How do I administer 2.5mg of a medication with a concentration of 18mg/ml using a 1ml per 100 unit syringe?

Medication Dose Calculation: 2.5mg from 18mg/ml Concentration

To administer 2.5mg from an 18mg/ml concentration using a 1ml per 100 unit syringe, draw up 14 units (0.14ml).

Calculation Method

The calculation follows this formula:

• Volume needed (ml) = Desired dose (mg) ÷ Concentration (mg/ml)
• 2.5mg ÷ 18mg/ml = 0.139ml (approximately 0.14ml)

Since your syringe is calibrated as 1ml = 100 units:

• 0.14ml × 100 units/ml = 14 units 1

Step-by-Step Administration

1. Verify the medication concentration is exactly 18mg/ml by checking the vial label 2

2. Draw up 14 units on your 100-unit syringe, which equals 0.14ml 1

3. Double-check your calculation before administration, as dosing errors with concentrated medications can have serious consequences 1

Critical Safety Considerations

• Never dilute injectable medications without verified manufacturer instructions, as improper dilution can lead to precipitation, inactivation, or toxicity 2

• Verify the generic name of the medication, as brand names may vary by region 2

• Use the most proximal IV site possible if administering intravenously, and follow with an immediate saline flush if indicated by the medication type 1

• For medications requiring slow administration, adjust the rate according to manufacturer guidelines to avoid adverse events 1

Common Pitfalls to Avoid

• Do not round excessively - 14 units is more accurate than rounding to 15 units, which would deliver 2.7mg instead of 2.5mg 1

• Ensure proper syringe selection - confirm your syringe is indeed a 1ml/100-unit insulin or tuberculin syringe, not a different calibration 1

• Check for precipitation before drawing up the medication, especially if it has been stored in a refrigerator 1