What does an FDA Orange Book “therapeutic equivalence code” mean for colchicine capsules and tablets?
The FDA Orange Book lists approved drug products and assigns a “therapeutic equivalence code” for each active-ingredient/manufacturer/strength/dosage-form combination. That code is meant to indicate whether two products are considered therapeutically equivalent (and therefore interchangeable without changing how the drug is used). [1]
Which therapeutic equivalence codes apply to colchicine capsules vs colchicine tablets?
To identify the exact therapeutic equivalence codes for colchicine capsules and colchicine tablets, you have to look up the specific Orange Book entries for:
- the dosage form (capsule vs tablet),
- the strength(s),
- and the manufacturer(s) listed for each product.
The Orange Book is the authoritative source for those codes by product listing. [1]
How to look up colchicine in the Orange Book and find the therapeutic equivalence code
A practical way to find the code is:
1. Search the Orange Book for “colchicine”.
2. Filter or scan results for the correct dosage form (capsule or tablet).
3. Open the product details page for the exact strength/manufacturer.
4. Read the “therapeutic equivalence” (and related substitution) information shown for that listing. [1]
Is “AA” the therapeutic equivalence code you should expect for colchicine generic products?
Some widely known therapeutic equivalence categories in the Orange Book (for example, “AB” for products rated therapeutically equivalent) are commonly referenced in general discussions, but the specific therapeutic equivalence code for colchicine depends on the exact Orange Book listing. The only way to confirm the code for a particular colchicine product is to check the Orange Book entry tied to that manufacturer/strength/dosage form. [1]
If I see different codes for colchicine generics, does that mean they are not interchangeable?
Different Orange Book therapeutic equivalence ratings for different listings can indicate limitations on substitution or therapeutic equivalence. If two colchicine products have different therapeutic equivalence ratings, you should confirm with the prescribing clinician or pharmacist before switching, because the Orange Book coding is what drives substitution expectations. [1]
Where to get the authoritative Orange Book page
Use the FDA Orange Book searchable database and search for “colchicine” to retrieve the therapeutic equivalence code for each specific capsule/tablet listing. [1]
Sources
[1] https://www.accessdata.fda.gov/scripts/cder/ob/