Influence of fasting on the absorption and effects of delta9-tetrahydrocannabinol after oral administration in sesame oil

Pharmacokinetics of Cannabis and Its Derivatives in Animals and Humans During Pregnancy and Breastfeeding

Cannabis is one of the most widely used illicit drugs during pregnancy and lactation. With the recent legalization of cannabis in many countries, health professionals are increasingly exposed to pregnant and breastfeeding women who are consuming cannabis on a regular basis as a solution for depression, anxiety, nausea, and pain. Cannabis consumption during pregnancy can induce negative birth outcomes such as reduced birth weight and increased risk of prematurity and admission to the neonatal intensive care unit. Yet, limited information is available regarding the pharmacokinetics of cannabis in the fetus and newborn exposed during pregnancy and lactation. Indeed, the official recommendations regarding the use of cannabis during these two critical development periods lack robust pharmacokinetics data and make it difficult for health professionals to guide their patients. Many clinical studies are currently evaluating the effects of cannabis on the brain development and base their groups mostly on questionnaires. These studies should be associated with pharmacokinetics studies to assess correlations between the infant brain development and the exposure to cannabis during pregnancy and breastfeeding. Our project aims to review the available data on the pharmacokinetics of cannabinoids in adults, neonates, and animals. If the available literature is abundant in adult humans and animals, there is still a lack of published data on the exposure of pregnant and lactating women and neonates. However, some of the published information causes concerns on the exposure and the potential effects of cannabis on fetuses and neonates. The safety of cannabis use for non-medical purpose during pregnancy and breastfeeding needs to be further characterized with proper pharmacokinetic studies in humans feasible in regions where cannabis has been legalized. Given the available data, significant transfer occurs to the fetus and the breastfed newborn with a theoretical risk of accumulation of products known to be biologically active.

Cannabinoids, the endocannabinoid system, and pain: a review of preclinical studies

ABSTRACT

This narrative review represents an output from the International Association for the Study of Pain's global task force on the use of cannabis, cannabinoids, and cannabis-based medicines for pain management, informed by our companion systematic review and meta-analysis of preclinical studies in this area. Our aims in this review are (1) to describe the value of studying cannabinoids and endogenous cannabinoid (endocannabinoid) system modulators in preclinical/animal models of pain; (2) to discuss both pain-related efficacy and additional pain-relevant effects (adverse and beneficial) of cannabinoids and endocannabinoid system modulators as they pertain to animal models of pathological or injury-related persistent pain; and (3) to identify important directions for future research. In service of these goals, this review (1) provides an overview of the endocannabinoid system and the pharmacology of cannabinoids and endocannabinoid system modulators, with specific relevance to animal models of pathological or injury-related persistent pain; (2) describes pharmacokinetics of cannabinoids in rodents and humans; and (3) highlights differences and discrepancies between preclinical and clinical studies in this area. Preclinical (rodent) models have advanced our understanding of the underlying sites and mechanisms of action of cannabinoids and the endocannabinoid system in suppressing nociceptive signaling and behaviors. We conclude that substantial evidence from animal models supports the contention that cannabinoids and endocannabinoid system modulators hold considerable promise for analgesic drug development, although the challenge of translating this knowledge into clinically useful medicines is not to be underestimated.

Oral THC produces minimal behavioral alterations in preadolescent rats

Although the oral route has traditionally been used for THC administration during the perinatal period in the rat, most studies administering THC during the postnatal period utilize intraperitoneal (ip) administration. In an effort to utilize the same route of administration in both prenatal and postnatal studies, we administered Delta-9-tetrahydrocannabinol (THC) in sesame oil by gavage during postnatal days 22-40 (equivalent to childhood to early adolescence) to male and female rats. We quantified behavior 40 min after administration in the Accuscan activity monitor on days 22, 29 and 40. In addition, we examined active and passive avoidance behaviors in treated adults. Acutely, THC had subtle effects on activity when measured during the period of drug administration and minimal effects on avoidance behaviors examined up to 140 days of age. Since several groups have found that lower doses of THC administered intraperitoneally to periadolescent rats do produce behavioral alterations, we suspect that the inordinately slow absorption of the drug via the oral route may be responsible for the paucity of significant findings in our study. Therefore, oral administration of THC, particularly under conditions of mild food deprivation, may lead to sub-psychoactive concentrations of the drug within the brain.

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).

Rectal bioavailability of delta-9-tetrahydrocannabinol from the hemisuccinate ester in monkeys

Oral administration of delta-9-tetrahydrocannabinal (delta 9-THC) was shown to result in low and erratic bioavailability, while the drug showed no bioavailability from various suppository formulations. delta 9-THC-Hemisuccinate was formulated as a prodrug for delta 9-THC in suppositories using Witepsol H15 base. The bioavailability of delta 9-THC from this formulation was evaluated in monkeys. The plasma levels of delta 9-THC and its metabolite 11-nor-delta 9-THC-9-COOH were determined using GC/MS analysis. The calculated bioavailability of delta 9-THC from this formulation was found to be 13.5%. Non-compartmental analysis of the plasma concentration data using statistical moments showed the mean residence time (MRT) for delta 9-THC in the body to be 3 h following iv administration of delta 9-THC or its hemisuccinate ester (3.4 and 2.7 h, respectively), as compared with 5.8 h following rectal administration of the delta 9-THC hemisuccinate. The observed rectal bioavailability of delta 9-THC from suppositories containing the hemisuccinate ester as a prodrug is of significant importance in developing an alternative approach to oral administration of the drug.

Factors influencing tolerance to the effects of delta9-THC on a conditioned avoidance response

Male, Fischer strain rats were resistant to the impairing effects of delta9--THC (15-60 mg/kg, IG) on performance of a conditioned pole-climb avoidance response (CAR) after daily subacute pretreatment for 4 or 6 days. A single administration of 20 mg/kg delta9--THC independent of the performance test did not attenuate the subsequent impairment caused by delta9--THC when tested 1-6 days later; however, administration 2 hr before each test attenuated the effect on subsequent tests given at intervals of 1-5 weeks. Similarly, subacute treatment with 20 mg/kg delta9--THC for 4 days independent of the performance test attenuated the impairment caused by delta9--THC during tests given to separate groups of rats 1 or 6, but not 14 days later. However, when the tests for tolerance were conducted repeatedly in the same rats, the attenuation appeared to persist for intervals up to 5 weeks. The results are discussed in terms of metabolic, functional and compensatory (behavioral) tolerance.