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.
- 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 and Physiologic States”, were created as parents of the MeSH classes contained in the tree, which are MeSH descriptors from the diseases ("C" tree) category.
- 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. |