How drugs get their generic names, from the USAN Council to WHO

At its meeting on June 23, 2026, the United States Adopted Names Council approved seven new word endings for new drug families. One of them, -aplin, will mark inhibitors of apolipoprotein L1 and lipoprotein(a); another, -solmin, will tag drugs meant to stop alpha-synuclein from clumping, according to the council's list of newly approved stems⁴. Each came with an example name, and a footnote marks examples that are "not yet an adopted USAN."

Those endings, called stems, are the reason lisinopril sounds like other blood pressure drugs ending in -pril and atorvastatin sounds like the other statins. The American Medical Association, which runs the program, says on its naming guidelines page¹ that the USAN Program names more than 200 substances a year.

Generic names are what pharmacists read off a prescription, what a generic label must print in large type, and what FDA uses in its databases. This explainer covers who coins them, how the United States system meshes with the World Health Organization's, what the pieces of a name mean, and what FDA's own role is. It also counts how many of the drugs GxRadar tracks carry a stem.

Who picks a generic name in the United States

In the early 1960s no single body in the United States had authority to assign generic drug names, and nothing required every company to use the same name for the same substance, the AMA recounts⁵. The AMA, the United States Pharmacopeial Convention and the American Pharmaceutical Association (now the American Pharmacists Association) set up a joint council to fix that. An FDA representative later joined it.

FDA's regulations describe the arrangement plainly. The USAN Council "is a private organization sponsored by the American Medical Association, the United States Pharmacopeia, and the American Pharmaceutical Association, and has been engaged in the assignment of names to drugs since January 1964," says 21 CFR 299.4⁶. The same section says FDA "cooperates with and is represented on the USAN Council" and encourages every new-drug sponsor to contact the council early.

A sponsor applies after it has filed an investigational new drug application with FDA; the USAN guidelines¹ say an IND number is required before review can begin. The council then negotiates with the company. If two companies submit the same substance, the guidelines say neither is told about the other, but each must accept the chosen name.

How the US system meshes with WHO's

An international layer sits on top, and it is older. The International Nonproprietary Name system "was initiated in 1950 by a World Health Assembly resolution WHA3.11 and began operating in 1953, when the first list of International Nonproprietary Names for pharmaceutical substances was published," according to WHO's 2017 guidance on INNs¹⁰. That document put the cumulative list at some 9,300 names.

Requests that originate in the United States can go to WHO through the USAN Council, WHO's selection page says⁹. All INN experts must agree on a name, which is first published as a proposed INN. Anyone then has four months to comment or lodge a formal objection, for example over similarity to a trademark. With no objection, the name is published again as a recommended INN.

Volume is steady. At the 82nd INN consultation in Geneva in April 2026, experts discussed 292 requests, including 266 new ones, and selected 275 new names, WHO's executive summary reports¹¹. Because of that coordination, national names such as USANs, British Approved Names and Japanese Adopted Names "are nowadays, with rare exceptions, identical" to the INN, WHO's INN page⁸ says.

Prefix, infix and stem

Modern names have three parts, the AMA explains. The prefix "means nothing" and exists only to tell one drug from others in its class. An optional infix subdivides the class. The stem, usually at the end, places the drug in a family. Its worked example is the -afil stem for PDE5 inhibitors: in sildenafil and vardenafil, a shared -den- infix signals similar chemical structures, while tadalafil carries only the stem.

Some building blocks are banned outright. Prefixes may not hint at the indication, the sponsor or a quality such as long duration, and the guidelines¹ cite "dura" and "forte" as examples. To ease translation, names avoid the letters h, k, j and w, use f for ph and t for th, and steer clear of starting with z or x. A few prefixes do carry meaning. Es- and lev- mark single mirror-image forms of a drug that already has a name, which is why escitalopram follows citalopram.

The council's cumulative stem list³, downloaded by GxRadar in November 2026, has 730 rows covering 506 distinct stems and their substems. Here are the ones that appear among the drugs on GxRadar's price pages.

What GxRadar's own drug list shows

GxRadar's price basket covers 46 distinct molecules (metoprolol appears twice, as two salts). Matching each name against the stem list, 29 end in a recognized stem. That count leaves out two coincidental matches; digoxin, for instance, ends in letters the list reserves for an unrelated class.

Several of the 29 are not members of a family so much as its namesake. The list defines -oxetine as "fluoxetine type," -semide as "furosemide type" and -farin as "warfarin analogs." Older drugs often supplied the pattern that later names copied. A handful more carry their stem at the front: glipizide (gli-, antidiabetics), gabapentin (gab-), prednisone (pred-) and estradiol (estr-). Cephalexin is spelled with the ph that today's rules replace with f; the list writes the cephalosporin stem as cef-.

A second word on a label is usually a salt. The guidelines allow a single modifying term to show "a chemical modification, such as salt or ester formation," as in metoprolol tartrate versus metoprolol succinate. GxRadar's piece on salt forms and drug names on labels covers how that second word affects strength statements.

Where FDA comes in

Federal law requires a drug's label to carry its "established name." Under 21 CFR 299.4⁶, that is an official name FDA designates under section 508 of the Food, Drug, and Cosmetic Act, added by the Kefauver-Harris amendments of 1962; failing that, the compendial title; failing that, the common or usual name. FDA says it "will not routinely designate official names," so in practice the USAN or the compendial name governs. Where a brand name appears, 21 CFR 201.10(g)(2)⁷ requires the established name in letters "at least half as large" as the brand.

That is why a generic's label reads almost entirely in its established name. GxRadar has explainers on how generic labeling must match the brand and on what USP after the name means.

FDA does coin one piece of the name for biologics. Its January 2017 guidance¹² said each originator biologic, related biologic and biosimilar would get "a distinguishing suffix that is devoid of meaning and composed of four lowercase letters," attached to a shared core name with a hyphen. GxRadar's article on the Purple Book covers how those products are listed.

Stems also limit brand names. WHO says trademarks "should neither be derived from INNs nor contain common stems used in INNs," and the USAN guidelines say stems should not be built into trade names. FDA's 2020 guidance on proprietary names¹³ recommends that sponsors "screen proposed proprietary names against the stem list created by the USAN Council," though it generally does not object to the five two-letter stems. The agency screens proposed brand names for confusion with existing names, a process covered in GxRadar's explainer on look-alike and sound-alike drug names.

What is changing

Monoclonal antibodies have seen the biggest recent change. The -mab suffix has been replaced by -bart, -mig, -ment and -tug under a scheme WHO published in May 2022, according to a note on the USAN stem list³. Biosimilars of existing antibodies keep the original core name under FDA's approach, so familiar -mab names persist on pharmacy shelves.

New stems keep arriving too. The AMA's stems page² says the council tries to reuse existing stems and puts "the burden of proof" on the applicant to show a new one is warranted. Even so, its June 2026 meeting added seven. WHO's INN page⁸ lists an 83rd consultation for October 2026. Names chosen there will appear first as proposed INNs, open to objection for four months before they become recommended names.