FDA bulk drug substances list
Also called: bulks list
Clinical reviewer: Jacob Moore, MD · Last checked September 16, 2026
What is the FDA 503A bulk substances list?
FDA bulk drug substances list refers to FDA's lists of active ingredients nominated for use in compounding, sorted into review categories that determine eligibility. A separate list applies to 503A pharmacies and to 503B outsourcing facilities. Being under evaluation, Category 1, is not the same as being added to the 503A bulks list.
What is FDA's bulk drug substances list?
Compounders can nominate a bulk substance for FDA's 503A bulks list, and FDA sorts each nomination into a review category [1]. Category 1 covers substances nominated with enough supporting information for FDA to evaluate them, that don't already appear on any other list; that status means evaluation is underway, not that the substance has been added to the 503A bulks list [1].
What do the review categories mean?
Category 3 covers substances nominated without adequate supporting information for FDA to evaluate them, though they can be re-nominated later with more evidence [1]. FDA's 503A nomination list, updated May 14, 2026, illustrates both categories: it places nicotinamide adenine dinucleotide (NAD) and NADH in Category 1, still under evaluation, while a related NAD salt form sits in Category 3 for insufficient support [2].
How does the 503A list differ from the 503B list?
A 503B outsourcing facility works from its own, separate bulks list: it may not compound with a bulk substance unless that substance is on the 503B list or the finished drug is on FDA's drug shortage list [3].
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This entry is for education and is not medical advice. Talk with a licensed clinician about your own situation before starting, stopping, or changing any treatment.
