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21 CFR 211.170 - Reserve Samples

Overview:

21 CFR 211.170 establishes requirements for retaining reserve samples of active ingredients and drug products to ensure quality and compliance with regulatory standards. 

It specifies the quantity, storage conditions, and retention periods for different drug products, including prescription, over-the-counter, and radioactive drugs. This regulation helps pharmaceutical manufacturers maintain product integrity and support investigations if quality issues arise.

Cross Reference

Link to an amendment published at 89 FR 51770, June 18, 2024.

(a) 

An appropriately identified reserve sample that is representative of each lot in each shipment of each active ingredient shall be retained. The reserve sample consists of at least twice the quantity necessary for all tests required to determine whether the active ingredient meets its established specifications, except for sterility and pyrogen testing. The retention time is as follows:

(1) For an active ingredient in a drug product other than those described in paragraphs (a) (2) and (3) of this section, the reserve sample shall be retained for 1 year after the expiration date of the last lot of the drug product containing the active ingredient.

(2) For an active ingredient in a radioactive drug product, except for nonradioactive reagent kits, the reserve sample shall be retained for:

(i) Three months after the expiration date of the last lot of the drug product containing the active ingredient if the expiration dating period of the drug product is 30 days or less; or

(ii) Six months after the expiration date of the last lot of the drug product containing the active ingredient if the expiration dating period of the drug product is more than 30 days.

(3) For an active ingredient in an OTC drug product that is exempt from bearing an expiration date under § 211.137, the reserve sample shall be retained for 3 years after distribution of the last lot of the drug product containing the active ingredient.

(b) 

An appropriately identified reserve sample that is representative of each lot or batch of drug product shall be retained and stored under conditions consistent with product labeling. The reserve sample shall be stored in the same immediate container-closure system in which the drug product is marketed or in one that has essentially the same characteristics. The reserve sample consists of at least twice the quantity necessary to perform all the required tests, except those for sterility and pyrogens. Except for those for drug products described in paragraph (b)(2) of this section, reserve samples from representative sample lots or batches selected by acceptable statistical procedures shall be examined visually at least once a year for evidence of deterioration unless visual examination would affect the integrity of the reserve sample. Any evidence of reserve sample deterioration shall be investigated in accordance with § 211.192. The results of the examination shall be recorded and maintained with other stability data on the drug product. Reserve samples of compressed medical gases need not be retained. The retention time is as follows:

(1) For a drug product other than those described in paragraphs (b) (2) and (3) of this section, the reserve sample shall be retained for 1 year after the expiration date of the drug product.

(2) For a radioactive drug product, except for nonradioactive reagent kits, the reserve sample shall be retained for:

(i) Three months after the expiration date of the drug product if the expiration dating period of the drug product is 30 days or less; or

(ii) Six months after the expiration date of the drug product if the expiration dating period of the drug product is more than 30 days.

(3) For an OTC drug product that is exempt for bearing an expiration date under § 211.137, the reserve sample must be retained for 3 years after the lot or batch of drug product is distributed.

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Signify helps regulatory and product compliance teams in CPG and durables manufacturing launch products faster by automating global compliance.

Signify is the leading compliance system for consumer products—leveraging AI agents to automate gap analysis, streamline conformity checks, and accelerate safe, high-quality product launches.

Signify SOC2 Type 2 Compliant

© 2025 Signify Technologies, Corp.

Use Cases

Supplier Check

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Why Now

21 CFR

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Compliance AI Agents

for consumer products

Signify helps regulatory and product compliance teams in CPG and durables manufacturing launch products faster by automating global compliance.

Signify is the leading compliance system for consumer products—leveraging AI agents to automate gap analysis, streamline conformity checks, and accelerate safe, high-quality product launches.

Use Cases

Supplier Check

Labeling

Internal Audits

Quality & Safety

Import & Export

Resources

Blog

Guides

Why Now

21 CFR

Company

About Us

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DPA

Signify SOC2 Type 2 Compliant

© 2025 Signify Technologies, Corp.