NSAID
Meaning of NSAID: The same enzyme block that relieves pain also strips prostaglandin protection from the stomach lining and from blood flow through the kidney.
Definition of NSAID
NSAID stands for nonsteroidal anti-inflammatory drug, a class of medicine that eases pain, brings down fever, and reduces swelling and redness. NSAIDs block cyclooxygenase enzymes, which the body uses to make prostaglandins, the chemical signals behind much inflammation and pain. The nonsteroidal part of the name separates them from corticosteroids, which calm inflammation by a different route.
What do the two enzyme forms do?
| Enzyme | Normal job | What blocking it produces |
|---|---|---|
| COX-1 | Present all the time; protects the stomach lining and lets platelets clump | Stomach irritation and ulcers, easier bruising and bleeding |
| COX-2 | Switched on at sites of injury and inflammation | Less pain, swelling and fever |
Most nonsteroidal anti-inflammatory drugs block both forms, which is why the wanted effect and the unwanted one arrive together. Drugs designed to act mainly on COX-2 were an attempt to separate them, and they do spare the stomach to a degree, though effects on the heart and blood vessels are weighed against that advantage.
Why do the side effects follow from the mechanism?
Prostaglandins are not only inflammation signals. In the stomach they drive the mucus and bicarbonate layer that keeps acid off the wall. In the kidney they keep the small artery feeding each filtering unit open when circulation is under strain. Removing them therefore exposes the stomach lining and narrows the kidney's own blood supply, and a kidney function test is a common way of watching for the latter. The same loss of prostaglandins encourages the body to hold on to salt and water, which nudges blood pressure upward. Risk rises with prolonged use, with dehydration, with older age, and when several drugs acting on the kidney are combined.
Where does aspirin fit?
Aspirin belongs to the class but behaves differently. It binds cyclooxygenase permanently rather than temporarily, and because platelets cannot manufacture fresh enzyme, a single dose disables them for the rest of their lifespan. That is why aspirin is used to discourage clotting while other NSAIDs are not. At the other end, acetaminophen is often grouped with NSAIDs in conversation but is not one. It lowers fever and pain without meaningfully reducing inflammation at the site, which matters in conditions such as rheumatoid arthritis where the inflammation itself is the target.
Also known as
Used in a sentence
An NSAID was recommended for the patient's musculoskeletal pain following the minor injury.
Good to know
NSAIDs and acetaminophen both relieve pain and fever, but only NSAIDs reduce inflammation at the site, since acetaminophen has little effect on the same enzymes in inflamed tissue.