Safety, pharmacodynamics, and pharmacokinetics of multiple oral doses of delta-9-tetrahydrocannabinol in older persons with dementia

In a small crossover trial, ten dementia patients (mean age 77) received low doses of oral THC (0.75 mg then 1.5 mg) or placebo twice daily for three days with a four-day washout. Only 6 of 98 reported adverse events were related to THC. Most pharmacodynamic measures (feeling high, external perception, body sway with eyes open, diastolic blood pressure) did not differ significantly from placebo. After 0.75 mg, internal perception and heart rate increased slightly; after 1.5 mg, body sway with eyes closed increased. Systolic blood pressure changed in opposite directions at each dose. THC was rapidly absorbed with dose-linear pharmacokinetics but wide interindividual variability. The authors conclude that pharmacodynamic effects were minor and call for further study of higher doses in older adults with dementia.

Study at a glance

Abstract

Data on safety, pharmacodynamics, and pharmacokinetics of tetrahydrocannabinol (THC) are lacking in dementia patients. In this randomized, double-blind, placebo-controlled, crossover trial, we evaluated the safety, pharmacodynamics, and pharmacokinetics of THC in ten patients with dementia (mean age 77.3 ± 5.6). For 12 weeks, participants randomly received oral THC (weeks 1–6, 0.75 mg; weeks 7–12, 1.5 mg) or placebo twice daily for 3 days, separated by a 4-day washout period. Only 6 of the 98 reported adverse events were related to THC. Visual analog scale (VAS) feeling high, VAS external perception, body sway-eyes-open, and diastolic blood pressure were not significantly different with THC. After the 0.75-mg dose, VAS internal perception (0.025 units; 95 % CI 0.010–0.040) and heart rate (2 beats/min; 95 % CI 0.4–3.8) increased significantly. Body sway-eyes-closed increased only after 1.5 mg (0.59°/s; 95 % CI 0.13–1.06). Systolic blood pressure changed significantly after both doses of THC (0.75 mg, −7 mmHg, 95 % CI −11.4, −3.0; 1.5 mg, 5 mmHg, 95 % CI 1.0–9.2). The median Tmax was 1–2 h, with THC pharmacokinetics increasing linearly with increasing dose, with wide interindividual variability (CV% up to 140 %). The mean Cmax (ng/mL) after the first dose (0–6 h) was 0.41 (0.18–0.90) for the 0.75-mg dose and 1.01 (0.53–1.92) for the 1.5-mg dose. After the second dose (6–24 h), the Cmax was 0.50 (0.27–0.92) and 0.98 (0.46–2.06), respectively. THC was rapidly absorbed and had dose-linear pharmacokinetics with considerable interindividual variation. Pharmacodynamic effects, including adverse events, were minor. Further studies are warranted to evaluate the pharmacodynamics and efficacy of higher THC doses in older persons with dementia.