March 28, 2023

Aspirin is a Non Steroidal Anti Inflammatory Drug(NSAID), which was originally used to treat fever, pain, and inflammation. But recently it is used as a cardiovascular drug due to its anti platelet effect.

Aspirin is a member of non-steroidal anti-inflammatory drugs or nsaids which are used to treat pain fever and inflammation and aspirin is commonly used as an anti-platelet medication due to its ability to inhibit platelets so first we will discuss about some important events occurring in inflammation whenever there is inflammation membrane viscolipids are taken

Up and converted into arachidonic acid by an enzyme called phospholipis this arachidonic acid is then converted to prostaglandins and prestasic lens by the enzyme cyclooxygenase one and two once released these substances cause visodilation and increases blood flow to the affected area they also attract immune cells especially neutrophils and lymphocytes and further

Aggravate the immune response and they act on the hypothalamus to set the temperature set point at a higher degree causing fever they also act on the nociceptive neurons and lower their threshold for painful stimuli in addition prostaglandins have other functions as well these include inducing the secretion of protective mucus in the gastric mucosa enhance uterine

Contractions and reduce gastric acid secretion now what nzeds do is they inhibit either cox one or two or both and reduce the secretion of prostaglandins and prestasic cleanse aspirin also known as acetyl salicylic acid was originally introduced as an anti-inflammatory agent however its usage is an anti-inflammatory agent is now replaced by better tolerated

Nsaids recently it is used as a cardiovascular drug due to its anti-platelet effect and aspirin elicits its pharmacological action by irreversibly inhibiting both cox-1 and cox-2 enzymes aspirin is usually taken priorly and a major proportion of the drug is absorbed by the small intestine its oral bioavailability is about 75 and it is available as suppositories

And iv preparations as well once in the bloodstream aspirin causes inhibition of platelet function to understand this we need to recall the function of prostaglandin and platelet aggregation in platelets arachidonic acid is formed by the membrane phospholipids and this arachidonic acid is converted into prostaglandin by the enzyme cox 1 then prostaglandin is

Converted to thromboxane a2 which causes platelet aggregation and formation of blood clots what aspirin does is it irreversibly inhibits cox-1 enzyme and reduces the formation of prostaglandin and thereby platelet aggregation and this will cause prolonged bleeding time without affecting prodroman time and activated partial from bop list in time and also even

Though aspirin has a shorter half-life it causes a prolonged inhibition of platelet function this is due to the irreversible nature of drug action and lack of nuclei in platelets once cox-1 is irreversibly inhibited the enzyme is no longer able to function and as platelets lack nuclei they cannot synthesize new 1 enzymes themselves so to achieve a normal level

Of cox-1 enzymes there should be new platelet formation in the bone marrow this is the reason for prolonged duration of action of the drug in the liver aspirin is hydrolyzed into salicylate this is the actual anti-inflammatory metabolite of aspirin but unlike aspirin it has no anti-platelet effect elimination of salicylate is primarily renal salicylate works by

Inhibition of cox-2 enzyme and this reduces the synthesis of prostaglandins which ultimately reduces inflammation pain and fever so aspirin is indicated in conditions like headache musculoskeletal and dental pain as well in addition it is used in the short-term management of chronic pain including osteoarthritis rheumatoid arthritis and ankylosing spondylitis as

We discussed before aspirin is mainly used in immediate and long-term management of cardiovascular disease so aspirin is given to patients immediately after a myocardial infarction this will prevent new clot formation and reduce the risk of developing a recurrent myocardial infarction it can also be given during a myocardial infarction to prevent further damage

To already ischemic myocardium most of the time aspirin is given along with other anticoagulants like lipid rule to increase the efficacy aspirin is also used as a prophylactic treatment for the patients who are at risk of developing thrombosis with other risk factors like dyslipidemia and diabetes mellitus now let’s see some common adverse effects of aspirin

Inhibition of cox one enzyme in stomach will reduce the amount of cytoprotective prostaglandins which can cause gastritis gastric ulcers and gi bleeding inhibition of cox 2 and kidneys will reduce prostaglandin synthesis and thereby dilation of renal arteries which ultimately results in reduced renal blood flow this may lead to acute kidney injury not only that

Reduced renal blood flow will activate renin angiotensin aldosterone pathway and this will lead to hypertension another well-known adverse effect of aspirin is hypersensitivity reactions one common example is aspirin-induced asthma the mechanism by which aspirin induces asthma is still not very clear however some theories suggest that inhibition of cox pathway by

Aspirin will reduce the prostaglandin synthesis and at the same time it up regulates the lipoxygenous pathway which results in increased lucotrium production and lukotriens are the major type of mediators responsible for the pathogenesis of asthma and another important fact to keep in mind is that aspirin should not be given to reduce fever in children with viral

Infections because it can cause ray syndrome which is characterized by liver damage and encephalopathy another serious adverse effect of aspirin is acute salicylate poisoning it is a medical emergency and occurs due to aspirin overdose commonly seen in children and attempted suicides it is characterized by tinnitus vertigo deafness nausea and vomiting and respiratory alkalosis

Transcribed from video
Aspirin : Indications, Mechanism of Action, Adverse and Toxic Effects, and Contraindications By Med Today