Aspirin
Aspirin. Irreversibly acetylates arachidonic acid cascade COX-1 (platelets, GI mucosa) + COX-2 (inflammation). At low dose (81 mg), COX-1… Oral half-life 0.4 h.
Irreversibly acetylates Arachidonic acid cascade COX-1 (platelets, GI mucosa) + COX-2 (inflammation). At low dose (81 mg), COX-1 inhibition dominates → Platelet aggregation TxA2 suppression → antiplatelet for 7–10 d (RBC lifetime). At higher dose, COX-2 contributes → analgesia, anti-inflammation. Unique vs other NSAIDs in being the only one that irreversibly inhibits platelet function.
PK: TWO OF MY THREE PRIORS ABOUT THIS RECORD WERE REFUTED, AND THE REAL DEFECT IS SCOPE. I proposed the solver Michaelis-Menten parameters for saturable kinetics — BUT THE SATURATION IS SALICYLATE, WHICH THIS RECORD DOES NOT MODEL, and within its own dose block salicylate half-life is still two to three hours, below the saturating regime; no abstract states a maximum rate or half-saturation constant for it in man anyway. I also asked what the record asserts through an effect compartment — IT ASSERTS NOTHING, correctly, having neither a keo nor an occupancy row, so there was nothing to fix. What is wrong is smaller and larger at once. The two field corrections are verbatim: "only 68% of the dose reaches the systemic circulation as aspirin" and "The terminal half-lives (t1/2) of ASA and SA were 0.4 and 2.1 hours", against a stored 0.7 and 0.3 that matched neither this citation nor any other. The absorption rate remains a range midpoint of "an absorption half-life ranging from 5 to 16 minutes". THE SCOPE PROBLEM IS LOGGED RATHER THAN ACTED ON because it changes the record identity: at 500 mg this record total exposure is UNDER TEN PERCENT of the salicylate exposure that actually produces the analgesia its 325-650 mg dose block is for, and salicylate IS representable in this solver. OUR OWN PROSE IS ALSO WRONG: it calls 7-10 days the red-cell lifetime; that is the PLATELET lifetime.
Pharmacokinetics
- Oral — t½ 24 min · F 68% · ka 4 h⁻¹ · Vd 11 L
Related compounds
- Ibuprofen — caution
- Apixaban — caution
- Dabigatran — caution
- Edoxaban — caution
- Valproate — major
Sources: PMID:3888490, PMID:6804150, PMID:8750369, PMID:14671681