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NSAIDs refer to non-steroidal anti-inflammatory drugs which are a group of medications used to relieve pain and reduce the effects of inflammation by reducing a chemical known as Prostaglandin which is responsible for promoting inflammation. These medications include: Aspirin, Paracetamol and Ibuprofen. NSAIDs mechanism of action involves the prevention of prostaglandin formation in cells.Prostaglandin is a very important chemical that is not stored in cells but synthesised when required by Cycloogenase (COX) enzyme which consists of two types COX-1 and COX-2. It is
COX enzyme has two active sites: peroxidase site and cyclooxygenase site, its function involves the oxidation of arachidonic acid to the endoperoxide PGGâ‚‚ at the cyclooxygenase site of the COX enzyme then followed by the reduction of PGGâ‚‚ to a second endoperoxide PGHâ‚‚ at the peroxidise site. The production of the important prostaglandins (PGDâ‚‚, PGFâ‚‚, PGEâ‚‚, PGIâ‚‚ and TXAâ‚‚ (thromboxane) depends on the presence of specific synthases.(1)
Prostaglandins are not stored in cells but synthesised as required using COX-1 and COX-2 enzymes. They bind to cells by different receptors found on the cell surface of different cells. These receptors are: DPâ‚, DPâ‚‚, EPâ‚, EPâ‚‚, EPâ‚ƒ, EPâ‚„, FP, IPâ‚, IPâ‚‚ and TP
Prostaglandins have many essential functions within the human body, these functions include:
The production of blood clots: when a blood clot is damaged, a type of prostaglandins, thromboxane, is produced to help the platelets to stick together and form a blood clot. On the other hand, this could cause blockages in the coronary arteries leading to heart attacks and strokes.
When a tissue is damaged, white blood cells produce prostaglandins to reduce tissue destruction by producing pain and fever.
They are used in some aspects of reproduction, for example, they are used as drugs to induce labour.
They also help to control the kidneys function by elevating renal blood flow and flow of fluids due to some prostaglandins vasodilatory properties.
Some prostaglandins have anti-asthmatic effects on the lungs by initiating EPâ‚ƒ receptor.
Prostaglandins minimise acid production in the gastrointestinal system while raising blood flow and the production of mucus.
NSAIDs work by inhibiting the function of the COX-1 and COX-2 enzymes, they bind to the enzyme's active site preventing it from reacting with arachidonic acid; therefore, stopping the creation of the prostaglandins. They do this by two pathways, one involves COX-1 which is associated tissue homeostasis and the other pathway involves COX-2 which is associated with inflammatory response.
The diagram shows the competitive inhibition of NSAIDs, they bind to the active site of COX enzymes and stopping the reaction with arachidonic acid.
As a result of this inhibition, prostaglandins will not be formed; therefore, the roles of the prostaglandins within the human body will not be carried out. NSAIDs have been found to be non selective inhibitors; this means that they inhibit the function of both COX-1 and COX-2. Restriction the function of COX-2 has antipyretic, analgesic and anti-inflammatory effects, whereas inhibition COX-1 seems to have undesired effects on platelets aggregation and gastrointestinal tract.
Antipyretic effect: NSAIDs stop the formation of prostaglandins in the hypothalamus, which is a part of the brain that controls the body temperature and maintain steadiness between temperature loss and temperature gain. In case of a fever, NSAIDs work to reduce temperature through sweating and dilation of blood vessels.
Analgesic effect: NSAIDs are used as painkillers due to their effectiveness against pain as they decrease the production of the prostaglandins that are sensitive to pain receptors (nociceptors). As a result, they are used to treat arthritis, muscular pain, toothache and dysmenorrhoea.
Anti-inflammatory effect: Inflammation is one of the many processes that occur naturally in the human body in response to infections or irritations. It is established by the cells of the damaged tissue at the site of infections, such as: microphages, kupffer cells and mastocytes. Cells of the damaged tissue produce prostaglandin by COX enzymes. This defensive process, inflammation, results in redness and heat due to the increased flow of blood to the damaged tissue as a result of vasodilatation of the blood vessels. Also, it causes the damaged tissue to become swollen due to the leakage of the tissue fluid at the site of infection. NSAIDs inhibit COX enzyme's function, as a results, prostaglandins are no longer created; therefore, inflammation is reduced. It is very vital that the process of inflammation is controlled by the body because acute inflammation could lead to a wide range of diseases, for example: hay fever, atherosclerosis and rheumatoid arthritis.
One of the main undesired effects of NSAIDs is gastrointestinal bleeding. This occurs due to blocking the action of COX-1 to synthesise prostaglandin which is responsible for inhibiting acid secretion and protecting the lining of the tract.
Aspirin is one of the commonly known non-steroidal anti-inflammatory drugs. It has analgesic effects and is widely used as a painkiller to relieve pain and fever. It also minimises the risk of heart attacks and strokes when used at low doses over a long period of time as it prevents the formation of blood clots in the coronary arteries by inhibiting the formation of prostaglandin which is essential for platelets to bind together and form a blood clot. In addition it can be given in low doses to patients after having a heart attack in order to minimise the possibility of a second heart attack due to its anti-clotting effects. It has also been found that taking aspirin at the age of 40's could minimise the risk of cancer in more advanced stages of someone's life according to the Cancer Research UK (http://www.medicalnewstoday.com/articles/161255.php)
On the other hand, aspirin is associated with many potential side effects; therefore, it is crucial to use it with caution, these side effects include: heartburn, vomiting, nausea, indigestion, stomach pain and allergic reactions and in some cases it could lead to gastrointestinal bleeding. Aspirin is not used for children because of its ability to increase the risk of Reye's syndrome. However, it is prescribed in special circumstances for Kawasaki disease and as anti-platelet after a heart surgery.
Prostaglandin is an essential chemical in the human body. It controls the process of blood clotting so when an injury occurs; thromboxane stimulates the platelets to bind together at the site of damage forming a blood clot. Also it sends impulses to the brain signalling that a specific part of the body is in pain. Prostaglandin has the ability to act upon different cell types because it is associated with a range of receptors (DP1-2, EP1-4, FP, IP1-2 and TP). The synthesis of this chemical is catalysed by the enzyme cyclooxygenase (COX-1 and COX-2).
Aspirin inhibit the function of COX enzymes by the formation of a covalent bond between the acetyl group on aspirin and the serine group on the active site of COX. This results in a change in the shape of the active site of the enzyme; therefore, it no longer can produce prostaglandins and the formation of this chemical is inhibited. As a result, pain is reduced because the brain will no longer receive signals about pain in injured parts of the body, thus aspirin can be used as a painkiller. In addition, preventing the formation of prostaglandins and thromboxane will inhibit platelets bindin together and thus preventing the formation of blood clots in the cornary arteries minimising the risk of heart attacks and strokes.
Furthermore, aspirin interacts with part of the brain that controls temperature, the hypothalaumus, causing it to counteract the increase in temperature due to an infection or injury and lowering the body temperature as a result.
Pracetamol is one of non-steroidal anti-inflammatory drugs which is widely used in everyday life and can be purchased over the counter and it can also be prescribed by doctors. It has, like other NSAIDs, analgesic and antipyretic effects. It is used to treat different types of pains and aches, to treat fever and is used as an important ingredient in flu medication.
Paracetamol has no or very few side effects compared to other NSAIDs when used withing the range of the recommended dose. However, in some cases it could lead to some gastrointestinal problems, such as: stomach bleeding if used in very high doses.
The mechanism of action of paracetamol is similar to that of all NSAIDs; it inhibits the synthesis of prostaglandin by cyclooxygenase enzymes (COX). Recent studies have shown that paracetamol is highly selective for COX-2 than COX-1; therefore, it does not affect the process of blood clotting. However, it can interact with the thermal regulation centre in the hypothalamus to lower the body temperature in the case of fever.
Ibuprofen belongs to the family of non-steroidal anti-inflammatory drugs and it is used to manage pain and fever. Furthermore, it is prescribed to treat arthritis and used as an anti-platelet and a vasodilator dilating coronary arteries and some blood vessels. Ibuprofen seems to have less adverse drug reactions compared to other NSAIDs when taken in small doses. However, it has a number of side effects, including: nausea, raised liver enzymes, diarrhoea, headache, constipation and gastrointestinal bleeding.
The mechanism of action of ibuprofen is similar to that of the all non-selective NSAIDs, it inhibits cyclooxygenase and thus prevents the formation of prostaglandins which promote inflammation and pain sense; therefore, ibuprofen can be used as analgesic and antipyretic.
There are some cases where NSAIDs cannot be used or prescribed, these cases include: any allergy to any NSAIDs, aspirin should not be used for children due to the risk of developing Reye's Syndrome, they are should not be given to pregnant women and breast-feeding mothers,