Δ9-tetrahydrocannabinol (THC) is present in the body between smoking sessions in occasional non-daily cannabis users

BACKGROUND

THC can be measured in blood up to a month after last intake in heavy cannabis users. The cognitive deficits during abstinence have been hypothesized to be at least in part due to residual THC in brain. To which extent THC accumulation will occur after occasional cannabis use has gained limited attention. We aimed to predict THC-levels between smoking sessions in non-daily as well as daily cannabis users and to compare these predictions with published THC levels.

METHODS

Predictions were based on pharmacokinetic principles on drug accumulation after repeated dosing, applied to different cannabis smoking patterns, using data from a three-compartment model for THC pharmacokinetics and results on the terminal elimination half-life of THC in humans. We searched the literature for THC measurements which could be compared with these predictions. We found no such results from controlled studies of long-term repeated cannabis consumption of known THC amounts. Thirteen published studies contained, however, enough information on cannabis use and results from THC-measurements to make tentative comparisons with the predictions.

RESULTS

The predictions of THC-plasma levels present after different cannabis smoking patterns assuming terminal elimination half-lives of THC of 21.5 h or longer, had some support in published THC levels measured in individuals self-reporting their cannabis consumption. We found no consistent discrepancies between the predictions and reported THC plasma levels after non-daily or daily cannabis use. The predictions indicate that THC might be present in plasma between smoking sessions above usual analytical limits when smoking every third and second day, and at lower levels after once weekly smoking.

CONCLUSIONS

The study indicates that THC might be present continuously even in non-daily smokers at low levels, even if the smoking occasions are separated by a week. This is different from alcohol, where ethanol has disappeared after a day. From a toxicological point of view the persistance of THC in the brain, raises questions whether this should be given more attention as with other toxicological thinking where long-term presence of bioactive substances gives rise to concern. There are some uncertainties in this analysis, and controlled studies on THC-accumulation accompanying different use patterns seem warranted.

The interplay between cognitive ability, alcohol consumption, and health characteristics

BACKGROUND

Higher cognitive ability is associated with favourable health characteristics. The relation between ability and alcohol consumption, and their interplay with other health characteristics, is unclear. We aimed to assess the relationship between cognitive ability and alcohol consumption and to assess whether alcohol consumption relates differently to health characteristics across strata of ability.

METHODS

For 63 120 Norwegian males, data on cognitive ability in early adulthood were linked to midlife data on alcohol consumption frequency (times per month, 0-30) and other health characteristics, including cardiovascular risk factors and mental distress. Relations were assessed using linear regression and reported as unstandardised beta coefficients [95% confidence interval (CI)].

RESULTS

The mean ± s.d. frequency of total alcohol consumption in the sample was 4.0 ± 3.8 times per month. In the low, medium, and high group of ability, the frequencies were 3.0 ± 3.3, 3.7 ± 3.5, and 4.7 ± 4.1, respectively. In the full sample, alcohol consumption was associated with physical activity, heart rate, fat mass, smoking, and mental distress. Most notably, each additional day of consumption was associated with a 0.54% (0.44-0.64) and 0.14% (0.09-0.18) increase in the probability of current smoking and mental distress, respectively. In each strata of ability (low, medium, high), estimates were 0.87% (0.57-1.17), 0.48% (0.31-0.66) and 0.49% (0.36-0.62) for current smoking, and 0.44% (0.28-0.60), 0.10% (0.02-0.18), and 0.09% (0.03-0.15) for mental distress, respectively.

CONCLUSIONS

Participants with low cognitive ability drink less frequently, but in this group, more frequent alcohol consumption is more strongly associated with adverse health characteristics.

Driving under the influence of non-alcohol drugs--An update. Part II: Experimental studies

Experimental studies on the impairing effects of drugs of relevance to driving-related performance published between 1998 and 2015 were reviewed. Studies with on-the-road driving, driving simulators, and performance tests were included for benzodiazepines and related drugs, cannabis, opioids, stimulants, GHB, ketamine, antihistamines, and antidepressants. The findings in these experimental studies were briefly discussed in relation to a review of epidemiological studies published recently. The studies mainly concluded that there may be a significant psychomotor impairment after using benzodiazepines or related drugs, cannabis, opioids, GHB, or ketamine. Low doses of central stimulants did not seem to cause impairment of driving behavior.

International trends in alcohol and drug use among vehicle drivers

Trends in the use of alcohol and drugs among motor vehicle drivers in Australia, Brazil, Norway, Spain, and the United States have been reviewed. Laws, regulations, enforcement, and studies on alcohol and drugs in biological samples from motor vehicle drivers in general road traffic and fatal road traffic crashes (RTCs) are discussed. Roadside surveys showed a reduction of drunk driving over time in the studied countries; however, the pattern varied within and between different countries. The reduction of alcohol use may be related to changes in road traffic laws, public information campaigns, and enforcement, including implementation of random breath testing or sobriety checkpoints. For non-alcohol drugs, the trend in general road traffic is an increase in use. However, drugs were not included in older studies; it is therefore impossible to assess the trends over longer time periods. Data from the studied countries, except Brazil, have shown a significant decrease in fatal RTCs per 100,000 inhabitants over the last decades; from 18.6 to 4.9 in Australia, 14.5 to 2.9 in Norway, 11.1 to 3.6 in Spain, and 19.3 to 10.3 in the United States. The number of alcohol-related fatal RTCs also decreased during the same time period. The proportion of fatal RTCs related to non-alcohol drugs increased, particularly for cannabis and stimulants. A general challenge when comparing alcohol and drug findings in biological samples from several countries is connected to differences in study design, particularly the time period for performing roadside surveys, biological matrix types, drugs included in the analytical program, and the cutoff limits used for evaluation of results. For RTC fatalities, the cases included are based on the police requests for legal autopsy or drug testing, which may introduce a significant selection bias. General comparisons between high-income countries and low- and middle-income countries as well as a discussion of possible future trends are included.

Driving Under the Influence of Non-Alcohol Drugs--An Update Part I: Epidemiological Studies

Epidemiological studies of the association between drug use and involvement in road traffic crashes (RTCs) published from January 1998 to February 2015 have been reviewed. Cohort andpopulation studies compared RTC involvement among drug users and non-drug users, case-control studies compared drug use among RTC-involved and non-RTC-involved drivers, and responsibility studies and case-crossover studies were performed for RTC-involved drivers. Difficulties associated with the types of studies are discussed with a special focus on case-control studies. Statistically significant associations between drug use and RTC involvement were found for benzodiazepines and z-hypnotics in 25 out of 28 studies, for cannabis in 23 out of 36 studies, for opioids in 17 out of 25 studies, for amphetamines in 8 out of 10 studies, for cocaine in 5 out of 9 studies, and for antidepressants in 9 out of 13 studies. It was a general trend among studies that did not report significant associations between the use of these drugs and increased RTC risk that they often had either poor statistical power or poor study design compared to studies that found an association. Simultaneous use of two or more psychoactive drugs was associated with higher RTC risk. Studies on the combination of alcohol and drugs have not been reviewed in this article even though this combination is known to be associated with the highest RTC risk.

Levels of heroin and its metabolites in blood and brain extracellular fluid after i.v. heroin administration to freely moving rats

BACKGROUND AND PURPOSE

Heroin, with low affinity for μ-opioid receptors, has been considered to act as a prodrug. In order to study the pharmacokinetics of heroin and its active metabolites after i.v. administration, we gave a bolus injection of heroin to rats and measured the concentration of heroin and its metabolites in blood and brain extracellular fluid (ECF).

EXPERIMENTAL APPROACH

After an i.v. bolus injection of heroin to freely moving Sprague-Dawley rats, the concentrations of heroin and metabolites in blood samples from the vena jugularis and in microdialysis samples from striatal brain ECF were measured by ultraperformance LC-MS/MS.

KEY RESULTS

Heroin levels decreased very fast, both in blood and brain ECF, and could not be detected after 18 and 10 min respectively. 6-Monoacetylmorphine (6-MAM) increased very rapidly, reaching its maximal concentrations after 2.0 and 4.3 min, respectively, and falling thereafter. Morphine increased very slowly, reaching its maximal levels, which were six times lower than the highest 6-MAM concentrations, after 12.6 and 21.3 min, with a very slow decline during the rest of the experiment and only surpassing 6-MAM levels at least 30 min after injection.

CONCLUSIONS AND IMPLICATIONS

After an i.v. heroin injection, 6-MAM was the predominant opioid present shortly after injection and during the first 30 min, not only in the blood but also in rat brain ECF. 6-MAM might therefore mediate most of the effects observed shortly after heroin intake, and this finding questions the general assumption that morphine is the main and most important metabolite of heroin.

Determination of ethylglucuronide in oral fluid by ultra-performance liquid chromatography- tandem mass spectrometry

An ultra-performance liquid chromatography-tandem mass spectrometry method has been developed and validated for the determination of ethylglucuronide (EtG) in oral fluid. Sample clean-up was achieved by solid-phase extraction with a Hyper-SEP SAX column. Negative ionization was performed in the multiple reaction monitoring mode. Two transitions were monitored for the analyte and one for the internal standard EtG-d(5). The calibration range was 4.4-222 ng/mL. The recovery of the analyte ranged from 86 to 99%, and the between-assay precisions ranged from 5 to 9% RSD. The limit of quantification was found to be 4.4 ng/mL. The concentration of EtG in oral fluid collected 2-14 h after a moderate alcohol intake varied from 13.3 to 57.7 ng/mL.

Road traffic accident risk in patients with diabetes mellitus receiving blood glucose-lowering drugs. Prospective follow-up study

AIM

To investigate, at a national level, whether patients using insulin or oral glucose-lowering agents had an increased risk of road traffic accidents compared with non-users.

METHODS

All Norwegians aged 18-69 years (3.1 million) were followed from April 2004 until September 2006. Information on drug prescriptions, road traffic accidents and emigration/death was obtained from the following population-based registries: the Prescription Database, the Road Accident Registry and the Central Population Registry. The exposure period was the time from the first prescription of insulin or oral glucose-lowering agent during the study period. The incidence of accidents in the exposed person-time was compared with the incidence of accidents in the unexposed person-time by standardized incidence ratio (SIR).

RESULTS

During the study period, 20 494 road traffic accidents with personal injuries were registered in Norway. One hundred and eighty-three accidents were registered for insulin users not taking oral glucose-lowering agents and 219 for users of oral blood glucose-lowering drugs without insulin. The SIR (95% confidence interval) for all ages and both genders combined were: insulin 1.4 (1.2-1.6), oral glucose-lowering agents 1.2 (1.0-1.3) and users of drugs for peptic ulcer and gastro-oesophageal reflux disease (negative comparators) 1.3 (1.2-1.4). The highest SIRs were found among the youngest insulin users (18-34 years old).

CONCLUSIONS

A slightly increased risk of being involved in a road traffic accident was observed for drivers prescribed insulin, while no increased risk was observed for drivers prescribed oral glucose-lowering agents. The increased risk observed for insulin users was similar to that observed for users of drugs for peptic ulcer and gastro-oesophageal reflux disease.

Rearrest rates among Norwegian drugged drivers compared with drunken drivers

The rearrest rates among Norwegian drugged (n=1102) and a group of drunken drivers (n=850) (BAC: 0.16-0.19%) apprehended during 1992, were 57% (n=629) and 28% (n=238), respectively, when followed prospectively for 7 years. The most important risk factors for recidivism among drugged drivers were previous arrests for drugged or drunken driving (rearrest rate among previous arrests: 73%, no previous arrest: 42%), multi-drug detection at selection (multi-drug: 62%, single drug: 41%), sex (male: 61%, female: 35%) and age (below 36 years: 60%, 36 years and older: 44%). Most of the recidivist drugged drivers were rearrested during the year of selection (21%), followed by 13, 7 and 6%, retrospectively, during the following years. When followed both retrospectively and prospectively for a period extending from 1984 to 1998, 71% (n=779) and 40% (n=344) of the selected drugged and drunken drivers, respectively, were arrested two or more times.

Urinary excretion of diazepam metabolites in healthy volunteers and drug users

Urinary excretion profiles of diazepam metabolites were investigated. The subjects were healthy volunteers receiving one single 10-mg dose of diazepam or drug abusers starting a prison sentence. Urinary excretion of metabolites was analysed by immunological screening, liquid chromatography and gas chromatography-mass spectrometry. Relating the metabolite concentration to creatinine concentration in the specimens decreased sample-to-sample variations. In some cases such correction could protect a subject from erroneous accusations of a new intake.

[Centrally acting muscle relaxants and traffic hazards]

BACKGROUND

An increasing number of the centrally acting muscle relaxants were withdrawn from the Norwegian market during the 1988-98 period. The only drug in this group now marketed in Norway is carisoprodol. The National Institute of Forensic Toxicology in Norway analyses all blood samples from suspected drugged drivers. In later years there has been a marked increase in the number of blood samples testing positive for carisoprodol or meprobamate (the major metabolite).

MATERIAL AND METHODS

480 cases testing positive for central muscle relaxants in the years 1984-1998 were further studied.

RESULTS

Compared with blood samples positive primarily for benzodiazepines, there were more women in the group (39% vs. 15%), and fewer drugs and less alcohol were detected.

INTERPRETATION

The positive samples may indicate misuse or abuse due to the fact that high drug concentrations and concomitant use of benzodiazepines were frequent. This knowledge should have implications for doctors prescribing centrally acting muscle relaxants.

Lack of crosstolerance between morphine and morphine-6-glucuronide as revealed by locomotor activity

Morphine-6beta-glucuronide is a major metabolite of morphine. We wanted to examine whether the effects related to opiate CNS stimulation could be mediated by different receptors for morphine and M6G by studying the development of crosstolerance between these two drugs. The effect studied was locomotor activity in C57BL/6JBom mice. We observed a dose-dependent development of tolerance to daily injections of morphine, with 20 micromol/kg giving the most rapid development of tolerance, apparent already on the second day of treatment. This was also observed for the same dose of M6G. Crosstolerance to M6G was measured both after 1 day pretreatment and 7 days pretreatment with morphine 20 micromol/kg, while the crosstolerance to morphine was tested only after 1 day pretreatment with M6G (20 micromol/kg). Lack of crosstolerance towards M6G after 1 day of morphine pretreatment was observed, whereas crosstolerance to M6G was observed after 7 days of exposure to morphine pretreatment. Crosstolerance after M6G pretreatment to morphine was observed. It was concluded that the main part of the effect caused by M6G was mediated through a specific M6G receptor.

Toxicity of drug abuse--amphetamine designer drugs (ecstasy): mental effects and consequences of single dose use

MDMA (3,4-methylendioxymethamphetamine) is the most commonly used substance within the 'ecstasy' group of drugs. MDMA interferes with serotonin and catecholamine transporters in the central nervous system to increase monoamine synaptic levels and thereby mediate the majority of its central nervous effects. These range from wanted effects like euphoria, central nervous stimulation, and feeling of closeness to mild hallucinations, impairment of cognition and co-ordination and further to serious reactions like agitation, disturbed and bizarre behaviour, and possibly psychosis. The full picture of the consequences of these transitory changes is not known. It has been assumed that the risk of being involved in fatalities and accidents during the state of MDMA influence is increased, but this possible risk increase has so far not been determined. Observations of the prevalence of MDMA involvement in cases of reckless driving and the MDMA blood concentrations measured indicate a risk increase comparable to that observed after use of amphetamines.

Driving under the Influence of Non-Alcohol Drugs

In this article the methodological basis for our knowledge within the field of driving under the influence of non-alcohol drugs is reviewed. The experimental and epidemiological studies on drugs in relation to driving do not constitute a complete basis for conclusions to be drawn, but give at the present state nevertheless a platform to indicate increased hazard connected with the use of several drugs. It appears that the main problem with respect to therapeutic use of medicinal drugs is experienced with benzodiazepines (BZDs) and related drugs, and to a lesser extent with opioids and antidepressants. Antihistamine use does not appear to be a serious problem. The major problem within the field of drugged driving as it emerges today in the US and Europe is the high dose use (abuse) of BZDs and related drugs, opioids and illicit drugs such as cannabis, amphetamines, cocaine and related drugs with accompanying danger to traffic safety. Methods determining clinical drug effects in people combined with measurements of drug blood concentrations seem to constitute the best basis for evaluation of "influence". New methods to detect drugged drivers are under development, with saliva tests presently being the most promising. Legislation in the field can be of the "zero tolerance" type or the "impairment" type; combinations of these principles might well turn out to be the most efficient. Detection of drugged driving is presently, in relation to population size, most frequent in Norway, a country with not too pronounced drug problems, indicating a large potential for future detection of drugged driving in other countries. The prevention of drugged driving, especially in the drug-abusing group which has a high recidivism rate, is a challenge for future policy in this field.

Urinary excretion of 11-nor-9-carboxy-delta9-tetrahydrocannabinol and cannabinoids in frequent and infrequent drug users

Urinary excretion of 11-nor-9-carboxy-delta9-tetrahydrocannabinol (THCCOOH) and cannabinoids was monitored in prison inmates. Urinary specimens were collected up to five times per day. EMIT (cutoff 20 ng/mL; EMIT20) and gas chromatography (GC) (cutoff 10.3 ng/mL, LOD 1.4 ng/mL) were used for cannabinoid screening and THCCOOH confirmation, respectively. Urinary creatinine concentrations were recorded. Of the samples with positive EMIT screens, 78% were confirmed by GC analysis. The plotting of THCCOOH/creatinine ratios (THCCOOH/C) versus time gave smoother excretion curves than THCCOOH concentrations alone. Based on THCCOOH/C the first 5 days after the last reported intake, the mean urinary excretion half-life was 1.3 days in infrequent users, and a median of 1.4 days was found in frequent users. In the latter group, apparent terminal urinary excretion half-lives up to 10.3 days were observed. The last positive specimens were found after 4 days for THCCOOH with cutoff 15.0 ng/mL (NIDA/SAMSHA), 5 days for THCCOOH with cutoff 10.3 ng/mL, and 12 days for cannabinoids (EMIT20) in infrequent users and after 17, 22, and 27 days, respectively, in frequent users. Increases in urinary cannabinoids were sometimes found without concomitant increase in THCCOOH or THCCOOH/C. One subject admitted new cannabis intake, after which marked increases in THCCOOH and THCCOOH/C were observed. In others, new intake was suspected. Considerable variations between consecutive specimens were also observed in THCCOOH concentration and THCCOOH/C ratio without suspicion of a new intake.

The extent of postmortem drug redistribution in a rat model

The aim of this study was to investigate the postmortem redistribution of several drugs in a rat model and to examine if any of the pharmacological properties was related to the extent of this phenomenon. One of the following drugs: phenobarbital (phenobarbitone), acetaminophen (paracetamol), carbamazepine, codeine, verapamil, amphetamine, mianserin, trimeprazine (alimemazine) or chloroquine was administered together with nortriptyline orally to rats 90 min prior to sacrifice. Heart blood was sampled immediately before sacrifice and after 2 h postmortem, as it has previously been shown that this is sufficient time for postmortem concentration changes to occur in heart blood. Blood was also sampled from the clamped abdominal inferior vena cava (representing peripheral blood) and tissue samples were taken from lungs, myocardium, liver, kidney, thigh muscle, forebrain, and vitreous humor together with a specimen from the minced carcass. Drugs were analyzed by high performance liquid or gas chromatography. For phenobarbital, acetaminophen and carbamazepine the postmortem to antemortem blood drug concentration ratios were close to 1.0 and tissue concentrations were low. The postmortem to antemortem heart blood drug concentration ratio for chloroquine (6.9 +/- 1.5) was higher than for nortriptyline (3.5 +/- 0.3), and the remaining drugs (codeine, verapamil, amphetamine, mianserin, and trimeprazine) showed ratios of the same magnitude as nortriptyline. The postmortem to antemortem blood drug concentration ratios for both heart blood and blood from the vena cava and also the lung to antemortem blood drug concentration ratio were closely related to the apparent volume of distribution for the drugs studied (p < 0.001). Accordingly, an apparent volume of distribution of more than 3-4 L/kg is a good predictor that a drug is liable to undergo postmortem redistribution with significant increments in blood levels. The postmortem drug concentration in blood from vena cava was closely related to the antemortem blood level, confirming that among the postmortem samples, the peripheral blood sample was the most representative for the antemortem blood concentration.

[Detection of zopiclone in many drivers--a sign of misuse or abuse]

In 1998 zopiclone had a 42% share of the prescribed hypnotic drug market in Norway. The National Institute of Forensic Toxicology analyses all blood samples from suspected drugged drivers. The rise in zopiclone prescription was partly reflected in an increase in the number of drivers with zopiclone detected in the blood. We looked closer at the test results from 101 drivers with zopiclone detected in their blood in the January 1994 to April 1999 period. 60% had blood concentrations of zopiclone above the concentration observed after intake of therapeutic doses; 80% had higher blood concentrations than those expected 8 hours after intake of therapeutic doses. The majority of the drivers also tested positive for illegal drugs, prescription drugs with abuse potential, or alcohol. This indicates that zopiclone is misused or abused. Therefore the same caution should be applied when prescribing zopiclone as is applied when prescribing e.g. benzodiazepines.

[Repeated driving under influence]

Many drivers arrested for driving under the influence have earlier been arrested and convicted for a similar type of violation. The article reviews Norwegian studies on car drivers influenced by alcohol, other drugs than alcohol, and also drivers influenced by amphetamine. The results show that between 10 and 30% of drivers convicted for driving under the influence of alcohol, are rearrested two or more times for the same violation during a subsequent three year period. The recurrence rate is dependent on blood alcohol concentration at the selection time. The recurrence rate among drivers under the influence of drugs other than alcohol is significantly larger (up to 54%), when studied over the same three year period. The number of drivers influenced by amphetamine has increased dramatically during recent years. The recurrence rate among drivers influenced by amphetamine is on part with that of drivers using other drugs than alcohol. There are indications that an increasing number of drunken drivers have changed their abuse pattern during recent years from alcohol to illegal drugs such as amphetamine.

Postmortem drug redistribution--human cases related to results in experimental animals

Femoral blood is widely accepted as the most reliable postmortem specimen for drug analysis in forensic toxicology. There is considerable evidence that the drug concentrations in peripheral blood samples are closer to the antemortem level than the concentration in cardiac blood. In the present study drug concentrations measured in postmortem femoral and/or heart blood samples from eight cases were compared with the concentration found in serum samples from the same subject collected antemortem or perimortem. The drugs involved were amitriptyline, nortriptyline, imipramine, verapamil and chloroquine. Two additional cases with very early postmortem blood samples, as well as femoral blood samples from later autopsy, involved amphetamine and tetrahydrocannabinol. The results from the human cases were compared with results from rat experiments on similar drugs. The samples were analyzed by high performance liquid or gas chromatography. The cases with tricyclic antidepressants had a median postmortern femoral blood to antemortem serum drug concentration ratio of 3.3, the 95% reference range being from 1.1 to 6.0 (pooled data). Large variations of the ratios were seen. The extremes noted were a postmortem femoral blood to antemortem serum drug concentration ratio of 0.9 in a case with nortriptyline and 49 in the case with chloroquine. The low ratio in the former case could be due to attempted resuscitation, while the high ratio in the latter case is probably due to the extremely high apparent volume of distribution and a high blood to plasma concentration ratio for chloroquine. Accordingly, it is dubious whether the drug concentration found in femoral blood at autopsy can be accepted as being representative for the antemortem level. The results obtained from the human cases in the present study were generally in reasonable agreement with previous rat experiments, confirming that the animal studies when interpreted carefully, are indicative of the changes observed in man as well as a previous study in pigs. Studies on drug concentrations in pigs are not necessarily more representative for the findings in humans than experiments with a smaller animal like the rat. The postmortem concentration changes observed for tetrahydrocannabinol in man were found to be unpredictable, while in the accompanying experimental rat study there was a significant postmortem decrease in the tetrahydrocannabinol blood concentration measured in blood from the inferior vena cava. In special cases where the diagnosis of overdose is to be used as judicial evidence, a single sample of blood may prove insufficient. In such cases, analyses of several samples of blood and tissue will increase the possibility of reaching a correct conclusion, but reference values on drug concentrations in tissues are often missing.

Differential inhibition of morphine glucuronidation in the 3- and 6-position by ranitidine in isolated hepatocytes from guinea pig

The influence of ranitidine on morphine metabolism, with special emphasise on the ratio between morphine-3-glucuronide and morphine-6-glucuronide was studied in isolated guinea pig hepatocytes. Ranitidine reduced the Kel of morphine dose-dependently with a maximum effect of 50%, and increased the relative concentration of morphine-6-glucuronide to morphine-3-glucuronide. These effects could be due to a direct or indirect effect on the conjugation enzymes involved, or an effect on the transport of morphine or glucuronides across cell membranes. The latter explanation was rejected on the basis of the observation that the ratios between intra- and extracellular concentrations of morphine, morphine-3-glucuronide and morphine-6-glucuronide were not influenced by ranitidine. Increasing concentrations of ranitidine gradually decreased the morphine-3-glucuronide/morphine-6-glucuronide ratio by up to 21%. This could stem from interference of energy or co-substrate supply, or through direct effects on the different UDPGTases involved. The observation that the present effect on morphine glucuronidation was the opposite of that observed when administering a known co-substrate (UDPGA) depletor, indicated that in all probability the effect of ranitidine was a direct inhibition on the uridine 5'-diphosphate glucuronyltransferases involved, with a more pronounced effect for the isoenzymes responsible for the 3'-glucuronidation.

Study of rearrests for drunken driving in Norway

The National Institute of Forensic Toxicology (NIFT) in Oslo receives blood samples from all Norwegian drivers suspected of driving under the influence of alcohol. It is well known that a large proportion of the arrested drunken drivers are repeat offenders. The purposes of this investigation was to find the arrest rates (the percentage of subjects arrested once or more) among drunken drivers followed retrospectively and prospectively during the 11-year period 1984-1994 and the probability of 'abstaining' from becoming a recidivist during the 9 years subsequent to the year of selection. By examining the rearrest rates during the 3 following years for drivers selected in 1986, 1989, 1991 and 1992 we tried to look for major effects due to the change in the Norwegian road traffic act of 1988. Altogether 45% of the selected drunken drivers were arrested two or more times. Totally the '9-year survival rate' (i.e. not being rearrested) was 60% for drivers with blood alcohol concentration (BAC) selected from the interval 0.06-0.09%; 56% from BAC 0.13-0.16% and 51% from 0.26-0.29%. The data were further evaluated with respect to frequency of rearrest during 3 years after selection, and was around 30% in 1986, while it was lower for drivers selected in 1992 (19%). An explanation for the reduction in rearrest rate may be the changes in the road traffic act which took place in 1988.

Postmortem amitriptyline pharmacokinetics in pigs after oral and intravenous routes of administration

In this study we have evaluated the postmortem pharmacokinetics of amitriptyline (Ami) and metabolites in pigs after oral and intravenous administration, and the results are compared with previous studies in rats and humans. In addition a meticulous investigation of blood and tissue concentrations after postmortem intravenous infusion of Ami was undertaken. Of a total of 9 over-night fasted pigs, 3 were given 25 mg/Kg Ami orally, and another 3 pigs received an intravenous infusion lasting 1 h of 3.3 mg/Kg Ami prior to death. The final 3 pigs were sacrificed and then given the intravenous infusion after death. After approximately 5 h at room temperature, all carcasses were subsequently stored at 4-5 degrees C. Postmortem blood samples were collected at 0.25, 1, 2, 4, 8, 24, 48, and 96 h through an indwelling intracardial needle. Postmortem examination with blood and tissue sampling was performed 96 h after death. Analysis was carried out by high performance liquid chromatography with ultraviolet detection. Postmortem blood samples from the heart of the orally dosed animals revealed large and variable concentration increases of 99(30-243)% for Ami and 96(52-429)% for the main metabolite 10-OH-Ami at 96 h. In the intravenously infused live pigs heart blood Ami increased by 55(33-69)% and 10-OH-Ami increased by 232(76-240)%. Blood from the atria had significantly higher Ami concentrations than blood from both ventricles in the animals dosed while alive, and the drug concentration in femoral blood was higher than in heart blood (p < 0.01). In the orally dosed pigs the left lobe of the liver had significantly higher Ami levels than the right lobe. Tissue/blood Ami concentration ratios were generally lower than previously reported in rats and approximating the levels reported in humans. The animals infused intravenously after death demonstrated high drug levels in blood samples from central vessels, heart, lungs as well as cerebrospinal fluid and vitreous humour. This implies that the presence of a lethal concentration of a drug in just one sample of heart blood can prove worthless in a case where agonal drug infusion may have occurred.

Morphine-6-glucuronide-induced locomotor stimulation in mice: role of opioid receptors

Morphine-6beta-glucuronide is a major metabolite of morphine with potent analgesic actions. To explore the importance of this opiate when administered as a drug by its own or in morphine action, we studied the locomotor activity response to morphine and morphine-6-glucuronide in drug-naive C57 BL/6JBom mice. The effects of administration of the two opiates on a battery of 7 different locomotor activities were studied and compared to saline controls. A dose of 20 micromol/kg morphine-6-glucuronide resulted in more locomotion than the same dose of morphine, while at higher doses (up to 120 micromol/kg), similar increases for most locomotor behaviours were recorded for both drugs. Pretreatment with naltrindole indicated that the delta-receptors play an equivalent but minor role in mediating both morphine-6-glucuronide and morphine hyperlocomotion. Administration of high naltrexone doses (10 mg/kg) completely abolished the locomotor stimulation induced by both opiates. However, at intermediate naltrexone doses of 0.25 and 0.5 mg/kg, morphine-induced behaviours was completely inhibited while morphine-6-glucuronide induced behaviours demonstrated partial resistance to naltrexone inhibition. The mu1-specific receptor antagonist naloxonazine caused 75% reduction of morphine induced behaviours and only 50% inhibition of morphine-6-glucuronide induced behaviors. Taken together our observations indicated general similarity but also marked differences between morphine and morphine-6-glucuronide with respect to opiate receptors mediating the locomotor stimulatory effect.

Urinary excretion of amphetamine after termination of drug abuse

Important issues in urinary drug testing are the variability between consecutive urine specimens, the duration of positive specimens after last intake, and the usefulness of creatinine concentration to correct for variability in urine concentration. These issues were addressed in the present study with amphetamine as the drug of abuse. Drug users who were starting their sentences in prison participated in the study. Urine specimens were collected 1 to 5 times per day. Screening was performed by EMIT d.a.u. (cutoff, 0.30 microgram/mL) and EMIT II (cutoff, 1.00 microgram/mL), and confirmation was performed with gas chromatography-mass spectrometry. Creatinine and pH were recorded. Amphetamine was demonstrated in seven subjects. The highest concentration was 135 micrograms/mL. The last positive-screened specimen was observed by EMIT d.a.u. after almost 9 days of imprisonment and by EMIT II after 3 days. Large concentration differences could be found between consecutive specimens, accompanied by considerable differences in creatinine and pH. The individual curves were generally smoother after creatinine correction of concentrations. As expected, urinary pH was observed to influence the excretion.

Drugged driving, a review based on the experience in Norway

Since 1959, the Norwegian Road Traffic Act has prohibited driving under the influence of drugs other than alcohol. On suspicion, the police request a clinical examination from any driver, as well as blood analyses for illegal and prescribed drugs affecting driving performance. During the last few years, there has been a marked increase in the number of drivers suspected of be influenced by drugs (1983, n = 900; 1995, n = 3329). The most commonly detected drugs are tetrahydrocannabinol, amphetamine, benzodiazepines and opiates. Multi-drug use is frequently found (> 60%). The occurrence of amphetamine (1991, n = 216; 1995, n = 937) and heroin (1991, n = 19; 1995, n = 172) has increased considerably. The frequency of drugged drivers apprehended in roadside traffic appears to be at least 10-fold higher in Norway than most other countries. This is probably mainly due to differences between national road traffic acts and the level of attention to the problem, and not to national differences in the prevalence of drugged driving.

Effects of ethanol on ethylmorphine metabolism in isolated rat hepatocytes: characterization by means of a multicompartmental model

Hepatic cytochrome P-450 enzymes mediate at least two important biotransformation pathways of codeine and ethylmorphine starting with either N-demethylation or O-dealkylation, producing polar metabolites which are then subsequently glucuronidated. The present study was designed to characterise the acute effects of ethanol on the metabolism of ethylmorphine and to compare it with the effects on codeine in suspensions of freshly isolated rat hepatocytes. Isolated rat hepatocytes from male Wistar rats were prepared by a collagenase perfusion method. Ethylmorphine, codeine and their metabolites were quantified by HPLC with UV detection. The total ethylmorphine elimination rate was reduced by 12% at 5mM and 38% at 100 mM ethanol. The corresponding percentages for codeine were 16 and 43%. In the presence of ethanol the concentrations of several intermediate and end products of ethylmorphine and codeine changed markedly from the control situation. The experimental data were applied to a mathematical compartmental linear model to estimate the influence of ethanol on the separate reaction rates in the two main metabolic pathways. The ratios between reaction rate constants in the ethylmorphine experiments at 100 and 0 mM ethanol were 0.65 for ethylmorphine-->norethylmorphine, 0.63 for norethylmorphine-->normorphine, 0.56 for ethylmorphine-->morphine, 0.49 for morphine-->normorphine, 0.31 for normorphine-->normorphine-3-glucuronide and 0.49 for morphine-->morphine-3-glucuronide. Almost similar effects of ethanol on codeine metabolism were found. In additional experiments, norethylmorphine or norcodeine (50 microM) was incubated with 5 mM to 100 mM of ethanol and the metabolism of both norethylmorphine and norcodeine was found to be inhibited by ethanol in a concentration-dependent manner. The glucuronidation of morphine and normorphine added in separate experiments was also inhibited by ethanol, from 22 to 36% for morphine-3-glucuronide and 30 to 60% for normorphine-3-glucuronide, respectively, in the presence of 5 mM to 100 mM of ethanol. It was concluded that all steps in the metabolism of ethylmorphine (and codeine) leading to the end products morphine-3-glucuronide and normorphine-3-glucuronide were inhibited by ethanol, and that the glucuronidation process were the ones most affected by ethanol.

Evidence for CYP2D1-mediated primary and secondary O-dealkylation of ethylmorphine and codeine in rat liver microsomes

The purpose of the present study was to investigate the role of specific CYPs responsible for the O-dealkylation of ethylmorphine (EM) and codeine (CD) to morphine (M), as well as that of norethylmorphine (NEM) and norcodeine (NCD) to normorphine (NM) in rat liver microsomes. Liver microsomes metabolize EM and CD to M, and NEM and NCD to NM, in the presence of an NADPH-generating system. The metabolites of EM and CD were determined by HPLC with UV and electrochemical detection. In the present study, the role of CYP2D1 in O-dealkylation of EM/NEM and CD/NCD was investigated by use of specific antiCYP antibodies. When testing rabbit antirat CYP2D1, 2E1, 2C11, and 3A2 antibodies, only the antiCYP2D1 antibody inhibited the EM/NEM and CD/NCD O-dealkylase activities significantly. The maximum inhibition achieved was approximately 80% at a protein ratio (IgG to microsomes) of 10:1, p = 0.001. The contribution of CYP2D1 to the O-dealkylation of EM/NEM and CD/NCD was further confirmed by use of the specific CYP2D1 inhibitors quinine and propafenone. Five microM of quinine inhibited the EM/NEM and CD/NCD O-dealkylase activities by approximately 80%. The CYP3A inhibitor troleandomycin (TAO) failed to inhibit the CYP2D1 catalyzed reaction, but did inhibit the N-demethylation of EM and CD. The O-dealkylation of NEM and NCD was also impaired in Dark Agouti rat (DA) liver microsomes. Taken together, the immunoinhibition and chemical-inhibitor studies of rat liver microsomes provided convincing evidence for the involvement of CYP2D1, the rat counterpart of human CYP2D6, in the metabolism of EM/NEM and CD/NCD to the corresponding O-dealkylated metabolites.

Recidivism among drunken and drugged drivers in Norway

The prevalence of re-arrest among drunken drivers in relation to different blood alcohol concentrations (BAC) at the time of the offences was studied. Between 38 and 50% of arrested drunk drivers were re-arrested for similar offences. The frequency of re-arrests was, however, reduced during 1992 compared with a986, but only significantly for those with a low BAC interval (60-90 mg/d). We conclude that drivers with high re-arrest rates have a careless attitude to the Road Traffic Act and require a different treatment and follow-up programme.

Ethanol interference with morphine metabolism in isolated guinea pig hepatocytes

It has previously been shown that guinea pig hepatocytes metabolise morphine in a fashion similar to humans. The metabolism of morphine (5 muM) and the formation of metabolites morphine-3-glucuronide, morphine-6-glucuronide and normorphine was studied in the absence and presence of ethanol (5, 10, 25, 60 and 100 mM) in freshly isolated guinea pig hepatocytes. In order to gain more detailed information, a mathematical model was estimated on experimental data and used to analyse the effects of ethanol on the reaction rates of the different morphine metabolites. Ethanol inhibited the rate of morphine elimination in a dose-related manner, at the high ethanol concentrations the elimination rate was 40 per cent of the control rate. The formation of morphine-glucuronides was influenced in a biphasic manner. Five and 10 mM ethanol increased both the morphine-3-glucuronide and morphine-6-glucuronide levels after 60 min incubation compared to the control, whereas at the higher ethanol concentrations (25-100 mM) the levels of morphine-glucuronides were reduced. Data from the mathematical model, however, demonstrated that the reaction rates for morphine-glucuronide formation were decreased at all ethanol concentrations and in a dose-dependent manner, the interpretation of this being that at the lower (5 and 10 mM) ethanol concentrations employed in this study, other metabolic pathways of morphine are more heavily inhibited than the glucuronidations, resulting in a shunting towards morphine-3-glucuronide and morphine-6-glucuronide. The pharmacodynamic consequences of these pharmacokinetic effects are thus somewhat difficult to predict since morphine-6-glucuronide has a higher agonist potency than morphine. At high concentrations ethanol inhibition of morphine metabolism will increase the concentration of morphine and subsequently the euphoric and the toxic effects. The lower quantities of morphine-6-glucuronide formed in the presence of high ethanol concentrations on the other hand most probably imply reduction of such effects and the net pharmacodynamic effect would be uncertain. At low ethanol concentrations, however, morphine-6-glucuronide concentrations increased and morphine metabolism was less inhibited leading to a possible potentiation of the effects of morphine. Thus, a low ethanol concentration might exert a more pronounced ethanol-drug effect interaction than a higher ethanol concentration.

Low level hyperbaric antagonism of diazepam's locomotor depressant and anticonvulsant properties in mice

Exposure to 12 atmospheres absolute (12 ATA) helium oxygen gas (heliox) (low level hyperbaric exposure) antagonizes the behavioral effects of ethanol and n-propanol, but not morphine. These and other results indicate that the mechanism of the antagonism is direct (pharmacodynamic) and selective. Our study further investigates the selectivity of low level hyperbaric antagonism by testing its effectiveness against diazepam, a high affinity binding drug that acts via allosteric modulation of GABAA receptors. C57BL/6J mice received injections i.p. of vehicle or diazepam, and were then exposed to 1 ATA air, 1 ATA heliox or 12 ATA heliox. Exposure to 12 ATA heliox antagonized the locomotor depressant effect of 4 and 6 mg/kg, but not 8 mg/kg diazepam. Hyperbaric exposure also antagonized the anticonvulsant effect of 8 and 24 mg/kg, but not 4 mg/kg, diazepam vs. 300 mg/kg isoniazid. Exposure to 12 ATA heliox did not significantly affect blood concentrations of diazepam or its metabolite n-desmethyl diazepam. The pharmacological characteristics of the antagonism (direct, surmountable, rightward shift in diazepam's dose-response curve) closely matched those seen in previous studies for hyperbaric antagonism of ethanol. The results add to the evidence that low level hyperbaric exposure is a direct, mechanistic antagonist that selectively antagonizes drugs that act via perturbation or allosteric modulation of receptor function. Moreover, the results suggest that allosteric coupling pathways, which transduce binding events on ligand-gated ion channels, may represent initial sites of action for ethanol.

Female drivers suspected for drunken or drugged driving

The National Institute of Forensic Toxicology in Oslo receives blood and urine samples from all Norwegian drivers apprehended on suspicion of driving under the influence of alcohol or drugs. In this study, sex differences in use of alcohol and drugs among Norwegian drunken and drugged drivers were presented. In 1992 and 1993, the institute received samples from 11,970 and 5642 suspected drunken and drugged drivers respectively. Women were underrepresented among both suspected drunken (7.6%) and drugged (10.9%) drivers. There were not observed dramatic gender differences in frequency and finding of drugs. The most frequent drugs in addition to alcohol were tetrahydrocannabinol, benzodiazepines and amphetamine. The data suggest that benzodiazepines are found relatively more often in blood from female than from male drugged drivers. Lower proportion of women with blood ethanol concentration over the legal limit was observed.

Distribution of morphine 6-glucuronide and morphine across the blood-brain barrier in awake, freely moving rats investigated by in vivo microdialysis sampling

Microdialysis was used to sample morphine 6-glucuronide (M6G) and morphine in striatal extracellular fluid after systemic administration in awake, freely moving rats. Morphine or M6G (25-67 mumol/kg) was given subcutaneously, and blood and striatal dialysate were sampled repeatedly during 120 min. Blood samples were obtained by indwelling catheters in the inferior vena cava. Opiates in serum or brain dialysate were analyzed with high-performance liquid chromatography. The functional intactness of the blood-brain barrier was verified by the use of sodium technetate (Na99mTcO4). The fractional penetration into the brain of morphine and M6G was approximately 350- and 90-fold higher than that of Na99mTcO4, respectively, with a relative difference in the transfer of morphine and M6G of about 4. No hydrolysis of M6G to morphine was detected. Striatal dialysate-to-serum ratios of M6G did not differ after 25 or 67 mumol/kg. Serum AUC0-120 min was 10 times higher for M6G than for morphine. This reflects both a smaller volume of distribution (Vd) for M6G and a decreased rate of elimination compared with morphine. The median t1/2 from serum was 36 and 32 min for morphine and M6G, respectively. The striatal dialysate AUC0-120 min of M6G was 2.9 times greater than that of morphine after an equimolar subcutaneous dose. Dialysate tmax was delayed approximately 40 min relatie to serum tmax for both drugs, and the median t1/2 from the dialysate was 82 and 48 min for M6G and morphine, respectively. These results represent direct evidence for the penetration of M6G into the brain after systemic administration to living rats.

Biotransformation and pharmacokinetics of ethylmorphine after a single oral dose

1. The pharmacokinetics of ethylmorphine after administration of a single dose of the cough mixture Cosylan were investigated in 10 healthy subjects. 2. The median urinary recovery of ethylmorphine and measured metabolites was 77% over 48 h. The median tmax of unchanged ethylmorphine was 45 min, and the terminal elimination t1/2 was 2 h. Ethylmorphine-6-glucuronide was found to be the major metabolite. 3. Two subjects had significantly lower urinary recovery (0.48 h) of morphine and morphine-glucuronides than the remainder. Furthermore, these two had urinary metabolic ratios (MRO) and partial metabolic clearances (CLmO) for O-deethylation of ethylmorphine tentatively classifying them phenotypically as poor metabolisers of the debrisoquine/sparteine type. 4. Genotyping for cytochrome P450 (CYP) 2D6 alleles revealed five homozygote (wt/wt) and five heterozygote subjects. Two subjects phenotypically classified as poor metabolisers were genotypically CYP2D6A/wt and CYP2D6D/wt, respectively. 5. Serum and urine samples taken more than 8 and 24 h after administration of ethyl-morphine respectively, contained morphine and morphine-glucuronides, but no ethylmorphine, ethylmorphine-6-glucuronide or (serum only) norethylmorphine. Norethylmorphine could be detected after hydrolysis of urine samples in all subjects. The urinary recovery of the active metabolites morphine and morphine-6-glucuronide after administration of ethylmorphine varied by a factor of 9 between individuals. 6. The wide variation in recovery of morphine and morphine-glucuronides after oral administration of ethylmorphine could not be explained simply by a difference in CYP2D6 genotype. Constitutional variation in other enzymatic pathways involved in ethylmorphine metabolism is probably crucial. Ratios of morphine to parent drug cannot be used to distinguish the source of morphine after administration of ethylmorphine. Norethylmorphine should be included in urine assays for opiates in forensic toxicology, and no firm conclusions about the source of morphine are possible based on serum samples obtained more than 24 h after drug administration.

Low-level hyperbaric exposure antagonizes locomotor effects of ethanol and n-propanol but not morphine in C57BL mice

Low-level hyperbaric exposure antagonizes a broad range of behavioral effects of ethanol in a direct, reversible, and competitive manner. This study investigates the selectivity of the antagonism across other drugs. C57BL/6 mice were injected with saline, ethanol, n-propanol, or morphine sulfate, and then were exposed to 1 atmosphere absolute (ATA) air, 1 ATA helium-oxygen gas mixture (heliox), or 12 ATA heliox. Locomotor activity was measured from 10 to 40 min following injection. N-propanol produced a dose-dependent depression of locomotor activity from 1.0 g/kg. Morphine produced a dose-dependent stimulation of locomotor activity at doses of 3.75-12.0 mg/kg. Exposure to 12 ATA heliox significantly antagonized the locomotor depressant effects of 1.0 g/kg n-propanol and 2.5 g/kg ethanol, without significantly affecting blood concentrations of these drugs measured at 40 min postinjection. Exposure to 12 ATA heliox did not significantly antagonize the locomotor-stimulating effects of the two morphine doses tested (3.75 and 7.5 mg/kg). These findings suggest that exposure to 12 ATA heliox antagonizes the behavioral effects of intoxicant-anesthetic drugs like ethanol and n-propanol, which are believed to act via perturbation or allosteric modulation of functional proteins, but does not antagonize the effects of drugs like morphine, which act via more direct mechanisms. This demonstration of selective antagonism adds important support for the hypothesis that low-level hyperbaric exposure is a direct mechanistic ethanol antagonist, with characteristics similar to a competitive pharmacological antagonist.

Ethylmorphine O-deethylation in isolated rat hepatocytes. Involvement of codeine O-demethylation enzyme systems

The O-dealkylation of ethylmorphine (EM) and codeine (CD) to morphine (M) co-segregates with debrisoquine/sparteine genetic polymorphism in man. CD O-demethylation is catalysed by cytochrome P450 2D1 (CYP2D1) in rats. In the present study, the O-deethylation of EM was examined and compared with that of CD in suspensions of freshly-isolated hepatocytes prepared by a collagenase method from Wistar rats with and without CYP2D1 inhibitors. Isolated hepatocytes were also prepared from Dark Agouti (DA) rats deficient in CYP2D1, and were incubated with EM or CD. EM, CD and their metabolites were quantified by HPLC with UV detection. EM had a similar pattern of metabolism to that of CD in suspensions of hepatocytes from Wistar rats. Both EM and CD were O-dealkylated to form M plus morphine-3-glucuronide (M3G) and N-demethylated to form norethylmorphine (NEM) or norcodeine (NCD), respectively, which were further metabolized to normorphine (NM) and finally glucuronidated to normorphine-3-glucuronide (NM3G). As compared to hepatocytes from Wistar rats, DA rats were characterized by a markedly decreased formation (70 approximately 75% reduction) of M plus M3G from both EM and CD. Quinine, quinidine, propafenone and sparteine all inhibited EM O-deethylation as well as CD O-demethylation. Quinine was the most potent inhibitor of both these O-dealkylations (Ki = 0.2 microM for both EM and CD, respectively). Quinine as well as the other inhibitors inhibited both EM and CD O-dealkylation competitively and with small differences in Ki versus EM and CD, respectively. The metabolism of EM to M plus M3G and that of CD to M plus M3G was highly correlated when results from the various separate cell suspensions were plotted. In conclusion all findings indicated that the enzyme responsible for O-demethylation of CD, CYP2D1 was also responsible for the O-deethylation of EM to M.

[Driving under the influence of benzodiazepines. Sale differences in the counties are reflected among drivers suspected of driving under the influence of a drug]

This study was based on all blood samples taken from drivers suspected of being influenced by alcohol and or drugs and sent to the National Institute of Forensic Toxicology in 1992. Benzodiazepines were among the most frequently detected drugs. The ratio between samples containing benzodiazepines and the total number of samples was compared with the sales of benzodiazepines in the different Norwegian provinces. In 95% of the benzodiazepine positive samples, either a combination with other drugs or a concentration significantly higher than usually found after ordinary therapeutic use was observed. These results indicated that the fraction of samples positive on benzodiazepines probably representing drug abuse or misuse correlated with the total prescription of benzodiazepines in the different Norwegian provinces.

Low-level hyperbaric antagonism of ethanol's anticonvulsant property in C57BL/6J mice

This study investigated the ability of hyperbaric exposure to antagonize ethanol's anticonvulsant effect on isoniazid (INH)-induced seizures. Drug-naive, male C57BL/6 mice were injected intraperitoneally with saline, 1.5, 2.0, or 2.5 g/kg ethanol followed immediately by an intramuscular injection of 300 mg/kg of INH. The mice were then exposed to either 1 atmosphere absolute (1 ATA) air, 1 ATA helium-oxygen gas mixture (heliox), or 12 ATA heliox at temperatures that offset the hypothermic effects of helium. Ethanol increased the latency to onset of myoclonus in a dose-dependent manner. Exposure to 12 ATA heliox antagonized ethanol's anticonvulsant effect at 2.0 and 2.5 g/kg, but not at 1.5 g/kg. Ethanol also increased the latency to onset of clonus in a dose-dependent manner beginning at 2.0 g/kg. Exposure to 12 ATA heliox antagonized this anticonvulsant effect. When exposed to 12 ATA heliox, the blood ethanol concentrations at time to onset of myoclonus were significantly higher in mice treated with 2.5 g/kg of ethanol as compared with blood ethanol concentrations of mice exposed to 1 ATA air. These findings extend the acute behavioral effects of ethanol known to be antagonized by hyperbaric exposure and support the hypothesis that low-level hyperbaric exposure blocks or reverses the initial action(s) of ethanol leading to its acute behavioral effects.

Carisoprodol elimination in humans

The elimination of the muscle relaxant drug, carisoprodol, was examined in 10 healthy volunteers after an oral dose of 700 mg. In nine subjects, carisoprodol was rapidly eliminated, with a mean half-life of 99 +/- 46 min, and extensively converted to meprobamate. Within 2.5 h after carisoprodol intake, meprobamate serum concentrations exceeded those of carisoprodol. Serum levels of meprobamate recorded (15-25 mumol/L) indicate that meprobamate might contribute to the effect(s) of carisoprodol. One subject eliminated carisoprodol with an overall half-life of 376 min, and only small amounts of meprobamate were recorded. This subject was found to be a poor metabolizer of mephenytoin. In spiked human sera, protein binding of carisoprodol was in the range of 41-67%, whereas meprobamate was bound to a lesser extent, 14-24%.

Drug analysis for control purposes in forensic toxicology, workplace testing, sports medicine and related areas

This MiniReview describes the present guidelines for drug testing in forensic toxicology, workplace testing and doping control of athletes. Such guidelines are established to secure the chain of custody, from sample collection through analysis with screening, confirmation methods and interpretation, to the final report of results. Specifications for good laboratory practice, facility maintenance and quality assurance programs are described. The advantages and limitation of immunological drug assays and the necessity of specific chromatographic confirmation methods are discussed. The importance of correct interpretation of positive test results is illustrated. The effect of drug testing on the prevalence of drug abuse, accident rates and effectivity at the workplace is discussed.

Postmortem release of amitriptyline from the lungs; a mechanism of postmortem drug redistribution

An experimental rat model was used to study postmortem redistribution of amitriptyline (AMI). Two hours after a subcutaneous injection with 20 mg of amitriptyline, the rats (n = 40) were anaesthetized and blood samples were drawn from the femoral vein and the heart. The rats were then sacrificed by CO2 and left at room temperature for either 0.1, 1, 2, 5, 24, 48, or 96 h. Postmortem blood samples from the heart and the inferior vena cava, and tissue samples from the lungs, heart, liver, right kidney, thigh muscle, the wall of the abdominal vena cava and brain were analyzed by high performance liquid chromatography. A significant increase was observed within 2 h postmortem in heart blood and later also in blood from the inferior vena cava. At 96 h postmortem the concentration increase was 4.4 +/- 0.5-fold (P < 0.01) and 3.0 +/- 1.1-fold (P < 0.05) as compared to the antemortem values observed in heart blood and blood from the inferior vena cava, respectively (mean +/- SEM). In the lungs there was a fall in the concentration of AMI from 148 +/- 16.7 mumol/kg at 0.1 h to 49.1 +/- 7.8 mumol/kg at 96 h postmortem (P < 0.01). In the vessel wall of the abdominal vena cava there was also a significant fall in drug concentration, while in heart muscle and liver an increase in drug concentration was observed. In animals where the lungs were removed agonally (n = 7), the drug concentration in heart blood had increased significantly less at 2 h postmortem.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphine-6-glucuronide: a potent stimulator of locomotor activity in mice

The present study tested the hypothesis that morphine glucuronides have stimulant properties by studying their effects on locomotor activity in mice. Drug-naive C57BL/6J male mice were injected with saline, morphine, morphine-6-glucuronide (M6G) or morphine-3-glucuronide (M3G). In some experiments, mice were injected with saline or naloxone 5 min prior to drug treatment. Injection of 40 mg/kg morphine or M6G, but not M3G, significantly increased activity versus saline. The extent of activation induced by M6G was markedly higher than for morphine. Subsequent dose-response studies across a somewhat lower dose range using equimolar doses of morphine and M6G (3-80 mumoles/kg) found that both drugs significantly increased locomotor activity beginning at 20 mumoles/kg. M6G increased locomotor activity from 1.3 to 2.1 times more than for equimolar doses of morphine. Pretreatment with naloxone (10 mg/kg) completely abolished the locomotor stimulation induced by 32 mumoles/kg morphine and M6G. These findings present evidence that M6G is an active metabolite of morphine which has behaviorally stimulating effects and may play an important role in mediating the reinforcing properties of morphine in humans.