Aspirin and paracetamol widely used over-the-counter
analgesics and antipyretics. Aspirin and NSAIDs also have anti-inflammatory
properties at higher doses however, Paracetamol only exhibits weak
anti-inflammatory activity. Aspirin discovered in the late 1890s in the form of
acetylsalicylic acid when chemist Felix Hoffmann at Bayer in Germany used it to
ease his father’s rheumatism. After that aspirin known worldwide and its belongs
to the group of medicines known as non-steroidal and anti-inflammatory drugs. Aspirin can be used to relieve pain
and inflammation caused
by rheumatic and muscular pain, sprains, backache, headache,
sore throat, toothache and period pain. Paracetamol was discovered in 1893 in
the urine of individuals who had taken phenacetin and was concentrated in to
white, crystalline compound with a bitter taste. Later in 1899, paracetamol was
found to be a metabolite of acetanilide. However, this discovery was largely
ignored at the time by most people. In 1963, Paracetamol known as worldwide and
its known as one of the successful painkiller. Paracetamol can be used to
comfort mild to moderate pain from headaches, toothache,
muscle and joint pains.

Mechanism
of action of Paracetamol

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Even though Paracetamol
was discovered in 1899s and has been extensively used in medical field in more
than half century. The mechanism of action has not been clarified until now.
Paracetamol has analgesic and antipyretic properties likewise NSAIDs. Paracetamol
known as Acetaminophen and the properties of this drug are obviously different compare
to the NSAIDs. This drug is on average, a weaker analgesic compares to NSAIDs
or COX-2 selective inhibitors but is often chosen by most people because of its
better tolerance. Regardless of enduring assertions that this drug acts by
inhibition of cyclooxygenase (COX)-mediated production of prostaglandins,
different from non-steroidal anti-inflammatory drugs (NSAIDs).  Even though this drug has similarities to NSAIDs,
the mode of action of paracetamol has been uncertain. However, it is now largely
accepted that it inhibits COX-1 and COX-2 through metabolism by the peroxidase
function of these isoenzymes. The outcome in inhibition of phenoxyl radical
formation from a dangerous tyrosine residue important for the cyclooxygenase
activity of COX-1 and COX-2 and prostaglandin (PG) synthesis. Paracetamol
highlights selectivity for inhibition of the synthesis of prostaglandin and
related factors when low levels of arachidonic acid and peroxides are available.
 However, paracetamol has little activity
at substantial levels of arachidonic acid and peroxides. The outcome id that
Paracetamol does not suppress the severe inflammation of rheumatoid arthritis
and acute gout but does inhibit the lesser inflammation. Furthermore, this drug
is very active in a many of inflammatory tests in experimental animals and its
often appears to have COX-2 selectivity. The apparent COX-2 selectivity of
action of paracetamol is revealed by its poor anti-platelet activity and good
intestinal tolerance. Both non-selective NSAIDs and selective COX-2
inhibitors, Paracetamol can inhibit other peroxidase enzymes including
myeloperoxidase. Inhibition of myeloperoxidase includes paracetamol oxidation
and concomitant decreased formation of halogenating oxidants. That can be
associated with several inflammatory pathologies including atherosclerosis and
rheumatic diseases, therefore, this drug reduces the development of these
diseases.

 

Paracetamol,
NSAIDs and selective COX-2 inhibitors all these have central and peripheral
effects. The analgesic effects of paracetamol are reduced by inhibitors of many
endogenous neurotransmitter systems including serotonergic, opioid and
cannabinoid systems.

https://link.springer.com/article/10.1007/s10787-013-0172-x

 Mechanism
of action of Aspirin

Aspirin is
also known as acetylsalicylic acid and it can be classified among the
nonsteroidal anti-inflammatory drugs (NSAIDs). This drug reduces the signs and
symptoms of inflammation and exhibit a broad range of pharmacologic activities,
including analgesic, antipyretic, and antiplatelet properties. Aspirin and NSAIDs
do not usually change the course of the most diseases process in those
conditions where both drugs used for symptomatic relief. The therapy of
rheumatism starts thousands of years ago with the use of herbs or plants such
as willow bark or leaves, most of which turned out to contain salicylates. Willow
bark were use by most people to reduce the pain of the patients. Felix Hoffman,
who was a chemist working at the Bayer company in Germany, made the acetylated
form of salicylic acid in 1897. The name of this drug was Aspirin, later became
the mostly widely used in medicine all the time. The mechanism of action of
Aspirin discovered by John Vane in 1971. He explained that Aspirin exerts
its anti-inflammatory, analgesic and antipyretic actions. Furthermore, he also
proved that Aspirin and other non-steroid anti-inflammatory drugs
(NSAIDs) inhibit the activity of the enzyme now called cyclooxygenase (COX).
This leads to the formation of prostaglandins (PGs)
that cause inflammation, swelling, pain and fever. However, by inhibiting this
key enzyme in PG synthesis, the Aspirin-like drugs also prevented the
production of physiologically important prostaglandins. This protect the
stomach mucosa from damage by hydrochloric acid, maintain kidney function and collective
platelets when required. The conclusion provided more clarification for the
therapeutic actions and shared side effects of the aspirin-like drugs.
After twenty years, the discovery of a second COX gene, it became clear for
everyone that there are two isoforms of the COX enzyme. The constitutive
isoform, COX-1, supports the beneficial homeostatic functions. on the other hand,
the inducible isoform, COX-2, becomes upregulated by inflammatory mediators and
its products can cause various of the symptoms of inflammatory diseases in
people such as: rheumatoid and osteoarthritis. The COX-2 inhibitors are potent
anti-inflammatory drugs without the damaging side effects on the stomach mucosa
of the non-selective aspirin-like inhibitors.

https://www.ncbi.nlm.nih.gov/pubmed/14592543

 

 

 

 

 

Paracetamol and Aspirin are
both analgesics painkillers with similar efficacy, however
because of its anti-inflammatory properties, aspirin can be more effective when
dealing with inflammation. Paracetamol can be given to children in limited
doses, whereas Aspirin is not recommended for children and adolescents because
this drug has a risk of Reye’s syndrome. Both medicine can be use daily for many purposes as they
are not on prescription. Paracetamol works
by being absorbed into the bloodstream. Once absorbed, it blocks the body’s production of prostaglandins, a
lipid compound in the body that causes
inflammation and fever. This drug is thought to reduce the intensity of pain
signals to the brain. Prostaglandins, increase pain and body temperature and
they are found throughout the body, but Paracetamol mostly works on those in
the brain. The World Health Organization consider paracetamol to be an
essential medicine in a basic health system. Furthermore, the side effect of
this drug is very rare but still it can include: flushing, low blood pressure and a fast heartbeat, blood disorders, liver and
kidney damage. If someone have one of these side effect, they should talk to
their Pharmacist or Doctor. Pregnant women can take Paracetamol because it is
safe drug compare to Aspirin. There is not clear evidence that Paracetamol has
any harmful effects on unborn baby whereas Aspirin does. The world health
organisation(NHS) encourage women to take Paracetamol During pregnancy as it
safe then other painkiller. Women who were taking Paracetamol daily had a 45% lower death rate
from ovarian cancer compare to women who were not taking it. Paracetamol is
very effective painkiller as it can be also uses for ovarian cancer. Aspirin
also gets absorbed into the bloodstream. Once in the bloodstream, Aspirin
inhibits chemicals, such as cyclo-oxygenase, which cause the production of
prostaglandins. Aspirin, which is an NSAID which is nonsteroidal
anti-inflammatory drug. It is mostly absorbed in the small intestine and
processed in the liver, stomach, and other organs. Aspirin is used to treat pain, and
reduce fever or inflammation. Furthermore, it more useable compare to other
painkiller because it can prevent heart attack and possible cancer. Aspirin can
cause stomach or intestinal bleeding, which can be fatal. Older people have a
higher risk of stomach bleeding, so they need to be careful while taking this
medicine. Those women who are pregnant need to tell their doctor before using
Aspirin. This is because Aspirin can cause harm to unborn baby or may face the
problem with delivery.

 

Overall, to
compare the mechanism of action of both drugs, the mechanism of Aspirin is more
clear and understandable compare to Paracetamol. Paracetamol is used in medical
field more than half century; but the mechanism is not completely understood,
whereas the main mechanism of this drug is the inhibition of COX. Furthermore,
Paracetamol has analgesic and antipyretic properties similarly to NSAIDs, but
contrary to them, it does not possess any anti-inflammatory activity. Due to
lack of an anti-inflammatory component, paracetamol has not been regarded as a
member of the NSAIDs family in pharmacological textbooks. On the other hand, Aspirin
was discovered before Paracetamol, so the mechanism action is more clear and understandable.
The mechanism of action of this drug discovered by John Van more clearly. The
mechanism of action of Aspirin is probably mediated through inhibition of
prostaglandin endoperoxide synthase or cyclooxygenase (COX) enzymes, though
other mechanisms may also exist.
 Moreover, Aspirin and other non-steroid
anti-inflammatory drugs (NSAIDs) inhibit the activity of the enzyme now called
cyclooxygenase (COX). Aspirin 1,000 mg reached its peak effect on fever
(lowered by 1.67°C) more quickly than paracetamol 1000 mg (lowered by 1.71°C). After
twenty years, the discovery of a second COX gene, it became clear for everyone that
there are two isoforms of the COX enzyme. The constitutive isoform, COX-1,
supports the beneficial homeostatic functions. on the other hand, the inducible
isoform, COX-2, becomes upregulated by inflammatory mediators and its products
can cause various of the symptoms of inflammatory diseases.