Teat Dip Colorants

If a coloring is included in a teat dip, does OMRI require that the coloring meets the excipient criteria?

By Sarah Peters

Excipients are defined at 7 CFR §205.2 as:

Any ingredients that are intentionally added to livestock medications but do not exert therapeutic or diagnostic effects at the intended dosage, although they may act to improve product delivery (e.g., enhancing absorption or controlling release of the drug substance). Examples of such ingredients include fillers, extenders, diluents, wetting agents, solvents, emulsifiers, preservatives, flavors, absorption enhancers, sustained-release matrices, and coloring agents.

In other words, in a livestock health care product, an excipient is any ingredient other than the active ingredient. 

Colorants are common excipients, and they are available in synthetic and nonsynthetic forms. In teat dip formulations, colorants are added both as indicators of treatment and as teat dip removal indicators. Coloring used in a teat dip is therefore considered an excipient by OMRI and accordingly must meet the review criteria for excipients. 

Color additives (colorants) are a subset of food additives, as defined by the FDA. A food additive is defined at §321(s) of the Food, Drug and Cosmetic (FD&C) Act as any substance the intended use of which results — or may reasonably be expected to result — in its becoming a component or otherwise affecting the characteristic of any food, either directly or indirectly. A color additive is defined at §321(t) of the FD&C Act as a dye, pigment or other substance that is capable of imparting color when added or applied to a food, drug, cosmetic, or to the human body.

According to §205.238(b), any excipient used in a livestock health care product must be either nonsynthetic or a synthetic that complies with §205.603(f). Section 205.603(f) allows for substances that are either:

1. Generally Recognized as Safe (GRAS)
   (https://www.hfpappexternal.fda.gov/scripts/fdcc/index.cfm?set=GRASNotices);
   
   
2. FDA approved as a food additive
   (https://www.hfpappexternal.fda.gov/scripts/fdcc/index.cfm?set=FoodSubstances)
   
   
3. included in the review of a New Animal Drug Application or New Drug Application
   (https://www.accessdata.fda.gov/scripts/cder/iig/index.Cfm); or
   
   
4. approved by APHIS for use in veterinary biologics
   (https://www.aphis.usda.gov/sites/default/files/currentprodcodebook.pdf). 

Color additives are identified on the Substances Added to Food or SATF list (formerly EAFUS), but also can be found listed separately from other excipients at http://www.fda.gov/ForIndustry/ColorAdditives/ColorAdditiveInventories/ucm106626.htm   

The absence of a colorant on one list does not indicate that it will not be found on another allowed list. Therefore, each list must be checked using both CAS# and alternate names, before making a determination on whether a colorant is an allowed excipient. 

This article was originally published in the spring 2020 edition of the OMRI Materials Review newsletter, and was revised in March 2025 by Technical Research Analyst Colleen Al-Samarrie.