Please use this link to access this publication. Abstract The bronchodilating activity of oral cannabinoids was evaluated in three double-blind experiments that involved the study of dose-response and interactive relationships and the potential development of tolerance. Data indicated that ▵8-tetrahydrocannabinol (▵8-THC), cannabinol (CBN), and cannabidiol (CBD) in maximal doses of 75 mg, 1200 mg, and 1200 mg, respectively, did not induce significant dose-related physiologic effects in experienced marijuana smokers. ▵8-THC (75 mg) was, however, associated with bronchodilation, tachycardia, and peak highs less than that after ▵9-tetrahydrocannabinol (▵9-THC). The combinations of CBN and CBD with low-dose ▵9-THC (5 mg) did not induce significant bronchodilation but...