Urinary excretion half-life of delta 1-tetrahydrocannabinol-7-oic acid in heavy marijuana users after smoking

A Case of Neuroleptic Malignant Syndrome in the Context of Lithium Toxicity and Aripiprazole Use

OBJECTIVE

Neuroleptic malignant syndrome (NMS) is a rare life-threatening condition that providers should be cognizant of when prescribing dopamine-receptor antagonists. Atypical antipsychotic agents were initially considered to have a lower risk of inducing the development of NMS compared with conventional antipsychotic. Considerable evidence, however, has suggested that atypical antipsychotics are associated with NMS, including the partial dopamine agonist, aripiprazole. There is growing evidence that other psychotropics, including lithium, cause this condition. Here, the authors present a case of a patient who developed NMS from lithium and aripiprazole and provide a literature review of reported NMS cases with either psychotropic.

METHOD AND RESULTS

The authors report the case of 60-year-old male patient who developed NMS over a hospital course during which both aripiprazole and lithium were prescribed. In addition, a literature review was performed and a summary of cases of NMS induced by either lithium and/or aripiprazole is provided.

CONCLUSIONS

This case adds to the growing body of literature of aripiprazole and lithium-induced NMS. Only 2 other cases are reported where concomitant aripiprazole and lithium use lead to NMS. Interestingly, our patient did develop lithium toxicity during hospitalization, but the NMS diagnosis occurred after lithium toxicity resolved. This varies from the other 2 cases where NMS developed despite lithium levels always being therapeutic. Unfortunately, there are more questions than answers surrounding this rare complication involving these 2 psychotropics and clinical vigilance is warranted when using these psychotropics especially in cases where aripiprazole and lithium are used in combination.

Urinary Excretion Profile of 11-Nor-9-Carboxy-Δ9-Tetrahydrocannabinol (THCCOOH) Following Smoked and Vaporized Cannabis Administration in Infrequent Cannabis Users

As cannabis has become more accessible, use of alternative methods for cannabis administration such as vaporizers has become more prevalent. Most prior controlled pharmacokinetic evaluations have examined smoked cannabis in frequent (often daily) cannabis users. This study characterized the urinary excretion profile of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THCCOOH), the primary analytical outcome for detection of cannabis use, among infrequent cannabis users following controlled administration of both smoked and vaporized cannabis. Healthy adults (N = 17), with a mean of 398 (range 30-1,825) days since last cannabis use, smoked and vaporized cannabis containing 0, 10, and 25 mg of Δ9-tetrahydrocannabinol (THC) across six outpatient sessions. Urinary concentrations of THCCOOH were measured at baseline and for 8 h after cannabis administration. Sensitivity, specificity, and agreement between three immunoassays (IA) for THCCOOH (with cutoffs of 20, 50, and 100 ng/mL) and gas chromatography-mass spectrometry (GC/MS) results (confirmatory concentration of 15 ng/mL) were assessed. THCCOOH concentrations peaked 4-6 h after cannabis administration. Median maximum concentrations (Cmax) for THCCOOH were qualitatively higher after administration of vaporized cannabis compared to equal doses of smoked cannabis. Urine THCCOOH concentrations were substantially lower in this study relative to prior examinations of experienced cannabis users. The highest agreement between IA and GC/MS was observed at the 50 ng/mL IA cutoff while sensitivity and specificity were highest at the 20 and 100 ng/mL IA cutoffs, respectively. Using federal workplace drug-testing criteria (IA cutoff of 50 ng/mL and GC/MS concentration ≥15 ng/mL) urine specimens tested positive in 47% of vaporized sessions and 21% of smoked sessions with active THC doses (N = 68). Urinary concentrations of THCCOOH are dissimilar after administration of smoked and vaporized cannabis, with qualitatively higher concentrations observed after vaporization. Infrequent users of cannabis may excrete relatively low concentrations of THCCOOH following acute inhalation of smoked or vaporized cannabis.

Association Between Self-reported Prenatal Cannabis Use and Maternal, Perinatal, and Neonatal Outcomes

IMPORTANCE

Recent evidence suggests that cannabis use during pregnancy is increasing, although population-based data about perinatal outcomes following in utero exposure remain limited.

OBJECTIVE

To assess whether there are associations between self-reported prenatal cannabis use and adverse maternal and perinatal outcomes.

DESIGN, SETTING, AND PARTICIPANTS

Population-based retrospective cohort study covering live births and stillbirths among women aged 15 years and older in Ontario, Canada, between April 2012 and December 2017.

EXPOSURES

Self-reported cannabis exposure in pregnancy was ascertained through routine perinatal care.

MAIN OUTCOMES AND MEASURES

The primary outcome was preterm birth before 37 weeks' gestation. Indicators were defined for birth occurring at 34 to 36 6/7 weeks' gestation (late preterm), 32 to 33 6/7 weeks' gestation, 28 to 31 6/7 weeks' gestation, and less than 28 weeks' gestation (very preterm birth). Ten secondary outcomes were examined including small for gestational age, placental abruption, transfer to neonatal intensive care, and 5-minute Apgar score. Coarsened exact matching techniques and Poisson regression models were used to estimate the risk difference (RD) and relative risk (RR) of outcomes associated with cannabis exposure and control for confounding.

RESULTS

In a cohort of 661 617 women, the mean gestational age was 39.3 weeks and 51% of infants were male. Mothers had a mean age of 30.4 years and 9427 (1.4%) reported cannabis use during pregnancy. Imbalance in measured maternal obstetrical and sociodemographic characteristics between reported cannabis users and nonusers was attenuated using matching, yielding a sample of 5639 reported users and 92 873 nonusers. The crude rate of preterm birth less than 37 weeks' gestation was 6.1% among women who did not report cannabis use and 12.0% among those reporting use in the unmatched cohort (RD, 5.88% [95% CI, 5.22%-6.54%]). In the matched cohort, reported cannabis exposure was significantly associated with an RD of 2.98% (95% CI, 2.63%-3.34%) and an RR of 1.41 (95% CI, 1.36-1.47) for preterm birth. Compared with no reported use, cannabis exposure was significantly associated with greater frequency of small for gestational age (third percentile, 6.1% vs 4.0%; RR, 1.53 [95% CI, 1.45-1.61]), placental abruption (1.6% vs 0.9%; RR, 1.72 [95% CI, 1.54-1.92]), transfer to neonatal intensive care (19.3% vs 13.8%; RR, 1.40 [95% CI, 1.36-1.44]), and 5-minute Apgar score less than 4 (1.1% vs 0.9%; RR, 1.28 [95% CI, 1.13-1.45]).

CONCLUSIONS AND RELEVANCE

Among pregnant women in Ontario, Canada, reported cannabis use was significantly associated with an increased risk of preterm birth. Findings may be limited by residual confounding.

Pharmacokinetics and Tolerability of Δ9-THC-Hemisuccinate in a Suppository Formulation as an Alternative to Capsules for the Systemic Delivery of Δ9-THC

The objectives of this study were: (1) to assess the safety, tolerability, and pharmacokinetics of ascending doses of Δ⁹-tetrahydrocannabinol-hemisuccinate (THC-HS) after rectal administration as suppositories in male volunteers; and (2) to compare the pharmacokinetics of oral administration of Δ⁹-tetrahydrocannabinol (Δ⁹-THC) with an equivalent amount of Δ⁹-THC delivered as THC-HS via the suppository formulation. In support of the pharmacokinetic evaluations, an analytical method was developed and validated for the determination of Δ⁹-THC and for its major circulating metabolites 11-hydroxy-Δ⁹-tetrahydrocannabinol (11-OH-THC) and 11-nor-Δ⁹-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) in human plasma. Δ⁹-THC, 11-OH-THC, and THC-COOH were extracted from plasma using solid phase extraction and analyzed by liquid chromatography-tandem mass spectrometry. The limits of detection and quantitation for all 3 analytes were 0.25 and 0.5 ng/mL, respectively. The method was validated over the range of 0.5-25 ng/mL. This method was used to quantify Δ⁹-THC and any THC-HS as Δ⁹-THC due to the inclusion of a hydrolysis step as part of the extraction procedure. Therefore, Δ⁹-THC measured was the total THC (free Δ⁹-THC plus Δ⁹-THC derived from THC-HS). The assay was reproducible for the measurement of all 3 analytes, with a variability of 7.2, 13.7, and 8.3%, respectively, at the 1 ng/mL level. The method was then used to assess the pharmacokinetics of Δ⁹-THC and metabolites from the suppository dosage form in doses equivalent to 1.25, 2.5, 5, 10, and 20 mg Δ⁹-THC per suppository as THC-HS. Systemic exposure to Δ⁹-THC, administered as THC-HS suppository, increased broadly dose proportionally. Systemic exposure and C_{max (obs)} estimates for 11-OH-THC and THC-COOH generally increased subproportionally. The pharmacokinetic profiles of Δ⁹-THC and metabolites were also compared after oral administration of 10 mg Δ⁹-THC (as dronabinol capsules) and after administration of 10 mg equivalents of Δ⁹-THC as THC-HS in suppository form. Total systemic exposure to Δ⁹-THC was considerably higher following rectal administration of THC-HS than after oral administration. The Δ⁹-THC area under the plasma concentration versus time curve (AUC_(0-∞)) for THC-HS was 2.44-fold higher (90% confidence interval: 1.78, 3.35) than for the capsule administration.

Metabolomics of Δ9-tetrahydrocannabinol: implications in toxicity

Cannabis sativa is the most commonly used recreational drug, Δ(9)-tetrahydrocannabinol (Δ(9)-THC) being the main addictive compound. Biotransformation of cannabinoids is an important field of xenobiochemistry and toxicology and the study of the metabolism can lead to the discovery of new compounds, unknown metabolites with unique structures and new therapeutic effects. The pharmacokinetics of Δ(9)-THC is dependent on multiple factors such as physical/chemical form, route of administration, genetics, and concurrent consumption of alcohol. This review aims to discuss metabolomics of Δ(9)-THC, namely by presenting all known metabolites of Δ(9)-THC described both in vitro and in vivo, and their roles in the Δ(9)-THC-mediated toxic effects. Since medicinal use is increasing, metabolomics of Δ(9)-THC will also be discussed in order to uncover potential active metabolites that can be made available for this purpose.

The rapidly increasing trend of cannabis use in burn injury

The use of cannabis is currently increasing according to U.S. Department of Health and Human Services (HHS). Surprisingly, cannabis use among burn patients is poorly reported in literature. In this study, rates of cannabis use in burn patients are compared with general population. Data from the National Burn Repository (NBR) were used to investigate incidence, demographics, and outcomes in relation to use of cannabis as evidenced by urine drug screen (UDS). Thousands of patients from the NBR from 2002 to 2011 were included in this retrospective study. Inclusion criteria were patients older than 12 years of age who received a drug screen. Data points analyzed were patients' age, sex, UDS status, mechanism of burn injury, total body surface area, length of stay, ICU days, and insurance characteristics. Incidence of cannabis use in burn patients from the NBR was compared against national general population rates (gathered by Health and Human Services) using chi-square tests. Additionally, the burn patient population was analyzed using bivariate analysis and t-tests to find differences in the characteristics of these patients as well as differences in outcomes. Seventeen thousand eighty out of over 112,000 patients from NBR had information available for UDS. The incidence of cannabis use is increasing among the general population, but the rate is increasing more quickly among patients in the burn patient population (P = .0022). In 2002, 6.0% of patients in burn units had cannabis+ UDS, which was comparable with national incidence of 6.2%. By 2011, 27.0% of burn patients tested cannabis+ while national incidence of cannabis use was 7.0%. Patients who test cannabis+ are generally men (80.1%, P < .0001) and are younger on average (35 years old vs 42, P < .0001). The most common mechanisms of injury among patients who test cannabis+ or cannabis- are similar. Flame injury makes up >60% of injuries, followed by scalds that are >15%. In comparing cannabis+/- patients, cannabis+ patients are more likely to be uninsured (25.2% vs 17.26%, P < .0001). Finally, patients who test cannabis+ have larger burns (TBSA% of 12.94 vs 10.98, P < .0001), have a longer length of stay (13.31 days vs 12.6, P = .16), spend more days in the ICU (7.84 vs 6.39, P = .0006), and have more operations (2.78 vs 2.05, P < .0001). The rate patients testing positive for cannabis in burn units is growing quickly. These patients are younger and are less likely to be insured. These patients also have larger burns, spend more time in ICUs, and have a greater number of operations. The increasing use of cannabis, as expected from legalization of cannabis in multiple states, among burn patient population may lead to increased burden on already tenuous health care resources.

Rapid elimination of Carboxy-THC in a cohort of chronic cannabis users

Urinary 11-nor-Δ(9)-tetrahydrocannabinol-9-carboxylic acid (Carboxy-THC) concentrations, normalised to creatinine output, have been demonstrated to be a useful tool in the interpretation of the results of a series of urine tests for cannabis. These tests, often termed historical data, can be used to identify potential chronic cannabis users who may present occupational health and safety risks within the workplace. Conversely, the data can also be used to support employee claims of previous regular, rather than recent, cannabis use. This study aimed at examining the mean elimination of Carboxy-THC in 37 chronic users undergoing voluntary abstinence over a 2-week period. Urine specimens were collected prior to the study and after 1 and 2 weeks of abstinence. Carboxy-THC levels in urine were measured by gas chromatography-mass spectrometry (GC-MS) following alkaline hydrolysis, organic solvent extraction and derivatisation to form its pentafluoropropionic derivative. The creatinine-normalised Carboxy-THC concentrations declined rapidly over the 2 weeks of abstinence period and the majority of chronic cannabis users (73%) reduced their urinary Carboxy-THC levels to below the 15-μg/L confirmatory cutoff within that time. The study further highlights the value of historical urinary Carboxy-THC data as a means of identifying potential occupational health and safety risks among chronic cannabis users.

Mismatch negativity in tobacco-naïve cannabis users and its alteration with acute nicotine administration

Chronic cannabis use may interact with factors, such as age of onset of cannabis use, family history, and genetic factors, to elicit schizophrenia (SZ)-like symptoms, including sensory and cognitive deficits. However, evidence of a relationship between cannabis use and cognitive impairment is confounded by concomitant use of tobacco. The objective of this study was to compare tobacco-naïve cannabis users with individuals without a history of tobacco/cannabis use on the auditory mismatch negativity (MMN) event-related potential (ERP), a neural measure of auditory deviance detection which is diminished in SZ. An exploratory arm of the study, conducted within a randomized, double-blind, placebo controlled design, examined the acute effects of nicotine gum (6mg) on MMN in cannabis users. MMN was recorded in response to 5 deviant stimuli within an optimal MMN paradigm in 44 healthy, non-tobacco smoking volunteers aged 18-26. Cannabis users (n=21) started smoking cannabis prior to age 17, at least 1 joint per month. To examine the effects of chronicity, users were grouped into relatively heavy long-term (HLT; n=11) users and light short-term (LST; n=10) users. Impaired deviance detection was shown in cannabis users vs. nonusers as reflected by a smaller MMN to duration deviants. Chronicity of use was also associated with MMN alterations, as HLTs displayed a reduced duration and gap MMN vs. LSTs. Compared with placebo, nicotine treatment enhanced select MMN deviants in cannabis user subgroups. As deficits associated with early and persistent cannabis use are similar to those seen in SZ, these dose-dependant disturbances in early sensory processing with cannabis use may be one cognitive pathway which mediates an increased risk for SZ in vulnerable youth, and be influenced by concurrent cigarette smoking behavior.

Delay- and dose-dependent effects of Δ⁹-tetrahydrocannabinol administration on spatial and object working memory tasks in adolescent rhesus monkeys

Among adolescents, the perception that cannabis can cause harm has decreased and use has increased. However, in rodents, cannabinoid administration during adolescence induces working memory (WM) deficits that are more severe than if the same exposure occurs during adulthood. As both object and spatial WM mature in a protracted manner, although apparently along different trajectories, adolescent cannabis users may be more susceptible to impairments in one type of WM. Here, we evaluate the acute effects of a range of doses (30-240 μg/kg) of intravenous Δ⁹-tetrahydrocannabinol (THC) administration on the performance of spatial and object WM tasks in adolescent rhesus monkeys. Accuracy on the object WM task was not significantly affected by any dose of THC. In contrast, THC administration impaired accuracy on the spatial WM task in a delay- and dose-dependent manner. Importantly, the THC-induced spatial WM deficits were not because of motor or motivational impairments. These data support the idea that immature cognitive functions are more sensitive to the acute effects of THC.

Extended urinary Delta9-tetrahydrocannabinol excretion in chronic cannabis users precludes use as a biomarker of new drug exposure

BACKGROUND

Generally, urinary 11-nor-9-carboxy-Delta9-tetrahydrocannabinol (THCCOOH) after alkaline hydrolysis is monitored to detect cannabis exposure, although last use may have been weeks prior in chronic cannabis users. Delta9-Tetrahydrocannabinol (THC) and 11-hydroxy-THC (11-OH-THC) concentrations in urine following Escherichia coli beta-glucuronidase hydrolysis were proposed as biomarkers of recent (within 8h) cannabis use.

OBJECTIVE

To test the validity of THC and 11-OH-THC in urine as indicators of recent cannabis use.

METHODS

Monitor urinary cannabinoid excretion in 33 chronic cannabis smokers who resided on a secure research unit under 24h continuous medical surveillance. All urine specimens were collected individually ad libidum for up to 30 days, were hydrolyzed with a tandem E. coli beta-glucuronidase/base procedure, and analyzed for THC, 11-OH-THC and THCCOOH by one- and two-dimensional-cryotrap gas chromatography mass spectrometry (2D-GCMS) with limits of quantification of 2.5 ng/mL.

RESULTS

Extended excretion of THC and 11-OH-THC in chronic cannabis users' urine was observed during monitored abstinence; 14 of 33 participants had measurable THC in specimens collected at least 24h after abstinence initiation. Seven subjects had measurable THC in urine for 3, 3, 4, 7, 7, 12, and 24 days after cannabis cessation. 11-OH-THC and THCCOOH were detectable in urine specimens from one heavy, chronic cannabis user for at least 24 days.

CONCLUSION

For the first time, extended urinary excretion of THC and 11-OH-THC is documented for at least 24 days, negating their effectiveness as biomarkers of recent cannabis exposure, and substantiating long terminal elimination times for urinary cannabinoids following chronic cannabis smoking.

Implications of plasma Delta9-tetrahydrocannabinol, 11-hydroxy-THC, and 11-nor-9-carboxy-THC concentrations in chronic cannabis smokers

Delta(9)-Tetrahydrocannabinol (THC) is commonly found in toxicological specimens from driving under the influence and accident investigations. Plasma cannabinoid concentrations were determined in 18 long-term heavy cannabis smokers residing on an in-patient research unit for seven days of monitored abstinence. THC, 11-hydroxy-THC, and 11-nor-9-carboxy-THC (THCCOOH) were quantified by two-dimensional gas chromatography-mass spectrometry with cryofocusing. THC concentrations were > 1 ng/mL in nine (50.0%) participants (1.2-5.5 ng/mL) on abstinence day 7. THCCOOH was detected (2.8-45.6 ng/mL) in all participants on study day 7. THC and THCCOOH median percent concentration decreases (n = 18) were 39.5% and 72.9% from day 1 to 7, respectively. Most (88.9%) of the participants had at least one specimen with increased THC compared to the previous day. Cannabis use duration and plasma THCCOOH concentrations were positively correlated on days 1-3 (R = 0.584-0.610; p = 0.007-0.011). There were no significant correlations between THC concentrations > 0.25 ng/mL and body mass index on days 1-7 (R = -0.234-0.092; p = 0.350-0.766). Measurable THC concentrations after seven days of abstinence indicate a potential mechanism for residual neurocognitive impairment observed in chronic cannabis users. THC's presence in plasma for seven days of abstinence suggests its detection may not indicate recent use in daily cannabis users.

Urinary elimination of 11-nor-9-carboxy-delta9-tetrahydrocannnabinol in cannabis users during continuously monitored abstinence

The time course of 11-nor-9-carboxy-Delta9-tetrahydrocannnabinol (THCCOOH) elimination in urine was characterized in 60 cannabis users during 24 h monitored abstinence on a closed research unit for up to 30 days. Six thousand, one hundred fifty-eight individual urine specimens were screened by immunoassay with values > or = 50 ng/mL classified as positive. Urine specimens were confirmed for THCCOOH by gas chromatography-mass spectrometry following base hydrolysis and liquid-liquid or solid-phase extraction. In 60%, the maximum creatinine normalized concentration occurred in the first urine specimen; in 40%, peaks occurred as long as 2.9 days after admission. Data were divided into three groups, 0-50, 51-150, and > 150 ng/mg, based on the creatinine corrected initial THCCOOH concentration. There were statistically significant correlations between groups and number of days until first negative and last positive urine specimens; mean number of days were 0.6 and 4.3, 3.2 and 9.7, and 4.7 and 15.4 days, respectively, for the three groups. These data provide guidelines for interpreting urine cannabinoid test results and suggest appropriate detection windows for differentiating new cannabis use from residual drug excretion.

Pharmacokinetics of 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (CTHC) after intravenous administration of CTHC in healthy human subjects

After cannabis consumption there is only limited knowledge about the pharmacokinetic (PK) and metabolic properties of 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (CTHC), which is formed by oxidative breakdown from Delta(9)-tetrahydrocannabinol (THC). Despite widely-varying concentrations observed in smoking studies, attempts have been made to interpret consumption behavior with special regard to a cumulated or decreasing concentration of CTHC in serum. Ten healthy nonsmoking white male individuals received 5 mg CTHC intravenously over 10 min. Highest serum concentrations of CTHC were observed at the end of the infusion (336.8+/-61.7 microg/l) followed by a quick decline. CTHC concentration could be quantified up to 96 h after administration, with a terminal elimination half-life of 17.6+/-5.5 h. Total clearance was low (91.2+/-24.0 ml/min), with renal clearance having only a minor contribution (0.136+/-0.094 ml/min). This first metabolite-based kinetic approach will allow an advanced understanding of CTHC PKs data obtained in previous studies with THC.

Delta(9)-tetrahydrocannabinol, 11-hydroxy-delta(9)-tetrahydrocannabinol and 11-nor-9-carboxy-delta(9)-tetrahydrocannabinol in human plasma after controlled oral administration of cannabinoids

A clinical study to investigate the pharmacokinetics and pharmacodynamics of oral tetrahydrocannabinol was performed. This randomized, double-blind, placebo-controlled, within-subject, inpatient study compared the effects of THC-containing hemp oils in liquid and capsule form to dronabinol (synthetic THC) in doses used for appetite stimulation. The National Institute on Drug Abuse Institutional Review Board approved the protocol and each participant provided informed consent. Detection times and concentrations of THC, 11-hydroxy-Delta-tetrahydrocannabinol (11-OH-THC), and 11-nor-9-carboxy-Delta-tetrahydrocannabinol (THCCOOH) in plasma were determined by gas chromatography-mass spectrometry [limits of quantification (LOQ)=0.5, 0.5, and 1.0 ng/mL, respectively] after oral THC administration. Six volunteers ingested liquid hemp oil (0.39 and 14.8 mg THC/d), hemp oil in capsules (0.47 mg THC/d), dronabinol capsules (7.5 mg THC/d), and placebo. Plasma specimens were collected during and after each dosing condition. THC and 11-OH-THC concentrations were low and never exceeded 6.1 ng/mL. Analytes were detectable 1.5 hour after initiating dosing with the 7.5 mg THC/d regimen and 4.5 hour after starting the 14.8 mg THC/d sessions. THCCOOH was detected 1.5 hour after the first dose, except for the 0.47 mg THC/d session, which required 4.5 hour for concentrations to reach the LOQ. THCCOOH concentrations peaked at 3.1 ng/mL during dosing with the low-dose hemp oils. Plasma THC and 11-OH-THC concentrations were negative for all participants at all doses within 15.5 hours after the last THC dose. Plasma THCCOOH persisted for at least 39.5 hours after the end of dosing and at much higher concentrations (up to 43.0 ng/mL). This study demonstrated that subjects who used high THC content hemp oil (347 mug/mL) as a dietary supplement had THC and metabolites in plasma in quantities comparable to those of patients using dronabinol for appetite stimulation. There was a significant correlation between body mass index and Cmax and body mass index and number of specimens positive for THC and 11-OH-THC.

Pharmacokinetics and metabolism of the plant cannabinoids, delta9-tetrahydrocannabinol, cannabidiol and cannabinol

Increasing interest in the biology, chemistry, pharmacology, and toxicology of cannabinoids and in the development of cannabinoid medications necessitates an understanding of cannabinoid pharmacokinetics and disposition into biological fluids and tissues. A drug's pharmacokinetics determines the onset, magnitude, and duration of its pharmacodynamic effects. This review of cannabinoid pharmacokinetics encompasses absorption following diverse routes of administration and from different drug formulations, distribution of analytes throughout the body, metabolism by different tissues and organs, elimination from the body in the feces, urine, sweat, oral fluid, and hair, and how these processes change over time. Cannabinoid pharmacokinetic research has been especially challenging due to low analyte concentrations, rapid and extensive metabolism, and physicochemical characteristics that hinder the separation of drugs of interest from biological matrices--and from each other--and lower drug recovery due to adsorption of compounds of interest to multiple surfaces. delta9-Tetrahydrocannabinol, the primary psychoactive component of Cannabis sativa, and its metabolites 11-hydroxy-delta9-tetrahydrocannabinol and 11-nor-9-carboxy-tetrahydrocannabinol are the focus of this chapter, although cannabidiol and cannabinol, two other cannabinoids with an interesting array of activities, will also be reviewed. Additional material will be presented on the interpretation of cannabinoid concentrations in human biological tissues and fluids following controlled drug administration.

Urinary cannabinoid detection times after controlled oral administration of delta9-tetrahydrocannabinol to humans

BACKGROUND

Urinary cannabinoid excretion and immunoassay performance were evaluated by semiquantitative immunoassay and gas chromatography-mass spectrometry (GC/MS) analysis of metabolite concentrations in 4381 urine specimens collected before, during, and after controlled oral administration of tetrahydrocannabinol (THC).

METHODS

Seven individuals received 0, 0.39, 0.47, 7.5, and 14.8 mg THC/day in this double-blind, placebo-controlled, randomized, clinical study conducted on a closed research ward. THC doses (hemp oils with various THC concentrations and the therapeutic drug Marinol) were administered three times daily for 5 days. All urine voids were collected over the 10-week study and later tested by Emit II, DRI, and CEDIA immunoassays and by GC/MS. Detection rates, detection times, and sensitivities, specificities, and efficiencies of the immunoassays were determined.

RESULTS

At the federally mandated immunoassay cutoff (50 microg/L), mean detection rates were <0.2% during ingestion of the two low doses typical of current hemp oil THC concentrations. The two high doses produced mean detection rates of 23-46% with intermittent positive tests up to 118 h. Maximum metabolite concentrations were 5.4-38.2 microg/L for the low doses and 19.0-436 micro g/L for the high doses. Emit II, DRI, and CEDIA immunoassays had similar performance efficiencies of 92.8%, 95.2%, and 93.9%, respectively, but differed in sensitivity and specificity.

CONCLUSIONS

The use of cannabinoid-containing foodstuffs and cannabinoid-based therapeutics, and continued abuse of oral cannabis require scientific data for accurate interpretation of cannabinoid tests and for making reliable administrative drug-testing policy. At the federally mandated cannabinoid cutoffs, it is possible but unlikely for a urine specimen to test positive after ingestion of manufacturer-recommended doses of low-THC hemp oils. Urine tests have a high likelihood of being positive after Marinol therapy. The Emit II and DRI assays had adequate sensitivity and specificity, but the CEDIA assay failed to detect many true-positive specimens.

Pharmacokinetics and pharmacodynamics of cannabinoids

Delta(9)-Tetrahydrocannabinol (THC) is the main source of the pharmacological effects caused by the consumption of cannabis, both the marijuana-like action and the medicinal benefits of the plant. However, its acid metabolite THC-COOH, the non-psychotropic cannabidiol (CBD), several cannabinoid analogues and newly discovered modulators of the endogenous cannabinoid system are also promising candidates for clinical research and therapeutic uses. Cannabinoids exert many effects through activation of G-protein-coupled cannabinoid receptors in the brain and peripheral tissues. Additionally, there is evidence for non-receptor-dependent mechanisms. Natural cannabis products and single cannabinoids are usually inhaled or taken orally; the rectal route, sublingual administration, transdermal delivery, eye drops and aerosols have only been used in a few studies and are of little relevance in practice today. The pharmacokinetics of THC vary as a function of its route of administration. Pulmonary assimilation of inhaled THC causes a maximum plasma concentration within minutes, psychotropic effects start within seconds to a few minutes, reach a maximum after 15-30 minutes, and taper off within 2-3 hours. Following oral ingestion, psychotropic effects set in with a delay of 30-90 minutes, reach their maximum after 2-3 hours and last for about 4-12 hours, depending on dose and specific effect. At doses exceeding the psychotropic threshold, ingestion of cannabis usually causes enhanced well-being and relaxation with an intensification of ordinary sensory experiences. The most important acute adverse effects caused by overdosing are anxiety and panic attacks, and with regard to somatic effects increased heart rate and changes in blood pressure. Regular use of cannabis may lead to dependency and to a mild withdrawal syndrome. The existence and the intensity of possible long-term adverse effects on psyche and cognition, immune system, fertility and pregnancy remain controversial. They are reported to be low in humans and do not preclude legitimate therapeutic use of cannabis-based drugs. Properties of cannabis that might be of therapeutic use include analgesia, muscle relaxation, immunosuppression, sedation, improvement of mood, stimulation of appetite, antiemesis, lowering of intraocular pressure, bronchodilation, neuroprotection and induction of apoptosis in cancer cells.

Cannabis use: consistency and validity of self-report, on-site urine testing and laboratory testing

AIMS

To evaluate the agreement between adolescent self-reported cannabis use, "on-site" qualitative urine screening, and quantitative laboratory testing.

DESIGN

A cross-sectional study of intake and follow-up data from 248 adolescents entering substance abuse treatment for cannabis use disorders (abuse or dependence). This is part of the multi-site cooperative agreement Cannabis Youth Treatment study.

SETTING

Data collected from adolescents randomly assigned to one of five outpatient treatments at four sites: Operation PAR, Inc., Florida; Chestnut Health Systems, Illinois; University of Connecticut Health Center, Connecticut; and Children's Hospital of Philadelphia, Pennsylvania.

PARTICIPANTS

The data represent 248 unique individuals from a sample of 297 adolescents ranging in age from 12 to 18 years.

MEASUREMENTS

Prevalence, agreement, kappa, sensitivity, specificity, positive and negative predictive value.

FINDINGS

The self-report rates were higher at intake than either urine test (82.4% vs. 77.0% vs. 52.7%), but both lower and higher at the 3-month follow-up (55.5% vs. 70.0% vs. 47.3%) and 6-month follow-up (60.2% vs. 73.5% vs. 55.8%). The disagreements went in both directions and the kappa coefficients were only in the moderate range (0.4). Over two-thirds of these frequent cannabis users tested positive when they said they had not used in 1 week and one-third tested positive even though they said it had been more than 4 weeks since last use.

CONCLUSIONS

The findings suggest both the advantages of multiple sources of information and the need for further work on the latency of cannabis metabolites in clinical populations.

Drug and chemical metabolites in clinical toxicology investigations: the importance of ethylene glycol, methanol and cannabinoid metabolite analyses

Metabolic pathways in humans have been elucidated for most therapeutic drugs, drugs of abuse, and various chemical/solvents. In most drug overdose cases and chemical exposures, laboratory analysis is directed toward identification and quantitation of the unchanged drug or chemical in a biologic fluid such as serum or whole blood. Specifically, most clinical laboratories routinely screen and quantitate unchanged methanol and/or ethylene glycol in suspected poisonings without toxic metabolite analysis. Martin-Amat established in 1978 that methanol associated toxicity to the optic nerve in human poisonings was due to the toxic metabolite formic acid found in methanol poisonings and not due to the direct action by unchanged methanol. Jacobsen reported in 1981 that ethylene glycol central nervous system and renal toxicity were primarily due to one acidic metabolite (glycolic acid) and not due to unchanged ethylene glycol. The first objective of this review is to describe clinical experience with formic acid and glycolic acid analysis in methanol and ethylene glycol human poisonings. Drug metabolite analysis also provides useful information in the assessment and monitoring of drug use in psychiatry and substance abusing populations. Drug analysis in substance abuse monitoring is focused on urine analysis of one or more major metabolites, and less frequently on the unchanged drug(s). Serial monitoring of the major urinary cannabinoid metabolite (delta(9)-THC-COOH) to creatinine ratios in paired urine specimens (collected at least 24 h apart) could differentiate new marijuana or hashish use from residual cannabinoid metabolite excretion in urine after drug use according to Huestis. The second objective is to demonstrate that creatinine corrected urine specimens positive for cannabinoids may help differentiate new marijuana use from the excretion of residual delta(9) -THC-COOH in chronic users of marijuana or hashish. Analysis of toxic chemical metabolites are helpful in the assessment and treatment of chemical poisoning whereas serial monitoring of urinary cannabinoid metabolites are predictive of illicit drug use in the substance abusing population.

Determination of 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid in urine using high-performance liquid chromatography and electrospray ionization mass spectrometry

High-performance liquid chromatography with electrospray ionization mass spectrometry was used to determine 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) in urine. After basic hydrolysis of conjugates, the compound was extracted using SPEC-PLUS-3ML-C18 solid-phase extraction columns. A deuterium labelled internal standard (d3-THC-COOH) was added prior to hydrolysis. Separation was performed on a reversed-phase Zorbax Eclipse XDB-C8 analytical column (150x3.0 mm I.D.) using a gradient program from 60 to 80% acetonitrile (4 mM formic acid) at a flow-rate of 0.5 ml/min. The compounds were detected by single ion monitoring of m/z 345 and m/z 348 for the protonated molecules [THC-COOH+H]+ and [d3-THC-COOH+H]+, respectively. The precision and accuracy were tested on spiked urine samples in the range 2.5-125 ng/ml. The mean recovery was 95% (n = 58), coefficients of variations were 2.2-4.3% and the limit of detection 2 ng/ml. Diagnostic qualifying ions of THC-COOH (m/z 327 and m/z 299) and d3-THC-COOH (m/z 330) were generated using up-front collision-induced dissociation. The relative ion intensities in clinical samples (n = 21) were within +/-20% deviation compared with standards. Using this tolerance and the presence of the ions m/z 327 and m/z 299 at the correct retention times as the acceptance criteria for identification of THC-COOH positive samples, the limit of detection was 15 ng/ml. The LC-MS method complies with the current recommendations on drugs of abuse testing, in which mass spectrometric detection is emphasized.

Urinary excretion half-life of 11-nor-9-carboxy-delta9-tetrahydrocannabinol in humans

The excretion of marijuana metabolites occurs over an extended period of time, yet few studies have been designed for accurate estimation of excretion half-lives. The authors monitored excretion of the primary urinary metabolite of marijuana, 11-nor-9-carboxy-delta9-tetrahydrocannabinol (THCCOOH), by gas chromatography-mass spectrometry in a controlled clinical study of marijuana smoking that included measurement of the drug in each urine void collected during the 3-week study. Terminal excretion half-lives of THCCOOH were determined in six healthy male subjects with histories of marijuana smoking; the study was conducted on the clinical research unit of a major medical institution. Subjects smoked a single marijuana cigarette (placebo, 1.75% or 3.55% THC) each week. Urine specimens (N=953) were analyzed under blind conditions for THCCOOH by gas chromatography-mass spectrometry. Mean+/-SEM half-lives calculated by the amount remaining to be excreted method after the low and high doses were 31.5+/-1.0 hours (range, 28.4 to 35.3 hours) and 28.6+/-1.5 hours (range, 24.9 to 34.5 hours), respectively, when a 7-day monitoring period was used. The amounts of THCCOOH excreted over a 7-day period were 93.9 +/-24.5 microg (range, 34.6 to 171.6 microg) and 197.4+/-33.6 microg after the low- and high-dose sessions. Longer half-lives, 44.3 to 59.9 hours, were obtained with a 14-day sample collection. This study documents the prolonged excretion of THCCOOH in urine and emphasizes the importance of study design in the precise estimation of terminal excretion half-lives. A sensitive analytical method and a prolonged specimen collection period are important study considerations in the monitoring of marijuana excretion.

Screening for drugs of abuse (II): Cannabinoids, lysergic acid diethylamide, buprenorphine, methadone, barbiturates, benzodiazepines and other drugs

Requirements for the provision of an efficient and reliable service for drugs of abuse screening in urine have been summarized in Part I of this review. The requirements included rapid turn-around times, good communications between requesting clinicians and the laboratory, and participation in quality assessment schemes. In addition, the need for checking/confirmation of positive results obtained for preliminary screening methods was stressed. This aspect of the service has assumed even greater importance with widespread use of dip-stick technology and the increasing number of reasons for which drug screening is performed. Many of these additional uses of drug screening have possible serious legal implications, for example, screening school pupils, professional footballers, parents involved in child custody cases, persons applying for renewal of a driving licence after disqualification for a drug-related offence, doctors seeking re-registration after removal for drug abuse, and checking for compliance with terms of probation orders; as well as pre-employment screening and work-place testing. In many cases these requests will be received from a general practitioner or drug clinic with no indication of the reason for which testing has been requested. This also raises the serious problems of a chain of custody, provision of two samples, stability of samples, and secure and lengthy storage of samples in the laboratory-samples may be requested by legal authorities several months after the initial testing. The need for confirmation of positive results is now widely accepted but it may be equally important to confirm unexpected negative results. Failure to detect the presence of maintenance drugs may lead to the patient being discharged from a drug treatment clinic and, if attendance at the clinic is one of the terms of continued employment, to dismissal. It seems likely that increasing abuse of drugs and the efforts of regulatory authorities to control this, will lead to the manufacture of more designer drugs. Production of substituted phenethylamines was facilitated by the drug makers' cook book, 'PIHKAL' (Phenethylamines I Have Known And Loved) by Dr Alexander Shulgin and Ann Shulgin, and production of substituted tryptamines is promised in their next book, TIHKAL. Looking to the future, laboratories will need to ensure that they can detect and quantitate an ever-increasing number of drugs and related substances. The question of confidence in results of drugs of abuse testing raised in 1993 by Watson has assumed even greater importance as a result of attention focused on the OJ Simpson trial in Los Angeles. Toxicological investigations are likely to be challenged more frequently in the future. Even if analyses have been performed by GC-MS, there is a need to establish the level of match between the spectrum of the unknown substance and a library spectrum which is considered acceptable for legal purposes. It will also be essential to ensure that computer libraries contain spectra for all substances likely to be encountered in drugs of abuse screening.