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Diabetes Disaster Averted #1: U-500 Pharmacy Error

Oct 7, 2010

Last year I converted a patient to Humulin R U-500 Insulin for use in her pump. I called a chain pharmacy to order the prescription and, to make sure there would not be any confusion, gave the pharmacist the NDC number….

This is the national drug code assigned by the FDA to each and every drug sold in the US and the number that the pharmacist can order a product by from any wholesaler.

The patient had been given new basal and bolus settings to use when the insulin came in.  She went to pick up the insulin and was given Ultralente (no longer available) insulin. When she questioned the pharmacist she was told that the ultra was the same thing and it was “ultra strong.” Luckily the patient was not comfortable and called me before using the Ultralente in her pump and I was able to stop her from doing it. This would have been a disaster if she had changed it.

Ultralente takes 4-8 hours to go to work, 10 -20 hours to reach a peak and can last over 36 hours. If the patient had used this insulin in her pump she would have depoted significant amounts of insulin. Each time she bolused there would be no improvement so she would be repeatedly trying to correct her high glucose readings. All this insulin would have reached its peak somewhere between 10 and 30 hours after her first dose.

This would mean that about a full day after she first started dosing she would have the most peaking of insulin and her glucose would start to fall. More than likely no amount of food would be able to compensate and she would have had no idea as to why she was going low. If the patient had not been able to get to the hospital there could have been a good chance she could lapse into a coma and possibly die.

Bottom Line
Although U-500R reaches its peak at about the same time U-100R does, it has a much longer tail. In practice many clinicians have found that the need for long acting insulin is diminished or not needed at all. Please be careful to reduce the amount of long acting insulin your patient is taking when starting on U-500R. Information on action curves available from Eli Lilly, USA.

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