Kinetic study of smoking marijuana

Area of Science:

• Pharmacology
• Cannabinoid Research

Background:

• Understanding the pharmacokinetics and pharmacodynamics of delta-9-tetrahydrocannabinol (THC) is crucial for assessing marijuana's effects.
• Previous research indicates THC's psychoactive and physiological impacts, but detailed temporal profiles require further investigation.

Purpose of the Study:

• To quantify plasma delta-9-tetrahydrocannabinol (THC) levels over time after smoking marijuana.
• To assess the time course of physiological (heart rate) and subjective (self-reported high) responses to smoked marijuana.
• To examine the correlation between THC plasma levels and observed effects.

Main Methods:

• Six subjects each smoked two 1% THC marijuana cigarettes, separated by two hours.
• Plasma THC concentrations were measured using radioimmunoassay for up to 9 hours post-smoking.
• Heart rate and self-reported 'high' were recorded for 2 hours after each cigarette.

Main Results:

• Plasma THC levels, heart rate, and self-reported high increased rapidly after smoking initiation, with peak concentrations (Cmax) occurring before smoking cessation.
• A significant negative correlation was observed between heart rate and plasma THC levels from 10 to 120 minutes post-smoking.
• All measured pharmacodynamic responses returned to baseline levels within approximately 2 hours.

Conclusions:

• Smoked marijuana produces rapid increases in THC plasma levels and associated physiological and subjective effects.
• The observed effects are strongly correlated with THC concentrations and are transient, returning to baseline within a short timeframe.
• These findings contribute to understanding the acute effects and time course of smoked cannabis.