Analgesics
L. Scheffler
Analgesics
Analgesics are common pain relievers.
Many analgesics also have antipyretic
properties as well. They can be used to
reduce fever
Some analgesics are also antiinflammatory drugs as well
Classification of Analgesics
Analgesics
Mild
Analgesics
Aspirin
Ibuprofen
Acetaminophen
Strong
Analgesics
Opium
Heroin
Codeine
Mild Analgesics
Mild Analgesics include
over-the-counter pain
relievers and fever
depressants.
Examples of mild
analgesics include
Aspirin, acetaminophen,
and ibuprofen
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
Salicyclic Acid
Aspirin
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
Aspirin
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.
Aspirin
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 prostrate cancer
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
Reye’s syndrome
Other Mild Analgesics
Acetaminophen (Paracetamol)
– Commonly sold as Tylenol
Ibuprofen
– Commonly sold under the name Advil
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
Ibuprofen
Ibuprofen is a more
powerful pain reliever
than aspirin in high
doses, but is inferior
for anti-inflammation
Side effects include
gastrointestinal bleeding and
irritation
Can aggravate kidney
problems
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 derived from
the opium poppy or synthetically produced
Basically three types: Natural,
semi-synthetic, and synthetic
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
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
Heroin
Originally sold as cough suppressant and pain
killer10 times stronger than Morphine
Incredibly addictive (many times, other strong
analgesics are needed for withdrawal)
Heroin
Synthesized from
morphine in a
esterification reaction
with acetyl chloride
It is absorbed by the
brain very quickly
resulting in a potent high
Many other problems are
associated with heroin
addiction including as
prostitution and AIDS.
Other Synthetic Strong Analgesics
Vicodin
Is solution of
acetaminophen and
hydrocodone (the latter
being the stronger)
Hydrocodone is addictive
and can cause highs.
Usually taken orally
Stronger than codeine but
not as strong than
Morphine
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.
Demerol
Demerol (Meperidine)
Used for moderate to
severe pain and to
stop muscle spasms.
Usually injected or
taken orally.
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.
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.
When these are absorbed by receptors in
the brain the body feels analgesia and the
pain is reduced.
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.
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.
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
History of Cocaine
Coca leaves have been chewed by South American
Indians for thousands of years. There were used to
induce feelings of euphoria
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)
Cocaine
The leaves of the coca plant
contain 0.6% - 1.8%
alkaloidal cocaine
To extract, cocaine
leaves are soaked in
kerosene and sulfuric
acid
HCl is added creating
cocaine hydrochloride,
which can be extracted as
powdery flakes or rocks
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
Effects of Cocaine
Subjective
Euphoria
Increased
sociability
Increased energy
Hyper vigilance
Physiological
Increased heart rate
Increased respiration
rate
Increased body
temperature
Increased blood
pressure
Pupil dilation
Derivatives of Cocaine
Cocaine is too addictive and in
appropriate for medicinal use
Two derivatives of cocaine are widely
used as local anesthetics
– Procaine or Novacaine
– Lidocaine
Procaine (Novacaine)
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
Lidocaine
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