Antifibrinolytic hemostatic used in severe hemorrhage. [PubChem]
Indication
For use in patients with hemophilia for short term use (two to eight days) to reduce or prevent hemorrhage and reduce the need for replacement therapy during and following tooth extraction. It can also be used for excessive bleeding in menstruation, surgery, or trauma cases.
Pharmacology
Tranexamic acid is an antifibrinolytic that competitively inhibits the activation of plasminogen to plasmin. Tranexamic acid is a competitive inhibitor of plasminogen activation, and at much higher concentrations, a noncompetitive inhibitor of plasmin, i.e., actions similar to aminocaproic acid. Tranexamic acid is about 10 times more potent in vitro than aminocaproic acid. Tranexamic acid binds more strongly than aminocaproic acid to both the strong and weak receptor sites of the plasminogen molecule in a ratio corresponding to the difference in potency between the compounds. Tranexamic acid in a concentration of 1 mg per mL does not aggregate platelets in vitro. In patients with hereditary angioedema, inhibition of the formation and activity of plasmin by tranexamic acid may prevent attacks of angioedema by decreasing plasmin-induced activation of the first complement protein (C1).
Toxicity
Oral LD50 in mice is >10 gm/kg. Symptoms of overdosage may be nausea, vomiting, orthostatic symptoms and/or hypotension.
Affected Organisms
Humans and other mammals
Biotransformation
Only a small fraction of the drug is metabolized (less than 5%).
Absorption
Absorption of tranexamic acid after oral administration in humans represents approximately 30 to 50% of the ingested dose and bioavailability is not affected by food intake.
Half Life
Biological half-life in the joint fluid is about 3 hours.
Protein Binding
The plasma protein binding of tranexamic acid is about 3% at therapeutic plasma levels and seems to be fully accounted for by its binding to plasminogen (does not bind serum albumin).
Elimination
Urinary excretion is the main route of elimination via glomerular filtration.
刺激性 (Xi)