The document "The Use of Common Stems in the Selection of INNs" is intended
primarily for persons and companies applying to the WHO INN Programme for the selection of an INN for a
new pharmaceutical substance and has been designed to assist in the process of devising a suitable proposal.
It will also be of assistance to institutions and specialists involved in the review of proposed INNs, including
drug regulatory authorities, pharmaceutical manufacturers, patent offices and trade mark officers as well as
for scientists, teachers, health professionals and other persons interested generally in drug nomenclature. The
document is composed of four main parts and annexes.
Part I "Introduction" describes the WHO INN Programme, INN selection
procedure, and criteria for name selection and gives general information on the INN stem system.
Part II contains the list of all INN stems. It is composed of two indexes,
one entitled "Alphabetical List of Common Stems" which presents the list of stems, and another entitled
"Alphabetical List of Common Stems and their definitions" which includes a definition for each stem.
Part III presents the stem classification system used by the INN Programme to
categorize the main activity of pharmaceutical substances. Each category included in the list is given an
appropriate code consisting of a capital letter and three digits. When INNs for substances belonging to a given category
include a specific stem, appropriate information is included in the table.
Part IV of the document entitled "Alphabetical List of Stems Together With
Corresponding INNs" serves as a listing of all proposed INNs (published in lists 1 - 105) containing INN
stems. The list is organized in alphabetical order (as set out in Part II) and includes all INNs containing individual stems.
In addition, under each stem heading information is given on INNs in which the preferred stem has been used but not
in accordance with its definition as well as on INNs which belong to the same group of pharmaceutical substances but
in which no preferred stem has been used. To facilitate the use of Part IV, the lay-out of information is
presented as a diagram on page 6 and is complemented by additional information given at the end of part I
Six annexes attached to the document are intended to be of assistance to
users. Annex 1 reproduces the Procedure for the Selection of Recommended International Nonproprietary Names
for Pharmaceutical Substances as approved by the WHO Executive Board in its resolution EB15.R7 as amended by
resolution EB115.R4. Annex 2 reproduces General Principles for Guidance in Devising International
Nonproprietary Names for Pharmaceutical Substances as approved by the WHO Executive Board in the above-mentioned
resolution, as amended. Annex 3 explains the nomenclature scheme for monoclonal antibodies. Annex 4 explains the
nomenclature scheme for Gene Therapy Products. Annex 5 gives reference to the volumes of the WHO Drug
Information in which proposed lists of INNs have been published. Annex 6 "Why INN?" gives general information on the
present situation of WHO INN Programme and its achievements.