Cannabinoid Drug Interactions

Description

Several studies have published findings indicating that cannabis use is associated with greater requirements of propofol anesthesia for endoscopic procedures.

In one case-controlled study of 318 subjects undergoing endoscopy, cannabis users required a significantly higher dose of propofol per kg per minute, with daily users more impacted than occasional users. While cannabis exposure appears to be an independent variable, factors such as age, weight, history of respiratory disease, smoking status and procedure duration also must be considered.

A prospective, randomized study of 60 subjects found that doses of propofol required to achieve appropriate bispectral index (BIS) values (a marker of adequate anesthesia prior to laryngeal mask insertion) were no different between cannabis users and nonusers but doses required to insert the laryngeal mask were significantly higher amongst cannabis users.

Propofol used for endoscopy is titrated to effect; however, when used in conjunction with neuromuscular blocking agents for mechanical ventilation, the impact of greater dosing requirements may be more significant.

Mechanism

The mechanism for this interaction is unclear; however, hypotheses include the down-regulation of the CB1 receptor in chronic cannabis users, and competitive agonism/antagonism at the CB1 receptor by phytocannabinoids

Evidence

Imasogie et al 2021
Twardowski et al 2019
Flisberg et al 2009

Disclaimer

The drug interaction information provided in this section is a compilation of published literature, including clinical trials and case reports and may include interpretation¹ by PCCC.

Additional information regarding theoretical drug interactions is also presented and is based on our evaluation of the potential for harm if such an interaction were to occur.

Criteria considered:

• Hepatic metabolism of the victim drug
• Cytochrome P450 involvement
• Drugs with a narrow therapeutic window
• Dose, frequency, and route of cannabis use