42 CFR § 428.100 - Definitions.

---
identifier: "/us/cfr/t42/s428.100"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "42 CFR § 428.100 - Definitions."
title_number: 42
title_name: "Public Health"
section_number: "428.100"
section_name: "Definitions."
chapter_name: "CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES"
subchapter_number: "B"
subchapter_name: "MEDICARE PROGRAM"
part_number: "428"
part_name: "MEDICARE PART D DRUG INFLATION REBATE PROGRAM"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "42 U.S.C. 1395w-114b, 1302, and 1395hh."
regulatory_source: "89 FR 98588, Dec. 9, 2024, unless otherwise noted."
cfr_part: "428"
---


# 428.100 Definitions.

As used in this subpart, the following definitions apply:

*Individual who uses such a drug or biological* means a unique Medicare Part D beneficiary who was dispensed the Part D drug or biological that was covered by their Part D plan sponsor during the applicable period, identified using Prescription Drug Event (PDE) data with dates of service during the applicable period and with gross covered prescription drug costs greater than zero.

*Gross covered prescription drug costs* has the meaning set forth in § 423.308 of this chapter.