The FDA is alerting veterinarians and veterinary pharmacologists that the strength of epinephrine might be expressed differently on the labels of certain human and animal epinephrine products. To avoid dosing errors, veterinarians should carefully review an epinephrine product’s label to determine if the strength is expressed as mg/mL or as a ratio.

The FDA also recommends that veterinary emergency dosage charts include epinephrine products that are labeled both ways (mg/mL and ratio) to reduce confusion and potential dosing errors, the agency said in its alert.

The warning to veterinarians follows an announcement made last month by the FDA that it was requiring labeling changes to three critical care medications approved for use in people, which also can be used extra-label by veterinarians in some situations. The changes affected the requirements for labeling the strength of these medications: epinephrine injection, isoproterenol hydrochloride injection, and neostigmine methylsulfate injection. In each case, the FDA ordered the removal of ratios expressing the drug’s strength (such as 1:1,000 and 1:10,000) and mandated that strength be given only as the amount per unit of volume (mg/mL).

In ordering the change in June, the FDA said that several reports of medication errors in human patients indicated that medication strength expressed as a ratio was confusing to health care providers.

Although the labeling order involved products approved for use in people, veterinarians are legally allowed to use approved human drugs for extra-label uses in animals under specified conditions.

To avoid potential confusion or incorrect dosage in an emergency, take time now to update your practice’s emergency protocols and charts with the new label information for the impacted pharmaceuticals you administer.