Ch. 15 Marijuana Flashcards
what is marijuana?
usually refers o the dried leaves and buds of the cannabis sativa or the cannabis indica plant. in the US, the dried leaves and buds of the plant are typically smoked, but in other parts of the world the use of hash or hash oil is the common form of use
what is the psychoactive chemical in cannabis?
primarily tetrahydrocannabinol (THC) but there are many other cannabinoids that share the drug experience. specifically, cannabidiol (CBD) has been linked to therapeutic effects and CBD oil is legal in areas where marijuana is not.
what has cannabis historically been used for?
- hemp fiber
- recreationally
- medicinally
- medical use of “Indian Hemp” were brought to Europe around 1841, and eventually came to America
- “Oil of cannabis” has long been used medicinally, but there was a significant variability in strength between sources, and the onset is very long for oral administration
marijuana and legal issues
- few countries have made marijuana completely legal; many however have decriminalized small quantities. in many countries it is de facto legal, or medicinal use only is okay
- even in countries where it is legal, there are limitations similar to those in the US for alcohol. growing, transporting and selling often remain legally murky
- marijuana remains a schedule 1 drug in the US
marijuana in the US
- almost all US states, plus DC, permit some degree of medical marijuana use, and a growing number have decriminalized it or allow small amounts of marijuana use and possession without penalty. some states allow use of CBD oil as long as THC content is minimal
- use is still illegal federally, even in states where it’s legal. Obama administration and Congress let states set their own laws for the most part and the Trump administration has its hands full with other stuff right now
- a company can fire an employee for a positive drug screen, even if the employee is using marijuana for medical purposes in a state where such use is approved
- because of the federal status, there are issues in growing and selling, insurance, banking, and prescription
who is Harry Anslinger
the commissioner of the bureau of narcotics. he was the first avid supporter of Prohibition but later turned his attentions to marijuana. his testimony to Congress was a huge factor in passing the Marijuana Tax Act in 1937. his testimony and many other claims all have the makings of an urban legend
Marijuana Tax Act
made it criminal to grow marijuana without a tax permit, and legal growing was fairly complicated. most growers did not seek the permit
The Boggs Act
increased penalties for marijuana possession. the 1970’s attitudes toward marijuana relaxed, and it appeared as though it might be legalized. the 1980’s, a hallmark of the Reagan presidency was the “War on Drugs”, and marijuana was grouped with “hard” drugs. mandatory sentencing became law in 1986.
how does marijuana work?
- cannabinoids are agonists at cannabinoid receptors; the natural ligand is the neurotransmitter anandamide
- anandamide works in a way very similar to opioids: anandamide binds to presynaptic receptors, and reduces neurotransmitter release
- anandamide is released from the post-synaptic surface of the neuron being stimulated and serves as a part of a negative feedback system
- anandamide decreased activity in the postsynaptic neuron but in a different way than GABA does
- anandamide receptors are found all over the higher brain in profuse numbers, but not in the brainstem
what are the properties of THC?
- believed to be the major psychoactive components
- very lipid soluble, easily passes through BBB
- taken up by fat readily, released when blood levels drop
- drug tests can show positive results long after cessation is use
- withdrawal isn’t readily evident under normal conditions. the effect of smoked THC is short (about 30 minutes) but the half-life of THC is about 19 hours
- THC leaves the brain relatively quickly, but not the body fat
what are the qualities of THC?
- oral THC has a delayed onset and a longer effect
- THC’s half-life is roughly a day, and primary metabolites of THC has longer half-lives (several days), meaning that a drug screen can pick up use after several days, and several weeks for a very heavy user
- the majority metabolite of THC is itself psychoactive. a person consuming marijuana orally is probably responding a great deal to the metabolite because of the first-pass issue
What are the effect of cannabinoid drugs on the different locations of the receptors in the brain?
frontal lobe: changes in consciousness, decreased clarity of thinking, altered time perception, relaxation
hippocampus: impaired short-term memory
motor areas: slowing of reflexes and reaction time
nucleus accumbens: mild euphoria
what are the medicinal uses of marijuana?
- most research is done with oral THC, which is the preferred medical form and has a reasonable duration of action
- some patients prefer smoking because the onset is faster and it’s easier to control the dose
- smoked marijuana will also have other cannabinoids
- a barrier to marijuana’s acceptance in mainstream medicine is the paucity of research
what are the effects of marijuana?
- most effects that have been carefully studied in a lab setting with placebo controls are acute effects
- chronic effects studies of any drug tend to be correlational and based on recall
- frequently, public information about marijuana will conflate chronic and acute effects
- chronic effects studies frequently indicate that occasional marijuana use is fine for adults, but is associated with problems on adolescents
how does marijuana and THC effect different disorders/symptoms?
Glaucoma: THC reduces pressure inside the eye, and thus counteracts glaucoma
Pain: THC suppresses glutamate and substance P release. numerous studies confirm that smoked cannabis has analgesic effects, albeit modest compared to opioids
Nausea: oral and smoked marijuana is reported to decrease nausea that accompanies chemotherapy
Appetite: patients who have poor appetites (AIDS, cancer) often respond well to oral THC
Seizures: this is less documented, but there are many reports of people who find at least some seizure relief by using marijuana. anti-seizure effects seem to be caused not by THC so much but buy cannabidiol
