The influence of acute cannabis smoking on cigarette and e-cigarette puff topography and subjective effects in people who use cannabis, cigarettes, and e-cigarettes.

Zamarripa C.; Spindle T.; Lee D.; Bergeria C.; Kumar L.; Shah K.; Weerts E.; Marusich J.; Peters E.; Vandrey R. · Experimental and clinical psychopharmacology · 2026

**Background & Methods** This double-blind randomized controlled trial enrolled 20 adults who regularly used cannabis, cigarettes, and e-cigarettes (6 infrequent cannabis users ≤2 times/week; 14 frequent users >2 times/week) across seven outpatient sessions. Participants received THC-dominant cannabis or placebo, followed by 5-hour ad libitum access to their preferred cigarette brand or JUUL e-cigarettes (3% or 5% nicotine), with measurement of puff topography, time-to-first use, and subjective/physiological effects. **Key Findings** • Cannabis administration significantly increased subjective drug effects (drug liking, pleasant effects) and heart rate compared to placebo, confirming pharmacological activity; however, these effects did not translate into altered subsequent tobacco use behavior. • Neither cigarette nor e-cigarette puff topography, timing of first use, nor overall consumption patterns differed between cannabis and placebo conditions, indicating acute cannabis did not increase "chasing" behavior of combustible or vapor nicotine products. • Concurrent or sequential tobacco use did not enhance, extend, or modify acute cannabis effects, suggesting the laboratory model did not capture mechanisms underlying naturalistic co-use patterns observed in real-world settings. **Dosage & Administration** THC-dominant cannabis doses varied by user frequency: 10 mg THC for infrequent users and 25 mg THC for frequent users. Placebo (0 mg THC) served as control. E-cigarette nicotine concentrations were 3% or 5% with JUUL devices. Participants had 5-hour ad libitum access to preferred tobacco products following cannabis/placebo administration. **Safety & Adverse Effects** Not formally reported as a primary outcome. Expected pharmacological effects (increased heart rate, subjective effects) occurred with THC administration but were comparable to previous cannabis research. **Evidence Quality** This study represents a well-controlled laboratory investigation with appropriate blinding and within-subject design; however, significant limitations include small sample size (N=20), artificial laboratory conditions with time-limited access that may not reflect naturalistic concurrent or sequential co-use patterns, and potential inability of the controlled environment to capture the complex psychosocial and situational factors driving real-world tobacco-cannabis co-use. The authors acknowledge that modeling naturalistic co-use in controlled settings remains challenging and recommend future research examining simultaneous use and alternative sequencing patterns. These findings suggest mechanisms underlying co-use require investigation beyond acute pharmacological interactions.

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