Essential medicines and health products

International Chemical Reference Substances (ICRS)

International Chemical Reference Substances (ICRS) are required to support the monograph specifications in The International Pharmacopoeia. They are established according to General guidelines for the establishment, maintenance and distribution of chemical reference substance, by the WHO custodian organization for ICRS, the European Directorate for the Quality of Medicines & HealthCare (EDQM), located in the Council of Europe, Strasbourg, France.

About WHO ICRS

Search the Online Database for the availability and price of ICRS by using substance name or Catalogue Code or Chemical Abstract Service (CAS) Registry Number.
Access to ICRS database and purchase of ICRS online at EDQM

ICRS are intended to be used as primary standards for physical and chemical tests and assays described in The International Pharmacopoeia; or to calibrate secondary standards according to the General guidelines for the establishment, maintenance and distribution of chemical reference substance.

Intended use of ICRS

The International Pharmacopoeia constantly develops new monographs and revises existing ones to stay abreast of advances in analytical science and regulatory affairs. Along with these changes the intended use of already established ICRS often needs to be adjusted, for example, because an ICRS previously used for identification only shall newly also be employed in quantitative tests.

The user of The International Pharmacopoeia finds information on the actually established intended uses of an ICRS in the leaflet enclosed with the substance when distributed or accessible via the ICRS online database. The information found in current leaflets is applicable to all standards of the respective batch number.

Authorization of ICRS

ICRS are adopted by the WHO Expert Committee on Specifications for Pharmaceutical Preparations following a procedure aligned with the WHO General guidelines for the establishment, maintenance and distribution of chemical reference substances.

List of reference substances of other pharmacopoeias found to be suitable for use according to The International Pharmacopoeia

In order to foster harmonization of pharmacopoeial standards and to exploit possibilities for work sharing between pharmacopoeias the WHO Expert Committee on Specifications for Pharmaceutical Preparations has prescribed reference substances that have been established by other pharmacopoeias for use according to The International Pharmacopoeia.
These reference substances are listed below.

The suitability of the listed reference substances for the additional intended use was assessed during the elaboration or revision of monographs or other tests in which they are mentioned. With the adoption of these texts the WHO Expert Committee on Specifications on Pharmaceutical Preparations authorizes the use of the respective reference substances for the purposes described in The International Pharmacopoeia.

To order these reference substances contact the issuing pharmacopoeia. Any question related to the use of such reference substances according to a monograph of The International Pharmacopoeia shall be addressed to the Secretariat of The International Pharmacopoeia.
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