Dosing errors have happened frequently to patients who drew doses from a vial into a U-100 or tuberculin syringe. Every unit on the U-100 syringe scale is equal to 5 units of U-500 insulin. So, a dose measuring “40” units in a U-100 syringe is really 200 units of U-500 insulin. With a tuberculin syringe, the U-500 insulin dose has to be measured in mL, not units. Both situations have led to serious insulin dosing errors.
Humulin R U-500 is also available in a prefilled pen, which also measures the concentrated insulin in 5-unit segments. With the Humulin R U-500 KwikPen, and now with the U-500 insulin syringe, the actual dose of U-500 insulin prescribed is the actual dose that is measured in the syringe or dialed with the pen. The updated information for physicians who prescribe Humulin R U-500 now requires all prescriptions for the U-500 insulin vials to be accompanied by prescriptions for the new U-500 insulin syringes. The updated information also recommends that healthcare providers:
• Instruct patients who use vials of U-500 to use only a U-500 insulin syringe
• Teach patients how to correctly draw the prescribed dose into the U-500 insulin syringe
• Confirm that the patient has understood the directions
If you are uncertain how to use the new syringe, ask your pharmacist, doctor, or office nurse.