oSIST prEN ISO 10993-11:2026

Biological evaluation of medical devices - Part 11: Tests for systemic toxicity (ISO/DIS 10993-11:2026)

ISO 10993-11:2017 specifies requirements and gives guidance on procedures to be followed in the evaluation of the potential for medical device materials to cause adverse systemic reactions.

Biologische Beurteilung von Medizinprodukten - Teil 11: Prüfungen auf systemische Toxizität (ISO/DIS 10993-11:2026)

Dieses Dokument legt Anforderungen fest und gibt eine Anleitung zu den Verfahren, die bei der Beurteilung der Wahrscheinlichkeit, dass Materialien für Medizinprodukte oder Endprodukte nachteilige systemische Reaktionen auslösen, zu befolgen sind.

Évaluation biologique des dispositifs médicaux - Partie 11: Essais de toxicité systémique (ISO/DIS 10993-11:2026)

ISO 10993-11:2017 spécifie des exigences et fournit des préconisations quant aux modes opératoires à suivre pour évaluer les éventuelles réactions systémiques défavorables causées par les matériaux de dispositifs médicaux.

Biološko ovrednotenje medicinskih pripomočkov - 11. del: Preskusi sistemske toksičnosti (ISO/DIS 10993-11:2026)

General Information

• Status: Not Published
• Public Enquiry End Date: 07-Jul-2026
• ICS: 11.100.20 - Biological evaluation of medical devices
• Technical Committee: VAZ - Healthcare
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 28-May-2026
• Due Date: 15-Oct-2026
• Directive: Harmonized Standard2017/745 - Regulation (EU) 2017/745 of the European Parliament and of the Council of 5 April 2017 on medical devices, amending Directive 2001/83/EC, Regulation (EC) No 178/2002 and Regulation (EC) No 1223/2009 and repealing Council Directives 90/385/EEC and 93/42/EEC
• Mandate: M/575 - Medical devices in support of Regulation (EU) 2017/745 and in vitro diagnostic medical devices in support of Regulation (EU) 2017/746
• Mandate: M/575 AMD 2 - Medical devices in support of Regulation (EU) 2017/745 and in vitro diagnostic medicial devices in support of Regulation (EU) 2017746
• Ref Project: prEN ISO 10993-11 - Biological evaluation of medical devices - Part 11: Tests for systemic toxicity (ISO/DIS 10993-11:2026)

Relations

• Revises: SIST EN ISO 10993-11:2018 - Biological evaluation of medical devices - Part 11: Tests for systemic toxicity (ISO 10993-11:2017)
• Effective Date: 26-Apr-2023

Overview

oSIST prEN ISO 10993-11:2026 is the Slovenian adoption of the forthcoming international standard ISO/DIS 10993-11:2026, "Biological evaluation of medical devices - Part 11: Tests for systemic toxicity." This standard, developed by the International Organization for Standardization (ISO) under Technical Committee ISO/TC 194, provides detailed requirements and guidance for assessing the potential of medical device materials to cause adverse systemic reactions in the body.

Systemic toxicity testing evaluates not only immediate local effects but also generalized and organ-specific effects that may arise due to absorption, distribution, and metabolism of device constituents. As medical devices become more complex and increasingly rely on novel biomaterials, a rigorous approach to biological evaluation is essential to ensure patient safety and regulatory compliance.

Key Topics

• Scope and Applicability: ISO 10993-11 outlines how to design and conduct systemic toxicity tests, emphasizing the need to consider all existing toxicological and chemical data before animal testing.
• Types of Systemic Toxicity: The standard discusses acute, subacute, subchronic, and chronic systemic toxicity, clarifying study durations and endpoints.
• Animal Models and Ethics: Recommendations are provided for selecting appropriate animal species, focusing on minimizing animal use according to the 3Rs (Replacement, Reduction, Refinement) principles.
• Test Sample Preparation: Guidance on preparing samples to accurately reflect final manufactured devices, including aspects like sterility, stability, and homogeneity.
• Dosing and Controls: Detailed instruction is given on determining dosage, frequency, and the incorporation of relevant control groups to ensure valid results.
• Reporting and Documentation: The standard specifies thorough documentation and reporting requirements, ensuring studies meet regulatory expectations and support product safety claims.

Applications

Medical Device Manufacturers

• Regulatory Submissions: Ensures biological evaluation reports meet the expectations of regulatory bodies including the European MDR 2017/745.
• Risk Assessment: Provides a foundation for comprehensive risk assessments, integrating systemic toxicity data with chemical characterization and other biocompatibility information.
• Product Development: Supports safer material selection and process optimization during device development.
• Market Access: Facilitates smoother certification and quicker market entry by aligning with internationally recognized practices.

Testing Laboratories

• Study Design: Offers clear guidelines for selecting animal models, setting group sizes, and choosing relevant test parameters for systemic toxicity tests.
• Compliance and Quality: Structures protocols in accordance with good laboratory practice (GLP) and national animal welfare requirements.

Regulatory Authorities

• Evaluation Consistency: Standardizes the approach for biological safety evaluation, enabling more consistent review of technical documentation.

Clinical Stakeholders

• Patient Safety: Underpins decisions relating to the safety of device materials and their potential for causing systemic harm.

Related Standards

• ISO 10993-1: Biological evaluation of medical devices - Part 1: Requirements and general principles for biological safety within a risk management process.
• ISO 10993-2: Biological evaluation of medical devices - Part 2: Animal welfare requirements.
• ISO 10993-6: Biological evaluation of medical devices - Part 6: Tests for local effects after implantation.
• ISO 10993-12: Biological evaluation of medical devices - Part 12: Sample preparation and reference materials.

Additional references include related documents addressing other specific endpoints, such as ISO 10993-3 (genotoxicity, carcinogenicity, and reproductive toxicity) and ISO 10993-10 (irritation and skin sensitization).

---

By adhering to oSIST prEN ISO 10993-11:2026, device manufacturers, test laboratories, and regulatory bodies can achieve thorough and systematic evaluation of systemic toxicity for medical devices, supporting both product safety and global regulatory acceptance. This standard is a critical component of the ISO 10993 biological evaluation framework, ensuring comprehensive risk management in the medical device industry.

Standards Content (Sample)

SLOVENSKI STANDARD
01-julij-2026
Biološko ovrednotenje medicinskih pripomočkov - 11. del: Preskusi sistemske
toksičnosti (ISO/DIS 10993-11:2026)
Biological evaluation of medical devices - Part 11: Tests for systemic toxicity (ISO/DIS
10993-11:2026)
Biologische Beurteilung von Medizinprodukten - Teil 11: Prüfungen auf systemische
Toxizität (ISO/DIS 10993-11:2026)
Évaluation biologique des dispositifs médicaux - Partie 11: Essais de toxicité systémique
(ISO/DIS 10993-11:2026)
Ta slovenski standard je istoveten z: prEN ISO 10993-11
ICS:
11.100.20 Biološko ovrednotenje Biological evaluation of
medicinskih pripomočkov medical devices
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 10993-11.2
ISO/TC 194
Biological evaluation of medical
Secretariat: DIN
devices —
Voting begins on:
Part 11: 2026-05-13
Tests for systemic toxicity
Voting terminates on:
2026-07-08
Évaluation biologique des dispositifs médicaux —
Partie 11: Essais de toxicité systémique
ICS: 11.100.20
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
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Reference number
ISO/DIS 10993-11.2:2026(en)
DRAFT
ISO/DIS 10993-11.2:2026(en)
International
Standard
ISO/DIS 10993-11.2
ISO/TC 194
Biological evaluation of medical
Secretariat: DIN
devices —
Voting begins on:
Part 11:
Tests for systemic toxicity
Voting terminates on:
Évaluation biologique des dispositifs médicaux —
Partie 11: Essais de toxicité systémique
ICS: 11.100.20
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document has not been edited by the ISO Central Secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2026
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
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Published in Switzerland Reference number
ISO/DIS 10993-11.2:2026(en)
ii
ISO/DIS 10993-11.2:2026(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General considerations . 3
4.1 General .3
4.2 Selection of animal model .4
4.3 Animal status .4
4.4 Animal care and husbandry .4
4.5 Size and number of groups.5
4.5.1 Size of groups .5
4.5.2 Number of groups .5
4.5.3 Treatment controls .6
4.6 Route of administration .6
4.7 Sample preparation .6
4.8 Dosing .6
4.8.1 Test sample administration considerations .6
4.8.2 Dose .7
4.8.3 Dosing frequency .7
4.9 Body weight and food/water consumption .8
4.10 Clinical observations .8
4.11 Clinical pathology .8
4.12 Anatomic pathology .9
4.13 Study designs .9
4.14 Quality of investigation .9
5 Acute systemic toxicity . 9
5.1 General .9
5.2 Study design .10
5.2.1 Pre-study activities .10
5.2.2 Experimental animals .10
5.2.3 Test conditions .10
5.2.4 Body weights . .11
5.2.5 Clinical observations .11
5.2.6 Pathology .11
5.3 Evaluation criteria . 12
5.3.1 General . 12
5.3.2 Evaluation of results . 12
5.4 Final report . 13
6 Long-term exposure systemic toxicity (subacute, subchronic and chronic systemic
toxicity) . 14
6.1 General .14
6.2 Study design .14
6.2.1 Pre-study activities .14
6.2.2 Experimental animals . 15
6.2.3 Test conditions . 15
6.2.4 Body weights . . 15
6.2.5 Clinical observations . 15
6.2.6 Pathology .16
6.3 Evaluation criteria .17
6.3.1 General .17
6.3.2 Evaluation of results .17
6.4 Final report .17

iii
ISO/DIS 10993-11.2:2026(en)
7 Material mediated pyrogenicity .18
Annex A (informative) Routes of administration . 19
Annex B (informative) Dose volumes .22
Annex C (informative) Common clinical signs and observations .23
Annex D (informative) Suggested haematology, clinical chemistry and urinalysis measurements .25
Annex E (informative) Suggested organ list for histopathological evaluation .27
Annex F (informative) Organ list for limited histopathology for medical devices subjected to
systemic toxicity testing .29
Annex G (informative) Information on pyrogens .30
Annex H (informative) Repeated Dose (14 d or 28 d) Toxicity Study in Rats — Dual routes of
parenteral administration .34
Annex ZA (informative) Relationship between this European Standard the General Safety and
Performance Requirements of Regulation (EU) 2017/745 aimed to be covered .37
Bibliography .39

iv
ISO/DIS 10993-11.2:2026(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent
rights identified during the development of the document will be in the Introduction or on the ISO list of
patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the World
Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL:
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 194 Biological and clinical evaluation of medical
devices, in collaboration with the European Committee for Standardization (CEN) Technical Committee
CEN/TC 206, Biocompatibility of medical and dental materials and devices, in accordance with the Agreement
on technical cooperation between ISO and CEN (Vienna Agreement).
This fourth edition cancels and replaces the third edition (ISO 10993-11:2017), which has been technically
revised with the following changes:
— emphasized risk assessment based on available data as a first step;
— added rabbits to Table 1 for group sizes;
— provided guidance on exaggeration of the human dose for toxicity studies;
— provided additional examples of clinical signs and observations in Annex C;
— revision of Annex G;
— provided clarification on study duration for studies described in Annex H;
— the Bibliography was updated.
A list of all parts in the ISO 10993 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

v
ISO/DIS 10993-11.2:2026(en)
Introduction
Systemic toxicity is a potential adverse effect of the use of medical devices. Generalized effects, as well as
organ and organ system effects can result from absorption, distribution and metabolism of constituents
from the device or its materials to parts of the body with which they are not in direct contact. This document
addresses the evaluation of generalized systemic toxicity, not specific target organ or organ system toxicity,
even though these effects may result from the systemic absorption and distribution of toxicants.
Given the broad range of medical devices, and their materials and intended uses, this document is not overly
prescriptive. While it addresses specific methodological aspects to be considered in the design of systemic
toxicity tests, proper study design should be uniquely tailored to the nature of the device’s materials and its
intended clinical application.
Other elements of this document are prescriptive in nature, including those aspects that address conformity
with good laboratory practices and elements for inclusion in reporting.
While some toxicity tests (e.g. long-term implantation or dermal toxicity studies) can be designed to study
systemic effects as well as local, carcinogenic or reproductive effects, this document focuses only on
those aspects of such studies, which are intended to address systemic effects. Studies which are intended
to address other biological effects are addressed in ISO 10993-3, ISO 10993-4, ISO 10993-5, ISO 10993-6,
ISO 10993-10, ISO 10993-23 and ISO/TS 10993-20.
Prior to conducting a systemic toxicity study, all reasonably available data and scientifically sound methods
in the planning and refinement of the systemic toxicity study design should be reviewed. This includes
the suitability of use of existing toxicological data, chemistry data or other biological test data (including
from in vitro tests and less invasive in vivo tests) for the refinement of study design (dose selection, or
selection of pathological endpoints). For the long-term exposure systemic toxicity study in particular, the
use of scientifically sound study design, the use of pilot studies and statistical study design and the use of
unbiased, quantitative endpoints or methods in the pathological assessment (including clinical pathology,
gross pathology and histopathology) are important so as to obtain data which have sufficient scientific
validity.
The outcome of any single test should not be the sole basis for making a determination of whether a device is
safe for its intended use.
vi
DRAFT International Standard ISO/DIS 10993-11.2:2026(en)
Biological evaluation of medical devices —
Part 11:
Tests for systemic toxicity
1 Scope
This document specifies requirements and gives guidance on procedures to be followed in the evaluation of
the potential for medical device materials or final products to cause adverse systemic reactions.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 10993-1, Biological evaluation of medical devices — Part 1: Requirements and general principles for the
evaluation of biological safety within a risk management process
ISO 10993-2, Biological evaluation of medical devices — Part 2: Animal welfare requirements
ISO 10993-6, Biological evaluation of medical devices — Part 6: Tests for local effects after implantation
ISO 10993-12:2021, Biological evaluation of medical devices — Part 12: Sample preparation and reference
materials
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 10993-1 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
biological harm
injury to humans from one or more adverse biological effects associated with a medical device or material
[SOURCE: ISO 10993-1:2025, 3.6]
3.2
constituent
chemical that is present in or on the finished medical device or its materials of construction
Note 1 to entry: Constituents can be intentionally or unintentionally added chemicals or compounds, such as: additives
(e.g. plasticizers, lubricants, stabilizers, anti-oxidants, colouring agents, fillers), manufacturing process residues (e.g.
monomers, catalysts, solvents, sterilant and cleaning agents), degradation products, reaction products, or impurities
or contaminants.
[SOURCE: ISO 10993-1:2025, 3.15]

ISO/DIS 10993-11.2:2026(en)
3.3
dose
amount of test sample administered (e.g. mass, volume) per unit of body weight or surface area
3.4
dosage
refers to a specific amount of drug administered at a specific frequency (and over a certain duration
3.5
dose-response effect
relationship of dosage to the spectrum of effects related to the exposure either in an individual or in a
population of individuals to a range of doses
3.6
leachable
substance that is released from a medical device or material during its clinical use
[SOURCE: ISO 10993-1:2025, 3.24]
EXAMPLE Additives, sterilant residues, process residues, degradation products, solvents, plasticizers, lubricants,
catalysts, stabilizers, anti-oxidants, colouring agents, fillers and monomers.
Note 1 to entry: Leachable substances related to the use of gas pathway devices can be evaluated according to the
ISO 18562-4.
3.7
limit test
use of a single group treated at a suitably high dosage of test sample in order to delineate the presence or
absence of a toxic hazard
Note 1 to entry: If the group is not toxic at this high dose, further testing at higher dosages is generally not necessary.
3.8
Long-term exposure
medical device that has a total exposure period of more than 30 d
Note 1 to entry: More information can be found in ISO 10993-1:2025, 6.4.2 c).
3.9
systemic toxicity
harm that occurs in an organ or system other than at the contact site
Note 1 to entry: Systemic toxicity can occur after a one-time exposure (i.e. acutely) or after repeated or ongoing
exposure (e.g. subacute or subchronic or chronic) to a harmful dose of a constituent released from a single medical
device or from use of multiple medical devices.
Note 2 to entry: The contact site is the specific location at which the medical device interfaces or interacts with the
tissue.
3.10
acute systemic toxicity
adverse effects occurring within 72 h following a single or repeated administration of a test sample for a
period of up to 24 h
3.11
subacute systemic toxicity
adverse effects occurring after repeated exposure or continuous exposure of a test sample for a period of up
to 28 d
Note 1 to entry: Exposure by implantation or topical application can be viewed as continuous exposure, Subacute
repeated intravenous and intraperitoneal studies are generally defined as exposure durations of ≤14 to 28 d for
rodents
ISO/DIS 10993-11.2:2026(en)
3.12
subchronic systemic toxicity
adverse effects occurring after long-term or continuous exposure of a test sample for a period of 90 d
3.13
chronic systemic toxicity
adverse effects occurring after long-term or continuous exposure of a test sample for a major part of the life
span
[35]
Note 1 to entry: Chronic toxicity studies usually have a duration of at least six months in rodents and rabbits or
[36]
nine months in large animal species .
3.14
test sample
medical device, component or material (or a representative sample thereof, manufactured and processed by
equivalent methods), or an extract or portion thereof that is subjected to biological evaluation testing
[SOURCE: ISO 10993-12:2021, 3.14]
4 General considerations
4.1 General
Before a decision to perform a systemic toxicity test is made, a biological evaluation as described in
ISO 10993-1 shall be conducted. To evaluate potential systemic toxicity risks of medical devices, consideration
should first be given to the availability and applicability of chemical characterization and toxicological
risk assessment data before pursuing systemic toxicity testing using an animal model. When there is
not sufficient data to estimate the risk of systemic toxicity using either relevant existing information or
chemical characterization according to ISO 10993-18 followed by a toxicological risk assessment according
to ISO 10993-17, then in vivo systemic toxicity studies should be considered. For example, when the outcome
of chemical characterization and toxicological risk assessment is inconclusive to assess tolerable risk and
worst-case exposure dose of extractable constituent is not well understood, then an in vivo systemic toxicity
test can be considered.
NOTE 1 Some devices can contain such low concentrations of extractable or leachable constituents that it is unlikely
to result in an observed adverse effect in a systemic toxicity test (see ISO 10993-18 and ISO 10993-17). Chemical
analysis of test sample extracts can provide information on whether in vivo systemic toxicity testing is potentially
useful to the overall biological evaluation.
EXAMPLE 1 The analytical results from a water extract can provide a reasonable estimate of the composition and
concentration of device constituents in the saline extract used for dosing an in vivo study, if:
— extraction conditions are similar and
— identification and quantitation are adequate.
EXAMPLE 2 The analytical results from all extracts in an exhaustive extraction study can provide a reasonable
estimate of the potential systemic exposure from a systemic toxicity study performed using implantation as the route
of exposure.
If available, such information shall be considered when designing a systemic toxicity study. Where
constituent concentrations correspond to a dose to the animal are less than approximately 0,015 mg/kg/
day to 0,15 mg/kg/day, in vivo effects are unlikely to be observed. Particularly, chemical characterization
according to ISO 10993-18 should inform whether the study will be useful for the overall biological
[4]
evaluation .
NOTE 2 A reasonable estimate of very low levels of extractables is that which would equate to a dose to the animal
of approximately 0,015 to 0,15 mg/kg/day. The high end of the range is based on the 5th percentile of the oral NOAELs
[5]
used to calculate the lowest Cramer Class TTC value. The low end of the range accounts for a potential 10-fold
difference in toxicity between oral NOAELs used to derive the TTC and parenteral routes used in most medical device
extract testing.
ISO/DIS 10993-11.2:2026(en)
EXAMPLE 3 A long-term medical device with a surface area of 300 cm was exhaustively extracted according to
ISO 10993-18. The water extract of the device contained a single extractable that was identified, and the total quantity
was reported to be 10 μg. For a systemic toxicity test using a saline extract, the 300-cm device would be extracted
at 6 cm /ml with a total extraction volume of 50 ml. Assuming the extraction efficiency of the extractable from the
device remains the same between water and saline and the same extraction conditions are used, the resulting saline
extract would contain the extractable at a concentration of 0,2 μg/ml. At a dose volume of 50 ml/kg IP, the dose to
the animal would be 10 μg/kg. If given daily, the dose would be 10 μg/kg/day (0,01 mg/kg/day), which is less than
0,015 mg/kg/day. This calculation indicates that a systemic toxicity test using a saline extract would be unlikely to
result in adverse effects and would not be useful for the overall biological evaluation of the device.
Testing shall be performed on the final product or representative component samples, or materials of the
final product. Test samples shall reflect the conditions under which the device is normally manufactured and
processed. If modifications to the manufacturing and processing conditions are necessary, these should be
documented by the manufacturer, together with their justification and captured in the biological evaluation
plan. For hazard identification purposes, it can be necessary to exaggerate exposure to the test samples. It
could also be necessary to determine the dose for implantation-based systemic toxicity studies, including,
but not limited to calculation of dose based on animal weight and worst-case clinical use, and accounting for
a safety factor.
Physical and chemical properties of the test sample including, for example, pH, stability, viscosity, osmolality,
buffering capacity, solubility and sterility, are some factors to consider when designing the study.
When animal tests are considered, all reasonably and practically available replacement, reduction and
refinement (3Rs) alternatives should be identified and implemented to satisfy the provisions of ISO 10993-2.
Animal studies should be tailored to address the specific type of systemic toxicity for which data or
information are lacking. For instance, if sufficient data exists for chronic toxicity but not for acute toxicity, in
vivo studies should be limited to acute toxicity designs.
4.2 Selection of animal model
There is no absolute criterion for selecting a particular animal species for systemic toxicity testing of
medical devices. However, the species used shall be scientifically justified and in line with the provisions of
ISO 10993-2. For acute oral, intravenous, dermal and inhalation studies of medical devices, rodents (mouse
or rat) are preferred. Rabbits, which are lagomorphs, are an option in dermal studies and preferred in the
case of implantation studies where a larger model is needed due to the size of the implant. Other non-rodent
species can be considered for testing, recognizing that a number of factors might dictate the number or
choice of species for study.
It is preferred that a single animal species and strain are used when a series of systemic toxicity studies of
different durations are performed, e.g. subacute, subchronic and chronic systemic toxicity. This minimizes
the variability between species and strains and facilitates an evaluation based primarily on study duration.
Should multiple species or strains be used, justification for their selection shall be documented.
4.3 Animal status
Generally, healthy purpose-bred young adult animals, as determined by qualified veterinary personnel, and,
of known species, strain, substrain, age, sex, source and with defined microbiological and pathogen health
status should be used. At the commencement of the study, the weight variation of animals used within a sex
should not exceed ±20 % of the mean weight. When females are used, they should be nulliparous and non-
pregnant. Animal selection shall be justified.
4.4 Animal care and husbandry
Care and handling of animals shall be in accordance with the animal care guidelines of the country in which
the test facility is located. Animals shall be acclimatized to the laboratory conditions prior to treatment and
the period of time documented. Control of environmental conditions and proper animal care techniques are
essential to animal well-being, minimization of stress-related physiological responses and the quality of the
results. Dietary constituents and bedding materials that are known to produce or influence toxicity should
be properly characterized and their potential to influence test results taken into account.

ISO/DIS 10993-11.2:2026(en)
The temperature and the relative humidity in the experimental animal rooms should be appropriate for the
species, e.g. (22 ± 3) °C and relative humidity of 30 % to 70 %, for rodents. Typically, the artificial lighting
sequence should be 12 h light, 12 h dark.
For feeding, standardized commercial laboratory diets may be used with an unlimited supply of drinking
water. Animals should be caged in-groups by sex or individually, as appropriate; for group housing not more
than five animals shall be housed per cage.
4.5 Size and number of groups
4.5.1 Size of groups
The study should use the least number of animals to detect meaningful differences in biological responses
and provide meaningful interpretation of the data (see ISO 10993-2). Recommended minimum group sizes,
with all routes of test sample administration considered, are given in Table 1.
a
Table 1 — Recommended minimum group sizes
Study type Rodent Non-rodent
Acute 5 3
Subacute 10 (5 per sex) 6 (3 per sex)
Subchronic 20 (10 per sex) 8 (4 per sex)
b
Chronic 30 (15 per sex) 12 (6 per sex)
a
Testing in a single sex is typical for acute and pharmacopeia-type testing. When a device
is intended for use in only one sex, testing should be done in that sex.
b
Expert statistical consultation for chronic study non-rodent group size is recommended.
The number of animals tested should be based on the minimum required to provide mean-
ingful data. Enough animals shall remain at the termination of the study to ensure proper
statistical evaluation of the results.
When the testing is designed to address both systemic toxicity and implantation endpoints, group sizes
shall meet both ISO 10993-11 and ISO 10993-6 requirements. If both sets of requirements can’t be met,
justification shall be provided and documented.
4.5.2 Number of groups
One dose group treated at a suitable dosage of test sample in a single species could delineate the presence
or absence of a hazard (i.e. limit test). However, other multi-dose or dose response studies require multiple
groups to delineate the toxic response.
The number of treatment groups may be increased when attempting to characterize a dose response using
exaggerated doses. The following examples for exaggerating the dose should be considered:
— multiples of the human dose based on device mass or number/per patient body weight;
— multiples of the surface area of human exposure per patient body weight;
— multiples of the duration of exposure;
— multiples of the amounts of extractable fraction or individual chemicals from the device per patient body
weight;
— multiple administrations within a 24-h period.
Other methods to exaggerate the dose may be acceptable. The method used shall be justified.

ISO/DIS 10993-11.2:2026(en)
4.5.3 Treatment controls
Depending on the objective of the study, the nature of the test sample and the route of exposure, negative
control, vehicle control, or sham-treated controls, shall be incorporated into all systemic toxicity studies.
These controls shall mimic the test sample preparation and treatment procedure.
4.6 Route of administration
Medical devices or their leachable constituent s may gain access to the body by multiple routes of exposure.
The test route of administration for a systemic toxicity test should be chosen based on the ability to
exaggerate the systemic dose balanced with clinical relevance. Sometimes parenteral dosing with device
extracts can exaggerate the dose more readily than implantation. However, there is limitation in repeated
administration of extracts into animals due to their inherent stress and physiological tolerance. Therefore,
extract studies (via intravenous and intraperitoneal administration) are typically limited to systemic toxicity
up to 28 d, see Annex H. The route of administration shall be justified. Examples of routes of administration
can be found in Annex A.
4.7 Sample preparation
The test and control samples and their preparation (such as pH, stability, homogeneity, osmolality, and
sterility, as appropriate) shall be described and justified. All samples and vehicles for parenteral delivery
should be prepared aseptically. Further guidance on sample preparation is given in ISO 10993-12.
4.8 Dosing
4.8.1 Test sample administration considerations
Procedures should be designed to avoid physiological changes or animal welfare problems not directly
related to the toxicity of the test material. Current proper handling and restraint techniques that minimize
aversion and anxiety levels in animals shall be practiced (for example, picking up mice through tunnel
or cupped hand instead of by the tail). If a single daily dose of a sufficient volume or concentration is not
possible, the dose may be given in smaller fractions over a period not exceeding 24 h.
Test samples shall be delivered at a physiologically acceptable temperature. Aseptic techniques shall be used
when samples are given parenterally. In general, test samples are used at or near room temperature (e.g.
25 °C) or body temperature (e.g. 37 °C), with the temperature documented and justified.
Vehicles administered by a parenteral route should be physiologically compatible. When necessary, if
gravimetric sedimentation is ineffective, extract centrifugation or filtration to remove particulates can
be used. These post-extraction manipulations shall be documented, and justified. In addition, alternate
administration routes (e.g. intraperitoneal injections) can be considered and shall be justified. When
medical devices or test samples in the form of nanomaterials are to be evaluated, special considerations may
be necessary for the sample preparation (e.g. the use of nano-object dispersions instead of extracts).
NOTE For more information, see ISO/TR 10993-22:2017, Clause 6.
Prolonged restraint of animals in long-term exposure systemic toxicity studies should be scientifically
justified and performed in a manner that is as humane as possible. Animals shall have adequate room for
thoracic and abdominal expansion during breathing, and comfortable surface for resting the head and body.
The nature and the duration of restraint should be the minimum required to meet the scientific objectives
and should not of themselves compromise the welfare of the test animals. Deviations shall be justified.
Further guidelines on prolonged restraint can be found in the Guide for the Care and Use of Laboratory
[22]
Animals. When restraint is required animals should be acclimatized to the restraint device prior to
test sample administration. Minimal effective restraint of test animals is a key factor to be considered for
prolonged infusion.
ISO/DIS 10993-11.2:2026(en)
4.8.2 Dose
Guidance on dose volume is summarized in Annex B. Multiple dose volume groups and use of dose volumes
greater than those given in Annex B shall be justified.
Large dose volumes administered by the oral route should be avoided because they have been shown to
overload the stomach capacity and pass immediately into the small bowel. Large volumes may also reflux
into the oesophagus.
Intramuscular administration is also volume-limited, depending on size of the animal and the muscular site.
Species-specific intramuscular administration volumes are addressed in Annex B.
Bolus intravenous injection volumes are usually given over a period of time dependent on the species. The
rate of injection is an important factor and a maximum of 2 ml/min is suggested for rodents.
Slow or timed inject
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