21 CFR Part 4 — Combination Products

21 CFR 3.2(e) defines combination products as products comprised of two or more regulated components (drug+device, biologic+device, drug+biologic, drug+device+biologic) physically, chemically or otherwise combined. Examples: a prefilled syringe (drug+device), a drug-eluting stent (drug+device), a kit containing a drug and a separate device, a cross-labelled product where the labelling specifies use with another regulated product.

Part 4.3 lets a single-entity combination-product manufacturer choose between:

1. Comply with all the cGMP applicable to each constituent (full drug cGMP per Part 210/211 AND full device QSR per Part 820 / QMSR per Part 820 as updated).
2. Comply with one constituent's cGMP regime in its entirety, PLUS specified provisions from the other regime ('streamlined approach').

Most manufacturers choose the streamlined approach. The decision and rationale must be documented.

A facility primarily operating under Part 211 (drug cGMP) for a drug-led combination product must additionally implement the following QSR/QMSR elements:

• Management responsibility (820.20)
• Design controls (820.30)
• Purchasing controls (820.50)
• Corrective and preventive action (820.100)
• Installation (820.170)
• Servicing (820.200)

Design controls and CAPA are the two recurring inspection-finding areas for drug-led manufacturers — drug cGMP does not contain an explicit design-control regime, and drug CAPA tends to be deviation-driven rather than systematic.

A facility primarily operating under Part 820 (or QMSR after Feb 2026) for a device-led combination product must additionally implement the following Part 211 elements:

• Testing and approval or rejection of components, drug product containers and closures (211.84)
• Calculation of yield (211.103)
• Tamper-evident packaging requirements for OTC human drug products (211.132)
• Expiration dating (211.137)
• Testing and release for distribution (211.165)
• Stability testing (211.166)
• Special testing requirements (211.167)
• Reserve samples (211.170)

Stability programmes, expiration-dating support and reserve-sample retention are the recurring finding areas for device-led manufacturers.

Combination products containing a biological constituent follow the relevant biological-product cGMP (typically Part 211 plus 21 CFR Parts 600-680 as applicable). The Part 4 streamlined approach is available; the chosen base regime determines which additional provisions apply. CBER-led products may have additional expectations.

• Constituent-only manufacturers — entities making only the drug or only the device that will later be combined elsewhere — operate under their constituent's cGMP. Part 4 applies to the entity bringing the constituents together into the single-entity combination product.
• Co-packaged combination products (drug + device in one kit) may have different facility regimes for each constituent and a separate set of expectations for the assembly site.
• Cross-labelled combination products: each labelled constituent is regulated under its own cGMP; Part 4 streamlining is not the typical structure.

For drug-led manufacturers, design controls under 820.30 require:

1. Design and development planning
2. Design inputs (user needs, intended use, performance, safety, regulatory)
3. Design outputs (drawings, specifications, code, labelling)
4. Design review at planned stages
5. Design verification (do outputs meet inputs?)
6. Design validation (does the finished device meet user needs?)
7. Design transfer to production
8. Design changes — change control through the lifecycle
9. Design History File maintained

Inspectors routinely find drug-led combination-product manufacturers without a DHF, without traceability from user needs to design output to verification protocol, and without formal design transfer. A risk-management file per ISO 14971 should anchor the design inputs.

21 CFR Part 4 Subpart B (effective 2017) consolidates post-marketing reporting requirements for combination products — including MDR/MedWatch for device-constituent AEs, ICSR for drug-constituent AEs, malfunction reporting, and field-alert reporting. The lead Center coordinates but the manufacturer must satisfy all applicable reporting streams.

FDA's Office of Combination Products (OCP) determines the lead Center (CDER, CBER, CDRH) based on the primary mode of action (PMOA). The lead Center handles premarket review and post-market regulation. The non-lead Center consults. A Request for Designation (RFD) under 21 CFR Part 3 is the formal mechanism to establish PMOA where uncertain.