Wheat is not used to a significant extent in the production of drug ingredients, and barley and rye are used either rarely or not at all.
The amount of gluten potentially contributed by a wheat-derived ingredient to a unit dose of an oral drug product (unless that ingredient is wheat gluten itself or wheat flour) is expected to be less than 0.5 mg, as a high estimate.
Thus, the amount of gluten potentially present in a unit dose of an oral drug product is less than the amount of gluten that could potentially be found in a single serving of a cookie (30 grams) labeled gluten-free or in a gluten-free diet (5 to 50 mg).
Any oral drug product that contains wheat gluten as an intentionally added ingredient, should be labeled to indicate its presence. For example, wheat starch (not starch) is the established name by which wheat starch must be identified in drug labeling.
If an ingredient is not recognized in an official compendium and does not have an applicable official name, then it must be identified in labeling by its common or usual name. Wheat gluten and wheat flour fall into this category, and should be considered their appropriate common or usual names.
Patients who are more sensitive to gluten will likely seek to eliminate all sources of ingested gluten, or at least minimize exposure as much as possible, because drug ingredients are identified in labeling, but not substances that are present merely as impurities.