Protocol for a mobile laboratory study of co-administration of cannabis concentrates with a standard alcohol dose in humans

Abstract

Cannabis is commonly used among people who drink alcohol, yet evidence on acute effects of co-use is conflicting. Two important variables that may influence the effects of cannabis and alcohol are cannabinoid content (i.e., the ratio of cannabidiol [CBD] and 9-tetrahydrocannabinol [THC]) as well as the order of use (i.e., cannabis before alcohol vs. alcohol before cannabis). Research is mixed regarding the acute imapct of cannabis on alcohol consumption and intoxication, with some studies suggesting additive effects of alcohol and cannabis, and others demonstrating negligible effects of combining these substances. Further complicating this, high-THC-content cannabis concentrates are increasingly popular on the legal-market, but to our knowledge, no studies have explored concentrate and alcohol co-use. In addition to cannabinoid content, order of use may influence intoxication and other acute effects, but is also understudied. Co-use studies typically administer a fixed dose of alcohol before cannabis, and there is a lack of data on the acute effects of cannabis before alcohol. Thus, there is a need for experimental co-use studies exploring the impact of cannabinoid content (particularly of highly potent cannabis concentrates) and order effects on intoxication. This study uses a federally-compliant mobile laboratory procedure to explore the effects of co-administration of legal-market cannabis concentrates with a moderate alcohol dose (.8g/kg) in a sample of community participants who regularly use alcohol and cannabis. The study will also explore alcohol and cannabis order effects (cannabis before alcohol vs. alcohol before cannabis). Outcomes are objective intoxication (measured using blood cannabinoid level, heart rate, psychomotor performance and breath alcohol level [BrAC]) and subjective intoxication (assessed via self-report measures). Overall, this study may influence harm-reduction recommendations for individuals who drink alcohol and use cannabis.

The effects of simultaneous alcohol and cannabis use on subjective drug effects: A narrative review across methodologies

“…Incongruent conclusions may be due to differences in the order of substance administration, although the effects of order were not a direct aim of this research. Karoly and colleagues (Karoly et al., 2022) recently proposed a mobile laboratory study to examine order effects (cannabis concentrates before alcohol vs. alcohol before cannabis concentrates) on objective and subjective intoxication. To date, only one study has examined the order of alcohol and cannabis use on consumption and consequences at the day‐level and found that using cannabis first on a co‐use day is associated with lower daily alcohol consumption but greater daily cannabis consumption (Gunn et al., 2021).…”

“…No prior laboratory work has directly examined the effect of the order of alcohol and cannabis administration, with the exception of Karoly et al. 's (2022) recent proposal to examine order effects on objective and subjective intoxication via a mobile laboratory study. To our knowledge, no study has examined the effects of the order of substance use on subjective drug effects in a naturalistic setting.…”