How Long Should Insulin Be Used Once a Vial Is Started?

Response to Grajower et al.

  1. Mark E. Molitch, MD
  1. From the Northwestern University Feinberg School of Medicine, Chicago, Illinois
  1. Address correspondence to Mark E. Molitch, MD, Northwestern University Feinberg School of Medicine, Tarry 15-731, 303 E. Chicago Ave., Chicago, IL 60611. E-mail: molitch{at}northwestern.edu

I wish to comment on the commentary by Grajower et al. (1) regarding how long insulin should be used once a vial is started. I agree with Dr. Grajower that this is an important issue, and I am glad that Dr. Mayer Davidson and Diabetes Care have chosen to obtain responses from the American Diabetes Association and the pertinent pharmaceutical manufacturers of insulin. However, I found the responses from Aventis, Eli Lilly, and Novo Nordisk to be totally unsatisfactory and self-serving.

Although Aventis provides data showing stability for 4 weeks, it does not provide data showing that Lantus becomes unstable after that time. Lilly provides data to suggest that the amount of potency lost with an unknown type of insulin (probably regular) is negligible at 30 days even when stored at room temperature. However, they use the Committee for Proprietary Medicinal Products standard to say that a bottle can be open for only 28 days from a sterility perspective. So why does Lilly recommend discarding Humulin NPH, Humalog Mix 75/25, and Humulin 70/30 after shorter times? Where are the data to support these recommendations? Novo Nordisk provides no information regarding their vialed regular, NPH, 70/30, lente, or buffered regular preparations and only quotes the U.S. Pharmacopoeia, which itself provides no data. They then provide no data on NovoLog either, except to say that it should be discarded after 28 days. They also state that NovoLog used in pumps should be discarded after 48 h. Then follows a bewildering set of varying recommendations for different times for Novolog, Novolog 75/25 FlexPens, and Novolin N, R, and 70/30 InnoLet pens that ranges from 10 to 28 days. Where are the data?

Without data showing that these insulins become unstable after specified periods of time or showing high contamination rates, the recommendations to discard the bottles and cartridges seem to be more based on a desire to sell more insulin rather than on facts related to safety and efficacy. Many of our patients use insulin doses <15 units/day and therefore would have to throw away bottles containing >50% of the original amount of insulin. At the current prices being charged by these manufacturers, this is a considerable loss of money on the patient’s part and a considerable excess profit for the manufacturers. The insulin-manufacturing community would do well to supply insulin vials in 5-ml amounts as well as 10-ml amounts.

Health care providers and patients deserve better information from these manufacturers. If there are data showing specified times for safety and efficacy, they should provide such data. The rambling responses provided here are unhelpful and seem to obfuscate rather than clarify a complex issue.

Footnotes

  • M.E.M. is currently receiving research support from Eli Lilly and Aventis and has received honoraria from Lilly, Aventis, and Novo Nordisk.

    Novo Nordisk and Aventis had no further comments on this issue.

References

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