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).

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.

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.



Class Types

RxClass contains thirteen drug class trees:
  • ATC1-4 - Anatomical Therapeutic Chemical (ATC) containing class levels 1 through 4. The ATC classification system divides the drugs into different groups 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.
  • Disposition - 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.
  • MeSHPA - Medical Subject Headings (MeSH) pharmacological actions. In MeSH, every drug and chemical MeSH heading has been assigned one or more headings that describe its pharmacological action (PA).
  • 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).
  • Structure - 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.
  • VA - VA drug classes from VANDF, whose members are clinical drugs.

Sources of Drug-Class Relations

There are nine sources which associate generic drugs to the classes listed above.
  • ATC (level 5). The fifth level of the ATC tree contains the drugs.
  • 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.
  • MeSH. MeSH drugs are associated with the pharmacological actions.
  • 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 SNOMED CT, linked to medicinal products (as RxNorm ingredients).
  • VA. The VA drugs are associated with the VA classes.

Note: the three sources - DailyMed, MEDRT and FDASPL - contain overlapping and redundant associations of drugs to some of the class trees (see tables below), so to avoid confusion only one of those sources is selected at any given time in RxClass.

The following table lists the drug sources and the classes they associate with .

Class \ Source ATC    DailyMed FDASPL FMTSME MEDRT  MeSH   RXNORM SNOMEDCT  VA   
ATC1-4    X                
Chem         X      X        X        
Disease              X        
Disposition                     X  
EPC         X      X            
MeSHPA               X      
MoA         X      X        X        
PE         X      X        X        
PK              X        
Schedule                   X    
Structure                     X  
TC            X          
VA                     X

Relationships to Drug Classes

The following table shows the relationships each drug source uses to identify with the drug class.

Drug Source Relation Drug Class Description
ATC (level 5) ATC1-4 Drug members of an ATC class
DailyMed has_EPC EPC Drug members of a FDA Established Pharmacologic Class
DailyMed has_Chemical_Structure Chem Drugs that have a chemical structure
DailyMed has_MoA MoA Drugs that have a Mechanism of Action
DailyMed has_PE PE Drugs that have a Physiologic Effect
FDASPL has_EPC EPC Drug members of a FDA Established Pharmacologic Class
FDASPL has_Chemical_Structure Chem Drugs that have a chemical structure
FDASPL has_MoA MoA Drugs that have a Mechanism of Action
FDASPL has_PE PE Drugs that have a Physiologic Effect
FMTSME has_TC TC Drugs that have Therapeutic Categories
MEDRT CI_ChemClass Chem Drugs that are contraindicated with a chemical class
MEDRT has_ingredient Chem Drugs that are members of a chemical class
MEDRT has_active_metabolites Chem Drugs that have active metabolites in a chemical class
MEDRT CI_with Disease Drugs that are contraindicated with a disease
MEDRT induces Disease Drugs that induce a disease
MEDRT may_diagnose Disease Drugs that may diagnose a disease
MEDRT may_prevent Disease Drugs that may prevent a disease
MEDRT may_treat Disease Drugs that may treat a disease
MEDRT CI_MoA MoA Drugs that are contraindicated with a Mechanism of Action
MEDRT has_MoA MoA Drugs that have a Mechanism of Action
MEDRT CI_PE PE Drugs that are contraindicated with a Physologic Effect
MEDRT has_PE PE Drugs that have a Physiologic Effect
MEDRT has_PK PK Drugs that are members of a Pharmacokinetics Class
MEDRT site_of_metabolism PK Drugs that have a site of metabolism in a Pharmacokinetics Class
MeSH MeshPA Drug members of a MeSH Pharmacologic Action
RXNORM has_schedule Schedule Drugs that are considered controlled substances under the Controlled Substances Act (CSA)
SNOMEDCT isa_disposition Disposition Drugs that have a "disposition" (e.g., mechanism of action)
SNOMEDCT isa_structure Structure Drugs that have a chemical structure
VA has_VAClass VA Clinical drugs that are members of a VA Class
VA has_VAClass_extended VA 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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