Pharmacopœia Pharmacometrika

Published

May 5, 2025

Pharmacopœia:
A collection of directions for the identification of medicines.

Drug facts that are good to know

This section presents a high-level overview of selected drug classes and their mechanisms of action. It is organized according to the Anatomical Therapeutic Chemical (ATC) classification system. The ATC system was developeed in Norway and was introduced in 1976 and is maintained by the World Health Organization Collaborating Centre for Drug Statistics Methodology (WHOCC). It classifies active substances based on the organ or system they act on, as well as their therapeutic, pharmacological, and chemical properties.

Drugs are classified in groups at five different levels.

  • ATC 1st level: Main anatomical or pharmacological group, shown in Table 2 below.
  • ATC 2nd level: Pharmacological or Therapeutic subgroup
  • ATC 3rd & 4th levels: Chemical, Pharmacological or Therapeutic subgroup
  • ATC 5th level: Chemical substance
Table 1: ATC count per level
ATC level Codes Different names/pharmaceuticals
Level 1 14 14
Level 2 94 94
Level 3 267 262
Level 4 889 819
Level 5 5067 4363

The 2nd, 3rd and 4th levels are often used to identify pharmacological subgroups when that is considered more appropriate than therapeutic or chemical subgroups.

Table 2: Codes in the first ATC level, the Anatomical main group
ATC code Contents
A Alimentary tract and metabolism
B Blood and blood forming organs
C Cardiovascular system
D Dermatologicals
G Genito-urinary system and sex hormones
H Systemic hormonal preparations, excluding sex hormones and insulins
J Antiinfectives for systemic use
L Antineoplastic and immunomodulating agents
M Musculo-skeletal system
N Nervous system
P Antiparasitic products, insecticides and repellents
R Respiratory system
S Sensory organs
V Various

Example: metformin

The complete classification of metformin illustrates the structure of the code:

Table 3: Anatomical Therapeutic Chemical (ATC) Classification System
Level Code Description
1: Anatomical main group A Alimentary tract and metabolism
2: Therapeutic subgroup A10 Drugs used in diabetes
3: Pharmacological subgroup A10B Blood glucose lowering drues, excl. insulins
4: Chemical subgroup A10BA Biguanides
5: Chemical substance A10BA02 Metformin

Thus, in the ATC system all plain metformin preparations are given the code A10BA02. For the chemical substance, the International Nonproprietary Name (INN) is preferred. If INN names are not assigned, USAN (United States Adopted Name) or BAN (British Approved Name) names are usually chosen.