USP Quality Review

No. 58, Issued 03/97

Humalog® (insulin lispro injection, rDNA origin)

Humalog, a new, rapid-acting insulin analog manufactured by Eli Lilly and Company, has been associated with a few error reports in the database.

Patients with diabetes may be asked to follow strict diets and complex insulin-dosing regimens. Insulin levels and the resulting blood glucose levels are predicted according to the product's half-life, which varies according to the type of insulin used and the time of its injection. To optimize control of post-meal glucose levels, patients try to schedule their meals and busy lifestyles according to the peak activity time of their insulin regimen, which can be difficult.

Humalog, used as an adjunct to a basal insulin therapy, accurately controls post-meal glucose levels. Its rapid absorption, rapid onset of action, and short duration of action are an advantage for patients with diabetes. Injected no more than 15 minutes before a meal, Humalog allows patients more flexibility and simplicity. Due to its short half-life (one hour), it needs to be used with a longer-acting insulin to regulate glucose levels throughout the day.

Pairing Humalog with long-acting human insulin preparations, such as Humulin® (Eli Lilly's brand of human insulin), may introduce factors with known potential for precipitating medication errors:

  • the prescribing of a new drug product

  • the prescribing of a new drug product with a name that may look or sound similar to the name of another product

  • using different products with similar-appearing labeling and packaging.

The names Humulin and Humalog may not seem similar at first to the well-trained and cautious eye and ear. However, both begin with the letters h-u-m, have three syllables, and contain the letter l in the third syllable. The insulin preparations are both available in 10-mL vials. The products are the same size and shape, their labels carry identical logos, and in accordance with federal regulations, the label information is printed in the same style and color. For differentiation, the manufacturer supplies a different-colored (magenta) crimp and cap for the Humalog and it can only be obtained with a prescription.

Errors with the use of Humalog, as can occur with the administration of any insulin preparation, have occurred for two common reasons: mistaken product identity and lack of knowledge on its proper administration. Three incidents reported to the USP MER Program describe circumstances that occurred for both reasons.