A 2025 phase 1 study compared a fixed-dose CBD and hydroxychloroquine capsule with separate reference products. Thirty-six participants were randomized to three groups. The combination and the CBD reference arm each received 150 mg CBD, allowing the researchers to compare plasma exposure at the same nominal dose.
The combination’s CBD peak concentration was about 50% higher, while estimates for area under the curve were roughly 10% higher. The authors reported nonsignificant differences in the comparisons, but the 90% confidence intervals for the CBD exposure ratios extended outside the study’s 80% to 125% acceptance range. The small groups leave meaningful uncertainty around the estimates.
A difference test asks whether the data are strong enough to show a change. A bioequivalence comparison asks whether the interval is narrow enough to rule out differences beyond preset bounds. This trial also compared different formulations as well as different combinations of ingredients, so the results cannot isolate the effect of hydroxychloroquine itself on the CBD peak.