Generic drug names—the often tongue-twisting terms in parentheses after brand names—might look like mashups of made-up morphemes, but they are created deliberately to explain chemical structures, actions or indications of active ingredients, and distinguish drugs within classes. A scientist from the agency responsible for developing these names offers insight into the process and how it affects patient safety and drug availability.
Following are highlights from an article published in the AMA Journal of Ethics® (@JournalofEthics) by Gail B. Karet, PhD, senior scientist with the United States Adopted Names (USAN) Program, the council that develops all legal nonproprietary names for active drug ingredients. She outlines a history of pharmaceutical naming and a taxonomy of generic drugs.
Seeking safety and clarity
In the early 1960s, while numerous organizations had long been evaluating pharmaceuticals and publishing formularies, no single entity in the U.S.—governmental or otherwise—had authority for assigning generic drug names.
“Concerns were raised that the existing system did not require selection of a nonproprietary name for each drug, that there was no central list of names, and that there was no legal requirement that all firms use the same name for a substance,” Karet wrote.
So, the United States Pharmacopeial Convention, the American Pharmacists Association (APhA) and the AMA, each of which had been conducting its own nomenclature activities, came together to establish the USAN Council, made up of representatives from each organization. The AMA was thereafter charged with assigning USAN names, while the USP agreed to adopt these names for its monograph titles and the APhA would use them in its National Formulary titles.
USAN also came to include a representative of the Food and Drug Administration, but operates independently.
What’s in a name
Prior to the USAN, generic drug names were created by simply shortening a compound’s systematic chemical name, but this led to complex, unmanageable or overused names, so the USAN Council devised a taxonomy based on of the following elements:
A stem or substem. Usually appearing at the end of the name, this signifies a chemical structure, indication or action at a specific receptor.
For example, for the cancer drug imatinib, “-tinib" refers to a drug’s action as a tyrosine kinase (TYK) inhibitor. Sometimes a substem is used to further classify drugs, such as how “-citinib” denotes drugs that inhibit a specific family of TYK inhibitors, the Janus kinases.
A one- or two-syllable prefix. This differentiates each drug from others in its class.
“The most important concern in choosing a prefix is patient safety—specifically, reducing the risk of medication errors,” Karet wrote. “For this reason, the USAN Council avoids prefixes that will create new names that are too similar either to other drugs in the same stem class or to names in other stem classes that might look or sound similar to the new name.”
Implications for safety, access
The class to which a drug is assigned can affect a manufacturer’s decisions about whether to continue developing a drug, so the USAN Council must balance pharmaceutical firms’ name preferences with its obligations regarding patient safety and access to drugs.
“Assignment of a new stem is rare, occurring only after the council determines that a drug is truly novel and does not fit into any existing group,” Karet wrote, noting that assigning a new stem unnecessarily could cause insurers and patients to pay more for a drug. “Similarly, an unfavorable nomenclature decision for the firm, if it contributes to a company’s decision to discontinue a developmental drug, might affect patient access.”
The USAN Council has developed a list of stems, a pronunciation guide and a drug finder for adopted names.
The August issue of AMA Journal of Ethics further explores, in articles and a podcast, clinicians’ roles in improving prescription drug safety and access.
