The tier type determines how review goals will apply to amendments. The different tiers are explained in FDA’s Commitment Letter on pages 10-11 as follows:
Tier 1 amendments include:
- All solicited first major and the first five minor amendments
- All unsolicited amendments indicated by sponsor and agreed by FDA to be a result of either delaying actions as determined by FDA’s Office of Generic Drugs taking into account the facts and information supplied by the ANDA applicant, or that otherwise would eventually be solicited (a delaying amendment).
Tier 2 amendments include:
- All unsolicited amendments not arising from delaying actions as determined by FDA’s Office of Generic Drugs taking into account the facts and information supplied by the ANDA applicant excepting those amendments which only remove information for review.
Tier 3 amendments include:
- Any solicited major amendment subsequent to the first major amendment
- Any solicited minor amendment subsequent to the fifth minor amendment
- The effect on the goals of the different tiers is explained in the Commitment Letter.