In the placebo-controlled study, 73 patients were randomized to receive 2.5 mg of dronabinol or 10 mg of dronabinol daily for up to 6 weeks, or placebo. At the end of treatment, researchers saw significant increases in the AHI among the patients on placebo, while those who received dronabinol showed decreases in the number of apnea and hypopnea events per hour. Patients given the 2.5-mg dose of dronabinol had a mean decrease of 10.7 events per hour, and those on the 10-mg dose had a mean decrease of 12.9 events per hour compared with placebo. The difference between the placebo and treatment arms was significant for both dosages, and the AHI decreases were similar between the two dosages of dronabinol.
These effects were largely due to reductions in apnea events; the largest reduction was seen in the REM apnea index in patients treated with the 10-mg dose of dronabinol. However, there were few effects on the expression of hypopneas, except in the higher-dose group.
After adjustment for age, race, ethnicity, and baseline AHI, the increases seen in the placebo group were no longer significant, but the decreases from baseline seen in the treatment arms were greater. Dronabinol treatment also was associated with significant decreases, compared with placebo, in non-REM AHI and REM AHI.
Overall, nearly 90% of patients in this trial reported at least one adverse event, with the rates having not differed significantly between the treatment and placebo arms. The most frequently reported adverse events were “sleepiness/drowsiness” (n = 25; 8% of total adverse events reported), headache (n = 24; 8%), “nausea/vomiting” (n = 23; 8%), and “dizziness/lightheadedness” (n = 12; 4%). In addition, one patient experienced diarrhea and vomiting that required admission to a hospital, which was judged as possibly related to the study medication. There were six other withdrawals due to adverse events, including dizziness and vision changes, vertigo, ECG arrhythmias, and headache with dizziness and vomiting.