Tranexamic acid
Tranexamic acid. Antifibrinolytic — synthetic lysine analog that competitively inhibits the lysine-binding sites on plasminogen, blocking its… Oral half-life 2 h.
Antifibrinolytic — synthetic lysine analog that competitively inhibits the lysine-binding sites on plasminogen, blocking its conversion to plasmin + plasmin-mediated fibrin degradation. Clinical use: heavy menstrual bleeding (PO), surgical bleeding (IV — orthopedic, cardiac, trauma; CRASH-2 + CRASH-3 trials showed mortality reduction in trauma + TBI when given within 3 hours), postpartum hemorrhage (WOMAN trial), epistaxis (topical), hereditary angioedema. T½ ~2 h, renally cleared. Contraindicated in active intravascular clotting + acquired defective color vision. Distinct from the topical cosmetic application (tranexamic-acid-topical slug) which targets PAR-2 in melanocytes for hyperpigmentation. PK (Lysteda label, 1300 mg PO multiple-dose SS in women): Cmax 13.83 → 16.41 µg/mL after 5 days SS, AUC 78 µg·h/mL, Tmax 3 h, t½ ~11 h (initial phase ~2 h), F 45%. Protein binding 3% (minimal — nearly all unbound). Renally cleared (>95% unchanged in urine) — dose-adjust in CKD. IV formulation has different PK (instant Cmax, F=1.0).
PK: THE RECORD INTERNAL CONTRADICTION IS RESOLVED IN FAVOUR OF THE STORED NUMBER. Its own label text read "t1/2 ~11 h" against a stored 2 h, and both figures are real but describe DIFFERENT QUANTITIES: 11 h is the terminal phase seen by modern long-sampling assays, while 2 h is the dominant elimination phase — "Most elimination took place during the first eight hours, giving an apparent elimination half-life of approximately two hours". Elimination is renal and about 90% complete by 24 hours, so the terminal phase carries negligible exposure and the stored 2 h is the right value for a one-compartment model. The LABEL TEXT was the error, not the number, and it is corrected. There is no flip-flop: absorption is much faster than elimination, so one value legitimately serves both routes. V 119 L is wrong by four to twelvefold — published volumes are about 13 to 27 L — and is replaced by a pooled population estimate, flagged because that source is a meta-analysis rather than a single primary. F 0.45 is the label figure for a modified-release tablet in women, while the cited paper states 34% for immediate release, which is what this row models. EFFECT OUTLASTS PLASMA: antifibrinolytic concentrations persist in tissue for about 17 hours against a 2 h plasma phase.
Pharmacokinetics
- Oral — t½ 2 h · F 34% · Vd 17.9 L
- IV — t½ 2 h · F 100% · Vd 17.9 L
Sources: PMID:7308275, PMID:31013357