How to pronounce retatrutide, tirzepatide, semaglutide and other peptide names
Peptide International Nonproprietary Names are accented according to the World Health Organization stem they end in. A name ending in -tide is stressed three syllables from the end, on the first syllable of the stem, and the final syllable rhymes with wide. A name ending in -relin, -relix, -pressin or -tocin is stressed one syllable later, on the second-to-last.
That single rule covers almost every name in a peptide reference list, which is why the tables below are organised by ending rather than alphabetically. The naming system behind it is described in the peptide overview, the individual entries and their approval status sit in the peptide list, and the regulatory side is covered under FDA-approved peptides.
How to read the two notation systems
Two notations appear side by side below. The first is the convention used by the United States Adopted Names (USAN) pronunciation guide, which was developed by the United States Pharmacopeia and approved by the USAN Council; the NIH consumer drug pages reprint it verbatim. The second is the International Phonetic Alphabet.
| Symbol | System | Meaning | Example |
|---|---|---|---|
| ' after a syllable | USAN / USP | primary accent | gloo' |
| " after a syllable | USAN / USP | secondary accent | sem" |
| space | USAN / USP | syllable boundary; no diacritics are used | sem" a gloo' tide |
| ˈ before a syllable | IPA | primary accent | ˈɡluː |
| ˌ before a syllable | IPA | secondary accent | ˌsɛm |
| aɪ | IPA | the vowel in wide | taɪd |
| uː | IPA | the vowel in food | ɡluː |
| ɛ | IPA | the vowel in bed | zɛp |
| ə | IPA | the unstressed vowel in about | ətaɪd |
The two systems disagree only on where the mark is placed: the pharmacopoeial notation puts it after the accented syllable, the phonetic alphabet puts it before.
Peptide names ending in -tide
CAPITALS mark the accented syllable. The fifth column gives the pronunciation exactly as published, in United States Pharmacopeia notation, with the source for that row. Rows marked † have no entry on the NIH consumer drug pages; for those names the published form sits in the USAN statement of adoption instead, which the USAN Drug Finder carries in public. A dash marks a row for which neither source holds a form, and the syllable and IPA columns there follow the stem pattern.
| Name | Syllables | IPA | Sounds like | Published pronunciation (USP notation) | Class and status |
|---|---|---|---|---|---|
| semaglutide | se-ma-GLU-tide | /ˌsɛməˈɡluːtaɪd/ | sem-uh-GLOO-tide | sem" a gloo' tide [9] | GLP-1 receptor agonist; prescription-only |
| tirzepatide | tir-ZEP-a-tide | /tɪrˈzɛpətaɪd/ | tir-ZEP-uh-tide | tir zep' a tide [10] | GIP and GLP-1 receptor agonist; prescription-only |
| retatrutide † | re-ta-TRU-tide | /ˌrɛtəˈtruːtaɪd/ | ret-uh-TROO-tide | ret" a troo' tide [28] | GIP, GLP-1 and glucagon receptor agonist; in clinical development, not approved |
| liraglutide | li-ra-GLU-tide | /ˌlɪrəˈɡluːtaɪd/ | lir-uh-GLOO-tide | lir" a gloo' tide [11] | GLP-1 receptor agonist; prescription-only |
| dulaglutide | du-la-GLU-tide | /ˌduːləˈɡluːtaɪd/ | doo-luh-GLOO-tide | doo" la gloo' tide [12] | GLP-1 receptor agonist; prescription-only |
| teduglutide | te-du-GLU-tide | /ˌtɛdjuˈɡluːtaɪd/ | ted-yoo-GLOO-tide | te" due gloo' tide [13] | glucagon-like peptide analogue; prescription-only |
| exenatide | ex-EN-a-tide | /ɛkˈsɛnətaɪd/ | ex-EN-uh-tide | ex en' a tide [15] | GLP-1 receptor agonist; prescription-only |
| lixisenatide | li-xi-SEN-a-tide | /ˌlɪksɪˈsɛnətaɪd/ | lix-ih-SEN-uh-tide | lix" i sen' a tide [14] | GLP-1 receptor agonist; prescription-only |
| pramlintide | PRAM-lin-tide | /ˈpræmlɪntaɪd/ | PRAM-lin-tide | pram' lin tide [16] | amylin analogue; prescription-only |
| cagrilintide † | ca-gri-LIN-tide | /ˌkæɡrɪˈlɪntaɪd/ | kag-rih-LIN-tide | ka" gri lin' tide [28] | amylin analogue; in clinical development, not approved |
| teriparatide | te-ri-PAR-a-tide | /ˌtɛrɪˈpærətaɪd/ | terr-ih-PAR-uh-tide | terr ih par' a tyd [17] | parathyroid hormone analogue; prescription-only |
| octreotide | oc-TRE-o-tide | /ɑkˈtriːoʊtaɪd/ | ok-TREE-oh-tide | ok tree' oh tide [18] | somatostatin analogue; prescription-only |
| bremelanotide | bre-me-LAN-o-tide | /ˌbrɛməˈlænoʊtaɪd/ | breh-meh-LAN-oh-tide | bre" me lan' oh tide [19] | melanocortin receptor agonist; prescription-only |
The published forms confirm the pattern without exception: in every one of them the prime sits after the third syllable from the end.
Peptide names ending in -relin, -relix, -pressin and -tocin
These stems belong to hormone-release groups rather than the general peptide group, and they shift the accent one place to the right.
| Name | Syllables | IPA | Sounds like | Published pronunciation (USP notation) | Class and status |
|---|---|---|---|---|---|
| tesamorelin | te-sa-mo-REL-in | /ˌtɛsəmoʊˈrɛlɪn/ | tess-uh-moh-REL-in | tes" a moe rel' in [20] | growth hormone-releasing factor analogue; prescription-only |
| sermorelin † | ser-mo-REL-in | /ˌsɜrmoʊˈrɛlɪn/ | sur-moh-REL-in | – | growth hormone release-stimulating peptide; not licensed as a medicine in most markets |
| ipamorelin † | i-pa-mo-REL-in | /ˌɪpəmoʊˈrɛlɪn/ | ip-uh-moh-REL-in | – | growth hormone release-stimulating peptide; research peptide, not approved |
| macimorelin † | ma-ci-mo-REL-in | /ˌmæsɪmoʊˈrɛlɪn/ | mass-ih-moh-REL-in | ma" si moe rel' in [28] | growth hormone secretagogue; prescription-only |
| gonadorelin † | go-na-do-REL-in | /ˌɡoʊnədoʊˈrɛlɪn/ | goh-nuh-doh-REL-in | – | pituitary hormone-release stimulating peptide; prescription-only [27] |
| degarelix | de-ga-REL-ix | /ˌdɛɡəˈrɛlɪks/ | deg-uh-REL-ix | deg" a rel' ix [21] | pituitary hormone-release inhibiting peptide; prescription-only |
| cetrorelix † | ce-tro-REL-ix | /ˌsɛtroʊˈrɛlɪks/ | set-roh-REL-ix | – | pituitary hormone-release inhibiting peptide; prescription-only |
| desmopressin | des-mo-PRESS-in | /ˌdɛsmoʊˈprɛsɪn/ | dess-moh-PRESS-in | des moe press' in [22] | vasopressin analogue; prescription-only |
| oxytocin | ox-y-TO-cin | /ˌɑksɪˈtoʊsɪn/ | ok-sih-TOH-sin | ox i toe' sin [23] | posterior pituitary hormone; prescription-only |
In the published forms the accent lands on REL, PRESS and TO, one syllable further right than in the -tide group. The stem -tocin is the one case where the parent hormone stands in the table under its own name: the stem book definition covers the names built on that hormone, not the parent name itself.
How INN names are built
An International Nonproprietary Name is not a marketing name. It is assigned by the World Health Organization INN Programme, published in Latin, English, French and Spanish, and placed in the public domain. Two of the WHO general principles shape how the names read. The first requires that names be distinctive in sound and spelling and not liable to confusion with names in common use. The second requires that a substance belonging to a group of pharmacologically related substances show that relationship where appropriate – which is what the stems do.
A further principle governs the letters themselves: to make translation and pronunciation easier, an INN uses f instead of ph, t instead of th, e instead of ae or oe and i instead of y, and avoids the letters h and k. That is why peptide names look phonetically flat and why they transfer reasonably well between languages.
| Stem | What WHO records it for | Position | Source |
|---|---|---|---|
| -tide | peptides and glycopeptides | main stem | [2] |
| -glutide | glucagon-like peptide (GLP) analogues and agonists | sub-stem of -tide | [3] |
| -enatide | GLP-1 receptor agonists, exenatide (exendin-4) and analogues | sub-stem of -tide | [3] |
| -dutide | oxyntomodulin analogues and other dual agonists of GLP-1R and the glucagon receptor | sub-stem of -tide | [3] |
| -paratide | parathyroid hormone analogues | sub-stem of -tide | [3] |
| -netide | neurological | sub-stem of -tide | [3] |
| -pultide | peptides and proteins used in pulmonary surfactants | sub-stem of -tide | [3] |
| -actide | synthetic polypeptides with a corticotropin-like action | own stem | [2] |
| -relin | pituitary hormone-release stimulating peptides | own stem | [2] |
| -morelin | growth hormone release-stimulating peptides | sub-stem of -relin | [2] |
| -tirelin | thyrotropin releasing hormone analogues | sub-stem of -relin | [2] |
| -relix | pituitary hormone-release inhibiting peptides | own stem | [2] |
| -pressin | vasoconstrictors, vasopressin analogues | own stem | [3] |
| -tocin | oxytocin derivatives | own stem | [2] |
The sub-stems -dutide, -enatide, -netide, -paratide and -pultide were added after the 2018 edition of the stem book and appear in the addendum dated 10 October 2023, which also widened -glutide from "GLP analogues" to "GLP analogues and agonists" and restated -pressin from "vasopressin derivatives" to "vasopressin analogues". The sequence -tatrutide shared by names in that class is a family resemblance, not a registered sub-stem: as of that addendum there is no published sub-stem for triple receptor agonists, so such a name still sits under the general -tide stem, and its middle syllables carry no group meaning.
Names such as pramlintide, amlintide and davalintide are listed in the stem book directly under -tide rather than under a -lintide sub-stem of their own; the shared -lintide sequence is a family resemblance rather than a registered stem.
Where the accent falls, by stem group
| Stem group | Accent position | Pattern |
|---|---|---|
| -tide and its sub-stems | third syllable from the end | ...-GLU-tide, ...-EN-a-tide, ...-PAR-a-tide |
| -actide | third syllable from the end | ...-SAC-tide |
| -relin and -morelin | second syllable from the end | ...-mo-REL-in |
| -relix | second syllable from the end | ...-REL-ix |
| -pressin | second syllable from the end | ...-PRESS-in |
| -tocin | second syllable from the end | ...-TO-cin |
A three-syllable name in -tide is not an exception: counting three from the end simply lands on the first syllable, which is why pram' lin tide is accented at the front. A secondary accent, written with a double prime or with the IPA mark, usually falls two syllables before the primary one, and most speakers drop it entirely in ordinary speech.
Why the stress is disputed
The disagreement is structural, not a matter of anyone being careless.
An INN list entry carries the name in four languages, a chemical name or description, a statement of action and use, a molecular formula, a CAS registry number and a graphic formula. It carries no phonetic transcription, no accent marks and no audio. The WHO principles govern spelling and sound patterns when the name is coined, and stop there.
Only the United States naming programme publishes a pronunciation. The USAN pronunciation guide is developed by the United States Pharmacopeia, approved by the USAN Council and applied to statements of adoption; the NIH consumer pages carry it into public view for products with an approved label. For a name still in development the published form sits in the statement of adoption rather than on those pages: the USAN naming guidelines record that the pronunciations "are included in the statement of adoption but are finalized after review by experts at USP", and the adoption statements themselves are published in the USAN Drug Finder. No comparable list is attached to the British Approved Name or to the European pharmacopoeial monograph. Outside the United States, the accent is therefore reconstructed from the spelling, and reconstruction is not deterministic.
The naming lists themselves diverge, which adds a second layer:
| WHO INN | United States Adopted Name | Effect |
|---|---|---|
| leuprorelin | leuprolide | the -relin stem is visible only in the INN; the US name ends in -lide and is pronounced loo proe' lide, with a different accent position |
| -relin (BAN wording) | -relin (USAN wording) | the stem book records the British definition as "hypophyseal hormone release-stimulating peptides" and the American one as "prehormones or hormone-release stimulating peptides" |
There is also documented inconsistency inside the system. A peer-reviewed analysis of 7,987 International Nonproprietary Names found that the stems used to show pharmacological relationships "are not spelled consistently and the guidelines do not impose an unequivocal order on them", and that pairs of names sharing a stem often sit very close together in spelling. Where the stem boundary is ambiguous, so is the syllable count, and so is the accent.
| What varies | Why it varies | Where it shows |
|---|---|---|
| the first vowel | English gives no fixed value to an unstressed opening syllable | tir- read as teer or tur; re- read as reh or ree; du- read as doo or dyoo |
| an unstressed i | the letter maps to either /ɪ/ or /aɪ/ | li-xi- read as lix-ih or lix-eye |
| the secondary accent | it is optional in speech and often dropped | sem" a gloo' tide spoken as sem-a-GLOO-tide |
| the whole word | no WHO pronunciation exists, so each language applies its own rules | the Latin form adds -um; the French and Spanish forms shift the accent |
What does not vary in the published record is the accented stem syllable itself. Across the published forms quoted above the accent falls on GLOO, ZEP, TROO, EN, PAR and REL wherever those syllables appear; the argument is about the syllables around them.
Names that are not INN names at all
A large part of a peptide reference list is made up of code designations rather than nonproprietary names. WHO guidance says that "the use of an isolated letter or number should be avoided" in an INN and that "hyphenated construction is also undesirable", so a string built from initials, digits and a hyphen does not follow INN construction and is not an International Nonproprietary Name. Those strings are laboratory, sequence or catalogue codes, and they are read out rather than pronounced as words.
| Code | Usually read as | What the parts are | Status |
|---|---|---|---|
| BPC-157 | B-P-C one fifty-seven | three initials plus a number | research peptide; not approved |
| TB-500 | T-B five hundred | two initials plus a number | research peptide; not approved |
| GHK-Cu | G-H-K copper | the one-letter codes for glycine, histidine and lysine, plus Cu, the chemical symbol for copper | research peptide; not approved |
| MOTS-c | MOTS-see | an acronym said as a word, plus a letter | research peptide; not approved |
| KPV | K-P-V | the one-letter codes for lysine, proline and valine | research peptide; not approved |
| AOD-9604 | A-O-D ninety-six-oh-four | three initials plus a number | research peptide; not approved |
The practical consequence is not phonetic. A code designation means no INN has been assigned, which in turn means the substance has not reached the point in development at which a nonproprietary name is normally requested. Whether possession and use are lawful is a separate question, covered under are peptides legal.
Common questions
Which syllable is stressed in a peptide name ending in -tide?
The third syllable from the end, which is normally the first syllable of the stem. The published United States pronunciations follow that pattern consistently and mark the primary accent with a prime sign after the accented syllable. Short three-syllable names keep the same rule, which puts the accent on the very first syllable.
How is the ending -tide pronounced?
As a full syllable rhyming with wide, transcribed /taɪd/ in the International Phonetic Alphabet. The published pronunciations always write it as a separate unaccented syllable, spelled out as tide or tyd, and never as a reduced -tid.
What does the stem -glutide mean?
It is a sub-stem of -tide in the World Health Organization stem list. The stem book defines it as glucagon-like peptide (GLP) analogues, and an addendum published in October 2023 widened that wording to glucagon-like peptide (GLP) analogues and agonists. A shared stem signals a shared pharmacological group, never a shared manufacturer or product.
What does the ending -relin mean, and where is the stress?
The World Health Organization defines -relin as pituitary hormone-release stimulating peptides, with -morelin as the narrower group of growth hormone release-stimulating peptides. Unlike names in -tide, these carry the accent on the second-to-last syllable, on REL. The mirror stem -relix marks pituitary hormone-release inhibiting peptides and is accented the same way.
Is there an official pronunciation for an International Nonproprietary Name?
Not from the World Health Organization. An INN list entry gives the name in Latin, English, French and Spanish together with the chemical name, molecular formula, CAS registry number and a short statement of action and use, and no phonetic transcription or audio at all. The only routinely published pronunciation is the United States one, issued through the USAN pronunciation guide and reprinted on the NIH consumer drug pages.
Why do two clinicians pronounce the same peptide name differently?
Because only one naming body publishes a pronunciation and everyone else reconstructs it from the spelling. English assigns no fixed value to an unstressed opening syllable, so the first vowel drifts while the accented stem syllable stays stable. A peer-reviewed analysis of 7,987 International Nonproprietary Names also found that the stems are not spelled consistently, which leaves room for more than one defensible reading.
How are peptide code names with letters and numbers read aloud?
Letter by letter, followed by the number. Strings of that shape are laboratory or sequence codes rather than International Nonproprietary Names: WHO guidance advises against isolated letters and numbers and calls hyphenated construction undesirable, so a name in that form does not follow INN construction and is not an International Nonproprietary Name; it therefore carries no approval status.
Do peptide names sound the same in other languages?
No. The World Health Organization publishes each INN in Latin, English, French and Spanish, and the Latin form carries a grammatical ending such as -um. Each language then applies its own stress and vowel rules, so the written stem stays recognisable across languages while the spoken form changes.
Sources
- World Health Organization. General principles for guidance in devising International Nonproprietary Names for pharmaceutical substances. https://www.who.int/docs/default-source/international-nonproprietary-names-(inn)/generalprinciplesen.pdf
- World Health Organization. The use of stems in the selection of International Nonproprietary Names (INN) for pharmaceutical substances (INN stem book). https://cdn.who.int/media/docs/default-source/international-nonproprietary-names-(inn)/stembook-2011-final.pdf
- World Health Organization. Addendum to "The use of stems in the selection of International Nonproprietary Names (INN) for pharmaceutical substances" WHO/EMP/RHT/TSN/2018.1, INN Working Document 23.573, 10 October 2023. https://cdn.who.int/media/docs/default-source/international-nonproprietary-names-(inn)/addendum-stembook2018-202310.pdf
- World Health Organization. INN stem book 2018 (publication record). https://www.who.int/publications/i/item/who-emp-rht-tsn-2018-1
- World Health Organization. Proposed INN: List 117, WHO Drug Information Vol. 31, No. 2, 2017 (entry structure of an INN list). https://cdn.who.int/media/docs/default-source/international-nonproprietary-names-(inn)/pl117.pdf
- World Health Organization. Lists of Recommended and Proposed INNs. https://www.who.int/teams/health-product-and-policy-standards/inn/inn-lists
- American Medical Association. USAN drug name pronunciation guide. https://www.ama-assn.org/about/united-states-adopted-names-usan/usan-drug-name-pronunciation-guide
- U.S. National Library of Medicine, MedlinePlus. Drug information index (pronunciations in USP notation). https://medlineplus.gov/druginformation.html
- MedlinePlus. Semaglutide Injection. https://medlineplus.gov/druginfo/meds/a618008.html
- MedlinePlus. Tirzepatide Injection. https://medlineplus.gov/druginfo/meds/a622044.html
- MedlinePlus. Liraglutide Injection. https://medlineplus.gov/druginfo/meds/a611003.html
- MedlinePlus. Dulaglutide Injection. https://medlineplus.gov/druginfo/meds/a614047.html
- MedlinePlus. Teduglutide Injection. https://medlineplus.gov/druginfo/meds/a613019.html
- MedlinePlus. Lixisenatide Injection. https://medlineplus.gov/druginfo/meds/a617005.html
- MedlinePlus. Exenatide Injection. https://medlineplus.gov/druginfo/meds/a605034.html
- MedlinePlus. Pramlintide Injection. https://medlineplus.gov/druginfo/meds/a605031.html
- MedlinePlus. Teriparatide Injection. https://medlineplus.gov/druginfo/meds/a603018.html
- MedlinePlus. Octreotide Injection. https://medlineplus.gov/druginfo/meds/a693049.html
- MedlinePlus. Bremelanotide Injection. https://medlineplus.gov/druginfo/meds/a619054.html
- MedlinePlus. Tesamorelin Injection. https://medlineplus.gov/druginfo/meds/a611035.html
- MedlinePlus. Degarelix Injection. https://medlineplus.gov/druginfo/meds/a609022.html
- MedlinePlus. Desmopressin. https://medlineplus.gov/druginfo/meds/a608010.html
- MedlinePlus. Oxytocin Injection. https://medlineplus.gov/druginfo/meds/a682685.html
- MedlinePlus. Leuprolide Injection. https://medlineplus.gov/druginfo/meds/a685040.html
- Bryan R, Aronson JK, ten Hacken P, Williams A, Jordan S. Patient safety in medication nomenclature: orthographic and semantic properties of International Nonproprietary Names. PLOS ONE 2015;10(12):e0145431. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0145431
- DailyMed, U.S. National Library of Medicine (repository of FDA-approved labeling). https://dailymed.nlm.nih.gov/dailymed/
- U.S. Food and Drug Administration. Drugs@FDA: FDA-Approved Drugs (approval and marketing status records). https://www.accessdata.fda.gov/scripts/cder/daf/
- American Medical Association. United States Adopted Name (USAN) Drug Finder (statements of adoption, each carrying the adopted pronunciation). https://searchusan.ama-assn.org/
- American Medical Association. United States Adopted Names naming guidelines. https://www.ama-assn.org/about/united-states-adopted-names-usan/united-states-adopted-names-naming-guidelines
Pronunciation is a language fact and nothing more: saying a name correctly says nothing about what the substance is, whether it is approved, or whether it may lawfully be held or used. For any substance that exists as an approved medicine, the approved label and the prescribing information are the governing documents, and questions about a specific product belong with a licensed physician or pharmacist.