How should I draw and administer a 110‑milligram dose of enoxaparin from a 120‑milligram/0.8‑milliliter vial?

Drawing and Administering 110 mg Enoxaparin from a 120 mg/0.8 mL Vial

To administer 110 mg from a 120 mg/0.8 mL vial, draw 0.73 mL using a standard 1 mL syringe and administer subcutaneously.

Calculation Method

• The concentration of your vial is 150 mg/mL (120 mg ÷ 0.8 mL = 150 mg/mL) 1
• To deliver 110 mg: divide 110 mg by 150 mg/mL = 0.73 mL 1
• Use a standard 1 mL syringe graduated in 0.01 mL increments for accurate measurement 2

Step-by-Step Administration Protocol

Drawing the Dose

• Remove the protective cap from the prefilled syringe or vial 1
• Draw exactly 0.73 mL into a 1 mL syringe (this equals 110 mg) 2
• Expel any air bubbles by tapping the syringe gently and pushing the plunger to the 0.73 mL mark 1
• Verify the volume is precisely at 0.73 mL before proceeding 2

Subcutaneous Injection Technique

• Select an injection site on the left or right anterolateral or posterolateral abdominal wall 1
• Do not inject into muscle tissue—enoxaparin must be given subcutaneously 1
• Pinch a fold of skin between thumb and forefinger 1
• Insert the entire length of the needle at a 90-degree angle into the skin fold 1
• Inject the full dose without aspirating 1
• Hold the skin fold throughout the injection and for 10 seconds after withdrawal 1
• Do not rub the injection site, as this increases bruising risk 1

Critical Safety Considerations

• Renal function check is mandatory: if creatinine clearance is <30 mL/min, the dose must be reduced to 1 mg/kg once daily instead of twice daily 3, 1
• For patients ≥75 years receiving this dose for acute coronary syndrome with fibrinolysis, the maximum dose should not exceed 75 mg per injection 3, 1
• Never switch between enoxaparin and unfractionated heparin once treatment is initiated, as this substantially increases bleeding risk 4, 3
• If the patient weighs <50 kg, consider anti-Xa monitoring due to increased bleeding risk with standard weight-based dosing 1

Common Pitfalls to Avoid

• Do not round to 0.7 mL or 0.75 mL—use the precise 0.73 mL calculation to avoid under- or over-dosing 2
• Avoid intramuscular injection, which can cause hematoma formation 1
• Do not administer within 10–12 hours of neuraxial anesthesia or epidural catheter removal 3, 1
• Never use insulin syringes for doses requiring decimal precision in adults—use a standard 1 mL syringe with 0.01 mL graduations 2