Relationships between several pharmacokinetic parameters and psychometric indices of subjective effects of delta 9-tetrahydrocannabinol in man

Acute subjective effects after smoking joints containing up to 69 mg Δ9-tetrahydrocannabinol in recreational users: a randomized, crossover clinical trial

RATIONALE

An increase in the potency of the cannabis cigarettes has been observed over the past three decades.

OBJECTIVES

In this study, we aimed to establish the impact of Δ9-tetrahydrocannabinol (THC) on the rating of subjective effects (intensity and duration of the effects), up to 23 % THC potency (69 mg THC) among recreational users.

METHODS

Recreational users (N = 24) smoked cannabis cigarettes with four doses of THC (placebo 29, 49 and 69 mg of THC) on four separate test days in a randomized, double-blind, placebo-controlled, crossover study. The participants filled in three different questionnaires measuring subjective effects during the exposure up to 8 h post-smoking. The 'high' feeling, heart rate, blood pressure and THC serum concentrations were also regularly recorded during these 8 h.

RESULTS

THC significantly increased the high feeling, dizziness, dry-mouthed feeling, palpitations, impaired memory and concentration, and 'down', 'sedated' and 'anxious' feelings. In addition, THC significantly decreased alertness, contentment and calmness. A cubic relationship was observed between 'feeling the drug' and 'wanting more'. The THC-induced decrease in 'feeling stimulated' and increase in anxiety lasted up to 8 h post-smoking. Sedation at 8 h post-smoking was increased by a factor of 5.7 with the highest THC dose, compared to the placebo.

CONCLUSIONS

This study shows a strong effect of cannabis containing high percentages of THC on the rating of subjective effects. Regular users and forensic toxicologists should be aware that the THC-induced increase in 'feeling sedated' continues longer with a 69 mg THC dose than with a 29 mg THC dose.

Cannabinoid self-administration in rats: sex differences and the influence of ovarian function

BACKGROUND AND PURPOSE

We recently demonstrated the existence of strain differences in self-administration of the cannabinoid CB1 receptor agonist WIN55,212-2 (WIN) by Long Evans (LE) and Lister Hooded (LH) but not Sprague-Dawley (SD) male rats. This follow-up study is aimed at verifying whether sex and ovarian hormones might also be critical factors in the initiation, retention and extinction of WIN self-administration.

EXPERIMENTAL APPROACH

LE, LH and SD male and female rats, the latter either intact or bilaterally ovariectomized (OVX), were trained to self-administer WIN (12.5 microg kg(-1) per infusion) under a FR1 reinforcement schedule, using lever-pressing.

KEY RESULTS

Data showed that contrary to the findings in SD rats, LE and LH rats developed robust cannabinoid intake, with rates of responding for WIN being constantly higher in intact females than in males (+45 and +42% for LE and LH strains, respectively). In comparison with intact females, OVX females of both strains acquired self-administration at lower rates, displaying slower acquisition, lower drug intake (-42 and -52% for LE and LH, respectively) and longer extinction.

CONCLUSIONS AND IMPLICATIONS

These findings provide the first evidence of significant sex differences in cannabinoid self-administration, females acquiring stable WIN intake at higher rates and more rapidly than males. Moreover, when compared to intact females, a lower percentage of LE and LH OVX rats acquired and maintained stable drug intake, suggesting that ovarian hormones might represent a critical factor in modulating the reinforcing effect of cannabinoids.

Sex differences in behavioral effects of cannabinoids

This review summarizes the existing literature on sex differences in the effects of cannabinoid drugs on behavior, primarily in the adult rodent. These preclinical studies, taken together with preliminary reports of sex differences in cannabinoid effects in humans, suggest that sex of subject may be an important modulating factor in a variety of cannabinoid effects. When sex differences are found, females are usually more sensitive than males to cannabinoids. Both pharmacokinetic and pharmacodynamic variables may contribute to sex differences in behavioral effects of cannabinoids. Given the significant therapeutic potential of cannabinoid agonists and antagonists--as well as their widespread recreational use--it will be important to determine the reliability and functional significance of, as well as mechanisms underlying sex differences in cannabinoid effects.

Being stoned: a review of self-reported cannabis effects

Although there has been considerable research into the adverse effects of cannabis, less attention has been directed toward subjective effects that may be associated with ongoing cannabis use. Examination of self-reported cannabis effects is an important issue in understanding the widespread use of cannabis. While reviews have identified euphoria as a primary factor in maintaining cannabis use, relaxation is the effect reported most commonly in naturalistic studies of cannabis users, irrespective of the method used. Self-reported effects in 12 naturalistic and 18 laboratory studies were compared. Regardless of methodology there was considerable variation in the effects experienced. Variation has been reported in terms of opposite effects being experienced by different individuals, variation of effects by individuals within a single occasion and between occasions of use. Factors that might explain this variation are outlined. Limitations of the available literature and suggested directions for future research are discussed. [Green B, Kavanagh D, Young R. Being stoned: a review of self-reported cannabis effects.

Electroencephalographic correlates of marihuana-induced euphoria

The present study was conducted to determine if there is a neurophysiological correlate of marihuana-induced good effects or euphoria. Three groups of 6 male occasional marihuana smokers were prepared for electroencephalographic (EEG) recording and smoked either placebo or marihuana cigarettes containing 1.26% or 2.53% delta 9-tetrahydrocannabinol (delta 9-THC) in a controlled laboratory setting. Using a continuously available non-verbal joystick device and a questionnaire, subjects reported changes in their subjective mood state while EEG activity was continuously recorded. Subjects reported multiple episodes of intense good effects or euphoria during the first 15 min after marihuana. These episodes of euphoria occurred while plasma delta 9-THC levels were rapidly rising. EEG alpha power during these discrete episodes of euphoria was significantly higher suggesting that these transient EEG changes may reflect a neurophysiological correlate of the reinforcing effects of marihuana.

Acute marijuana effects on social conversation

The present study assessed the acute effects of smoked marijuana on social conversation. Speech quantity was recorded continuously in seven moderate marijuana users during separate 1 h experimental sessions following the paced smoking of 0, 1.01, 1.84, and 2.84% THC marijuana cigarettes. Subjects engaged in conversation with undrugged partners who smoked placebo marijuana cigarettes. The active marijuana produced significant decreases in speech quantity, increases in heart rate, and increases in self-reports of "high" and sedation. Partners showed no effects in speech quantity or self-reports of drug effects that were systematically related to the doses administered to the subject pair members. The effects on speech quantity observed in the present study after acute dosing are similar to the effects on social conversation reported previously during chronic marijuana dosing. Marijuana appears to be an exception to the general rule that drugs of abuse increase verbal interaction.