Jl. Azorlosa et al., MARIJUANA SMOKING - EFFECTS OF VARYING PUFF VOLUME AND BREATHHOLD DURATION, The Journal of pharmacology and experimental therapeutics, 272(2), 1995, pp. 560-569
Two studies were conducted to quantify biological and behavioral effec
ts resulting from exposure to controlled doses of marijuana smoke. In
one study, puff volume (30, 60 and 90 mi) and in a second study, breat
hhold duration (0, 10 and 20 sec) were systematically varied while hol
ding constant other smoking topography parameters (number of puffs = 1
0, interpuff interval = 60 sec and inhalation volume = 25% of vital ca
pacity). Each study also varied levels of Delta(9)-tetrahydro-cannabin
ol marijuana cigarette content (1.75% and 3.55%). Regular marijuana us
ers served as subjects (n = 7 in each experiment). Subjects smoked 10
puffs in each of six sessions; a seventh, nonsmoking session (all meas
ures recorded at the same times as in active smoking sessions) served
as a control. Variations in puff volume produced significant dose-rela
ted changes in postsmoking plasma Delta(9)-tetrahydro-cannabinol level
s, carbon monoxide boost and subjective effects (e.g., ''high''). In c
ontrast, breathholding for 10 or 20 sec Versus 0 sec increased plasma
Delta(9)-tetrahydro-cannabinol levels but not CO boost or subjective e
ffects. Task performance measures were not reliably influenced by mari
juana smoke exposure within the dosing ranges examined. These findings
confirm the utility of the controlled smoking technology, support the
notion that cumulative puff volume systematically influences biologic
al exposure and subjective effects, but cast doubt on the common belie
f that prolonged breathholding of marijuana smoke enhances classical s
ubjective effects associated with its reinforcing value in humans.