Of these , the metabolite produces the greatest psychoactive effects .
Cannabidiol ( CBD ) is not psychoactive but plays a modulating role on cannabis psychoactive effects .
The proportion of 9-THC in plant material is higher ( up to 40 % ) than in other cannabinoids ( up to 9 % ) .
Conclusions Findings reveal that 9-THC contributes the most to cannabis psychoactivity .
Due to lower psychoactive potency and smaller proportions in plant material , other psychoactive cannabinoids have a weak influence on cannabis final effects .
Objective This systematic review aims to summarize current evidence on which naturally present cannabinoids contribute to  cannabis psychoactivity  , considering their reported concentrations and pharmacodynamics in humans .
Antinociceptive, subjective and behavioral effects of smoked marijuana in humans.
The purpose of this study was to determine whether marijuana produced dose-dependent antinociception in humans and , if so , whether endogenous opiates modulate this effect . A total of five male regular marijuana users participated in three test sessions during which they smoked cigarettes containing 0 % ( placebo ) and 3 . 55 % Delta(9)-tetrahydrocannabinol ( Delta(9)-THC ) ( active ) . Each of four controlled smoking bouts per session , spaced at 40-min intervals , consisted of nine puffs from active and placebo cigarettes ( three cigarettes , three puffs per cigarette , one puff per min ) . During successive bouts , participants smoked 0 , 3 , 6 and 9 ( 0 , 3 , 9 and 18 cumulative ) puffs from active marijuana cigarettes , with the remainder of puffs from placebo cigarettes . Test sessions were identical , except for naltrexone 0 , 50 or 200 mg p.o . ( r and omized , double-blind ) administration 1 h before the first smoking bout on the different days . Before smoking , between smoking bouts and postsmoking , participants completed an assessment battery that included antinociceptive ( finger withdrawal from radiant heat stimulation ) , biological , subjective , observer-rated signs and performance measures . Marijuana produced significant dose-dependent antinociception ( increased finger withdrawal latency ) and biobehavioral effects . Naltrexone did not significantly influence marijuana dose-effect curves , suggesting no role of endogenous opiates in marijuana-induced antinociception under these conditions
Of these , the metabolite produces the greatest psychoactive effects .
Cannabidiol ( CBD ) is not psychoactive but plays a modulating role on cannabis psychoactive effects .
The proportion of 9-THC in plant material is higher ( up to 40 % ) than in other cannabinoids ( up to 9 % ) .
Conclusions Findings reveal that 9-THC contributes the most to cannabis psychoactivity .
Due to lower psychoactive potency and smaller proportions in plant material , other psychoactive cannabinoids have a weak influence on cannabis final effects .
Objective This systematic review aims to summarize current evidence on which naturally present cannabinoids contribute to  cannabis psychoactivity  , considering their reported concentrations and pharmacodynamics in humans .