Analgesics
Analgesics
Analgesics are common pain relievers.
Some analgesics also have antipyretic
properties as well. They can be used to
reduce fever.
Some analgesics are also antiinflammatory drugs. They reduce
inflamation as well
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Classification of Analgesics
Analgesics
Strong
Analgesics
Mild
Analgesics
Aspirin
Ibuprofen
Acetaminophen
Opium
Heroin
Codeine
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Mild Analgesics
Mild Analgesics include
many over-the-counter pain
relievers and fever
depressants.
Examples of mild
analgesics include aspirin,
acetaminophen, and
ibuprofen.
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Mechanism of Mild Analgesics
The mechanism by which
mild analgesics act is still
controversial.
It is believed that they
inhibit the formation of
prostaglandins at the site of
the injury.
Prostaglandins are involved
in the transmission of pain
signals to the brain
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Aspirin
Aspirin is a derivative
of salicyclic acid
Salicyclic acid was
found in the bark of
the willow tree and
was used as a pain
reliever and as a way
to relieve fever
symptoms of malaria.
Aspirin
Salicyclic Acid
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Aspirin
In 1899, Felix Hoffman, a chemist from the
Bayer Company, developed a low-cost
process to synthesize an ethanoate ester
of salicyclic acid, called aspirin
In the synthesis of aspirin, the ethanoic
acid forms an ester with the alcohol group
on the second carbon
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Aspirin
As a mild analgesic,
aspirin is believed to
inhibit the enzyme,
Prostaglandin Synthase
which is formed at the site
of an injury.
This inhibits the
production of
prostaglandins which
produce fever and
swelling as well as
transmitting pain signals
to the brain.
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Aspirin -- Uses and Benefits
Aspirin is able to reduce pain and fevers
and dilate blood vessels
Aspirin enlarges blood vessels which
helps prevent blood clots.
This vasodilation of the surface blood
vessels also allows an increase of heat
released which lowers the temperature of
a fever
Aspirin is also taken to prevent
recurring heart attacks
It may also be effective in
preventing prostate cancer
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Side Effects of Aspirin
Aspirin can irritate the stomach lining which
may lead to ulcers
If aspirin is used over long periods of time, it
may lead to problems with blood clotting
An overdose on aspirin, such as the case with
some arthritis sufferers, may lead to dizziness,
ringing in the ears, gastrointestinal problems,
mental confusion, and bleeding.
Some people are allergic to aspirin leading to
bronchial asthma
In children under 12 Aspirin has been linked to
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Reye’s syndrome
Other Mild Analgesics
Acetoaminophen (Paracetamol)
– Commonly sold as Tylenol
Ibuprofen
– Commonly sold under the name Advil
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Acetoaminophen
Acetoaminophen can be easily synthesized from phenol
The relative ease with which acetoaminophen can be
synthesized makes it a rather common inexpensive
analgesic
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Acetaminophen
Acetaminophen is a pain
reducer, such as Tylenol but
does not reduce inflammation.
When taken at recommended
doses, it has negligible side
effects.
It’s low level side effects make
it favorable to arthritis patients
and children.
Overuse and overdoses can
lead to acute liver failure and
kidney damage.
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Ibuprofen
Ibuprofen is a more
powerful pain reliever
than aspirin in high
doses, but is inferior
as an anti-inflammatory
drug.
Side effects include
gastrointestinal bleeding
and irritation
Can aggravate kidney
problems.
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Strong Analgesics
Only available by prescription
Used to relieve severe pain associated with
injuries, heart attacks, or chronic diseases
such as cancer.
Most strong analgesics are opiates that are
derived from the opium poppy or
synthetically produced
Basically three types: Natural,
semi-synthetic, and synthetic
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Morphine
Naturally occurring
in the poppy- Only
needs to be isolated
Very strong pain
reliever but also
very addictive (2nd
to Heroin)
Usually injected but
can be smoked,
sniffed or swallowed
Commonly used in
hospitals
Large illegal street
culture
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Codeine
Most commonly used
strong analgesic
Similar to Morphine
except for the
replacement of a (OH) group for (OCH3)
group
Commonly used with
Tylenol as a more mild
analgesic
1/6 as strong as
Morphine and less
addictive
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Heroin
Originally sold as cough suppressant and pain
killer. 10 times stronger than Morphine
Incredibly addictive (many times, other strong
analgesics are needed for withdrawal)
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Heroin
Synthesized from
morphine in a
esterification reaction
with acetyl chloride
It is absorbed by the
brain very quickly
resulting in a potent high.
The ester group in heroin
makes it less polar and
therefore more fat
soluble. It is more easily
absorbed in brain tissue.
Many other problems are
associated with heroin
addiction including as
prostitution and AIDS.
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Other Synthetic Strong
Analgesics
Vicodin
Is solution of
acetaminophen and
hydrocodone (the latter
being the stronger
analgesic)
Hydrocodone is addictive
and can cause highs.
Usually taken orally
Stronger than codeine
but not as strong than
morphine.
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Synthetic Strong Analgesics
(Opioids)
The active area of
morphine has been
identified and can be
synthesized.
This has produced
many synthetic
analgesics and has
allowed scientists to
eliminate some of the
harmful side effects
of more natural
analgesics.
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Demerol
Demerol (Meperidine)
Used for moderate to
severe pain and to
stop muscle spasms.
Usually injected or
taken orally.
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Methadone
Compared to most
strong analgesics it is
weaker.
Has been synthesized
to not have euphoric
properties and mild
withdrawal effects but
is still addictive.
Used as an analgesic
but most commonly to
help in the withdrawal
for Heroin addicts.
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Mechanism of Strong
Analgesics
The human body contains “natural
opiates” in the brain called endorphins
These are produced in the body during
extreme conditions such as “running
high” and extreme injuries.
Strong analgesics bind to the
endorphin receptors in the brain.
When these are absorbed by receptors
in the brain the body feels analgesia
and the pain is reduced.
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Mechanism of Strong Analgesics
cont.
Opiates derived from the poppy act in the same
way as endorphins but are not natural to the
human body.
The “high” is produced because of the
absorption of opiates is quicker than endorphins
Drugs such as naloxone act to fill the receptors
in the brain but are not analgesics and thus are
used to prevent overdoses on analgesics.
Endorphins are not used as analgesics because
the cannot be stored and are unstable.
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Side Effects of Strong Analgesics
Short term
Dulling of Pain
Euphoria
Slow Nervous system
Slowed heart rate
Loss of cough reflex
Nausea
Overdoses can lead
to death
Possibility of stroke
Overall slowdown of
biological systems
Long Term
Addiction and very strong
withdrawal effects
Constipation
Loss of libido
Disruptions in
menstruation
“Cross-tolerance”
Loss of appetite
Problems associated with
buying street drugs i.e.
sharing needles AIDS and
prostitution.
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Local Anesthetics -Cocaine
Cocaine used in
1885 as a local
anesthetic.
Extracted from the
plant Erythoxylum
coco
([1R-(exo,exo)]-3-(Benzoyloxy)-8-methyl-8azabicyclo[3.2.1]octane-2-carboxylic acid methyl ester
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History of Cocaine
Coca leaves have been chew by South
American Indians for thousands of years
Was banned by Spanish settlers in the 1500s
but the ban was repealed when it became
apparent that slaves worked harder while on it
United States cocaine was used in soft drinks
until it was classified as narcotic in 1914
Clinically used as a local anaesthetic for eye
operations and in modified synthetic forms for
dental treatment (novocaine) and sore throats
(benzocaine)
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Cocaine
The leaves of the coca plant
contain 0.6% - 1.8%
alkaloidal cocaine
To extract, cocaine
leaves are soaked in
kerosine or sulphuric
acid
HCl is added creating
cocaine hydrochloride,
which can be extracted as
powdery flakes or rocks
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Clinical Action
Acts as a reuptake blocker for the monoamines
dopamine, norepinephrine and serotonin.
Interacts with serotonin and muscarinic
acetylcholine receptors and the sodium channels.
Influence on the axonal voltage-gated sodium
channels that provides cocaine's local anaesthetic
properties.
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Derivatives of Cocaine
Cocaine is too addictive and in
appropriate for medicinal use
Two derivatives of cocaine are widely
used as local anesthetics
– Lidocaine
– Procaine (Novacaine)
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Effects of Cocaine
Subjective
Euphoria
Increased
sociability
Increased energy
Hypervigilance
Physiological
Increased heart rate
Increased respiration
rate
Increased body
temperature
Increased blood
pressure
Pupil dilation
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Lidocaine
First modern local anesthetic agent
Sodium channel blocker
Administered parenterally for ventricular
arrhythmias, subcutaneously for minor
surgical procedures, and topically to
mucosal surfaces prior to invasive
procedures
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Procaine (Novacaine)
Principal use in dentistry for temporary
numbing of mouth area
First synthesized in 1905 and was the first
injectable man-made local anesthetic
Restricts blood vessels, reducing bleeding
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