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Marijuana
Adam Williamson
&
Jessica Chilcott
Introduction to Pharmacology of
Psychoactive Drugs
1
Marijuana is a cannabinoid drug.
Cannabinoids are
characterized by the
chemical compound
Tetrahydrocannabinol
(THC) and include
hashish, hashish oil, and
marijuana.
2
History
2737 B.C. Early writings in China note prescribing marijuana to
treat every thing from gout to absentmindedness.
1600s American Colonies mandated the growth of Cannabis
Sativa for the hemp which was needed for rope and fabric
among other things.
1765 George Washington thought to use cannabis for hemp
product, medicinal, as well as recreational use.
As late as 1850 Cannabis Sativa grown for hemp products as well
as for
medicinal purposes.
1915-1927 Cannabis begins to be prohibited for non-medical use
in the U.S.
3
1936 The government released the
docudrama “Reefer Madness”.
The film has since become a cult
classic
1937 Marijuana Tax Act taxed
growers, purchasers and, users.
While not making marijuana
illegal the act made marijuana
virtually impossible to obtain.
State laws later made marijuana
illegal.
4
1960 -70s During a time of social
upheaval marijuana use becomes
somewhat more accepted,
especially with the large numbers
of popular public figures using
marijuana
1970 The Controlled Substance Act,
reported that marijuana had no
potential medicinal use.
Determining marijuana’s status as
a Schedule 1 Drug.
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1970 Congress passed the
Comprehensive Drug Abuse
Prevention and Control Act,
which categorized marijuana
separately from other drugs and
eliminated mandatory Federal
sentences for possession of small
amounts.
1985 Dronabinol (Marinol), or
synthetic THC, classified as a
schedule II drug, was approved by
the Government for treating
nausea and vomiting associated
with cancer chemotherapy.
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1988 DEA administrative law Judge Francis Young
finds after thorough hearings that marijuana has
clearly established medical use and should be
reclassified as a prescriptive drug. The
recommendation is turned down.
1996 Arizona and California pass laws allowing
marijuana to be prescribed for medicinal purposes.
Compassionate Use Act
2001 United States Supreme Court ruled 8-0 against
medicinal marijuana under federal law. Despite the
fact that 9 States allow medicinal use of marijuana,
United States federal law prohibits medicinal use of
marijuana.
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What is Marijuana?
Marijuana is the dried mix
of flowers and leaves
form the female
Cannabis Sativa plant.
Hashish is the resin, or
sap, harvested from the
plant.
Hashish oil is the essential
oil of the female
Cannabis Sativa plant.
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Marijuana: Modes of Absorption
The most common method
of absorption is
smoking. Either in a
loosely rolled cigarette
called a joint, or through
a pipe or water pipe.
However, it can also be
cooked in foods or
brewed as a tea.
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Smoking and the Body
THC enters the body through the Lungs.
The smoke is inhaled and held in the lungs.
Depth of inhalation
How long the smoke is held
Potency of the marijuana
All affect how much THC will enter the plasma
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THC crosses the blood
barrier through the
capillaries in the lungs
After inhalation THC can
reach the brain in about
14 seconds
11
Effects are felt as the THC
begins to bind to the large
numbers of natural
cannabinoid receptors in the
brain.
Cannabinoid receptors are
found on the presynaptic
nerve terminals and inhibit
calcium (Ca++) ion flux. As
a result glutamate and
neurotransmitter release is
inhibited.
12
Receptors in the Basil
Ganglia and
Cerebellum involved
with many forms of
movement and
postural control, are
affected by smoking
marijuana.
13
In the Cerebral Cortex, cannabinoid receptors are activated which
distortions in sense of time, reduces the ability to concentrate
and, produces a dream like state. As well as altering how
sound and taste are perceived.
The Hippocampus which is responsible for movement of short
term memories into long term memory storage, is affected.
Damaging memory formation capabilities
14
Cannabinoid Receptors
15
Cannabinoid receptors are G-Protein coupled receptors,
usually thought to mediate inhibition of adenylyl
cyclase, reducing cyclic AMP levels
Brain stem structures do not bind with cannabinoids,
therefore THC does not affect basal bodily functions
such as breathing, explaining the nonlethality of
smoking marijuana.
16
Certain Cannabinoid
(cannabinoid 2) receptors
are found in the lymphatic
system. These receptors are
thought to produce the
immunosuppressive effects
of THC.
While not dangerous to most
individuals, THC can
produce increased heart rate
and blood pressure. This can
be observed when the blood
vessels in the eyes dilate.
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Effects on the respiratory system are the same as
smoking cigarettes.
Chronic use of marijuana can reduce testosterone
levels in men as well as reducing the
production of sperm.
In women follicle-stimulating hormone,
luteinizing hormone are reduced. The
menstrual cycle can also be affected.
18
Smoking Marijuana
during pregnancy
has many of the
same effect as
smoking cigarettes,
mild fetal growth
retardation.
There have been
cases of infants
born with THC
dependence and
withdrawal.
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Physical Effects
Most of the time, senses may be enhanced and
the perception of time is usually altered. Users
also report an increased sense of well-being ,
mild euphoria, relaxation, and relief from
anxiety.
Contrary to popular belief, illusions and
hallucinations occur infrequently.
20
Dependence and Addiction
Dependence is usually classified as:
1. Preoccupation with the acquisition of the drug.
2. Compulsive use of the drug.
3. Relapse to or recurrent use of the drug
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There is little evidence that marijuana can cause
physical dependence. However, some
individuals experience withdrawal syndrome
with symptoms including anxiety sleep
disturbances. Withdrawal symptoms usually
begin within 48 hours of cessation.
22
There is support for the possibility of
psychological dependence occurring.
Psychological dependence is based on
maintaining the good feelings associated with
smoking marijuana.
23
Tolerance and Withdrawal
Tolerance to the effects of Marijuana can develop
especially in long term and chronic marijuana.
Tolerance to Marijuana develops from two mechanisms
1. Cannabinoid induced down regulation and gradual
desensitizing of brain cannabinoid receptors.
2. Rapid receptor internalization following agonist
binding and receptor activation.
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Treatment
Because around 20% of illicit drug users use
marijuana in conjunction with other drugs,
there is not treatment program specifically for
marijuana users.
However, treatments such as psychotherapy with
an emphasis in behavior modification can be
appropriate.
25
Use Rates
Marijuana is the number
one drug of choice in
the United States.
An estimated 16 million
people regularly smoke
marijuana
An estimated 35-50
million people have
tried marijuana.
26
As with the use rates for alcohol. Students over
estimate peer use rates. Most students believe
that their peers are smoking around once a
week when in actuality around one third of
students use marijuana.
Parents on the other hand underestimate use
rates. Around 14% of parents believe that their
children have tried marijuana, 38% of their
children admit to experimenting with
marijuana.
27
Medicinal Marijuana
The use of marijuana for
medicinal proposes
dates back more then
5ooo years.
However, the debate over
medicinal marijuana
rages today in the
United States
28
Marijuana has been used across cultures for
medicinal purposes for over 5,000 years.
Renewed interest in the use of marijuana for
therapeutic purposes has popped up within the
last 15 years.
29
Research on the therapeutic
uses of cannabis has been
slowed due to the bad
reputation marijuana
obtained in this country
especially in the 1930’s
when marijuana was billed
as the Assassin of the Youth
and was purported to induce
a desire to commit violent
crimes.
30
There were also concerns,
voiced among others, by
the first head of the
Bureau of Narcotics,
Harry Anslinger about
the use of marijuana
having “sexual
connotations”
especially on college
campuses
31
Between the 1970 Controlled Substance Act and
marijuana’s subsequent classification as a
Schedule 1 drug reduced the research
possibilities for medicinal marijuana.
In 1999 the Institute of Medicine determined that
cannabinoids have therapeutic value, but that
an ingestion route other than smoking should
be used.
32
In 1988 Judge Francis Young was quoted as saying : "In
strict medical terms marijuana is far safer than many
foods we commonly consume. For example, eating
10 raw potatoes can result in a toxic response. By
comparison, it is physically impossible to eat enough
marijuana to induce death. Marijuana in its natural
form is one of the safest therapeutically active
substances known to man. By any measure of rational
analysis marijuana can be safely used within the
supervised routine of medical care.”
33
There has been a lot of
concern that legalizing
marijuana for medicinal
use will undermine drug
resistance programs
aimed at youth and
encourage the push to
legalize recreational
marijuana use.
34
In 1985 the synthetic THC drug Marinol® was approved to
treat nausea and vomiting in Cancer patients.
In 1992 Marinol was approved for the treatment of appetite
loss and subsequent severe anorexia in AIDS patients.
35
Unauthorized therapeutic benefits of
marijuana include:
Reduction of intraocular pressure associated with
glaucoma.
Use as a bronchodilator in asthmatics.
Relief of muscle spasms in such disorders as
multiple sclerosis.
Preventing seizures associated with epilepsy.
Treatment of depression.
Treatment of chronic pain, and migraines.
36
There are those who
support the actual
smoking of marijuana
over the use of
Marinol® arguing that
smoking marijuana
activates more of the
receptor sites.
37
However, the ability to regulate dosing is a
problem.
In 1960 the average potency of smoked
marijuana was around 1-2%, currently the
potency average is around 6% which can
change the based on quality and grade of the
plants. Marinol ® has controlled doses at 2.5,
5, and 10 mg
38
Sociology of Marijuana
While the debate rages over the use of marijuana
for medicinal purposes a very active subculture
surrounding the recreational use of marijuana
has developed.
39
Popular figures in movies, television, and the
music industry support the use of marijuana.
40
Or are perceived as supporting marijuana use
41
And of course the internet
where you can look up
recipes, order seeds, get
cultivation advice and
paraphernalia.
42
Social Costs
Students who smoke marijuana get lower grades
in school and are less likely to graduate, that
students who do not smoke marijuana.
Employees who smoke marijuana have more
accidents, increases tardiness rates, more
accidents, reduced attentiveness and, a general
loss in productivity.
43
Research has shown that marijuana negatively
affects driving ability because of altered sense
of time and space as well as slowed reaction
time.
In 2000 46.5% of arrests for drug abuse
violations were for marijuana.
646,042 people were arrested for possession of
marijuana.
44
Compared to Cocaine, Heroin,
Methamphetamines, and other drugs.
Marijuana accounts for an estimated 3.9%
of crime.
Marijuana accounts for an estimated $10.7
billion (16.3%) in drug related spending
each year.
45
Conclusion
Marijuana is an intensely popular drug, it is
estimated that one third if the population uses
marijuana.
Marijuana is a controversial drug whose true
social cost has not really been measured.
Marijuana is also a drug with exceptional
medical possibilities, if it can over come its
bad reputation.
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