ATC and USP classifications

A drug class consists of a group of medications with certain similarities. Various ways are used to classify drugs, including their chemical structure, mechanism of action, therapeutic use, organ system, formulary, and abuse potential.

ATC classification

The WHO classification for drugs is known as Anatomical Therapeutic Chemical (ATC) classification. In the ATC system, the active substances are divided into different groups in a hierarchy according to the organ or system on which they act and their therapeutic, pharmacological, and chemical properties. Drugs are classified at five different levels, levels 1 to 5. The system has fourteen main anatomical/pharmacological groups or 1st levels. Each ATC main group is divided into 2nd levels.

For example, Metformin is a medication used in diabetes mellitus to control blood glucose levels. Metformin is given the code A10BA02, as follows:

A - for 1st level, Alimentary tract and metabolism

A10 - for 2nd level, therapeutic subgroup, Drugs used in diabetes

A10B - for 3rd level, pharmacological subgroup, Blood glucose lowering drugs, excl. insulins

A10BA - for 4th level, chemical subgroup, Biguanides

A10BA02 - for 5th level, chemical substance, metformin

USP classification

The United States Pharmacopeia (USP) classifies medications into 47 broad categories, depending on therapeutic use, mechanism of action, and formulary classification. It helps to prescribe medications under the Medicare Prescription Drug Benefit. Some categories are analgesics, antivirals, cardiovascular agents, etc.

A formulary, also known as a drug list, is a list of prescription drugs covered by a prescription drug plan or another insurance plan offering prescription drug benefits.