A clinical trial tested whether cannabidiol (CBD) can reduce the adverse effects of tetrahydrocannabinol (THC) and improve its tolerability as an analgesic. Healthy volunteers received THC alone or with different doses of CBD. Contrary to expectations, the highest CBD dose (450 mg) significantly increased THC's subjective, psychomotor, cognitive, and autonomous effects—for example, feeling high increased by 60.5%—and did not enhance pain relief. Lower CBD doses had no significant effect on THC's effects. CBD also increased blood levels of THC and its active metabolite. The findings do not support using CBD to reduce oral THC's adverse effects or to improve its analgesic properties.
Intravenous DMT administered as a 30-second bolus followed by a 6-hour infusion, reaching peak blood concentrations around 35 ng/mL, is safe in healthy volunteers. No serious adverse events occurred; all side effects were mild and self-limiting. Vital signs, electrocardiography, and measures of suicidality or psychopathology showed no significant abnormalities. Mild psychedelic effects were accompanied by temporary decreases in sustained attention, postural stability, and occipital alpha brain wave power at the highest dose. Moderate variability in drug levels between individuals was observed. These findings support further testing of prolonged DMT infusion as a potential treatment to promote neuroplasticity in stroke recovery.