Usage
Tranexamic acid is prescribed for preventing or reducing bleeding in various medical conditions, including heavy menstrual bleeding (menorrhagia), hereditary angioedema, and bleeding associated with surgery or trauma. Its pharmacological classifications include antifibrinolytic and haemostatic. It works by reversibly blocking the lysine binding sites on plasminogen, thus inhibiting the conversion of plasminogen to plasmin, the enzyme responsible for fibrin degradation. This action stabilizes blood clots and reduces bleeding.
Alternate Names
While “tranexamic acid” is the generic name, it is marketed under various brand names such as Lysteda, Cyklokapron, and Evana Heavy Period Relief.
How It Works
Pharmacodynamics: Tranexamic acid exerts its antifibrinolytic effect by competitively inhibiting the activation of plasminogen to plasmin. It reversibly binds to lysine receptor sites on plasminogen, preventing its interaction with fibrin and subsequent clot breakdown.
Pharmacokinetics:
- Absorption: Tranexamic acid is well-absorbed orally, with peak plasma concentrations reached within 3 hours. Intravenous administration results in immediate therapeutic levels. It also comes in mouthwash and topical forms.
- Metabolism: It undergoes minimal metabolism.
- Elimination: It is primarily eliminated unchanged through renal excretion (approximately 95%), with a half-life of 2-11 hours.
Mode of Action: Tranexamic acid’s primary mode of action involves reversible blockade of lysine binding sites on plasminogen, effectively inhibiting plasmin formation and fibrinolysis.
Dosage
Standard Dosage
Adults:
- Oral: 1000-1500 mg two to three times a day. For heavy menstrual bleeding, 1300 mg three times a day for up to 5 days during menstruation.
- Intravenous: 10-15 mg/kg every 6-8 hours, not exceeding 3g in a 24 hour period. For dental extraction, 10 mg/kg as a single IV dose before the procedure and then the same IV dose 3-4 times a day for 2-8 days or switch to oral tranexamic acid depending upon bleeding and other clinical factors.
Children:
- Pediatric dosing is weight-based and varies depending on the indication. For example, children undergoing cardiac surgery might receive 10mg/kg pre-surgical followed by an intraoperative infusion, or repeat bolus as deemed appropriate by the clinical team. For children two years or older a dose of 10 mg/kg followed by a repeat bolus, or a 10 mg/kg pre-surgical bolus followed by an infusion, all intra-operatively is another commonly employed regimen. Dosages can be adjusted based on the clinical situation. This must be done by an experienced clinician.
Special Cases:
- Elderly Patients: Dose adjustments might be necessary in cases of renal impairment. It is important to consider a reduction in dose, in accordance with reduced creatinine clearance.
- Patients with Renal Impairment: Dosage reduction is crucial based on the estimated glomerular filtration rate (eGFR). If the eGFR is 30-59 mL/min, the intravenous dose should be reduced. If the eGFR is below 29 mL/min a greater reduction in IV dose is required. This must be done under the guidance of a healthcare professional. Oral tranexamic acid regimens also require a reduction in dose in line with decreasing creatinine clearance.
- Patients with Hepatic Dysfunction: No dose adjustment is typically required.
- Patients with Comorbid Conditions: Consider potential drug interactions and disease-specific factors.
Clinical Use Cases:
- Intubation: Tranexamic acid is not typically administered during intubation itself, but may be used to manage associated bleeding complications.
- Surgical Procedures: IV doses of 10-15 mg/kg or a 1 gram slow IV bolus at the start and end of surgery are common, with variations based on the type of surgery.
- Mechanical Ventilation: Tranexamic acid is not routinely indicated for mechanical ventilation unless there is associated bleeding.
- Intensive Care Unit (ICU) Use: Dosing is guided by the specific indication and patient condition, typically for managing hemorrhage. For hemorrhagic shock, a 1 gram intravenous bolus is frequently given over 10 minutes, which can be repeated in 8 hours. However, the total dose should not exceed 2 grams.
- Emergency Situations: 1 gram IV bolus over 10 minutes for major hemorrhage, potentially repeated, but with a max dose of 2 grams total.
Dosage Adjustments:
Adjustments are based on renal function, concomitant medications, and clinical response.
Side Effects
Common Side Effects:
Nausea, vomiting, diarrhea, dizziness, hypotension.
Rare but Serious Side Effects:
Seizures (especially with high IV doses or inadvertent intrathecal administration), thromboembolic events, anaphylaxis, visual disturbances (blurred vision, altered color perception).
Long-Term Effects:
The potential for long-term effects of tranexamic acid is not fully known.
Adverse Drug Reactions (ADR):
Thromboembolic events, seizures, anaphylaxis, severe allergic reactions.
Contraindications
Absolute contraindications include active thromboembolic disease, history of thromboembolism, acquired color vision defects, subarachnoid hemorrhage, and hypersensitivity to tranexamic acid.
Drug Interactions
Tranexamic acid can interact with combined hormonal contraceptives, factor IX complex concentrates, and tretinoin, increasing the risk of thrombosis.
Pregnancy and Breastfeeding
It is classified as Pregnancy Category B; use with caution if benefits outweigh risks. While present in breast milk in small amounts, neonatal effects are minimal.
Drug Profile Summary
- Mechanism of Action: Inhibits plasmin formation, reducing fibrinolysis and stabilizing clots.
- Side Effects: Nausea, vomiting, diarrhea, dizziness, seizures, thromboembolic events.
- Contraindications: Active thromboembolic disease, color vision defects.
- Drug Interactions: Hormonal contraceptives, factor IX concentrates, tretinoin.
- Pregnancy & Breastfeeding: Category B; use with caution if benefits outweigh risks.
- Dosage: Varies depending on the route, indication, and patient characteristics.
- Monitoring Parameters: Bleeding status, vital signs, renal function, coagulation parameters.
Popular Combinations
Tranexamic acid can be used in conjunction with other hemostatic agents, uterotonics (in postpartum hemorrhage), and other medications.
Precautions
Assess renal function, monitor for thromboembolic events and visual disturbances. Caution in patients with risk factors for thrombosis. Exercise prudence in patients with a history of seizures.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Tranexamic Acid?
A: Dosage depends on the route of administration, indication, and patient characteristics. Consult the detailed dosage guidelines provided above.
Q2: How does Tranexamic Acid differ from other antifibrinolytics?
A: Tranexamic acid specifically inhibits plasminogen activation, while other antifibrinolytics, like aprotinin, target different components of the fibrinolytic system.
Q3: Can Tranexamic acid be used in patients with renal impairment?
A: Yes, but with careful dose adjustments based on eGFR. Close monitoring is essential.
Q4: What are the major drug interactions to be aware of with Tranexamic Acid?
A: Concomitant use with hormonal contraceptives, factor IX concentrates, and tretinoin can increase the risk of thromboembolic events.
Q5: Is Tranexamic Acid safe during pregnancy and breastfeeding?
A: It is generally considered safe but should be used cautiously during pregnancy (Category B). Small amounts are present in breast milk, generally not causing problems in infants. It is advisable for the baby to be medically supervised, if tranexamic acid is required by the mother.
Q6: What are the signs of Tranexamic acid overdose?
A: Symptoms of overdose can include nausea, vomiting, diarrhea, dizziness, hypotension, and potentially seizures.
Q7: How should Tranexamic acid be administered for surgical procedures?
A: Typically, an intravenous bolus is given at the beginning and end of surgery. Dosages can vary and a slow IV infusion is frequently used. The specific surgical case will dictate how tranexamic acid should be employed.
Q8: Can tranexamic acid be used in patients with a history of seizures?
A: Tranexamic acid should be used with caution in patients with a seizure history, especially at higher doses or via intravenous administration, due to the potential increased risk of seizures. EEG monitoring may be considered in high-risk cases. Intrathecal or epidural administration should be strictly avoided.
Q9: How does tranexamic acid affect the coagulation cascade?
A: Tranexamic acid primarily affects the fibrinolytic pathway, not the coagulation cascade itself. It prevents clot breakdown rather than promoting clot formation. It has no effect on platelet function or other factors within the coagulation cascade.
Q10: What are the common indications for intravenous tranexamic acid?
A: Intravenous tranexamic acid is commonly used for acute bleeding situations, including trauma, postpartum hemorrhage, major surgery, and certain bleeding disorders.
