The U.S. Food and Drug Administration is requiring labeling changes to three critical care medications that are approved for use in people and are also used in animals in the practice of veterinary medicine. Veterinarians who use these products in animals should be aware of these changes.
The labeling changes affect epinephrine injection, isoproterenol hydrochloride injection, and neostigmine methylsulfate injection for use in people. The FDA is requiring drug manufacturers to remove ratio expressions of strength (such as 1:1,000 and 1:10,000) from the labeling of these products. Strength will now be expressed only as the amount per unit of volume (mg/mL). For example, once these changes are made, the labeling for Epinephrine Injection, USP, 1:1,000 will state Epinephrine Injection, USP, 1 mg/mL.
Several reports of medication errors in human patients indicated that medication strength expressed as a ratio on product labeling was confusing to health care providers and contributed to the errors.
These products are approved for use in humans, but veterinarians are legally allowed to use approved human drugs for extra-label uses in animals under specified conditions. Extra-label use means using an approved drug in a way that isn’t in accordance with the approved labeling. It is sometimes called off-label because the use is “off the label."
Additionally, the FDA alerts veterinarians and veterinary pharmacologists that the strength of epinephrine might be expressed differently on the labeling on certain human and animal epinephrine products. To avoid dosing errors in animals, the FDA recommends that veterinarians carefully review an epinephrine product’s labeling before administering the drug to determine if 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.