DREXEL PSY 310 - Chapter 15- Marijuana (6 pages)

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Chapter 15- Marijuana



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Chapter 15- Marijuana

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Pages:
6
School:
Drexel University
Course:
Psy 310 - Drugs & Human Behavior
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Chapter 15 Marijuana The Cannabis Plant Marijuana is a preparation of leafy material from the Cannabis plant that is usually smoked Three species Cannabis sativa used primarily for its fibers from which hemp rope is made Cannabis indica grown for its psychoactive resins Cannabis ruderalis grows primarily in Russia Cannabis Preparations delta 9 tetrahydrocannabinol THC Primary psychoactive agent in Cannabis THC is concentrated in the resin Potency of Cannabis preparations depends on the amount of resin present Most of the resin is in the flowering tops Less in the leaves Little in the fibrous stalks Hashish Most potent preparation In its purest form it consists of pure resin that has been carefully removed from the surface of leaves and stems Relatively rare in the U S About 1 of confiscated marijuana samples Sinsemilla 2nd most potent preparation Consists of dried flowering tops of plants with pistillate flowers i e female plants Average THC content is 11 Smokable marijuana in U S can vary widely in potency from Marijuana History Earliest mention 2737 BC Chinese pharmacy book Recommended several medical uses 1000 AD Social use of the plant had spread to the Muslim world and North Africa Hashishiyya religious cult carried out political murders o Origin of the word assassin Hashish use mentioned frequently in The Arabian Nights U S Regulation 1926 Series of newspaper articles linked marijuana and crime Public interest increased 1936 All states had laws regulating the use sale and or possession of marijuana Most early regulation efforts Based on concerns about use and criminal behavior Concerns not based on direct evidence Marijuana Tax Act of 1937 Followed the regulation by taxation theme of the 1914 Harrison Act Grower distributor seller and buyer were taxed Result administratively almost impossible to deal in Cannabis State laws made possession and use illegal 1969 U S Supreme Court declared the Marijuana Tax Act unconstitutional After the Marijuana Tax Act Cost of marijuana increased significantly LaGuardia Report 1944 Concluded that marijuana use had less serious effects than commonly believed Report elicited strong negative reactions Use of marijuana increased throughout the 1950s 1960s Use peaked in 1970s Marijuana use decreased in the 1980s But rose again in the 1990s Cannabinoid Chemicals Chemistry of Cannabis is complex More than 400 chemicals in marijuana About 70 are cannabinoids delta 9 tetrahydrocannabinol THC The most pharmacologically active cannabinoid synthesized in 1964 Major active metabolite is 11 hydroxy delta 9 THC Pharmacology After smoking THC is absorbed rapidly by the blood and travels to the brain and then the rest of the body Peak mood altering and cardiovascular effects occur within 5 to 10 minutes After oral administration THC is absorbed more slowly Peak effects occur about 90 minutes following ingestion Metabolism THC has a half life of 19 hours Complete elimination of THC and its metabolites may take 2 3 weeks Mechanism of Action THC binds to two receptors CB1 receptors Found primarily in the brain but also throughout the body CB2 receptors Found mainly outside the brain in immune cells High density in specific brain regions Basal ganglia and cerebellum movement coordination Hippocampus memory storage Cerebral cortex higher cognitive functions Nucleus accumbens reward Potential role of cannabinoids in the modulation of the immune system Cardiovascular Effects Dose dependently increases heart rate Time course differs depending on route of administration Other Psychological Effects Reddening of the eyes Dryness of the mouth and throat Pulmonary effects Acute Few effects on breathing Chronic Heavy marijuana smoking over a long period could lead to clinically significant impairment of pulmonary function Behavioral Effects Self administration Studies show both animals and humans will self administer both smoked marijuana and oral THC Under controlled laboratory conditions Marijuana cigarettes with higher THC content are preferred Participants choose more oral THC during periods of social interaction Data indicate The abuse potential of THC Cannabis self administration is influenced by social factors Subjective effects Euphoria high mellowness hunger and stimulation Infrequent users experience similar but more intense effects compared with experienced smokers At high THC concentrations infrequent users may report negative effects such as mild paranoia Food intake Marijuana and oral THC significantly increase total daily calorie intake Verbal behavior Verbal exchanges decrease nonverbal social interactions increase Cognitive Effects Acute Infrequent users marijuana disrupts cognitive performance Slowed cognitive processing Impaired short term memory Impaired inhibitory control Loss of sustained concentration or vigilance Impaired visuospatial processing Frequent users marijuana causes less dramatic effects Slowed cognitive processing Frequent users may be tolerant to cognitive effects Chronic Difficult to make definitive statements about effects on long term cognitive functioning Studies have had divergent findings and interpretations Current evidence suggests that after abstaining for more than a month regular marijuana use produces few effects on cognition Medical Uses of Cannabis Medical use declined before the 1937 Marijuana Tax Act for several reasons New and better drugs were developed to treat most illnesses Variability of product Active ingredient insoluble in water and thus can t be injected Oral dose has delayed onset of action 1970s present renewed interest in medical uses Glaucoma Cancer treatment related nausea Dronabinol Dronabinol Brand Name Marinol Oral THC preparation Used as an antiemetic 1985 FDA approved for sale to cancer patients experiencing nausea from chemotherapy Used to stimulate appetite 1993 FDA approved for sale to AIDS patients State and Federal Action 1999 Institute of Medicine issued report that recommended use of marijuana when certain conditions are met Failure of currently approved medications Symptoms will be relieved by a rapid onset Treatment is under medical supervision Oversight strategy for dispensation Legal medical use as of early 2012 16 states and DC have legislation allowing medical use Abuse and Dependence Tolerance Tolerance to many marijuana effects develops after high levels of regular use May not develop uniformly to all effects Withdrawal DSM IV No listing of cannabis withdrawal Research suggests a


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