Passive consumption of marijuana through milk: a low level chronic exposure to delta-9-tetrahydrocannabinol(THC)

Cannabis sativa grows abundantly among other natural vegetation in the northern part of Pakistan. Buffalo, the common dairy animals of the region, are allowed to graze upon this vegetation. These animals ingest significant amounts of marijuana, which after absorption is metabolized into a number of psychoactive agents which are ultimately excreted through the urine and milk. This potentially contaminated milk is used by the people of the region. Depending upon the amount of milk ingested and the degree of contamination, the milk could result in a low to moderate level of chronic exposure to Delta-9-Tetrahydrocannabinol (THC) and other metabolites especially among the children raised on this milk. This research was conducted to investigate the extent of passive consumption of marijuana by the consumers of potentially contaminated milk. Urine and milk specimens were obtained from buffalo and were analyzed for 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) which is a major metabolite for THC. The analysis was done by using gas chromatography/mass spectrometry. It was observed that during the months of June and July, 60 percent of the buffalo contained detectable levels of THC-COOH in their urine and 50 percent of these animals produced milk which was contaminated with THC or other metabolites. Analysis of the urine obtained from children with ages ranging from six months to 3 years, who were being raised on the milk from these animals, indicated that 29 percent of them had low levels of THC-COOH in their urine.(ABSTRACT TRUNCATED AT 250 WORDS)     

Neuropsychopharmacology of delta-9-tetrahydrocannabinol

Today, the main route of introduction of tetrahydrocannabinol (THC), the main active substance of cannabis, into the human body is via the lungs, from smokes produced by combustion of a haschich-tobacco mixture. The use of a water pipe (nargileh-like) intensifies its fast supply to the body. THC reaches the brain easily where it stimulates CB1 receptors; their ubiquity underlies a wide variety of effects. THC disappears from extracellular spaces by dissolving in lipid rich membranes, and not by excretion from the body. This is followed by a slow release, leading to long lasting effects originating from brain areas containing a large proportion of spare receptors ("reserve receptors"). Far from mimicking the effects of endocannabinoids, THC caricatures and disturbs them. It induces both psychical and physical dependencies, but the perception of withdrawal is weak on account of its very slow elimination. THC disturbs cognition. Acutely, it develops anxiolytic- and antidepressant-like effects, which causes a lot of users to abuse THC, thus leading to a tolerance (desensitization of CB1 receptors) making anxiety and depression to reappear more intensely than originally. THC has close relationships with schizophrenia. It incites to tobacco, alcohol and heroine abuses.     

Metabolism of n-hexyl-homologues of delta-8-tetrahydrocannabinol and delta-9-tetrahydrocannabinol in the mouse

n-Hexyl-delta-8-tetrahydrocannabinol (n-hexyl-delta-8-THC) and n-hexyl-delta-9-THC were synthesized by condensation of (1S)-cis-verbenol with 5-n-hexyl-1,3-dihydroxybenzene and administered intraperitoneally to male Charles-River CD-1 mice. Hepatic metabolites were isolated by solvent extraction and chromatography on Sephadex LH-20 and identified by GC/MS. Eleven metabolites were identified from n-hexyl-delta-8-THC and sixteen from n-hexyl-delta-9-THC. The pattern of metabolites was intermediate between that previously observed from the pentyl homologues and that from n-heptyl-delta-9-THC with the major biotransformation pathway being hydroxylation and oxidation at C-11. Other metabolites were mainly hydroxylated derivatives of these compounds. Metabolites containing two hydroxy groups in the side-chain were present in low concentration. These have not been observed from lower homologues but are major metabolites of n-heptyl-delta-9-THC. Compared with the metabolism of the n-pentyl homologue, there was a trend towards the production of more hydroxy metabolites at the expense of carboxylic acids, in keeping with the general reduction of oxidation observed with other homologous cannabinoids as the chain length increases.     

Shock-elicited fighting and delta-9-tetrahydrocannabinol

The frequency with which electric shock to the feet elicited fighting in five pairs of albino rats was not altered significantly by intraperitoneal injections of delta-9-tetrahydrocannabinol (THC) in doses ranging from 0.064–6.4 mg/kg, although chlordiazepoxide reduced the frequency of such fighting in a dose-related manner. This finding held true despite manipulations of THC vehicle, injection-test interval, and the previous drug experience of the subjects. In contrast, doses of 4.0 mg/kg produced a striking reduction in lever-pressing maintained by an FI 60 schedule of food reinforcement.     

Tissue glutathione levels in mice treated with delta-9-tetrahydrocannabinol.

Glutathione (GSH) is widely distributed among living cells and is involved in many biological functions. It provides the sulfhydryl groups for conjugation of toxic metabolites of several xenobiotica. Acetaminophen (Tylenol) toxicity is a classical example of this property. For this purpose, we studied the effects of delta-9-tetrahydrocannabinol (THC) on tissue levels of GSH in the mice. Groups of male Swiss Webster mice weighing 25 +/- 5 g were treated with 50 mg/kg, PO THC at 1300 h. Control mice were given equal volume of sesame oil (5 ml/kg, PO) which was the vehicle for THC. Ninety minutes following THC administration, mice were sacrificed, their plasma, brain, heart, liver, kidney and testis were collected. All tissues were homogenized in 5% TCA/EDTA solution and supernatant solutions of these homogenates were diluted. In these diluted samples, levels of GSH were determined by a modified spectrophotometric procedure and the GSH levels were expressed as micromoles of GSH/g tissue. In this study, THC caused no effects on GSH levels in brain, heart, testis and plasma. However, GSH levels in liver and kidney were decreased by 14% and 7% respectively. Although the decrease in kidney GSH levels were insignificant, these changes in liver and kidney could be indicative of a possible metabolic and/or dispositional interaction between THC and different commonly available drugs such as acetaminophen.     

Penetration of delta-9-tetrahydrocannabinol and 11-OH-delta-9-tetrahydrocannabinol through the Blood-brain Barrier

Abstract The relative brain uptake (extraction into brain) of delta-9-tetrahydro-cannabinol (delta-9-THC) and the primary metabolite 11-OH-delta-9-tetrahydrocannabinol (11-OH-delta-9-THC) was measured after close intracarotid injection in rats of radiolabelled moities using labelled antipyrine as reference. The extraction percentage was of the same magnitude when injections were given in saline, 66 ± 11 % and 70 ± 9 % respectively after 5 sec., 59 ± 4 and 67 ± 8 respectively after 15 sec. While the extraction of 11-OH-delta-9-THC was the same when injected into plasma, the extraction of delta-9-THC was only about half of the extraction from saline, and also half the extraction of the metabolite from plasma. The higher uptake quantity of the metabolite into the brain may account for the relatively greater effect on the central nervous system of the metabolite than of the parent compound at equal concentrations in plasma. Moreover our experiments demonstrate that 11-OH-delta-9-THC formed in the liver after cannabis (delta-9-THC) administration may exert significant brain effects.     

Passive inhalation of cannabis smoke

Six volunteers each smoked simultaneously, in a small unventilated room (volume 27 950 litre), a cannabis cigarette containing 17·1 mg Δ⁹-tetrahydrocannabinol (THC). A further four subjects – passive inhalers – remained in the room during smoking and afterwards for a total of 3 h. Blood and urine samples were taken from all ten subjects and analysed by radioimmunoassay for THC metabolites. The blood samples from the passive subjects taken up to 3 h after the start of exposure to cannabis smoke showed a complete absence of cannabinoids. In contrast, their urine samples taken up to 6 h after exposure showed significant concentrations of cannabinoid metabolites (≤6·8 ng ml^?1). These data, taken with the results of other workers, show passive inhalation of cannabis smoke to be possible. These results have important implications for forensic toxicologists who are frequently called upon to interpret cannabinoid levels in body fluids.     

Anticonvulsant activity of delta-8- and delta-9-tetrahydrocannabinol in rats

Intraperitoneal injections of Δ⁸-tetrahydrocannabinol (THC) and Δ⁹-THC, two major psychoactive constituents of cannabis, produced dose-related protection against tonic extension induced by electroshock in rats. The cannabinoids provided protection against clonic convulsions induced by pentylenetetrazol (Metrazol) only at very high and sometimes lethal doses, and the protection was quantal rather than dose-related. The two isomers of the THC were equipotent in terms of behavioral toxicity and protection against tonic convulsions. However, the significance of the drugs' anticonvulsant activity must be qualified by the observatin that protection was provided by either drug only at doses producing marked toxic behavioral reactions.     

Delta-9-tetrahydrocannabinol content and human marijuana self-administration

The role of marijuana delta-9-tetrahydrocannabinol (THC) content in controlling marijuana smoking behavior was examined in ten regular marijuana smokers. Each subject was allowed to self-administer marijuana of low, medium or high THC content freely over a 30-min period. Each potency of marijuana was color coded, and subjects smoked each potency on five separate occasions to provide the opportunity for them to learn from prior exposures the relative potencies of each marijuana type. Total intake of marijuana smoke during each session was estimated by measuring the post-smoking increase in expired air carbon monoxide (CO) level. Measures of marijuana effect included heart rate and standardized subjective effects scales. There were no differences among the three potencies of marijuana in post-smoking CO boost, and all measures that were sensitive to marijuana showed a clear dose response. Tolerance was observed over the course of the study to the heart-rate increasing effect of marijuana. These results indicate that subjects failed to regulate their intake of marijuana smoke in response to substantial (4-fold) changes in marijuana THC content.     

The identification, isolation, and preservation of delta-9-tetrahydrocannabinol (delta-9-THC)

(—)-trans-Δ⁹-Tetrahydrocannabinol (Δ⁹-THC) was isolated from marihuana plant extract, by adsorptive column and glc. The adsorptive column chromatography method consisted of chromatographing marihuana extract on a column packed with a mixture of silica gel (gas chromatography grade (100/120 mesh), silver nitrate and calcium sulphate (CaSO₄·H₂O) (3:1:0·5) with benzene as the eluting solvent. The glc method consisted of chromatographing the extract on a 3 ft silanized glass column (3/8 inch o.d.) packed with 1·5 ft of 2% QF-1 and 1·5 ft of 2% OV-17 on chromosorb W, AW 30–60 mesh, prep grade. A purity of 99% for the isolated Δ⁹-THC was confirmed by infrared spectroscopy, nuclear magnetic resonance, mass spectroscopy. The effects of storage conditions on Δ⁹-THC stability, monitored by glc, indicated the best method for preserving Δ⁹-THC was at 0°, protected from light, stored under nitrogen.     

Ethanol and delta-9-tetrahydrocannabinol: Mechanism for cross-tolerance in mice

The pharmacological interaction between equipotent doses of ethanol (1.35 g/kg) and delta-9-tetrahydrocannabinol (THC, 17 mg/kg) was evaluated in mice using rotarod performance as a measure of drug action. Tolerance to the effects of ethanol and THC as well as a symmetrical cross-tolerance between these two drugs was demonstrated. Ethanol elimination was not altered by previous treatment with either ethanol or THC as determined by measuring blood ethanol concentrations with an enzymatic assay. THC metabolite ratios in blood, brain and liver tissues determined after a dose of ³H-THC demonstrated that THC treatment had no effect upon THC metabolism or disposition. Ethanol treatment altered the distribution of THC and also altered hepatic THC metabolism as evidenced by the occurrence of increased proportions of polar THC metabolites. No treatment regimens produced lower whole brain levels of subsequent ethanol or THC suggesting that tolerance to ethanol or THC and cross-tolerance between these two drugs does not develop due to lower brain concentrations. A vehicle effect was shown when treatment with a mixture of propylene glycol and Tween-80 altered the metabolic and behavioral effects of subsequently administered THC.     

The effect of delta-9-tetrahydrocannabinol and 11-hydroxy-delta-9-tetrahydrocannabinol on T-lymphocyte and B-lymphocyte mitogen responses

Previous studies have shown that delta-9-tetrahydrocannabinol (THC) suppresses T-lymphocyte proliferation when added to human cell cultures. We report that THC when added to mouse splenocyte cultures suppressed T-lymphocyte (Con A, PHA) and B-lymphocyte (LPS) mitogen-induced proliferation. Although the ED50 concentrations (5 micrograms/ml; 1.6 X 10(-5)M) of THC were similar for suppressing all three mitogen responses, higher threshold concentrations of drug were required to effect suppression of the T-lymphocyte mitogen responses. Complete suppression of T- and B-lymphocyte responses was achieved with THC concentrations (8 micrograms/ml or 2.6 X 10(-5)M) which were not directly toxic as judged by vital dye exclusion. The hydroxylated metabolite of THC, 11-hydroxy-THC, was observed to be much less potent in the inhibition of lymphocyte proliferation. However, as with the parent compound, B-lymphocyte responses appeared to be the most affected by the drug. Additional studies demonstrated that both T- and B-lymphocyte proliferation is rapidly suppressed following THC treatment, not affected by a 24 hr. pretreatment with THC, and not as readily suppressed by THC in cultures containing 20% serum. Thus, THC appears to inhibit both T- and B-lymphocyte proliferation with B-lymphocyte responses displaying greater inhibition at lower drug concentration. The 11-hydroxy metabolite is much less suppressive in this system than the parent compound.     

Chronic marijuana smoke exposure in the rhesus monkey. IV: Neurochemical effects and comparison to acute and chronic exposure to delta-9-tetrahydrocannabinol (THC) in rats.

THC is the major psychoactive constituent of marijuana and is known to produce psychopharmacological effects in humans. These studies were designed to determine whether acute or chronic exposure to marijuana smoke or THC produces in vitro or in vivo neurochemical alterations in rat or monkey brain. For the in vitro study, THC was added (1-100 nM) to membranes prepared from different regions of the rat brain and muscarinic cholinergic (MCh) receptor binding was measured. For the acute in vivo study, rats were injected IP with vehicle, 1, 3, 10, or 30 mg THC/kg and sacrificed 2 h later. For the chronic study, rats were gavaged with vehicle or 10 or 20 mg THC/kg daily, 5 days/week for 90 days and sacrificed either 24 h or 2 months later. Rhesus monkeys were exposed to the smoke of a single 2.6% THC cigarette once a day, 2 or 7 days a week for 1 year. Approximately 7 months after the last exposure, animals were sacrificed by overdose with pentobarbital for neurochemical analyses. In vitro exposure to THC produced a dose-dependent inhibition of MCh receptor binding in several brain areas. This inhibition of MCh receptor binding, however, was also observed with two other nonpsychoactive derivatives of marijuana, cannabidiol and cannabinol. In the rat in vivo study, we found no significant changes in MCh or other neurotransmitter receptor binding in hippocampus, frontal cortex or caudate nucleus after acute or chronic exposure to THC. In the monkey brain, we found no alterations in the concentration of neurotransmitters in caudate nucleus, frontal cortex, hypothalamus or brain stem.(ABSTRACT TRUNCATED AT 250 WORDS)     

Plasma concentrations of delta-9-tetrahydrocannabinol and impaired motor function

Fifty-nine volunteer subjects were allowed to smoke marijuana cigarettes until a satisfactory level of 'high' was obtained. They then had blood samples taken 5, 30, 90 and 150 min following smoking after which they were tested with the roadside sobriety test. Attempts to correlate passing or failing on three coordination tests with plasma concentrations of delta-9-tetrahydrocannabinol (THC) showed that if concentrations measured at 5 min were ignored, failures were almost inevitably associated with plasma concentrations of THC above 25-30 ng/ml. Overall, 94% of subjects failed to pass the test 90 min after smoking and 60% after 150 min, despite the fact that by then plasma concentrations were rather low. It would seem that establishing a clear relation between THC plasma concentrations and clinical impairment will be much more difficult than it has been for alcohol.     

Delta-9-tetrahydrocannabinol levels in street samples of marijuana and hashish: correlation to user reactions.

In a 6-year period, 435 alleged cannabis samples were accessioned by an urban street drug analysis program, and clinical histories were correlated with laboratory results. The most common reason for submission of a sample was suspicion of adulteration; however, such samples were usually unadulterated but had high potency as measured by delta 9-tetrahydrocannabinol concentration. Adverse reactions occurring in nonadulterated samples were not associated with high potencies. The validity of cannabis products distributed illicitly and analyzed was over 94%. Exotic varieties were more potent than less expensive cannabis. The absolute amount of delta 9-tetrahydrocannabinol ranged from 1.5 to 144.9 mg.     

Synergistic affective analgesic interaction between delta-9-tetrahydrocannabinol and morphine

Evidence for an analgesic interaction between delta-9-tetrahydrocannabinol (Delta(9)-THC) and morphine was sought using an experimental pain model applied to normal volunteers. The study incorporated a double blinded, four treatment, four period, four sequence, crossover design. Subjects received Delta(9)-THC 5 mg orally or placebo and 90 min later morphine 0.02 mg/kg intravenously or placebo. Fifteen minutes later subjects rated the pain associated with the application of thermal stimuli to skin using two visual analog scales, one for the sensory and one for the affective aspects of pain. Among sensory responses, neither morphine nor Delta(9)-THC had a significant effect at the doses used, and there was no significant interaction between the two. Among affective responses, although neither morphine nor Delta(9)-THC had a significant effect, there was a positive analgesic interaction between the two (p = 0.012), indicating that the combination had a synergistic affective analgesic effect. The surprisingly limited reported experimental experience in humans does not support a role for Delta(9)-THC as an analgesic or as an adjunct to cannabinoid analgesia, except for our finding of synergy limited to the affective component of pain. Comparison of our results with those of others suggests that extrapolation from experimental pain models to the clinic is not likely to be a straight-forward process. Future studies of Delta(9)-THC or other cannabinoids in combination with opiates should focus upon clinical rather than experimental pain.     

Effects of delta-9-tetrahydrocannabinol on evaluation of emotional images

There is growing evidence that drugs of abuse alter processing of emotional information in ways that could be attractive to users. Our recent report that Δ(9)-tetrahydrocannabinol (THC) diminishes amygdalar activation in response to threat-related faces suggests that THC may modify evaluation of emotionally-salient, particularly negative or threatening, stimuli. In this study, we examined the effects of acute THC on evaluation of emotional images. Healthy volunteers received two doses of THC (7.5 and 15 mg; p.o.) and placebo across separate sessions before performing tasks assessing facial emotion recognition and emotional responses to pictures of emotional scenes. THC significantly impaired recognition of facial fear and anger, but it only marginally impaired recognition of sadness and happiness. The drug did not consistently affect ratings of emotional scenes. THC's effects on emotional evaluation were not clearly related to its mood-altering effects. These results support our previous work, and show that THC reduces perception of facial threat. Nevertheless, THC does not appear to positively bias evaluation of emotional stimuli in general.     

Effects of delta-9-tetrahydrocannabinol, 11-hydroxy-delta-9-tetrahydrocannabinol and cannabidiol on neuromuscular transmission in the frog

Intracellular recording techniques were used on neuromuscular junctions of the sartorius muscle of the frog, in vitro, to define the synaptic pharmacology of delta-9-tetrahydrocannabinol (THC), 11-hydroxy-THC and cannabidiol (CBD). The frequency of miniature endplate potentials was increased by THC, decreased by CBD and was unaffected by 11-hydroxy-THC, whereas the amplitude of the miniature endplate potentials was depressed by all three cannabinoids. In addition, the mean quantum content of the endplate potential (m) was first increased and then decreased by THC and 11-hydroxy-THC, but CBD produced only depression. Changes in m and the frequency of the miniature endplate potential indicated presynaptic sites of drug action and reduction of the amplitude of the miniature endplate potential suggested a postsynaptic site. The findings suggest possible mechanisms of action for the central excitatory and depressant properties of the cannabinoids.     

Rectal bioavailability of delta-9-tetrahydrocannabinol from various esters.

The bioavailability of delta-9-tetrahydrocannabinol (delta 9-THC) from suppository formulations containing several polar esters was studied. The esters tested were the hemisuccinate, N-formyl alaninate, N-methyl carbamate, and methoxy acetate. These esters were administered to monkeys in both lipophilic and hydrophilic suppository bases, namely, Witepsol H15 and polyethylene glycol, respectively. Each suppository contained a dose equivalent to 10 mg delta 9-THC. Blood samples were analyzed for both delta 9-THC and its carboxylic acid metabolite (ll-nor-delta 9-THC-9-COOH) using gas chromatography/mass spectrometry. The data showed that, with the exception of the hemisuccinate, no delta 9-THC or its metabolite was detected in the blood samples using the Witepsol H15. Using polyethylene glycol, low levels of delta 9-THC and its metabolite were detected in blood for all esters tested. The levels, however, were lower than those observed with delta 9-THC hemisuccinate using Witepsol H15. Subsequent studies in the conscious dog using the hemisuccinate in Witepsol H15 showed 67% bioavailability of delta 9-THC with a linear response in the dose range equivalent to 5-20 mg of delta 9-THC. No significant bioavailability differences were found when delta 9-THC hemisuccinate ester was administered in various lipophilic bases (Hydrokote 25, Kaomel, Suppocire AIML, and Witepsol H15).     

Cannabinoid concentrations in plasma after passive inhalation of marijuana smoke

delta-9-tetrahydrocannabinol (THC) and its metabolite, 9-carboxy-THC, were detected in the plasma of a subject during a one-hour passive exposure to the smoke from four marijuana cigarettes containing a total of 104.8 mg of THC. Plasma concentrations of THC were determined by RIA and reached an apparent steady-state concentration of 2.2 ng/mL after 20 minutes of exposure. The presence of THC was confirmed by GC/MS analysis. Results from the two analyses exhibited excellent correlation (r = 0.990), although the concentrations determined by GC/MS were higher than those determined by RIA. Concentrations of 9-carboxy-THC were also determined by GC/MS, and remained consistently below the GC/MS determined concentrations of THC. By administering an infusion of THC, the dose that was inhaled and absorbed during the passive exposure was estimated to be 3.2 micrograms/min.