December 6, 2012 — The FDA has published a Drug Safety Communication to announce label updates for heparin, a blood-thinning medication. The revised labels will clearly state the strength of the entire container of the medication, including how much of the medication is in 1 milliliter (mL). This will reduce the risk of calculation errors when caregivers measure a dose.

Manufacturers will be required to update the labels on “Heparin Lock Flush, USP” and “Heparin Sodium Injection, USP” by May 1, 2013.

The current label includes the bold-face text, “5,000 USP units per mL,” on a 10mL bottle. If the caregiver fails to realize that the bottle actually contains 50,000 USP units, they might under-dose a patient. The revised label will include the following bold-face text: “50,000 USP units per 10 mL, (5,000 USP units per mL)” on a 10 mL bottle.

Until the label updates take effect, the FDA is recommending that hospitals separate the “current” and “revised” labeled heparin, and finish all supplies of the “current” medication before transitioning to the “revised” medication.

Since 2003, experts have been aware that dosing errors often occur because the bottle is labeled with the “dose per mL” instead of the total drug content. Since 2009, labeling standards have required the total strength to be the primary bold-face text on the label. Medication labels that have already been changed have had no reported medication errors.

Heparin is a blood-thinning medication. It is used to reduce the risk of blood clots in patients who have underlying medical conditions or are at risk of blood clots from medical procedures. It inhibits the clotting ability of blood, which prevents existing blood clots from growing larger. It is often prescribed to people with long-term catheters.