Aspirin: Uses, mechanism of action, side effects, preparations. - be healthy

mechanism of action 

1- Anti-thrombotic [ Anti-platelet ].

It inhibits cyclo-oxygenase enzyme-1 ( COX-1 ) in a low dose and this action is irreversible.

It inhibits also Thromboxane A2 ( TXA2), by this action platelet aggregation is inhibited.

2- Analgesic, Anti-pyretic, Anti-inflammatory.

In a higher dose, it obtains all these actions like 300 mg tds or more than 2 gm tds as Anti-inflammatory inhibits ( COX-2 ) enzyme, and inhibits prostaglandin formation.

Uses

1- Anti-thrombotic

   

It is used in angina pectoris and also in myocardial infarction, transient ischemic attack, cerebral infarction.

2- Analgesic

It is used in mild to moderate pain like headaches, dental pain, muscle pain. 

It is used also in gynecological pain.

3- Anti-pyretic

It is used to decrease fever, but an alternative like acetaminophen ( panadol ) is recommended.

4- Anti-inflammatory

It is prescribed widely by doctors if you have "Rheumatic fever" or arthritis.

5- It was used recently in colon cancer and cataract and pregnancy-induced hypertension.

Side effects

• On GIT: Heartburn, Peptic ulcer, Hematemesis due to loss of protective prostaglandins and local acidic action.

• Bleeding tendency: It is more if aspirin is combined with warfarin, don't increase the dose until the doctor tell you because this is dangerous on your circulatory system.
• Reye's syndrome ( It is preferred to take paracetamol instead of aspirin )
• Increase hepatic enzymes: SGOT and SGPT 
• Hypersensitivity: Skin rash, bronchospasm ( Aspirin-induced asthma ). due to increased leukotrienes synthesis. 
• Renal adverse effects:

        - Salt and water retention ( Hypertension and edema )

        - Hyperkalemia 

        - Acute papillary necrosis

            - Nephrotic syndrome

• prolong gestation and teratogenic ( premature closure of ductus arteriosus ).
• Hyperuricemia

        - Contraindicated in gout

• Acute salicylate toxicity 

         - Tinnitus

         - Vertigo

         - Problems with hearing

         - Metabolic acidosis and Respiratory alkalosis

         - Respiratory acidosis as it causes respiratory center                           depression

Some information about aspirin

• COX-1 enzyme is present in platelets, stomach, and maybe endothelium
• COX-2 enzyme is present in other tissues
• Selective COX-2 enzyme inhibitor ( Celecoxib ) does not cause bleeding or peptic ulcer
• Aspirin although it inhibits the endothelial COX-1 enzyme, it does not inhibit prostacyclin synthesis as the endothelial cells are nucleated and can form another enzyme in contrast to platelet which is non-nucleated, also low aspirin spare endothelial COX-2 enzyme. 

Alternative drug better than aspirin 

Paracetamol is better than aspirin due to fewer side effects and the drug is actually safe. The only adverse effect of it is liver damage which occurs when someone takes a large dose. Its toxicity is treated by "Methionine" or " Acetyl-cysteine" within 24 hours.

It is used instead of aspirin in the following conditions:

• Salicylate allergy
• Peptic ulcer
• Gout
• Bleeding tendency 
• Viral infection in children

Summary 

Aspirin is a drug that is prescribed to patients suffering inflammations and pain and Heart problems. 

Talk to your doctor before taking aspirin. This is important as its side effects are totally bad for your overall health. 

If you notice any side effects, call your doctor immediately and don't hesitate. 

Talk to your doctor about any side medication used for clotting because this may affect the effectiveness of aspirin and may cause toxicity in such a large dose. 

Talk to your doctor about your past medical history of certain diseases like heart problems or kidney problems. In this situation, your doctor will look for alternative medications, and aspirin will be a second choice. 

Follow the prescribed regimen carefully and talk to your doctor about your overall health, is it getting better or not.

It is important to tell your doctor about peptic ulcer medications or food that you eat. This may help you avoid peptic ulcers. In such a situation your doctor may look for alternative medications or stop some medications.