A peptide drug's name ends in -tide because the World Health Organization assigns that ending to peptides, and on its own it tells you almost nothing else.1 Endings are handed out by molecular family and mechanism, never by how well something worked. Past -tide the system gets more precise than most people expect, and semaglutide, mazdutide and tirzepatide end three different ways, each one a published stem with its own written definition.123 Two things complicate that. Retatrutide's ending is not a published stem, and sits instead on a separate WHO list of provisional suffixes.4 Of the 408 single-substance compounds in this library, only 96 carry a name the stem system can decode at all.5
What does -tide mean on a drug name?
-tide means peptides and glycopeptides. That is the whole of the definition.1 That ending belongs to the international nonproprietary name, the generic name a substance receives so that regulators, prescribers and researchers in every country are naming the same substance. WHO's INN Expert Group is the committee that selects it.
Stems exist so that an unfamiliar name is still readable by someone who has never encountered the molecule, and a stem signals that the substances carrying it are pharmacologically related. WHO's guidance on creating new ones sets a demanding bar.6 Existing stems are preferred wherever they can be made to fit. A new stem requires a group of several substances demonstrating a confirmed novel mechanism of action, and the applicant has to supply substantial clinical and preclinical data establishing that nothing in the existing nomenclature applies.6
An ending is therefore the output of a development program that got large enough to need one. That is useful information about a name. It is also a separate matter from evidence that the molecule does anything for the person injecting it.
Which peptide endings are published stems, and what does each cover?
Below is the peptide side of the published list as it stood on November 9, 2026, alongside the document each definition was read in. WHO maintains a current edition of the stem book plus a cumulative addendum carrying everything selected since that edition appeared. The edition is dated October 14, 2024, and the newest addendum is dated September 26, 2026.37
| Ending | What it covers | Status |
|---|---|---|
| -tide | Peptides and glycopeptides1 | Published stem |
| -glutide | Analogues of glucagon-like peptide, widened in 2024 to analogues and agonists12 | Published stem |
| -dutide | Oxyntomodulin analogues and other dual agonists at the GLP-1 and glucagon receptors: bamadutide, cotadutide, mazdutide2 | Published stem |
| -patide | GIP receptor agonists, with or without GLP-1 receptor activity: tirzepatide, acmopatide, ganipatide, cenupatide3 | Published stem |
| -lintide | Amylin receptor agonists, including dual amylin and calcitonin receptor agonists: pramlintide, cagrilintide, amlintide3 | Published stem |
| -relin | Peptides that stimulate pituitary hormone release, with -morelin for the growth hormone ones: sermorelin, anamorelin, buserelin, goserelin, leuprorelin, triptorelin1 | Published stem |
| -relix | Peptides that inhibit hormone release, specifically GnRH inhibitors1 | Published stem |
| -tocin | Oxytocin and its derivatives1 | Published stem |
| -pressin | Vasopressin derivatives acting as vasoconstrictors1 | Published stem |
| -trutide | Antihyperglycemic triple agonists at the GLP-1, glucagon and GIP receptors4 | Pre-stem, meaning not published |
| -melanotide | Melanocortin receptor agonists, to be shortened to -melnotide4 | Pre-stem, meaning not published |
| -glipron | Antihyperglycemics acting as GLP-1 receptor agonists: orforglipron, danuglipron3 | Published stem, filed under -gli and not under -tide |
Two of those entries are recent. The amylin and GIP endings both landed inside the window the September 2026 addendum covers, so tirzepatide and cagrilintide were in wide circulation before their endings were documented as stems.3
The growth hormone family is the one most readers here will recognize as a set. Sermorelin, ipamorelin and tesamorelin share the -relin stem for peptides that stimulate pituitary hormone release, with the narrower -morelin marking the growth hormone ones. Our guide to the growth hormone peptides distinguishes what each of them actually does. One quiet amendment in the September 2026 addendum matters more than it looks: -morelin was redefined from growth hormone release-stimulating peptides to growth hormone release-stimulating substances, eliminating the word peptides from the definition.3 So an ending inside the peptide family no longer guarantees, by itself, that the molecule carrying it is a peptide.
Why is retatrutide's ending not the same kind of thing as semaglutide's?
Retatrutide's ending is a pre-stem, not a published stem. WHO publishes a second and separate list of suffixes used during INN selection, and the entries on it are endings that usually carry a meaning for their group without that meaning having been published or protected yet.4 A published stem constitutes a commitment. The definition is written down and the syllable is reserved against anything that does not qualify. A pre-stem is a provisional convention operating inside the naming process, visible to anyone who opens the list but not yet fixed.
-trutide sits on that pre-stem list, grouped under the -tide family, covering antihyperglycemic triple agonists at the GLP-1, glucagon and GIP receptors, and no example name is printed beside it.4 Semaglutide's -glutide, mazdutide's -dutide and tirzepatide's -patide all sit on the published side of the system.123 So the tidy single, dual, triple progression these four names appear to spell out is really three published stems and one provisional suffix. One of those stems answers a different receptor question altogether, and the suffix has never been defined in public.
The ending is still doing real work. Another triple agonist, efocipegtrutide, appears in WHO's Proposed INN List 126 described as a chimeric peptide acting at the glucagon, GIP and GLP-1 receptors, and it carries exactly the same ending.8 Naming committees are evidently applying the suffix consistently. What the suffix lacks is a published definition. A reader cannot look it up the way they can look up -glutide. It appears as a published stem in none of the four stem documents read for this page, running from the 2013 edition through the cumulative addenda of May 31, 2018, February 26, 2024 and September 26, 2026.1923 The 2024 edition's own text is the one document in that chain not read here, so treat this as the softest claim on the page.
How many peptides have a name the stem system can decode?
Only 96 of the 408 single-substance compounds in this library have one, and 287 have no stem-shaped name anywhere on the card.5 The gap falls hardest on the compounds people actually buy. Our compound index held 429 cards on November 8, 2026, and 21 of them are blends or other multi-component products with no single name to decode, leaving 408 to count.
Narrow it to what is actually for sale and the picture gets sharper. Among the 159 single-substance compounds with at least one tracked listing, 24 carry a stem in the name the site lists, and 125 carry no stem-shaped name at all.5 The four most heavily listed compounds in the library sit in that second group: BPC-157 at 641 listings, GHK-Cu at 486, TB-500 at 416 and MOTS-c at 385.5 The naming system tracks the development pipeline. The gray market shelf is somewhere else, and the names on it were never meant to be read this way.
One useful exception runs the other direction. For 25 of those compounds a decodable name does exist, filed on the card as an alias while the name everyone uses is a laboratory code.5 PT-141 is bremelanotide. DSIP is emideltide. SS-31 is elamipretide, ARA-290 is cibinetide, Melanotan I is afamelanotide and GHRP-2 is pralmorelin. Each of those carries a readable ending, so looking up the alias on our names and aliases page often decodes a compound whose label never does.
That count tests the shape of a name, not the INN register. A name passes by ending in one of the stem families WHO publishes, and a reader can check that by eye. A compound could hold an INN that no seller and no alias records, and the count would miss it.
What does a peptide's ending not tell you?
It cannot tell you whether anybody took the compound, or what happened to them if they did. Stem rules turn on mechanism and chemistry, and nothing in them addresses clinical outcomes. A compound carrying a published stem can still have no completed human efficacy trial behind it, and both our guide to why most peptides have no human evidence and the per-compound counts on our evidence page set out how often that happens.
An ending can also be read in the wrong direction entirely. Orforglipron gets discussed in peptide circles and sold alongside peptides, while its name is filed under the -gli stem with the antihyperglycemics instead of under -tide with the peptides.3 Here the naming system reports something accurate about the molecule that the shelf it sits on obscures. Our guide to Foundayo and orforglipron covers the drug itself, and whether everything a vendor sells is a peptide covers the broader version of the same confusion.
At the point of sale even the nonproprietary name often disappears, replaced by a house code, and our guide to what the GLP vendor codes mean decodes the ones in circulation. One compound can carry four names at once: the chemical description, the nonproprietary name, the brand name, and the seller's abbreviation.
Common questions
What does the -tide at the end of a drug name mean?
It means the substance is a peptide or a glycopeptide, and that is the entire published definition of the stem.1 It carries no information about the dose, the route, the evidence or any regulator's decision.
What does -glutide mean?
It is the published stem for analogues of glucagon-like peptide, widened in 2024 to cover analogues and agonists.12 Semaglutide, liraglutide and dulaglutide all carry it.
Is -trutide a real stem?
Not a published one. It appears on WHO's pre-stem list of suffixes, covering antihyperglycemic triple agonists at the GLP-1, glucagon and GIP receptors, with the meanings on that list recorded as neither published nor protected yet.4 It does not appear as a published stem in the 2013 stem book or in the cumulative addenda dated May 31, 2018, February 26, 2024 or September 26, 2026.1923
Does -tide mean a drug is FDA approved?
No. Endings are assigned on molecular class by WHO's INN Expert Group, and they communicate no information whatsoever about any regulator's decision.16 Approved and investigational compounds carry identical endings, so the designation cannot distinguish between them.
Why does orforglipron not end in -tide?
Its name is filed under the -gli stem for antihyperglycemics acting as GLP-1 receptor agonists, alongside danuglipron, instead of under the peptide stem.3 That ending is the clearest available signal that the molecule occupies a different chemical family from the injectables it gets compared against.
Why do BPC-157 and TB-500 not end in -tide?
Neither name is an international nonproprietary name. BPC-157 is a laboratory designation and TB-500 is a product-era label attached to a fragment, so there is no stem in either one to read. They are the two most heavily listed compounds in this library, at 641 and 416 tracked listings.5
What ending do the amylin drugs use?
-lintide, a published stem for amylin receptor agonists including the dual amylin and calcitonin receptor agonists, with pramlintide, cagrilintide and amlintide given as examples.3 Eloralintide and petrelintide carry the same ending.
Sources
- World Health Organization,The use of stems in the selection of International Nonproprietary Names (INN) for pharmaceutical substances, WHO/EMP/RHT/TSN/2013.1, 2013. https://www.who.int/docs/default-source/international-nonproprietary-names-(inn)/stembook-2013-final.pdf?sfvrsn=7aa2f0b1_5 read via a reproduction ↩1 ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9 ↩10 ↩11 ↩12 ↩13 ↩14 ↩15
- World Health Organization,Addendum to "The use of stems in the selection of International Nonproprietary Names for Pharmaceutical Substances", INN Working Document 24.583, February 26, 2024; a cumulative list of stems added since the 2018 edition. https://cdn.who.int/media/docs/default-source/international-nonproprietary-names-(inn)/addendum-stembook2018-202402.pdf read via a reproduction ↩1 ↩2 ↩3 ↩4 ↩5 ↩6 ↩7
- World Health Organization,Addendum to "The use of stems in the selection of International Nonproprietary Names for Pharmaceutical Substances" 2024, INN Working Document 26.653, September 26, 2026; a cumulative list of stems added since the 2024 edition. https://cdn.who.int/media/docs/default-source/international-nonproprietary-names-%28inn%29/addendum-stembook2025-202609.pdf?sfvrsn=cf78470a_3&download=true read via a reproduction ↩1 ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9 ↩10 ↩11 ↩12 ↩13
- World Health Organization, Pre-stems: Suffixes used in the selection of INN, INN Working Document 26.639 rev., September 30, 2026. https://cdn.who.int/media/docs/default-source/international-nonproprietary-names-%28inn%29/prestem-suffixes-202609.pdf?sfvrsn=37fe81d7_3&download=true read via a reproduction ↩1 ↩2 ↩3 ↩4 ↩5 ↩6
- World Health Organization, Guidance on the establishment of new INN stems, INN Working Doc. 07.215, June 11, 2007. https://cdn.who.int/media/docs/default-source/international-nonproprietary-names-%28inn%29/finalinn-stems-policy-explanation.pdf?sfvrsn=8f450727_6 read via a reproduction ↩1 ↩2 ↩3
- World Health Organization,Use of stems in the selection of International Nonproprietary Names (INN) for pharmaceutical substances, 2024, publication record dated October 14, 2024. https://www.who.int/publications/i/item/9789240099388 read via a reproduction ↩1
- World Health Organization, Proposed INN: List 126, WHO Drug Information Vol. 35, No. 4, 2021, dated January 28, 2022. https://cdn.who.int/media/docs/default-source/international-nonproprietary-names-(inn)/pl126.pdf?sfvrsn=a37e0953_7&download=true read via a reproduction ↩1
- World Health Organization,Addendum to "The use of stems in the selection of International Nonproprietary Names (INN) for pharmaceutical substances" WHO/EMP/RHT/TSN/2013.1, INN Working Document 18.435, May 31, 2018; a cumulative list of stems added since 2013. https://www.who.int/docs/default-source/international-nonproprietary-names-%28inn%29/addendum-stembook2013-201805.pdf read via a reproduction ↩1 ↩2