Natural Highs: The Oldest Drugs Flashcards

1
Q

From Reefer Madness
to High Economy:
Cannabis

A
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2
Q

What IS
cannabis,
anyway?

A

 One of the world’s oldest crops (hemp harvested in China 8500 years ago).
 However, cannabis is very mysterious.
 Current broad use of the term ‘cannabis’ is often vague, unscientific, and confusing.
 Unsure if the genus Cannabis is monotypic (one species) or polytypic (three or more
species?)
 Why so weird?
 ancient origin.
 extremely long evolutionary and domestication history (including artificial
selection) – may have wiped out other variants.
 widespread geographic dispersal.
 prohibition made it hard to investigate scientifically.

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2
Q

By the end of this lecture, you will be
able to…

A

 Describe the botanical profile of cannabis.
 Describe key events in the cultivation and use of cannabis
in the US and Australia.
 Describe the basic pharmacodynamics and
pharmacokinetics of cannabis.
 Describe the benefits and limitations of cannabis as a
medical treatment, based on current evidence.

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2
Q

A ‘third strain’
– ruderalis?

A

 Molecular genetics is providing increasing evidence that cannabis
is a polytypic genus.
 Some classify cannabis as three sub-species:
 Indica
 Sativa
 Ruderalis
 Ruderalis plants are small and yield relatively little medicine with
low potency?
 Seems to have a different flowering and life cycle.
 Ruderalis strains are typically avoided by breeders and cultivators.
 Medical cannabis is usually indica or sativa strains (whatever they
may be!)

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3
Q

Cannabis in
the US

A

 Hemp grown in North American colonies from early seventeenth
century (by slaves).
 American hemp industry peaked before 1860 - declined after
Civil War (loss of slaves; rise of industrialisation).
 Medicinal cannabis included in the American pharmacopoeia by
1851.
 Imported from India via Britain.
 Medical uses were sporadic and ill-defined.
 By the early 1900s, US government began experimenting with
domestic production of drugs, including cannabis.

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3
Q
A
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4
Q

Recreational
uses

A

 Early reports of recreational cannabis use in the US - Southwest
and the port of New Orleans, c.1900.
 New term - ‘marijuana’ - smoked version of cannabis indica.
 Racist fears about Mexican immigrants and drug trade.
 In 1915, El Paso, Texas was first US municipality to ban the nonmedical cannabis trade (fears of Mexican drug trade).
 Street name was ‘muggles’!
 Recreational marijuana smoking spread rapidly during the 1920s:
 industrial hubs like Kansas City and Chicago – working class, youth,
Black associations.
 jazz musicians like Louis Armstrong brought ‘reefers’ to various gigs
across the country

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4
Q

The 1950s and 1960s

A

1950s Beatnik movement – cannabis use.
 1960s – growing counterculture.
 American soldiers sampled Thai and Vietnamese varieties while
serving in Vietnam.
 Mostly imported cannabis – wild cannabis has little THC.
 By the 1970s, harvesting of wild cannabis was common in the US.
 Led to chemical pesticide spraying by local governments.

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5
Q
A
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6
Q

1980s and the USWar on Drugs –
dope goes indoors

A

 Greater US state and federal law enforcement campaigns.
 After 1989, growers moved largely indoors – labs, hydroponics.
 1996 - California became the first state to re-legalise marijuana for
medicinal use.
 Indoor growing became the norm.
 2012: Colorado and Washington state re-legalise adult use of
marijuana.
 Both states focused on regulating - and privileging - energyguzzling indoor cultivation!

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7
Q

Australia’s cannabis history

A

 As with the US, medicinal cannabis available in colonial Australia.
 No data on extent of use.
 Opium was seen as a much more dangerous drug of abuse and
traffic (racist associations with Chinese).
 1938: the term ‘marihuana’ appears in Australia in connection with
the ‘reefer madness’ moral panic in the US.
 Medical cannabis finally phased out in the 1960s in Australia.
 Destruction of wild crops in 1970s.
 Similar VietnamWar and counterculture influences in Australia.

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8
Q

Current
cannabis law in
Australia

A
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8
Q

ACT, 1977 –
Australian
Marijuana
Party

A
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9
Q
A
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9
Q

Legalisation – the high economy

A

Impact of legalisation of recreational and medicinal use in the US:
 23 US states allow adult recreational use, 38 allow medical sales.
 2020: legal sales = $17.5 billion, a 46% increase from 2019.
 By comparison, craft beer industry in the US = $41 billion in annual sales.
 Estimated creation of just over 6,000 new full-time jobs in retail and
production.
 Also marketing, data analysts, lawyers, health professionals.
 Reduction of cannabis-related criminal convictions – similar use rates,
but black people are 3.6 times more likely to be arrested for marijuana
possession compared to whites.

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9
Q

Legalise
Cannabis Party
- bill

A

 20 June 2023 - bill introduced in state parliaments in Victoria, New
South Wales andWestern Australia.
 Legalise Cannabis Party has representation in all three states’
upper houses.
 Bill would allow adults to possess and grow small quantities of
cannabis at home.
 Similar toACT model.
 The bill is NOT currently supported by WA’s ALP government
(Roger Cook).

10
Q

Legalisation – the high economy

A

Impact of legalisation of recreational and medicinal use in the US:
 State and federal taxes, fair wages, infrastructure and regulation all cost
small business owners.
 They can’t always make a profit.
 California – very complex state laws: selling 500g for $3000 illegally, or
selling 500g for $600 legally?
 Most cannabis trade still illegal.
 Illicit cannabis sales estimated at $100 billion each year.
 Both legal and illegal sellers use a mix of bricks-and-mortar, e-commerce
and ‘rideshare’ type delivery systems.
 Legal traders rely on government to shut down illegal traders.

11
Q

How it gets into the body

A

 Inhaled as smoke: cannabinoids travel rapidly from the
lungs to the blood and brain.
 This leads to higher levels of THC in blood plasma.
 Ingested: absorbed from the intestines => liver where it is
metabolised (first-pass metabolism)
 This leads to lower levels of THC in blood plasma.

11
Q

Cannabinoid receptors

A

 The two major identified cannabinoid receptors in the body are CB1 and
CB2
 G-protein-coupled receptors (see eTute 1).
 CB1
receptors: mostly CNS and peripheral NS.
 CB2
receptors: mostly immune cells and spleen; also GI tract, skeletal
muscle, skin, cardiovascular system, reproductive system, liver.
 CB2
receptor agonists [stimulate a response] are targets of emerging
research due to their potential analgesic, anti-inflammatory, and
immune-modulating properties.
 https://www.azolifesciences.com/article/Comparison-of-ReceptorPharmacology-in-Cannabinoids.aspx

12
Q

How is it
turned into
product?

A

 Most cannabis produced and consumed in the world is herbal:
dried flowers and smallest leaves and stems of the female
cannabis plant.
 sinsemilla (‘seedless’) crops: remove all male plants from field.
 hashish (‘grass’) or resin: paste-like substance obtained by
compressing the resin glands (trichomes) of the female cannabis
plant.
 bhang: edible paste-like cannabis, used in foods and drinks during
some Hindu and/or Sikh religious occasions.
 butane hash oil (BHO): a solvent-extracted, cannabis
resin concentrate made with liquid butane.
 rosin: solvent-less extract - heat and pressure with heating
hydraulic press.
 edibles: gummies, tea, powders, butter/oil, brownies.

13
Q

Pharmacodynamics

A

 Cannabis is a polypharmaceutical substance (comprised of many
compounds, including cannabinoids).
 Those of primary interest are:
 Cannabidiol (CBD)
 Tetra-hydro-cannabinol (THC)
 Cannabinoid receptors are located throughout the body: brain,
major organs, connective tissues, glands, immune cells.
 The human body has cannabinoid receptors …
 … which means the human body has endocannabinoids!
 anandamide - discovered and named in 1992
 responsible for biological effects such as increasing appetite,
decreasing nausea, decreasing pain sensitivity, and providing
anti-inflammatory activity.

14
Q

What goes
where?

A

 All cannabinoids are not equal!
 THC has equal affinity to both CB1 and CB2 (partial agonist).
 Synthetic cannabinoids are “fussy” - highly selective agonists or
antagonists to one of the receptor types.
 CBD does not directly affect either CB receptor (antagonist):
 It modifies the receptors’ ability to bind endocannabinoids.
 For example, CBD enhances the activity of anandamide.
 CBD is thought to interact with several other receptors like the μreceptor and serotonin (5-HT) receptors.

15
Q

How does THC
get you high?

A

 Good question …
 May cause short-term dopamine flooding (and long-term blunting of
dopamine effects).
 THC seems to unplug the brain’s ‘default mode’ network (how we daydream
and think about past and future).
 Psychedelics such as LSD and psilocybin seem to have a similar effect on the
brain’s ‘default mode’ network.
 Difficulties in studying this phenomenon: illegality, subjective experience of
‘high’.

16
Q

Pharmacokinetics -
smoking

A

 This depends on:
 The route of administration.
 The cannabinoid involved.
 The physical characteristics of the user.
 Both THC and CBD are highly lipophilic -> they like to snuggle in your fat cells.
 THC produces the ‘high’.
 CBD acts without euphoric effects.
 Bioavailability of inhaled THC is highly variable: between 10% and 35%.
 The THC content also varies depending on how inhaled:
 Doobs: less THC content partially due to pyrolysis at higher temperatures and
loss due to side smoke; more tar and impurities.
 Vaping: highest content of THC and cleaner vapour.
 Smoking effect can occur within seconds; can be fully apparent within minutes; lasts up
to 3 hours.

17
Q

Pharmacokinetics -
edibles

A

 The amount of THC absorbed from edibles depends on your body
mass index, metabolism, gender, and eating habits.
 bioavailability of THC and CBD from edibles also widely variable -
4% to 12%.
 Edibles can have a longer effect compared to inhaled THC – 6-12
hours.
 But: higher risk of toxicity!
 THC and CBD content labelling may be inconsistent: as high as
23% for under-labelling and 60% for over-labelling

18
Q

THC -
Evidence from
meta-analyses

A

 Human brain has considerable neuronal plasticity = potentially
vulnerable to ongoing THC use due to effects on cannabinoid
receptors.
 Literature overall supports causal and correlational relationships with
ongoing THC use:
 reduced cognitive and motivational abilities - verbal memory and
attention (reversible with abstinence?Variables like use, age, THC
content can moderate risk?)
 associated psychosis, depression, anxiety, addiction, violence.
 Robust relationship between chronic marijuana use and increased risk
of suicide.
 Paediatric exposure is highly risky.
 Risks to adolescent brain: brain connectivity, CNS grey matter, altered
CB1R signaling, potential short-term memory dysfunction via
hippocampal changes = increased risk of neurodevelopmental
conditions, psychosis.
 https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2782160

19
Q

THC -
Evidence
from metaanalyses

A

 Cannabis smoke inhalation increases risks of
pneumonia, bronchiolitis, pneumothorax,
emphysema, and pulmonary
haemorrhage.
 Evidence suggests cannabis smoke is
carcinogenic.
 Cardiovascular system:
 increased myocardial oxygen
demand.
 pro-oxidative stress.
 decreased myocardial contractility.
 promotion of atrial and ventricular
arrhythmia.
 Arrhythmia.
 Stroke.
 Arteritis.
 arterial dissection.
 myocardial infarction, and
 sudden cardiac death.

20
Q

Medicinal uses
of CBD – the
most recent
evidence

A

Presently available data do not allow any firm recommendations
for the use of cannabinoids (usually CBD) in pain management or
opioid use disorders.
Three examples:
1) Adult cancer-related pain – the addition of cannabinoids to
opioids did not reduce cancer pain.
2) Acute pain management - low-quality evidence that
cannabinoids may be a safe alternative for a small but
significant reduction in subjective pain score – only with
intramuscular injection.
3) Movement disorders – not enough good quality data to
determine that any forms of cannabis are effective.

20
Q

Medicinal uses
of CBD – the
evidence

A

There IS some evidence for other areas (these are just some examples):
1) Treatment resistant epilepsies – some evidence that CBD oil is a good
adjunct therapy.
2) Multiple sclerosis - potential therapeutic symptomatic effects, including
alleviation of pain, spasticity, and bladder dysfunction.
3) Nausea from cancer treatment – good evidence for relief.
Two principal objections to medicinal CBD use:
1) We have better medicines already available for these conditions.
2) There are known and unknown interactions between CBD and other
standard treatments, some of which are potentially harmful.
Cannabis in Medicine: An evidence-based approach (Springer, 2020) - UWA
Library online

21
Q
A
22
Q

Legalisation – the high economy

A

The historical push for legalisation has always been
about recreational use.
 But legalisation came first for medicinal cannabis – based
on tenuous medical evidence.
 Bonus question: Is legalising medicinal use a way of
smoothing the path to increased legal recreational use?

22
Q

Summing up

A

 Cannabis is tricky and elusive, botanically and chemically.
 Although a very old drug, it’s still misunderstood because of the
legal/illegal divide.
 It has a recent modern history that has made this more complicated.
 It’s still hard to develop a global picture of its growth, trade, and uses.
 It has different ways of preparation and use for extraction and ingestion.
 Its two main interesting cannabinoids behave differently in the body:
 THC is fun - but tends to be mostly harmful to the body.
 CBD is less fun, and can be therapeutic, but the evidence base is
still very much in development.
 There are both risks and benefits associated with the legalisation of
recreational and medicinal cannabis.

22
Q

Therapeutic
Goods
Administration
(TGA)
Australia

A

 Category 1: CBD medicinal cannabis product (CBD ≥ 98%) - Prescription only
(Schedule 4).
 Category 2: CBD dominant medicinal cannabis product (CBD ≥ 60% and < 98%) -
Controlled drug (Schedule 8).
 Category 3: Balanced medicinal cannabis product (CBD <60% and ≥ 40%) -
Controlled drug (Schedule 8).
 Category 4: THC dominant medicinal cannabis product (THC 60% - 98%) -
Controlled drug (Schedule 8).
 Category 5:THC medicinal cannabis product (THC >98%) -
Controlled drug (Schedule 8).
 Want to know more? Try the Medicinal Cannabis Hub -
https://www.tga.gov.au/products/unapproved-therapeutic-goods/medicinalcannabis-hub