Humulin U-500: Counseling Your Patients

Pharmacists looking to counsel patients on Humulin R U-500 can use counseling points that are very similar to U-100, which patients often find comforting.

To begin with the product, which is a concentrated insulin that is typically considered in patients injecting large volumes of U-100, should be clear and colorless at all times. They should be administering the insulin 30 minutes before their meal(s).

The most common adverse effect reported with Humulin R U-500 is hypoglycemia. Studies show that patients are at risk for severe hypoglycemia as long as 18-24 hours post injection and should always be considered a risk factor if the patient is found unresponsive. For this reason patients should also be cautious while driving/operating heavy machinery at all times, but especially when first starting this medication as well as any dose changes. To minimize the risk of hypoglycemia, Humulin R U-500 should not be administered IV, IM, or via insulin pump in a hospital setting or outpatient. Other common adverse effects would include lipodystrophy, weight gain, edema, allergic reactions, and/or immunogenicity (antibody formulation).

Considered a Pregnancy Category B, this product, like other insulin products should be used in pregnant women with both caution and care but it is noteworthy that Humulin R U-500 does not pose any greater risk. The insulin does pass into the breast milk and gets ingested by the infant, however, the insulin is broken down into the gastrointestinal tract and does not raise any concern, therefore, it is safe to administer while breastfeeding.

Commercially available as both a KwikPen and vials, the KwikPens are 3 mL and contain 1,500 units in each pen available in packs of 2 and 3 pens, while the vials are available as 20 mL containing 10,000 units of insulin. Both the pens and vials should be stored in the refrigerator when not being used. Once the KwikPen is being used it should be stored at room temperature, it cannot be stored in the refrigerator. The KwikPen has an expiration date of 28 days when opened. The vial, however, can be stored in the refrigerator when it is open or at room temperature and has an expiration date of 40 days once opened.

Humulin R U-500 from vials should only be administered using U-500 syringes and patients should not be converting U-500 doses to U-100 syringes due to a high risk of potential adverse effects. U-500 syringes allow 5 to 250 units per injection.

KwikPen can administer 5 to 300 units in a single injection and should be dialed according to the U-500 units for injection. The dose does not need to be converted from the U-100 dose, it is correctly labeled to the U-500 dose. On the pen when dialing, the even numbers are indicated numerically while the odd numbers are shown as lines between the even numbers. While administering the insulin, the patient should hold the needle in their skin for at least 5 seconds. Once they remove the pen the dose vial window should indicate "0" to tell them they have received their full dose. If it does not say '0" they can re-inject to finish their dose. Never re-start the process by drawing up more insulin to inject because the risk for hypoglycemia is greater due to receiving a high dose.

Reference

Humulin U-500 [package insert]. Lilly USA, LLC, Indianapolis, IN; July 2016.

http://pi.lilly.com/us/humulin-r-u500-pi.pdf.

Accessed November 15, 2016.