Medical cannabis is effective for cancer-related pain: Quebec Cannabis Registry results

Drug Interactions of Tetrahydrocannabinol and Cannabidiol in Cannabinoid Drugs

BACKGROUND

Cannabinoid drugs containing tetrahydrocannabinol (THC), or its structural analogues, as monotherapeutic agents or as extracts or botanical preparations with or without cannabidiol (CBD) are often prescribed to multimorbid patients who are taking multiple drugs. This raises the question of the risk of drug interactions.

METHODS

This review of the pharmacokinetics and pharmacodynamics of interactions with cannabinoid drugs and their potential effects is based on pertinent publications retrieved by a selective literature search.

RESULTS

As THC and CBD are largely metabolized in the liver, their bioavailability after oral or oral-mucosal administration is low (6-8% and 11-13%, respectively). The plasma concentrations of THC and its active metabolite 11-OH-THC can be increased by strong CYP3A4 inhibitors (verapamil, clarithromycin) and decreased by strong CYP3A4 inductors (rifampicin, carbamazepine). The clinical significance of these effects is unclear because of the variable plasma level and therapeutic spectrum of THC. The metabolism of CBD is less dependent on cytochrome P450 enzymes than that of THC. THC and CBD inhibit CYP2C and CYP3A4; the corresponding clinically relevant drug interactions probably are likely to arise only with THC doses above 30 mg/day and CBD doses above 300 mg/day.

CONCLUSION

Potential drug interactions with THC and CBD are probably of little importance at low or moderate doses. Strong CYP inhibitors or inductors can intensify or weaken their effect. Slowly ramping up the dose of oral cannabinoid drugs can lessen their pharmacodynamic interactions, which can generally be well controlled. Administration by inhalation can worsen the interactions.

Use of Medical Cannabis by Patients With Cancer: Attitudes, Knowledge, and Practice

CONTEXT

Demand for medical cannabis (MC) is growing among Israeli patients with cancer.

OBJECTIVES

The study sought to assess factors contributing to the demand for MC among patients with cancer.

METHODS

Patients applying for a permit to receive MC at a pain and palliative clinic of a university-affiliated cancer center in Israel in 2020-2021 were asked to complete self-report questionnaires assessing attitudes, knowledge, and expectations regarding MC use. Findings were compared between first-time and repeat applicants. Repeat applicants were asked to report their indications for requesting MC, patterns of use, and treatment effect.

RESULTS

The cohort included 146 patients: 63 first-time applicants and 83 repeat applicants. First-time applicants were more likely to consult sources other than their oncologist for MC-related information (P < 0.01) and expressed more concern about addiction (P < 0.001) and side effects (P < 0.05). They often erroneously assumed the treatment was subsidized (P < 0.001). Repeat applicants were younger (P < 0.05) and included more smokers (P < 0.05) and recreational cannabis users (P < 0.05); 56.6% were cancer survivors and 78% used high-potency MC. Most patients believed to some degree that MC is more effective than conventional medications for symptom control, and over half thought that MC helps to cure cancer.

CONCLUSION

Misconceptions regarding the effectiveness of MC for symptom management and treatment may explain the motivation of patients with cancer to apply for a permit. There seems to be an association of young age, cigarette smoking, and recreational cannabis use with ongoing use of MC among cancer survivors.