APPLICATIONS

RxClass Overview

The RxClass Browser is a web application for exploring and navigating through the class hierarchies to find the RxNorm drug members associated with each class.

The RxClass API is available for users to include RxClass data in their applications.

RxClass links drug classes with several drug sources to their RxNorm drug members (usually ingredients, precise ingredients and multiple ingredients).

A sample view of the RxClass Browser is shown below.

sample view of RxClass Browser

RxClass allows users to search by class name or identifier to find the RxNorm drug members or, conversely, search by RxNorm drug name or identifier to find the classes that the RxNorm drug is a member of.

The RxClass search bar is shown below.

RxClass search bar image

The search by class can be done either by navigating the class tree in the left side of the RxClass window, or by typing in a name in the search box. When typing in a class name, RxClass will give suggestions of class names containing the string. For example, when the term “coxib” is entered in the search box, the following class suggestions are provided:

RxClass suggestions image

A search by drug name or RxCUI will bring up a pop-up menu containing all the classes the drug is a member of. The example below shows the window when the name “fomivirsen” is entered as a drug name:

RxClass search result example image

While most sources of drug/class relationships relate ingredients to classes, some sources relate products to classes. To facilitate comparison of classes from distinct sources, RxClass ordinarily displays a normalized view of class members as ingredients, transparently translating products to their ingredients. Alternatively, you can view class members as provided by the source, including any ID or name in the mapped vocabulary, by selecting the Show Source Data checkbox.

When the show source data box is checked, additional columns will be displayed in the drug table showing the source data that is mapped into RxNorm. The following images show the tables without and with the source data.

RxClass tables with and without source data example image

By default, RxClass does not show source data and the drug table(s) are displayed as ingredients. While most drug to class mappings occur at the ingredient level, CSA Schedule, VA and ATC Product map drug products to these classes. When the source data box is checked, for those classes the drug products are shown in the table. For example:

RxClass tables with CSA Schedule and VA classes example image

Additionally, once a class is selected, RxClass offers similar classes in drug membership.



Class Types

RxClass contains fourteen drug class trees displayed on the left side of the view.

RxClass drug class browser

The class types are explained below:
  • ATC1-4 - Anatomical Therapeutic Chemical (ATC) containing class levels 1 through 4. The ATC classification system groups drugs according to the organ or system on which they act and according to their chemical, pharmacological and therapeutic properties. The drugs are divided into 14 main groups (first level), with two therapeutic/pharmacological subgroups (second and third levels). The fourth level is a therapeutic/pharmacological/chemical subgroup and the fifth level is the chemical substance. The second, third and fourth levels are often used to identify pharmacological subgroups when these are considered to be more appropriate than therapeutic or chemical subgroups.
  • Chem - Chemical structure and classification containing chemicals or other drug ingredients, organized into a chemical structure classification hierarchy. The high level non-MeSH classes, including the top level node of "Substances and Cells", were created as parents of the MeSH classes contained in the tree, which are part of the drugs and chemicals ("D" tree) category in MeSH. Note that some relations from MED-RT may not be included if they map to classes not contained in the Chem tree.
  • Disease - Disease classification containing pathophysiologic as well as certain non-disease physiologic states that are treated, prevented, or diagnosed by an ingredient or drug product. May also be used to describe contraindications. The high level non-MeSH classes, including the top level node of "Diseases, Life Phases, Behavior Mechanisms and Physiologic States”, were created as parents of the MeSH classes contained in the tree. Specifically, the RxClass Disease tree incorporates the following high-level MeSH classes (MeSH tree ids in parenthesis) and their subclasses:
    • Diseases (C)
    • Behavior and Behavior Mechanisms (F01)
    • Mental Disorders (F03)
    • Reproductive Physiological Phenomena (G08.686)
    • Immune System Phenomena (G12)
    • Age Groups (M01.060)
    Note that some MED-RT disease relations may not be included if they map to classes not contained in the tree.
  • DISPOS - Drug classification from SNOMED CT based on the “dispositions” of medicinal products (e.g., mechanism of action).
  • EPC - FDA Established Pharmacologic Classes. In support of the FDA Structured Product Labeling (SPL) initiative, a hierarchy of FDA. Established Pharmacologic Class (EPC) concepts are contained in MED-RT.
  • MoA - Mechanism of Action in MED-RT, containing molecular, subcellular, or cellular effects of drug generic ingredients, organized into a chemical function classification hierarchy, beneath the “Cellular or Molecular Interactions” concept.
  • PE - Physiologic Effects in MED-RT, containing tissue, organ, or organ system effects of drug generic ingredients, organized into an organ system classification hierarchy, beneath the “Physiological Effects” concept.
  • PK - Pharmacokinetics in MED-RT, containing collections of concepts describing the absorption, distribution, and elimination of drug active ingredients, beneath the “Clinical Kinetics” concept.
  • Schedule - The Controlled Substances Act (CSA) drug schedules (1-5), whose members are drug products (generic and branded).
  • STRUCT - Drug classification from SNOMED CT based on the chemical structure of medicinal products.
  • TC - Therapeutic Categories from MED-RT, a small, experimental collection of general therapeutic intents of drug generic ingredients, organized into an organ system-oriented classification hierarchy, beneath the “Therapeutic Categories [TC]” concept.
  • THERAP - Drug classification from SNOMED CT based on the therapeutic role of medicinal products and medicinal product forms.
  • VA - VA drug classes from VANDF, whose members are clinical drugs.

Sources of Drug-Class Relations

There are ten sources which associate generic drugs to the classes listed above.
  • ATC. Drug (ingredient-level) ATC class members are curated by the World Health Organization Collaborating Center for Drug Statistics Methodology.
  • ATCPROD. Drug (product-level) ATC class members are curated by the National Library of Medicine.
  • DailyMed. The DailyMed API maps substances through their UNII Code values to EPC, Chem, MoA and PE classes.
  • FDASPL. The FDASPL drug source maps drug concepts in MED-RT to EPC, Chem, MoA and PE classes.
  • FMTSME. The FMTSME drug source maps drug concepts in MED-RT to TC classes.
  • MEDRT. Drug concepts in MED-RT are associated to Disease, MoA, Chem, PE, and PK classes.
  • RxNorm. CSA schedules for drug products are contained in the RxNorm data set in several drug sources.
  • SNOMEDCT. Drug classes (groupers) from the medicinal product hierarchy of the U.S. Edition of SNOMED CT, linked to medicinal products and medicinal product forms (as RxNorm ingredients).
  • VA. The VA drugs are associated with the VA classes.


Note: In June 2018, NDF-RT was replaced by MED-RT as a source of drug class relations. Additionally, the VA drug-class relations contained in NDF-RT were replaced by VANDF data.

SNOMED CT® Usage Conditions

RxClass includes SNOMED Clinical Terms® (SNOMED CT®) which is used by permission of the International Health Terminology Standards Development Organisation (IHTSDO). All rights reserved. SNOMED CT® was originally created by the College of American Pathologists. “SNOMED”, “SNOMED CT” and “SNOMED Clinical Terms” are registered trademarks of the IHTSDO.

Use of SNOMED CT in RxClass is subject to the SNOMED CT Affiliate license provisions (incorporated in the License Agreement for Use of the UMLS Metathesaurus as Appendix 2) issued by the National Library of Medicine on behalf of SNOMED International.



The following table lists the class-member sources available in RxClass for each type of class.

Multiple sources map drugs to some class types. RxClass presents them as alternatives. For example, RxClass shows Chem class members from DailyMed by default, but you may select FDASPL or MEDRT instead, by choosing Edit Drug Sources.

The table below marks with “X” the sources of drug/class mappings, and marks with “X**” the source shown in RxClass by default.

Class Type Drug Source
ATC    ATCPROD DailyMed FDASPL FMTSME MEDRT  RXNORM SNOMEDCT VA 
ATC1-4    X    X**              
Chem       X**      X        X      
Disease                X      
DISPOS                     X  
EPC         X**      X          
MoA         X**      X        X      
PE         X**      X        X      
PK                X      
Schedule                   X    
STRUCT                     X  
TC              X        
THERAP                     X  
VA                   X

Relationships to Drug Classes

The following table shows term types of RxNorm drug concepts that are members of a class (identified by class type and membership source) and the relationship by which RxClass signals the association.

Drug Source Class Type Relation Member Types Description
ATC ATC1-4 IN MIN PIN Drug (ingredient-level) ATC class membership curated by the World Health Organization Collaborating Center for Drug Statistics Methodology
ATCPROD ATC1-4   BPCK GPCK SBD SCD Drug (product-level) ATC class membership curated by the National Library of Medicine
DailyMed EPC has_EPC IN MIN PIN Drug members of a FDA Established Pharmacologic Class
DailyMed Chem has_Chemical_Structure IN MIN PIN Drugs that have a chemical structure
DailyMed MoA has_MoA IN MIN PIN Drugs that have a Mechanism of Action
DailyMed PE has_PE IN MIN PIN Drugs that have a Physiologic Effect
FDASPL EPC has_EPC IN MIN PIN Drug members of a FDA Established Pharmacologic Class
FDASPL Chem has_Chemical_Structure IN MIN PIN Drugs that have a chemical structure
FDASPL MoA has_MoA IN MIN PIN Drugs that have a Mechanism of Action
FDASPL PE has_PE IN MIN PIN Drugs that have a Physiologic Effect
FMTSME TC has_TC IN MIN PIN Drugs that have Therapeutic Categories
MEDRT Chem CI_ChemClass IN MIN PIN Drugs that are contraindicated with a chemical class
MEDRT Chem has_ingredient IN MIN PIN Drugs that are members of a chemical class
MEDRT Chem has_active_metabolites IN MIN PIN Drugs that have active metabolites in a chemical class
MEDRT Disease CI_with IN MIN PIN Drugs that are contraindicated with a disease
MEDRT Disease induces IN MIN PIN Drugs that induce a disease
MEDRT Disease may_diagnose IN MIN PIN Drugs that may diagnose a disease
MEDRT Disease may_prevent IN MIN PIN Drugs that may prevent a disease
MEDRT Disease may_treat IN MIN PIN Drugs that may treat a disease
MEDRT MoA CI_MoA IN MIN PIN Drugs that are contraindicated with a Mechanism of Action
MEDRT MoA has_MoA IN MIN PIN Drugs that have a Mechanism of Action
MEDRT PE CI_PE IN MIN PIN Drugs that are contraindicated with a Physologic Effect
MEDRT PE has_PE IN MIN PIN Drugs that have a Physiologic Effect
MEDRT PK has_PK IN MIN PIN Drugs that are members of a Pharmacokinetics Class
MEDRT PK site_of_metabolism IN MIN PIN Drugs that have a site of metabolism in a Pharmacokinetics Class
RXNORM Schedule has_schedule primarily BPCK GPCK SBD SCD; few IN PIN Drugs that are considered controlled substances under the Controlled Substances Act (CSA)
SNOMEDCT DISPOS isa_disposition IN MIN PIN Drugs that have a "disposition" (e.g., mechanism of action)
SNOMEDCT STRUCT isa_structure IN MIN PIN Drugs that have a chemical structure
SNOMEDCT THERAP isa_therapeutic IN MIN PIN Drugs that have a therapeutic role
VA VA has_VAClass primarily BPCK GPCK SBD SCD SCDF SCDG; few IN MIN PIN Clinical drugs that are members of a VA Class
VA VA has_VAClass_extended GPCK SBD SCD Related clinical and branded drugs that are derived members of a VA Class. For example, branded drugs related to clinical drugs that are mapped to a VA class, or clinical drugs that have a different dosages from ones that are mapped to a VA class.

 
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