Propranolol effects on acute marihuana intoxication in man

Area of Science:

• Pharmacology
• Neuroscience

Background:

• Marihuana's psychoactive effects are mediated by delta-9-THC.
• Beta-adrenergic blocking agents like propranolol affect cardiovascular and central nervous system functions.

Purpose of the Study:

• To investigate the interaction between marihuana and the beta-adrenergic blocking agent propranolol.
• To determine if propranolol modifies marihuana's physiological and cognitive effects.

Main Methods:

• Six healthy, experienced marihuana smokers participated.
• Participants received propranolol (120 mg), marihuana (10 mg delta-9-THC), or both drugs.
• Cognitive performance (psychomotor speed, attention, memory, learning) and physiological responses were assessed.

Main Results:

• Propranolol alone reduced resting heart rate (HR) and blood pressure (BP) but did not affect cognitive performance.
• Marihuana alone increased HR, BP, and caused conjunctival injection, impairing learning but not attention.
• Propranolol pre-treatment blocked marihuana's cardiovascular effects, prevented learning impairment, and reduced subjective "high" effects.

Conclusions:

• Propranolol effectively counteracts many physiological and cognitive effects of marihuana.
• The cardiovascular and learning impairments induced by marihuana are mediated through pathways affected by beta-adrenergic blockade.
• Beta-adrenergic pathways play a significant role in mediating marihuana's effects.