Guidance for Industry: Impurities in New Drug Products: ICH Topic Q3B(R)

September 25, 2003

Notice

Our file number: 03-118463-690

This guidance document is a revised version of the original ICH document of the same title. The revised guidance document, as the original, is intended to provide guidance on the identification, qualification, and control of impurities in new drug products produced from chemically synthesised new drug substances. The revised guidance document clarifies some ambiguities in the original document as well as provides some additional guidance in other areas. A number of editorial inconsistencies have been addressed. This revised guidance document supecedes the previous version.

This guidance document is complementary to the ICH guidance document Q3A(R) - Impurities in New Drug Substances, which should be consulted for basic principles.

This guidance has been developed by the appropriate ICH Expert Working Group and has been subject to consultation by the regulatory parties, in accordance with the ICH Process. The ICH Steering Committee has endorsed the final draft and recommended its adoption by the regulatory bodies of the European Union, Japan and USA.

In adopting this ICH guidance, Health Canada endorses the principles and practices described therein. This document should be read in conjunction with this accompanying notice and with the relevant sections of other applicable Health Canada guidances.

It is recognized that the scope and subject matter of current Health Canada guidances may not be entirely consistent with those of the ICH guidances that are being introduced as part of our commitment to international harmonization and the ICH Process. In such circumstances, Health Canada adopted ICH guidances take precedence.

Health Canada is committed to eliminating such discrepancies through the implementation of a phasedin work plan that will examine the impact associated with the adoption of ICH guidances. This will result in the amendment or, depending on the extent of revisions required, withdrawal of some Health Canada guidances.

This and other Guidance documents are available on the Therapeutic Products Directorate / Biologics and Genetic Therapies Directorate / Marketed Health Products Directorate Website (s) (http://www.hc-sc.gc.ca/dhp-mps/index-eng.php). The availability of printed copies of guidance documents may be confirmed by consulting the Guidelines and Publications Order Forms (available on the TPD/BGTD/MHPD Website) or by contacting the Publications CoordinatorFootnote 2.

Should you have any questions regarding the content of the guidance, please contact:

Bureau of Pharmaceutical Sciences
Therapeutic Products Directorate
Health Canada
Finance Building (A/L 0202A2)
Ottawa, Ontario
K1A 1B9

Internet: bps_enquiries@hc-sc.gc.ca
Phone: (613) 941-3184
Fax: (613) 957-3989

Guidance for Industry

Published by authority of the Minister of Health

Date Adopted 2003/09/25

Effective Date 2004/01/01

Health Products and Food Branch Guidance Document

© Minister of Public Works and Government Services Canada 2003

Available in Canada through
Health Canada - Publications
Brooke Claxton Building, A.L. #0913A
Tunney's Pasture
Ottawa, Ontario
K1A 0K9

Tel: (613) 954-5995
Fax: (613) 941-5366

Catalogue No. H42-2/94-2003E
ISBN 0-662-34661-0

Foreword

This guidance has been developed by the appropriate ICH Expert Working Group and has been subject to consultation by the regulatory parties, in accordance with the ICH Process. The ICH Steering Committee has endorsed the final draft and recommended its adoption by the regulatory bodies of the European Union, Japan and USA.

In adopting this ICH guidance, Health Canada endorses the principles and practices described therein. This document should be read in conjunction with the accompanying notice and the relevant sections of other applicable guidances.

Guidance documents are meant to provide assistance to industry and health care professionals on how to comply with the policies and governing statutes and regulations. They also serve to provide review and compliance guidance to staff, thereby ensuring that mandates are implemented in a fair, consistent and effective manner.

Guidance documents are administrative instruments not having force of law and, as such, allow for flexibility in approach. Alternate approaches to the principles and practices described in this document may be acceptable provided they are supported by adequate scientific justification. Alternate approaches should be discussed in advance with the relevant program area to avoid the possible finding that applicable statutory or regulatory requirements have not been met.

As a corollary to the above, it is equally important to note that Health Canada reserves the right to request information or material, or define conditions not specifically described in this guidance, in order to allow the Department to adequately assess the safety, efficacy or quality of a therapeutic product. Health Canada is committed to ensuring that such requests are justifiable and that decisions are clearly documented.

Table of Contents

1. Introduction

1.1 Objective of the Guidance Document

This document provides guidance for registration applications on the content and qualification of impurities in new drug products produced from chemically synthesised new drug substances not previously registered in a region or member state.

1.2 Background

This guidance document is complementary to the ICH Q3A(R) guidance document "Impurities in New Drug Substances", which should be consulted for basic principles. The ICH Q3C guidance document "Residual Solvents" should also be consulted, if appropriate.

1.3 Scope of the Guidance Document

This guidance document addresses only those impurities in new drug products classified as degradation products of the drug substance or reaction products of the drug substance with an excipient and/or immediate container closure system (collectively referred to as "degradation products" in this guidance document). Generally, impurities present in the new drug substance need not be monitored or specified in the new drug product unless they are also degradation products (see ICH Q6A guidance document on specifications).

Impurities arising from excipients present in the new drug product or extracted or leached from the container closure system are not covered by this guidance document. This guidance also does not apply to new drug products used during the clinical research stages of development. The following types of products are not covered in this guidance document: biological/biotechnological products, peptides, oligonucleotides, radiopharmaceuticals, fermentation products and semi-synthetic products derived therefrom, herbal products, and crude products of animal or plant origin. Also excluded from this document are: (1) extraneous contaminants that should not occur in new drug products and are more appropriately addressed as good manufacturing practice (GMP) issues, (2) polymorphic forms, and (3) enantiomeric impurities.

2.Rationale for the Reporting and Control of Degradation Products

The applicant should summarise the degradation products observed during manufacture and/or stability studies of the new drug product. This summary should be based on sound scientific appraisal of potential degradation pathways in the new drug product and impurities arising from the interaction with excipients and/or the immediate container closure system. In addition, the applicant should summarise any laboratory studies conducted to detect degradation products in the new drug product. This summary should also include test results of batches manufactured during the development process and batches representative of the proposed commercial process. A rationale should be provided for exclusion of those impurities that are not degradation products (e.g., process impurities from the drug substance and impurities arising from excipients). The impurity profiles of the batches representative of the proposed commercial process should be compared with the profiles of batches used in development and any differences discussed.

Any degradation product observed in stability studies conducted at the recommended storage condition should be identified when present at a level greater than (>) the identification thresholds given in (Attachment 1). When identification of a degradation product is not feasible, a summary of the laboratory studies demonstrating the unsuccessful efforts to identify it should be included in the registration application.

Degradation products present at a level of not more than (≤) the identification threshold generally would not need to be identified. However, analytical procedures should be developed for those degradation products that are suspected to be unusually potent, producing toxic or significant pharmacological effects at levels not more than (≤) the identification threshold. In unusual circumstances, technical factors (e.g., manufacturing capability, a low drug substance to excipient ratio, or the use of excipients that are crude products of animal or plant origin) can be considered as part of the justification for selection of alternative thresholds based upon manufacturing experience with the proposed commercial process.

3. Analytical Procedures

The registration application should include documented evidence that the analytical procedures have been validated and are suitable for the detection and quantitation of degradation products (see ICH Q2A and Q2B guidance documents on analytical validation). In particular, analytical procedures should be validated to demonstrate specificity for the specified and unspecified degradation products. As appropriate, this validation should include samples stored under relevant stress conditions: light, heat, humidity, acid/base hydrolysis, and oxidation. When an analytical procedure reveals the presence of other peaks in addition to those of the degradation products (e.g., the drug substance, impurities arising from the synthesis of the drug substance, excipients and impurities arising from the excipients), these peaks should be labeled in the chromatograms and their origin(s) discussed in the validation documentation.

The quantitation limit for the analytical procedure should be not more than (≤) the reporting threshold.

Degradation product levels can be measured by a variety of techniques, including those that compare an analytical response for a degradation product to that of an appropriate reference standard or to the response of the new drug substance itself. Reference standards used in the analytical procedures for control of degradation products should be evaluated and characterised according to their intended uses. The drug substance can be used to estimate the levels of degradation products. In cases where the response factors are not close, this practice can still be used if a correction factor is applied or the degradation products are, in fact, being overestimated. Acceptance criteria and analytical procedures, used to estimate identified or unidentified degradation products, are often based on analytical assumptions (e.g., equivalent detector response). These assumptions should be discussed in the registration application.

Differences between the analytical procedures used during development and those proposed for the commercial product should also be discussed.

4. Reporting Degradation Products Content of Batches

Analytical results should be provided in the registration application for all relevant batches of the new drug product used for clinical, safety, and stability testing, as well as batches that are representative of the proposed commercial process. Quantitative results should be presented numerically, and not in general terms such as "complies", "meets limit" etc. Any degradation product at a level greater than (>) the reporting threshold (see Attachment 1), and total degradation products observed in the relevant batches of the new drug product, should be reported with the analytical procedures indicated. Below 1.0%, the results should be reported to the number of decimal places (e.g., 0.06%) in the applicable reporting threshold; at and above 1.0%, the results should be reported to one decimal place (e.g., 1.3%). Results should be rounded using conventional rules (see Attachment 2). A tabulation (e.g., spreadsheet) of the data is recommended. Degradation products should be designated by code number or by an appropriate descriptor, e.g., retention time. If a higher reporting threshold is proposed, it should be fully justified. All degradation products at a level greater than (>) the reporting threshold should be summed and reported as total degradation products.

Chromatograms with peaks labelled (or equivalent data if other analytical procedures are used) from representative batches, including chromatograms from analytical procedure validation studies and from long-term and accelerated stability studies, should be provided. The applicant should ensure that complete degradation product profiles (e.g., chromatograms) of individual batches are available, if requested.

For each batch of the new drug product described in the registration application, the documentation should include:

  • Batch identity, strength, and size
  • Date of manufacture
  • Site of manufacture
  • Manufacturing process
  • Immediate container closure
  • Degradation product content, individual and total
  • Use of batch (e.g., clinical studies, stability studies)
  • Reference to analytical procedure used
  • Batch number of the drug substance used in the new drug product
  • Storage conditions for stability studies

5. Listing of Degradation Products in Specifications

The specification for a new drug product should include a list of degradation products expected to occur during manufacture of the commercial product and under recommended storage conditions. Stability studies, knowledge of degradation pathways, product development studies, and laboratory studies should be used to characterise the degradation profile. The selection of degradation products in the new drug product specification should be based on the degradation products found in batches manufactured by the proposed commercial process. Those individual degradation products with specific acceptance criteria included in the specification for the new drug product are referred to as "specified degradation products" in this guidance document. Specified degradation products can be identified or unidentified. A rationale for the inclusion or exclusion of degradation products in the specification should be presented. This rationale should include a discussion of the degradation profiles observed in the safety and clinical development batches and in stability studies, together with a consideration of the degradation profile of batches manufactured by the proposed commercial process. Specified identified degradation products should be included along with specified unidentified degradation products estimated to be present at a level greater than (>) the identification threshold given in (Attachment 1). For degradation products known to be unusually potent or to produce toxic or unexpected pharmacological effects, the quantitation/detection limit of the analytical procedures should be commensurate with the level at which the degradation products should be controlled. For unidentified degradation products, the procedure used and assumptions made in establishing the level of the degradation product should be clearly stated. Specified unidentified degradation products should be referred to by an appropriate qualitative analytical descriptive label (e.g., "unidentified A", "unidentified with relative retention of 0.9"). A general acceptance criterion of not more than (≤) the identification threshold (Attachment 1) for any unspecified degradation product and an acceptance criterion for total degradation products should also be included.

For a given degradation product, its acceptance criterion should be established by taking into account its acceptance criterion in the drug substance (if applicable), its qualified level, its increase during stability studies, and the proposed shelf life and recommended storage conditions for the new drug product. Furthermore, each acceptance criterion should be set no higher than the qualified level of the given degradation product.

Where there is no safety concern, degradation product acceptance criteria should be based on data generated from batches of the new drug product manufactured by the proposed commercial process, allowing sufficient latitude to deal with normal manufacturing and analytical variation and the stability characteristics of the new drug product. Although normal manufacturing variations are expected, significant variation in batch-to-batch degradation product levels can indicate that the manufacturing process of the new drug product is not adequately controlled and validated (see ICH Q6A guidance document on specifications, decision tree #2, for establishing an acceptance criterion for a specified degradation product in a new drug product).

In this guidance document, the use of two decimal places for thresholds (See Attachment 1) does not necessarily indicate the precision of the acceptance criteria for specified degradation products and total degradation products.

In summary, the new drug product specification should include, where applicable, the following list of degradation products:

  • Each specified identified degradation product
  • Each specified unidentified degradation product
  • Any unspecified degradation product with an acceptance criterion of not more than (≤) the identification threshold
  • Total degradation products.

6. Qualification of Degradation Products

Qualification is the process of acquiring and evaluating data that establishes the biological safety of an individual degradation product or a given degradation profile at the level(s) specified. The applicant should provide a rationale for establishing degradation product acceptance criteria that includes safety considerations. The level of any degradation product present in a new drug product that has been adequately tested in safety and/or clinical studies would be considered qualified. Therefore, it is useful to include any available information on the actual content of degradation products in the relevant batches at the time of use in safety and/or clinical studies. Degradation products that are also significant metabolites present in animal and/or human studies are generally considered qualified. Degradation products could be considered qualified at levels higher than those administered in safety studies based on a comparison between actual doses given in the safety studies and the intended dose of the new drug product. Justification of such higher levels should include consideration of factors such as: (1) the amount of degradation product administered in previous safety and/or clinical studies and found to be safe; (2) the increase in the amount of the degradation product; and (3) other safety factors, as appropriate.

If the qualification thresholds given in (Attachment 1) are exceeded and data are unavailable to qualify the proposed acceptance criterion of a degradation product, additional studies to obtain such data can be appropriate (see Attachment 3).

Higher or lower thresholds for qualification of degradation products can be appropriate for some individual new drug products based on scientific rationale and level of concern, including drug class effects and clinical experience. For example, qualification can be especially important when there is evidence that such degradation products in certain new drug products or therapeutic classes have previously been associated with adverse reactions in patients. In these instances, a lower qualification threshold can be appropriate. Conversely, a higher qualification threshold can be appropriate for individual new drug products when the level of concern for safety is less than usual based on similar considerations (e.g., patient population, drug class effects, and clinical considerations). Proposals for alternative thresholds would be considered on a case-by-case basis.

The "Decision Tree for Identification and Qualification of a Degradation Product" (Attachment 3) describes considerations for the qualification of degradation products when thresholds are exceeded. In some cases, reducing the level of degradation product (e.g., use of a more protective container closure or modified storage conditions) to not more than (≤) the threshold can be simpler than providing safety data. Alternatively, adequate data could be available in the scientific literature to qualify a degradation product. If neither is the case, additional safety testing should be considered. The studies considered appropriate to qualify a degradation product will depend on a number of factors, including the patient population, daily dose, and route and duration of new drug product administration. Such studies can be conducted on the new drug product or substance containing the degradation products to be controlled, although studies using isolated degradation products can sometimes be appropriate.

Although this guidance is not intended to apply during the clinical research stage of development, in the later stages of development the thresholds in this guidance can be useful in evaluating new degradation products observed in new drug product batches prepared by the proposed commercial process. Any new degradation product observed in later stages of development should be identified (see the "Decision Tree for Identification and Qualification of a Degradation Product" in Attachment 3) if its level is greater than (>) the identification threshold given in (Attachment 1). Similarly, qualification of the degradation product should be considered if its level is greater than (>) the qualification threshold given in (Attachment 1).

Safety studies should provide a comparison of results of safety testing of the new drug product or drug substance containing a representative level of the degradation product with previously qualified material, although studies using the isolated degradation products can also be considered.

7. Glossary

Degradation Product:
An impurity resulting from a chemical change in the drug substance brought about during manufacture and/or storage of the new drug product by the effect of, for example, light, temperature, pH, water, or by reaction with an excipient and/or the immediate container closure system.
Degradation Profile:
A description of the degradation products observed in the drug substance or drug product.
Development Studies:
Studies conducted to scale-up, optimise, and validate the manufacturing process for a drug product.
Identification Threshold:
A limit above (>) which a degradation product should be identified.
Identified Degradation Product:
A degradation product for which a structural characterisation has been achieved.
Impurity:
Any component of the new drug product that is not the drug substance or an excipient in the drug product.
Impurity Profile:
A description of the identified and unidentified impurities present in a drug product.
New Drug Substance:
The designated therapeutic moiety that has not been previously registered in a region or member state (also referred to as a new molecular entity or new chemical entity). It can be a complex, simple ester, or salt of a previously approved substance.
Qualification:
The process of acquiring and evaluating data that establishes the biological safety of an individual degradation product or a given degradation profile at the level(s) specified.
Qualification Threshold:
A limit above (>) which a degradation product should be qualified.
Reporting Threshold:
A limit above (>) which a degradation product should be reported.
Specified Degradation Product:
A degradation product that is individually listed and limited with a specific acceptance criterion in the new drug product specification. A specified degradation product can be either identified or unidentified.
Unidentified Degradation Product:
A degradation product for which a structural characterisation has not been achieved and that is defined solely by qualitative analytical properties (e.g., chromatographic retention time).
Unspecified Degradation Product:
A degradation product that is limited by a general acceptance criterion, but not individually listed with its own specific acceptance criterion, in the new drug product specification.

Attachment 1:

Thresholds for Degradation Products in New Drug Products
Maximum Daily DoseTable 1 footnote 1 ThresholdTable 1 footnote 2,Table 1 footnote 3
Reporting Thresholds
≤ 1 g 0.1%
> 1 g 0.05%
Identification Thresholds
< 1 mg 1.0% or 5 µg TDI, whichever is lower
1 mg - 10 mg 0.5% or 20 µg TDI, whichever is lower
>10 mg - 2 g 0.2% or 2 mg TDI, whichever is lower
> 2 g 0.10%
Qualification Thresholds
< 10 mg 1.0% or 50 µg TDI, whichever is lower
10 mg - 100 mg 0.5% or 200 µg TDI, whichever is lower
>100 mg - 2 g 0.2% or 3 mg TDI, whichever is lower
> 2 g 0.15%

Notes on Attachment 1

Table 1 footnotes

Table 1 footnote 1

The amount of drug substance administered per day

Return to table 1 footnote 1 referrer

Table 1 footnote 2

Thresholds for degradation products are expressed either as a percentage of the drug substance or as total daily intake (TDI) of the degradation product. Lower thresholds can be appropriate if the degradation product is unusually toxic.

Return to table 1 footnote 2 referrer

Table 1 footnote 3

Higher thresholds should be scientifically justified.

Return to table 1 footnote 3 referrer

Illustration of Thresholds for Reporting, Identification, and Qualification of Degradation Products in New Drug Products as a Function of Maximum Daily Dose

Note: Actual threshold values should be taken from the preceding table in this attachment.

Attachment 2:

Illustration of Reporting Degradation Product Results for Identification and Qualification in an Application
50 mg Maximum Daily Dose
'Raw' Result
(%)
Reported Result
(%)
(Reporting Threshold = 0.1%)
Total Daily Intake (TDI) of the Degradation Product (rounded result in µg) Action
Identification Threshold 0.2% Qualification Threshold
200 µg TDI (equivalent to 0.4%)
0.04 Not reported 20 None None
0.2143 0.2 100 None None
0.349 0.31 150 Yes NoneTable 2 footnote 1
0.55 0.61 300 Yes YesTable 2 footnote 1
1.9 gram Maximum Daily Dose
'Raw' Result
(%)
Reported Result
(%)
(Reporting Threshold = 0.05%)
Total Daily Intake (TDI) of the Degradation Product (rounded result in mg) Action
Identification Threshold 2 mg TDI (equivalent to 0.11%) Qualification Threshold
3 mg TDI (equivalent to 0.16%)
0.049 Not reported 1 None None
0.079 0.08 2 None None
0.183 0.181 3 Yes NoneTable 2 footnote 1,Table 2 footnote 2
0.192 0.191 4 Yes YesTable 2 footnote 1

Notes on Attachment 2

Table 2 footnotes

Table 2 footnote 1

After identification, if the response factor is determined to differ significantly from the original assumptions, it can be appropriate to re-measure the actual amount of the degradation product present and re-evaluate against the qualification threshold (see Attachment 1).

Return to table 2 footnote 1 referrer

Table 2 footnote 2

Although the reported result of 0.18% exceeds the calculated threshold value of 0.16%, in this case the action is acceptable since the TDI (when rounded) does not exceed 3mg.

Return to table 2 footnote 2 referrer

Attachment 3: Decision Tree for Identification and Qualification of a Degradation Product

Attachment 3: Decision Tree for Identification and Qualification of a Degradation Producte

Notes on Attachment 3

  1. If considered desirable, a minimum screen (e.g., genotoxic potential), should be conducted. A study to detect point mutations and one to detect chromosomal aberrations, both in vitro, are considered an appropriate minimum screen.
  2. If general toxicity studies are desirable, one or more studies should be designed to allow comparison of unqualified to qualified material. The study duration should be based on available relevant information and performed in the species most likely to maximise the potential to detect the toxicity of a degradation product. On a case-by-case basis, single-dose studies can be appropriate, especially for single-dose drugs. In general, a minimum duration of 14 days and a maximum duration of 90 days would be considered appropriate.
  3. Lower thresholds can be appropriate if the degradation product is unusually toxic.
  4. For example, do known safety data for this degradation product or its structural class preclude human exposure at the concentration present?
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