What volume (mL) of protamine (anticoagulant reversal medication) corresponds to 1 milligram (mg)?

Protamine Concentration and Volume Conversion

Protamine sulfate is supplied at a standard concentration of 10 mg/mL, therefore 1 mg of protamine equals 0.1 mL. 1

Standard Formulation

• Protamine sulfate injection is universally formulated as 10 mg per mL in sterile, isotonic solution 1
• Available vial sizes include:
  • 5 mL vials containing 50 mg total (10 mg/mL) 1
  • 25 mL vials containing 250 mg total (10 mg/mL) 1

Volume Calculation

• For any protamine dose in mg, divide by 10 to get the volume in mL 1
• Examples:
  • 50 mg protamine = 5 mL 1
  • 250 mg protamine = 25 mL 1
  • 1 mg protamine = 0.1 mL 1

Clinical Context for Dosing

While the question asks about volume conversion, understanding protamine dosing is critical for safe administration:

Unfractionated Heparin Reversal

• Standard dosing is 1 mg protamine per 100 units of heparin given in the previous 2-3 hours, with a maximum single dose of 50 mg 2, 3
• Administer by slow IV injection over approximately 10 minutes 2
• Time-adjusted dosing: 0.5-0.75 mg per 100 units if heparin given 30-60 minutes prior 3

LMWH Reversal

• For enoxaparin given within 8 hours: 1 mg protamine per 1 mg of enoxaparin (maximum 50 mg) 2
• For enoxaparin given 8-12 hours prior: 0.5 mg protamine per 1 mg enoxaparin 2

Critical Safety Considerations

• Rapid administration causes severe systemic hypotension 3
• Excess protamine induces paradoxical anticoagulation and increased bleeding risk 2, 4
• The 25 mL vial (250 mg) contains 5 times more protamine than the 5 mL vial (50 mg)—verify dose carefully 1
• Store at 20-25°C; do not freeze 1