What is the recommended intravenous (IV) dose of tranexamic acid for a patient weighing 49 kilograms (kg)?

Tranexamic Acid IV Dosing for 49kg Patient

For a 49kg patient, administer tranexamic acid 490mg (10 mg/kg) as an IV bolus, followed by a maintenance infusion of 49-245mg/hour (1-5 mg/kg/hour), with the specific rate and duration determined by the clinical indication.

Weight-Based Calculation

• Loading dose: 10 mg/kg × 49kg = 490mg IV bolus 1
• Maintenance infusion: 1-5 mg/kg/hour × 49kg = 49-245mg/hour 1
• The FDA-approved dosing for hemophilia patients is 10 mg/kg actual body weight as a single dose, which would be 490mg for this patient 2

Clinical Context-Specific Dosing

For Trauma/Major Bleeding (CRASH-2 Protocol)

• Loading dose: 1g IV over 10 minutes (regardless of weight) 1
• Maintenance: 1g IV infusion over 8 hours 1
• Must be administered within 3 hours of injury for mortality benefit 1
• This fixed-dose regimen from the landmark CRASH-2 trial supersedes weight-based dosing in trauma settings, as it demonstrated a 9% relative risk reduction in all-cause mortality 1

For Cardiac Surgery

• Loading dose: 490mg (10 mg/kg) IV bolus 1
• Maintenance: 49mg/hour (1 mg/kg/hour) continuous infusion 1
• Maximum total dose should not exceed 4,900mg (100 mg/kg) to avoid seizure risk 1, 3
• The Horrow regimen (10 mg/kg bolus + 1 mg/kg/hour) achieves therapeutic plasma levels of 10 μg/mL required to inhibit fibrinolysis 1

For Cirrhosis-Related Bleeding

• Fixed dose: 1g IV every 6 hours 1
• This is not weight-adjusted and represents a rescue measure for active bleeding 1

Critical Administration Details

Infusion Rate

• Infuse no faster than 1 mL/minute (100mg/minute) to avoid hypotension 2
• For the 490mg loading dose, this means infusion over at least 5 minutes 2

Renal Dose Adjustments (Essential)

For serum creatinine 1.36-2.83 mg/dL:

• 490mg (10 mg/kg) IV twice daily only 2

For serum creatinine 2.83-5.66 mg/dL:

• 490mg (10 mg/kg) IV once daily only 2

For serum creatinine >5.66 mg/dL:

• 490mg (10 mg/kg) IV every 48 hours OR 245mg (5 mg/kg) every 24 hours 2

• Failure to adjust for renal dysfunction leads to drug accumulation and increased risk of seizures and neurotoxicity, as 90% is renally excreted 2, 4

Safety Considerations and Contraindications

Absolute Contraindications

• Active intravascular clotting or thrombosis 2
• Subarachnoid hemorrhage (risk of cerebral edema and infarction) 2
• Known hypersensitivity to tranexamic acid 2

Avoid Concomitant Use With

• Hormonal contraceptives (increased thrombotic risk) 2
• Factor IX concentrates 2
• Anti-inhibitor coagulant concentrates 2
• These combinations significantly increase thromboembolic risk 2

Seizure Risk

• Doses exceeding 100 mg/kg total are associated with significantly increased seizure risk, particularly in cardiac surgery patients over 50 years 1, 3
• For this 49kg patient, the maximum safe total dose is 4,900mg 1, 3
• Tranexamic acid is an independent predictor of postoperative seizures with odds ratio of 14.3 3

Duration of Therapy

• Continue infusion until bleeding is adequately controlled 1
• For trauma: 8-hour infusion protocol per CRASH-2 1
• For dental procedures in hemophilia: may continue 10 mg/kg 3-4 times daily for 2-8 days post-procedure 2
• Discontinue as soon as hemostasis is achieved to minimize thrombotic complications 1

Common Pitfalls to Avoid

• Never administer intrathecally - serious adverse reactions including seizures and cardiac arrhythmias have occurred with incorrect route 2
• Do not mix with penicillin-containing solutions - tranexamic acid is a synthetic amino acid incompatible with penicillin 2
• Do not mix with blood products - mix only with electrolyte, carbohydrate, amino acid, or dextran solutions 2
• Assess renal function before every dose - even mild renal impairment requires dose reduction 2, 4
• In trauma, do not delay for weight calculation - use the fixed 1g + 1g protocol if weight unknown 1