“Background: In humans, the effect of cannabis on ventilatory control is poorly studied, and consequently, the effect of Δ⁹-tetrahydrocannabinol (THC) remains unknown, particularly when THC is combined with an opioid. We studied the effect of THC on breathing without and with oxycodone pretreatment. We hypothesised that THC causes respiratory depression, which is amplified when THC and oxycodone are combined.

Methods: In this randomised controlled crossover trial, healthy volunteers were administered inhaled Bedrocan® 100 mg (Bedrocan International B.V., Veendam, The Netherlands), a pharmaceutical-grade high-THC cannabis variant (21.8% THC; 0.1% cannabidiol), after placebo or oral oxycodone 20 mg pretreatment; THC was inhaled 1.5 and 4.5 h after placebo or oxycodone intake. The primary endpoint was isohypercapnic ventilation at an end-tidal Pco₂ of 55 mm Hg or 7.3 kPa (V_E55), measured at 1-h intervals for 7 h after placebo/oxycodone intake.

Results: In 18 volunteers (age 22 yr [3]; 9 [50%] female), oxycodone produced a 30% decrease in V_E55, whereas placebo was without effect on V_E55. The first cannabis inhalation resulted in V_E55 changing from 20.3 (3.1) to 23.8 (2.4) L min^-1 (P=0.06) after placebo, and from 11.8 (2.8) to 13.0 (3.9) L min^-1 (P=0.83) after oxycodone. The second cannabis inhalation also had no effect on V_E55, but slightly increased sedation.

Conclusions: In humans, THC has no effect on ventilatory control after placebo or oxycodone pretreatment.”

https://pubmed.ncbi.nlm.nih.gov/36725378/

“In pain management, the use of THC or its combination with an opioid can be advantageous, as the combination has an opioid-sparing effect.

However, this is only of advantage provided the combination of these two drug classes does not exacerbate opioid-induced respiratory depression.

In this study, we examined the effect of inhaled medicinal-grade cannabis, containing a high THC dose, on ventilatory control in healthy human volunteers with placebo or oxycodone pretreatment. 

THC has no effect on ventilatory control after placebo or oxycodone pretreatment.

In summary, in human volunteers, THC has no significant effect on ventilatory control after placebo or oxycodone pretreatment.”

https://www.bjanaesthesia.org/article/S0007-0912(22)00743-7/fulltext