectrometry (LC/MS). It was found that methylphenidate is hydrolyzed to ritalinic acid by the same esterase that degrades cocaine. In the presence of ethanol this is inhibited and the active metabolite ethylphenidate is formed. The pharmacokinetic evaluation showed that methylphenidate concentrations were not markedly affected by ethanol, but ritalinic acid concentrations were lower, especially if ethanol was ingested first. Ethylphenidate concentrations were low with only about 10% of methylphenidate concentrations suggesting that concurrent ethanol use does not impair methylphenidate's therapeutic efficacy. Unexpectedly one subject exhibited a methylphenidate hydrolysis defect yielding very high methylphenidate and low ritalinic acid concentrations in all study conditions.

Pharmacokinetic properties of delta9-tetrahydrocannabinol in oral fluid of occasional and chronic users.

Saliva is of continuing interest in detecting the influence of drugs while driving. Commercial tests are currently available where cannabis detectability is a major challenge. The present study aids in the understanding of tetrahydrocannabinol (THC) pharmacokinetics in oral fluid. The oral fluid analyses exhibited no significant differences between 12 occasional users and 12 chronic users smoking a standardized cannabis joint, except for the maximum concentrations in the first samples (occasional users, 397- 6438 ng/g; chronic users 387-71,747 ng/g). THC was detectable in all samples with medians in the last samples (8 h) of 6.3 and 11.3 ng/g in occasional and chronic users, respectively. The elimination half-life in both groups was 1.6 +/- 0.4 h. A series of samples was obtained over a period of 8 h without actual drug use representing a later elimination phase. Of these oral fluid samples, only 4.3% were negative for THC despite positive serum, and 24.1% of serum samples were negative despite positive oral fluid. This confirms that THC is detectable for longer in oral fluid than in serum. The oral fluid-to-serum ratios were 0.3 to 425 (median 16.5) with no difference between chronic and occasional users. The large inter- and intraindividual variability observed precludes a reliable estimation of THC serum concentrations from oral fluid data using this collection device.

Determination of clopidogrel main metabolite in plasma: a useful tool for monitoring therapy?

This study was performed to determine whether analysis of clopidogrel and its main carboxylic acid metabolite in plasma provides additional information about the wide variability of platelet aggregation inhibition in clopidogrel-treated patients with peripheral arterial occlusive disease. Consecutive outpatients (n = 56) with stable peripheral arterial occlusive disease treated with 75 mg clopidogrel daily, without co-administration of aspirin, were investigated. With use of a standardized questionnaire, the time of drug intake was documented. Blood sampling was performed within 24 hours after the most recent drug intake. Platelet function was measured by optical aggregometry using adenosine diphosphate (ADP) (2 mumol/L) as the agonist. Plasma concentrations of clopidogrel and its main metabolite, clopidogrel carboxylic acid, were quantitated using high-performance liquid chromatography analysis coupled to mass spectrometry. In 95% (53/56) of patients, clopidogrel carboxylic acid was detected. In 40% (22/56) of patients, the ADP-induced aggregation response was within the normal range despite clopidogrel treatment. In 14% (3/22) of these patients, neither clopidogrel nor its main metabolite could be detected. Two of these patients agreed to ingest 75 mg/d clopidogrel under observation and to undergo blood sampling after 2, 12, and 24 hours. Clopidogrel carboxylic acid and a significant inhibition of platelet aggregation were detected even after 24 hours in both patients, confirming noncompliance as the reason for the lack of inhibition of ADP-induced platelet aggregation observed in the initial measurements. In the subgroup of patients who had taken clopidogrel within 4 hours before blood sampling, a large range of carboxylic acid concentrations was detected, indicating a high variability of drug metabolism among patients. In conclusion, determining clopidogrel metabolite plasma concentrations could be a useful tool for identifying poor compliance and variable metabolism in clopidogrel-treated patients. Nevertheless, in the majority of clopidogrel-treated patients, the variability of platelet response is not caused by noncompliance.

Criminal poisoning of commuters in Bangladesh: prospective and retrospective study.

Travel-related poisoning is an emerging social and public health emergency in Bangladesh but its cause and significance have not been determined. To investigate this syndrome we performed a prospective clinical study and retrospective analysis of hospital records in a general medicine unit of a public tertiary care teaching hospital in Dhaka, Bangladesh, using toxicological analysis by fluorescence polarization immunoassay (FPIA) and liquid chromatography coupled to time-of-flight mass spectrometry (LC-TOF MS). The participants of the prospective study were 130 consecutive patients aged 16-80 years who were admitted with central nervous system depression (Glasgow Coma Score 3-14) after using public transportation, in the absence of other abnormalities, from January through June 2004, and a convenience sample of 15 such patients admitted during 3 days in May 2006. In 2004-2006, travel-related poisoning increased from 6.1 to 9.5% of all admissions (210-309 of 3266-3843 per year), representing 46.6-55.7% of all admitted poisoning cases. Incidents were associated with bus (76%), taxi, train, and air travel, or local markets; 98% of patients remembered buying or accepting food or drinks before losing consciousness. Direct financial damage (missing property) was diverse and frequently existential. Among 94 urine samples analyzed by FPIA, 74% tested positive for benzodiazepines. Among 15 urine samples analyzed by LC-TOF MS, lorazepam was detected in all; five also contained diazepam or metabolites; nitrazepam was present in three. FPIA results obtained for these 15 samples were below the recommended cut-off in eight (53%; lorazepam only). Our findings show that the massive medicosocial emergency of travel-related poisoning in Bangladesh is the result of drug-facilitated organized crime and that benzodiazepine drugs are used to commit these crimes, suggesting modifications to the local emergency management of the victims of this type of poisoning. They also highlight the need for more research in the neglected field of acute poisoning in Bangladesh, and for criminal investigations of the use of benzodiazepine drugs in this country.