What does “AB rated” mean on the FDA Orange Book for colchicine?
On the FDA’s Orange Book, an “AB” rating generally indicates that a generic drug has been approved and is considered therapeutically equivalent to the reference listed drug (RLD). In practice, AB-rated generics are expected to meet FDA requirements for bioequivalence to the RLD.
Where do “colchicine capsules/tablets” and “AB” show up on the Orange Book?
The Orange Book lists colchicine products by active ingredient and dosage form (for example, capsules and tablets) and then shows applicant details, approval status, and ratings such as “AB.” To confirm the exact colchicine capsule versus tablet entries and which ones are AB-rated, you need to look up the specific Orange Book listing for colchicine and the specific dosage form/strength you care about.
How to verify the exact colchicine “AB” rating you’re seeing
Because colchicine has multiple strengths and product lines, the quickest way to verify the AB rating is to:
1. Search the FDA Orange Book for “colchicine”
2. Filter/select the matching dosage form (capsule vs tablet)
3. Check the “Rating” column for each listed generic (look for “AB”)
If you tell me the strength (for example, 0.6 mg) and whether you mean capsule or tablet, I can help you pinpoint what the Orange Book shows for that exact product line.
Does “AB” change anything for patients or prescribers?
An AB rating is about therapeutic equivalence to the RLD. It does not tell you dosing instructions or side effects, but it does indicate that FDA expects the generic to act like the reference product when used as directed.
Can Orange Book ratings change over time?
Yes. Orange Book listings can be updated as FDA approves new strengths/applicants or as regulatory status changes. If you saw an “AB” label for colchicine at one point, re-checking the Orange Book entry is the right way to confirm the current rating.
Sources:
- [1] https://www.accessdata.fda.gov/scripts/cder/ob/