Concept Hierarchy & Relationship Mapping
RxNorm Concept Unique Identifier (RxCUI) 21478 represents a standardized clinical drug concept used for cross-system interoperability. This concept aggregates multiple Atom IDs (AUIs), which are specific naming variations and synonyms used across pharmaceutical databases to ensure accurate medication mapping for: C3d receptor.
The following semantic concepts and normalized strings are associated with this clinical entity:
Type (TTY)
Clinical Name / Synonym
Atom ID
Details
This clinical crossover tool is designed for healthcare professionals, pharmacists, and data analysts to safely compare substitute products and manage medication interoperability.
SY
Synonym (SY):
C3d receptor
(Atom ID: 400967)
Clinical Status & Identity
Prescribable Status
NO (Reference)
Part of the RxNorm Current Prescribable Content subset including all drugs available for prescription in the USA.
Concept Description
C3d receptor
Official description of the drug concept as defined in the source vocabulary.
Suppress Flag
N
N: Not suppressible | O: Obsolete | Y: Suppressed by editor | E: Unquantified non-prescribable drug.
Interoperability & Coding
Concept ID (RxCUI)
21478
RxNorm Unique Identifier for the standardized concept.
Atom ID (RXAUI)
400967
Unique identifier for this specific name variation (Atom).
Term Type (TTY)
SY
Synonym (Synonym of another TTY, given for clarity.)
Source Code
21166007
The "Most useful" identifier asserted by the original source vocabulary.
Source & Registry Data
Source Name
US Edition of SNOMED CT (SNOMEDCT_US)
The official name and abbreviation for the vocabulary source.
Source Version
2026_01_31
The specific version of the vocabulary provided by the source.
Update Date
June 01, 2026
The date when this RxNorm data was last updated by the NLM.
License Contact
National Library Of Medicine, NLM is a Charter Member of SNOMED International on behalf of the U.S., National Library of Medicine, 8600 Rockville Pike, , Bethesda, MD, United States, 20894, 1-888-FIND-NLM (1-888-346-3656), , https://support.nlm.nih.gov/support/create-case/,
Source licensing contact information.
SY
Synonym (SY):
CD21
(Atom ID: 401002)
Clinical Status & Identity
Prescribable Status
NO (Reference)
Part of the RxNorm Current Prescribable Content subset including all drugs available for prescription in the USA.
Concept Description
CD21
Official description of the drug concept as defined in the source vocabulary.
Suppress Flag
N
N: Not suppressible | O: Obsolete | Y: Suppressed by editor | E: Unquantified non-prescribable drug.
Interoperability & Coding
Concept ID (RxCUI)
21478
RxNorm Unique Identifier for the standardized concept.
Atom ID (RXAUI)
401002
Unique identifier for this specific name variation (Atom).
Term Type (TTY)
SY
Synonym (Synonym of another TTY, given for clarity.)
Source Code
21166007
The "Most useful" identifier asserted by the original source vocabulary.
Source & Registry Data
Source Name
US Edition of SNOMED CT (SNOMEDCT_US)
The official name and abbreviation for the vocabulary source.
Source Version
2026_01_31
The specific version of the vocabulary provided by the source.
Update Date
June 01, 2026
The date when this RxNorm data was last updated by the NLM.
License Contact
National Library Of Medicine, NLM is a Charter Member of SNOMED International on behalf of the U.S., National Library of Medicine, 8600 Rockville Pike, , Bethesda, MD, United States, 20894, 1-888-FIND-NLM (1-888-346-3656), , https://support.nlm.nih.gov/support/create-case/,
Source licensing contact information.
SY
Synonym (SY):
CD21 - Cluster of differentiation antigen 21
(Atom ID: 400988)
Clinical Status & Identity
Prescribable Status
NO (Reference)
Part of the RxNorm Current Prescribable Content subset including all drugs available for prescription in the USA.
Concept Description
CD21 - Cluster of differentiation antigen 21
Official description of the drug concept as defined in the source vocabulary.
Suppress Flag
N
N: Not suppressible | O: Obsolete | Y: Suppressed by editor | E: Unquantified non-prescribable drug.
Interoperability & Coding
Concept ID (RxCUI)
21478
RxNorm Unique Identifier for the standardized concept.
Atom ID (RXAUI)
400988
Unique identifier for this specific name variation (Atom).
Term Type (TTY)
SY
Synonym (Synonym of another TTY, given for clarity.)
Source Code
21166007
The "Most useful" identifier asserted by the original source vocabulary.
Source & Registry Data
Source Name
US Edition of SNOMED CT (SNOMEDCT_US)
The official name and abbreviation for the vocabulary source.
Source Version
2026_01_31
The specific version of the vocabulary provided by the source.
Update Date
June 01, 2026
The date when this RxNorm data was last updated by the NLM.
License Contact
National Library Of Medicine, NLM is a Charter Member of SNOMED International on behalf of the U.S., National Library of Medicine, 8600 Rockville Pike, , Bethesda, MD, United States, 20894, 1-888-FIND-NLM (1-888-346-3656), , https://support.nlm.nih.gov/support/create-case/,
Source licensing contact information.
SY
Synonym (SY):
Cluster of differentiation antigen 21
(Atom ID: 400991)
Clinical Status & Identity
Prescribable Status
NO (Reference)
Part of the RxNorm Current Prescribable Content subset including all drugs available for prescription in the USA.
Concept Description
Cluster of differentiation antigen 21
Official description of the drug concept as defined in the source vocabulary.
Suppress Flag
N
N: Not suppressible | O: Obsolete | Y: Suppressed by editor | E: Unquantified non-prescribable drug.
Interoperability & Coding
Concept ID (RxCUI)
21478
RxNorm Unique Identifier for the standardized concept.
Atom ID (RXAUI)
400991
Unique identifier for this specific name variation (Atom).
Term Type (TTY)
SY
Synonym (Synonym of another TTY, given for clarity.)
Source Code
21166007
The "Most useful" identifier asserted by the original source vocabulary.
Source & Registry Data
Source Name
US Edition of SNOMED CT (SNOMEDCT_US)
The official name and abbreviation for the vocabulary source.
Source Version
2026_01_31
The specific version of the vocabulary provided by the source.
Update Date
June 01, 2026
The date when this RxNorm data was last updated by the NLM.
License Contact
National Library Of Medicine, NLM is a Charter Member of SNOMED International on behalf of the U.S., National Library of Medicine, 8600 Rockville Pike, , Bethesda, MD, United States, 20894, 1-888-FIND-NLM (1-888-346-3656), , https://support.nlm.nih.gov/support/create-case/,
Source licensing contact information.
SY
Synonym (SY):
Complement receptor 2
(Atom ID: 400980)
Clinical Status & Identity
Prescribable Status
NO (Reference)
Part of the RxNorm Current Prescribable Content subset including all drugs available for prescription in the USA.
Concept Description
Complement receptor 2
Official description of the drug concept as defined in the source vocabulary.
Suppress Flag
N
N: Not suppressible | O: Obsolete | Y: Suppressed by editor | E: Unquantified non-prescribable drug.
Interoperability & Coding
Concept ID (RxCUI)
21478
RxNorm Unique Identifier for the standardized concept.
Atom ID (RXAUI)
400980
Unique identifier for this specific name variation (Atom).
Term Type (TTY)
SY
Synonym (Synonym of another TTY, given for clarity.)
Source Code
21166007
The "Most useful" identifier asserted by the original source vocabulary.
Source & Registry Data
Source Name
US Edition of SNOMED CT (SNOMEDCT_US)
The official name and abbreviation for the vocabulary source.
Source Version
2026_01_31
The specific version of the vocabulary provided by the source.
Update Date
June 01, 2026
The date when this RxNorm data was last updated by the NLM.
License Contact
National Library Of Medicine, NLM is a Charter Member of SNOMED International on behalf of the U.S., National Library of Medicine, 8600 Rockville Pike, , Bethesda, MD, United States, 20894, 1-888-FIND-NLM (1-888-346-3656), , https://support.nlm.nih.gov/support/create-case/,
Source licensing contact information.
SY
Synonym (SY):
Complement receptor II
(Atom ID: 401006)
Clinical Status & Identity
Prescribable Status
NO (Reference)
Part of the RxNorm Current Prescribable Content subset including all drugs available for prescription in the USA.
Concept Description
Complement receptor II
Official description of the drug concept as defined in the source vocabulary.
Suppress Flag
N
N: Not suppressible | O: Obsolete | Y: Suppressed by editor | E: Unquantified non-prescribable drug.
Interoperability & Coding
Concept ID (RxCUI)
21478
RxNorm Unique Identifier for the standardized concept.
Atom ID (RXAUI)
401006
Unique identifier for this specific name variation (Atom).
Term Type (TTY)
SY
Synonym (Synonym of another TTY, given for clarity.)
Source Code
21166007
The "Most useful" identifier asserted by the original source vocabulary.
Source & Registry Data
Source Name
US Edition of SNOMED CT (SNOMEDCT_US)
The official name and abbreviation for the vocabulary source.
Source Version
2026_01_31
The specific version of the vocabulary provided by the source.
Update Date
June 01, 2026
The date when this RxNorm data was last updated by the NLM.
License Contact
National Library Of Medicine, NLM is a Charter Member of SNOMED International on behalf of the U.S., National Library of Medicine, 8600 Rockville Pike, , Bethesda, MD, United States, 20894, 1-888-FIND-NLM (1-888-346-3656), , https://support.nlm.nih.gov/support/create-case/,
Source licensing contact information.
SY
Synonym (SY):
CR II - Complement receptor II
(Atom ID: 401004)
Clinical Status & Identity
Prescribable Status
NO (Reference)
Part of the RxNorm Current Prescribable Content subset including all drugs available for prescription in the USA.
Concept Description
CR II - Complement receptor II
Official description of the drug concept as defined in the source vocabulary.
Suppress Flag
N
N: Not suppressible | O: Obsolete | Y: Suppressed by editor | E: Unquantified non-prescribable drug.
Interoperability & Coding
Concept ID (RxCUI)
21478
RxNorm Unique Identifier for the standardized concept.
Atom ID (RXAUI)
401004
Unique identifier for this specific name variation (Atom).
Term Type (TTY)
SY
Synonym (Synonym of another TTY, given for clarity.)
Source Code
21166007
The "Most useful" identifier asserted by the original source vocabulary.
Source & Registry Data
Source Name
US Edition of SNOMED CT (SNOMEDCT_US)
The official name and abbreviation for the vocabulary source.
Source Version
2026_01_31
The specific version of the vocabulary provided by the source.
Update Date
June 01, 2026
The date when this RxNorm data was last updated by the NLM.
License Contact
National Library Of Medicine, NLM is a Charter Member of SNOMED International on behalf of the U.S., National Library of Medicine, 8600 Rockville Pike, , Bethesda, MD, United States, 20894, 1-888-FIND-NLM (1-888-346-3656), , https://support.nlm.nih.gov/support/create-case/,
Source licensing contact information.
SY
Synonym (SY):
CR2
(Atom ID: 401009)
Clinical Status & Identity
Prescribable Status
NO (Reference)
Part of the RxNorm Current Prescribable Content subset including all drugs available for prescription in the USA.
Concept Description
CR2
Official description of the drug concept as defined in the source vocabulary.
Suppress Flag
N
N: Not suppressible | O: Obsolete | Y: Suppressed by editor | E: Unquantified non-prescribable drug.
Interoperability & Coding
Concept ID (RxCUI)
21478
RxNorm Unique Identifier for the standardized concept.
Atom ID (RXAUI)
401009
Unique identifier for this specific name variation (Atom).
Term Type (TTY)
SY
Synonym (Synonym of another TTY, given for clarity.)
Source Code
21166007
The "Most useful" identifier asserted by the original source vocabulary.
Source & Registry Data
Source Name
US Edition of SNOMED CT (SNOMEDCT_US)
The official name and abbreviation for the vocabulary source.
Source Version
2026_01_31
The specific version of the vocabulary provided by the source.
Update Date
June 01, 2026
The date when this RxNorm data was last updated by the NLM.
License Contact
National Library Of Medicine, NLM is a Charter Member of SNOMED International on behalf of the U.S., National Library of Medicine, 8600 Rockville Pike, , Bethesda, MD, United States, 20894, 1-888-FIND-NLM (1-888-346-3656), , https://support.nlm.nih.gov/support/create-case/,
Source licensing contact information.
SY
Synonym (SY):
EBV - Epstein-Barr virus receptor
(Atom ID: 400996)
Clinical Status & Identity
Prescribable Status
NO (Reference)
Part of the RxNorm Current Prescribable Content subset including all drugs available for prescription in the USA.
Concept Description
EBV - Epstein-Barr virus receptor
Official description of the drug concept as defined in the source vocabulary.
Suppress Flag
N
N: Not suppressible | O: Obsolete | Y: Suppressed by editor | E: Unquantified non-prescribable drug.
Interoperability & Coding
Concept ID (RxCUI)
21478
RxNorm Unique Identifier for the standardized concept.
Atom ID (RXAUI)
400996
Unique identifier for this specific name variation (Atom).
Term Type (TTY)
SY
Synonym (Synonym of another TTY, given for clarity.)
Source Code
21166007
The "Most useful" identifier asserted by the original source vocabulary.
Source & Registry Data
Source Name
US Edition of SNOMED CT (SNOMEDCT_US)
The official name and abbreviation for the vocabulary source.
Source Version
2026_01_31
The specific version of the vocabulary provided by the source.
Update Date
June 01, 2026
The date when this RxNorm data was last updated by the NLM.
License Contact
National Library Of Medicine, NLM is a Charter Member of SNOMED International on behalf of the U.S., National Library of Medicine, 8600 Rockville Pike, , Bethesda, MD, United States, 20894, 1-888-FIND-NLM (1-888-346-3656), , https://support.nlm.nih.gov/support/create-case/,
Source licensing contact information.
SY
Synonym (SY):
Epstein-Barr virus receptor
(Atom ID: 400956)
Clinical Status & Identity
Prescribable Status
NO (Reference)
Part of the RxNorm Current Prescribable Content subset including all drugs available for prescription in the USA.
Concept Description
Epstein-Barr virus receptor
Official description of the drug concept as defined in the source vocabulary.
Suppress Flag
N
N: Not suppressible | O: Obsolete | Y: Suppressed by editor | E: Unquantified non-prescribable drug.
Interoperability & Coding
Concept ID (RxCUI)
21478
RxNorm Unique Identifier for the standardized concept.
Atom ID (RXAUI)
400956
Unique identifier for this specific name variation (Atom).
Term Type (TTY)
SY
Synonym (Synonym of another TTY, given for clarity.)
Source Code
21166007
The "Most useful" identifier asserted by the original source vocabulary.
Source & Registry Data
Source Name
US Edition of SNOMED CT (SNOMEDCT_US)
The official name and abbreviation for the vocabulary source.
Source Version
2026_01_31
The specific version of the vocabulary provided by the source.
Update Date
June 01, 2026
The date when this RxNorm data was last updated by the NLM.
License Contact
National Library Of Medicine, NLM is a Charter Member of SNOMED International on behalf of the U.S., National Library of Medicine, 8600 Rockville Pike, , Bethesda, MD, United States, 20894, 1-888-FIND-NLM (1-888-346-3656), , https://support.nlm.nih.gov/support/create-case/,
Source licensing contact information.
PT
Designated preferred name (PT):
Lymphocyte antigen CD21
(Atom ID: 400993)
Clinical Status & Identity
Prescribable Status
NO (Reference)
Part of the RxNorm Current Prescribable Content subset including all drugs available for prescription in the USA.
Concept Description
Lymphocyte antigen CD21
Official description of the drug concept as defined in the source vocabulary.
Suppress Flag
N
N: Not suppressible | O: Obsolete | Y: Suppressed by editor | E: Unquantified non-prescribable drug.
Interoperability & Coding
Concept ID (RxCUI)
21478
RxNorm Unique Identifier for the standardized concept.
Atom ID (RXAUI)
400993
Unique identifier for this specific name variation (Atom).
Term Type (TTY)
PT
Designated preferred name ()
Source Code
21166007
The "Most useful" identifier asserted by the original source vocabulary.
Source & Registry Data
Source Name
US Edition of SNOMED CT (SNOMEDCT_US)
The official name and abbreviation for the vocabulary source.
Source Version
2026_01_31
The specific version of the vocabulary provided by the source.
Update Date
June 01, 2026
The date when this RxNorm data was last updated by the NLM.
License Contact
National Library Of Medicine, NLM is a Charter Member of SNOMED International on behalf of the U.S., National Library of Medicine, 8600 Rockville Pike, , Bethesda, MD, United States, 20894, 1-888-FIND-NLM (1-888-346-3656), , https://support.nlm.nih.gov/support/create-case/,
Source licensing contact information.
FN
Full form of descriptor (FN):
Lymphocyte antigen CD21 (substance)
(Atom ID: 401010)
Clinical Status & Identity
Prescribable Status
NO (Reference)
Part of the RxNorm Current Prescribable Content subset including all drugs available for prescription in the USA.
Concept Description
Lymphocyte antigen CD21 (substance)
Official description of the drug concept as defined in the source vocabulary.
Suppress Flag
N
N: Not suppressible | O: Obsolete | Y: Suppressed by editor | E: Unquantified non-prescribable drug.
Interoperability & Coding
Concept ID (RxCUI)
21478
RxNorm Unique Identifier for the standardized concept.
Atom ID (RXAUI)
401010
Unique identifier for this specific name variation (Atom).
Term Type (TTY)
FN
Full form of descriptor ()
Source Code
21166007
The "Most useful" identifier asserted by the original source vocabulary.
Source & Registry Data
Source Name
US Edition of SNOMED CT (SNOMEDCT_US)
The official name and abbreviation for the vocabulary source.
Source Version
2026_01_31
The specific version of the vocabulary provided by the source.
Update Date
June 01, 2026
The date when this RxNorm data was last updated by the NLM.
License Contact
National Library Of Medicine, NLM is a Charter Member of SNOMED International on behalf of the U.S., National Library of Medicine, 8600 Rockville Pike, , Bethesda, MD, United States, 20894, 1-888-FIND-NLM (1-888-346-3656), , https://support.nlm.nih.gov/support/create-case/,
Source licensing contact information.
