Acetylsalicylic acid
Trombyl · Aspirin
Irreversibly acetylates COX-1, eliminating thromboxane synthesis in platelets for their entire lifespan. This is why a low once-daily dose is sufficient, and why the effect persists for 7–10 days after discontinuation.
Gastrointestinal bleeding, particularly in combination with NSAIDs, anticoagulants, or corticosteroids. Do not give to children with viral infections — Reye's syndrome.
Dosing in adults
| Indication | Regimen | Comment |
|---|---|---|
| Acute coronary syndrome, loading dose | 300–500 mg orally, chewed | administer immediately on suspicion |
| Secondary prevention | 75 mg orally once daily | lifelong in established atherosclerotic disease |
| After PCI, dual antiplatelet therapy | 75 mg daily together with P2Y12 inhibitor | duration based on bleeding risk |
| Preeclampsia prophylaxis | 75–150 mg at night from week 12 | in high-risk patients |
Avoid as analgesic at eGFR < 30; low cardiovascular doses can often be maintained.
Avoid in severe hepatic failure and coagulopathy.
Not given as analgesic or antipyretic to children. Exception: Kawasaki disease.
Primary prevention in individuals without known atherosclerotic disease now offers limited benefit relative to bleeding risk — reassess ongoing treatment when there is no clear indication.
Pharmacokinetics
- BIOAVAIL.
- 50–75 %
- Vd
- 0,15 l/kg
- t½
- 15–20 min (effect is irreversible)
- PROTEIN BINDING
- 90 %
- METABOLISM
- Hydrolysis to salicylate
- EXCRETION
- Renal
- EFFECT DURATION
- 7–10 days
- ONSET
- 20 min (chewed)