Aspirin
An NSAID that eases pain and fever at higher doses and, at low dose, stops platelets clumping to prevent heart attack and stroke.
Also called acetylsalicylic acid (chemical name) or ASA (abbreviation).
Drug card
- Class
- NSAID
- How it works
- Blocking COX-1 and COX-2, so less prostaglandin is made
- Used for
- Preventing heart attack and stroke in vascular disease
- Suspected heart attack, given straight away
- Lowering stroke risk after a TIA or ischemic stroke
- Preventing pre-eclampsia in pregnancy
- Known for
- Bleeding from the stomach or gut
- Reye's syndrome in children and teenagers
- Ringing in the ears (tinnitus) at high levels
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does aspirin work?
Aspirin acetylates a serine in the COX enzymes and blocks them irreversibly. In platelets this stops thromboxane A2, a strong trigger of clumping, so even a low dose inhibits clotting, and for longer than other NSAIDs do. Higher doses also lower prostaglandins, easing pain, fever and inflammation.
Like other non-steroidal anti-inflammatory drugs: NSAIDs block the cyclooxygenase enzymes COX-1 and COX-2, which turn arachidonic acid into prostaglandins and thromboxane. With less prostaglandin, nerve endings are less sensitized, inflammation settles and fever falls. Losing COX-1 products in the stomach and platelets, and the prostaglandins that keep blood flowing through the kidney, explains their ulcers, bleeding and kidney harm.
See its molecule in 3DPubChem CID 2244Uses
What is aspirin used for?
- Preventing heart attack and stroke in vascular disease
- Suspected heart attack, given straight away
- Lowering stroke risk after a TIA or ischemic stroke
- Preventing pre-eclampsia in pregnancy
- Mild to moderate pain
- Fever
Side effects
Side effects of aspirin
- Bleeding from the stomach or gutKnown forSerious
- Reye's syndrome in children and teenagersKnown forSerious
- Ringing in the ears (tinnitus) at high levelsKnown for
- Indigestion and stomach pain
- Nausea and vomiting
- Bleeding more easily, including in the brainSerious
- Stomach and duodenal ulcersSerious
- Wheezing and asthma attacks in aspirin-sensitive peopleSerious
- Hives and swelling of the face (angioedema)Serious
- Severe allergic reactions (anaphylaxis)Serious
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Avoid in children and teenagers, especially with flu or chickenpox, because of the risk of Reye's syndrome.
- Bleeding risk rises with anticoagulants, other antiplatelets, other NSAIDs, steroids and heavy alcohol use.
- Contraindicated in NSAID allergy and in the triad of asthma, rhinitis and nasal polyps.
- Avoid pain-relief doses in the last 3 months of pregnancy; low doses are used to prevent pre-eclampsia.
Good to know: Other NSAIDs affect platelets less, for a shorter time and reversibly; aspirin's block on platelet COX is permanent, which is why it is used as an antiplatelet drug.
Remember it
A way to remember it
NSAID
- N
- Nephrotoxicity: acute kidney injury
- S
- Stomach ulcers and bleeding
- A
- Asthma attacks in aspirin-sensitive people
- I
- Increased risk of heart attack and stroke
- D
- Ductus arteriosus closing early in late pregnancy
Written for biofideX
Its class
Non-steroidal anti-inflammatory drugs
Other non-steroidal anti-inflammatory drugs with a card:
Easily mixed up with selective COX-2 inhibitors, paracetamol and glucocorticoids.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Low dose aspirin 81 mg: OTC label (DailyMed)
- Aspirin and extended-release dipyridamole capsules: label (DailyMed)
- Aspirin (NCI Thesaurus)
- Aspirin (NHS)
- Heart attack (NHS)
- Ibuprofen tablets: label (DailyMed)
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Pain, fever and inflammation
Aspirin is one of 15 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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