Why are ipamorelin and anamorelin grouped together in WADA classification despite different research uses?

Both compounds act on the same receptor system — the ghrelin receptor, also known as the growth hormone secretagogue receptor (GHS-R1a) — which is what anchors WADA's peptide hormone classification, not the specific research context each compound has been studied in. Ipamorelin is studied as a selective growth hormone secretagogue, binding GHS-R1a on somatotroph cells to amplify pulsatile growth hormone release while producing comparatively little prolactin or cortisol elevation relative to older, non-selective compounds (PMID 41880199). Anamorelin works through the same GHS-R1a mechanism but has been studied in cancer-associated cachexia research, where ghrelin receptor agonism is investigated for its effects on appetite stimulation and lean body mass preservation (PMID 41950300). Despite that different research literature, WADA's S2 "Peptide Hormones, Growth Factors, Related Substances and Mimetics" category tracks receptor mechanism and structural class rather than study population or intended research application — which is why a cachexia-focused ghrelin receptor agonist and a bodybuilding-associated growth hormone secretagogue end up classified under the same prohibited framework.

Does an FDA 503A compounding recommendation change a peptide's WADA anti-doping status?

No, and MOTS-c is a clear example of why these two frameworks should not be conflated. On July 23, 2026, the FDA's Pharmacy Compounding Advisory Committee voted to recommend MOTS-c for inclusion on the Section 503A Bulk Drug Substances List for proposed obesity and osteoporosis research indications — a nonbinding advisory recommendation about which bulk substances compounding pharmacies may use to prepare research formulations under FDA rules. That evaluation asks an entirely different question from WADA's anti-doping classification, which evaluates chemical structure and biological effect against the Prohibited List's S2 peptide hormone category and its broader "similar biological effect" language. A change in FDA compounding status does not automatically imply a change in WADA classification, and vice versa — the two regulatory tracks operate independently, with different governing bodies, different evidentiary standards, and different annual revision cycles. Researchers should verify status separately against each framework's current official documentation rather than assuming a determination in one track applies to the other.

WADA 2026 Prohibited List: Peptide Classification Guide for Researchers

Q: Is MOTS-c on the WADA prohibited list?

MOTS-c does not carry the same long history of explicit S2 listing that classic growth hormone secretagogues such as ipamorelin carry, since it is a 16-amino-acid peptide encoded within the mitochondrial 12S rRNA gene and studied primarily for glucose homeostasis, AMPK pathway activation, and insulin sensitivity rather than growth hormone release (PMID 41945630). However, WADA's Prohibited List has increasingly used broadened language covering "any substance with a similar chemical structure or similar biological effect" to already-listed peptide hormones — language specifically designed to close gaps that would otherwise let novel peptide analogues escape classification simply because they were not individually named. That places MOTS-c in a genuine gray zone rather than a confirmed prohibited or confirmed exempt status. Researchers should also not conflate anti-doping classification with other regulatory tracks: the FDA's Pharmacy Compounding Advisory Committee separately voted in July 2026 to recommend MOTS-c for the 503A Bulk Drug Substances List for proposed obesity and osteoporosis research indications, which is a compounding-access recommendation, not a WADA determination. Researchers should check the current official Prohibited List directly rather than assume either inclusion or exclusion.

Q: Are semaglutide and tirzepatide banned under WADA rules?

Research and public interest in GLP-1/GIP receptor agonists has grown rapidly, but this compound class has followed a monitoring-oriented pattern rather than the blanket S2 prohibition that applies to classic growth hormone secretagogues like ipamorelin and anamorelin. Semaglutide is a GLP-1 receptor agonist studied extensively for glucose homeostasis and satiety signaling (PMID 42027588), while tirzepatide is a dual GLP-1/GIP receptor agonist studied for cardio-metabolic-kidney outcomes alongside weight-related endpoints (PMID 42029986); both have drawn research interest at a scale that dwarfs the classic growth hormone secretagogue literature, largely driven by metabolic and obesity research rather than athletic performance research. WADA's separate monitoring framework tracks substances of research or usage interest — watching for patterns of use and potential performance-adjacent effects such as rapid body-composition change — without necessarily placing a compound on the Prohibited List itself. That "monitored" versus "prohibited" distinction can shift with each annual list revision, so researchers needing a compliance-relevant determination should verify current status against the official WADA Prohibited List rather than a secondary summary.

Q: What is the difference between WADA's prohibited list and its monitoring program?

The Prohibited List is the binding document: it names substances and methods banned in competition, out of competition, or in particular sports, and a positive test for a listed substance carries anti-doping consequences. The separate monitoring program serves a different research function — it tracks substances of emerging research or usage interest without prohibiting them outright, which allows WADA to observe usage patterns and gather additional pharmacological and detection data before deciding whether formal prohibition is warranted. GLP-1/GIP receptor agonists such as semaglutide and tirzepatide currently sit in this monitored category rather than the explicitly prohibited S2 peptide hormone category that governs classic growth hormone secretagogues. This distinction matters for researchers because a compound generating substantial research or public interest, or one that produces performance-adjacent physiological changes such as rapid weight or body-composition shifts, is not automatically banned — the compound must be formally added to the Prohibited List through WADA's annual revision process for prohibition to take effect.

The WADA 2026 Prohibited List continues to shape how research institutions and anti-doping laboratories classify peptide compounds, and researchers working with growth hormone secretagogues, ghrelin receptor agonists, and novel metabolic peptides increasingly need a working map of where their compounds of interest sit relative to that classification system. Peptide research spans a wide range of mechanisms, and the World Anti-Doping Agency does not evaluate them individually so much as by chemical class and biological effect, which means compounds a researcher might consider unrelated can end up governed by the same prohibited category.

Research reference only. All information on this page is a summary of peer-reviewed scientific literature and does not constitute medical advice. See individual library profiles for full compound data.

Quick Answer: Growth hormone secretagogues and ghrelin receptor agonists such as ipamorelin and anamorelin fall under WADA's long-standing S2 peptide hormone category and are prohibited at all times, while GLP-1/GIP receptor agonists like semaglutide and tirzepatide have instead drawn attention through WADA's separate monitoring framework rather than outright prohibition, and novel mitochondria-derived peptides such as MOTS-c sit in a gray zone shaped by the list's broader "similar biological effect" language.

TL;DR:

Growth hormone secretagogues (ipamorelin) and ghrelin receptor agonists (anamorelin) share a receptor mechanism that places them under WADA's peptide hormone prohibition class.
Novel mitochondria-derived peptides like MOTS-c illustrate how WADA's broadened structural-similarity language can reach compounds without a compound-specific listing.
GLP-1/GIP receptor agonists (semaglutide, tirzepatide) are a distinct case, tracked for research interest without carrying the same blanket prohibited status as classic growth hormone secretagogues.
Anti-doping classification and FDA compounding status (such as 503A Bulk Drug Substances List review) are separate regulatory tracks that researchers should not conflate.
Researchers should always confirm current classification against the official WADA Prohibited List rather than relying on secondary summaries, since annual revisions can shift a compound's category.

How we categorized these compounds

This overview groups five peptides cited across the Clinical Peptide research library into three classification patterns that recur in WADA-related literature: peptide hormone secretagogues with an established S2 prohibition history, emerging metabolic peptides whose regulatory status is still being worked out, and incretin receptor agonists whose research profile has grown fastest in the general population rather than in athletic contexts. The grouping draws on each compound's receptor pharmacology, the language WADA has historically used to define its S2 "Peptide Hormones, Growth Factors, Related Substances and Mimetics" category, and the compound-specific research entries in the peptide library. It is not a substitute for the official Prohibited List, which WADA publishes and revises on an annual cycle, and researchers should treat any compound-specific determination here as a starting point for further verification rather than a final answer.

1. Growth hormone secretagogues and ghrelin receptor agonists

Ipamorelin and anamorelin both act on the same receptor system that has anchored WADA's peptide hormone category for years: the ghrelin receptor, also known as the growth hormone secretagogue receptor (GHS-R1a). Ipamorelin is studied as a selective growth hormone secretagogue, binding GHS-R1a on somatotroph cells to amplify pulsatile growth hormone release while producing comparatively little prolactin or cortisol elevation relative to older, non-selective compounds (PMID 41880199). That selectivity has not changed its regulatory classification — a 2026 review covering peptide and peptide-analog use in sport explicitly names growth hormone secretagogues, including ipamorelin, among the compounds WADA has responded to by expanding detection technology, even as analytical challenges persist because of their structural similarity to endogenous hormones and short half-lives.

Anamorelin works through the same GHS-R1a mechanism but has been studied in a different research context: cancer-associated cachexia, where ghrelin receptor agonism is investigated for its effects on appetite stimulation and lean body mass preservation rather than athletic performance (PMID 41950300). The receptor mechanism, not the study population, is what places a compound in WADA's peptide hormone framework, which is why a cachexia-focused ghrelin receptor agonist and a bodybuilding-associated growth hormone secretagogue can end up discussed under the same prohibited class despite very different research literatures. Full profiles for both compounds, including molecular data and additional citations, are available on the ipamorelin library page and the anamorelin library page.

2. Novel mitochondria-derived and metabolic peptides

MOTS-c illustrates a harder classification problem. It is a 16-amino-acid peptide encoded within the mitochondrial 12S rRNA gene, studied for its role in glucose homeostasis, AMPK pathway activation, and insulin sensitivity rather than for growth hormone release (PMID 41945630). It does not fit neatly into the classic growth hormone secretagogue category, but WADA's list has increasingly used broader language intended to capture "any substance with a similar chemical structure or similar biological effect" to already-listed peptide hormones — language designed specifically to close gaps that would otherwise let novel peptide analogues escape classification simply because they were not named individually.

MOTS-c also demonstrates why researchers should not conflate anti-doping classification with other regulatory tracks. On July 23, 2026, the FDA's Pharmacy Compounding Advisory Committee voted to recommend MOTS-c for inclusion on the Section 503A Bulk Drug Substances List for proposed obesity and osteoporosis research indications — a nonbinding advisory recommendation about compounding access under FDA rules, not a WADA anti-doping determination. The two frameworks evaluate different questions using different criteria, and a change in one does not automatically imply a change in the other. See the MOTS-c library profile and the FDA PCAC docket guide for the compounding-status side of that distinction.

3. GLP-1/GIP receptor agonists: a different research and monitoring pattern

Semaglutide and tirzepatide represent a third pattern. Semaglutide is a GLP-1 receptor agonist studied extensively for glucose homeostasis and satiety signaling (PMID 42027588), while tirzepatide is a dual GLP-1/GIP receptor agonist studied for cardio-metabolic-kidney outcomes alongside weight-related endpoints (PMID 42029986). Both have drawn research and public interest at a scale that dwarfs the classic growth hormone secretagogue literature, largely because of metabolic and obesity research rather than athletic performance research.

Unlike ipamorelin and anamorelin, GLP-1/GIP receptor agonists have not carried the same long-standing blanket prohibition under WADA's S2 category. Instead, this class of compound has been the kind of emerging research subject that anti-doping monitoring frameworks are built to track — watching for patterns of use and potential performance-adjacent effects (such as rapid weight or body-composition change) without necessarily placing a compound on the Prohibited List itself. That distinction between "monitored" and "prohibited" matters for researchers trying to characterize a compound's regulatory status accurately, and it is a distinction that can change from one annual list revision to the next. Full mechanism data is available on the semaglutide library page, the tirzepatide library page, and in the standalone semaglutide mechanism of action reference.

Comparison table

Compound	Primary mechanism	WADA classification pattern	Research context
Ipamorelin	GHS-R1a (ghrelin receptor) agonist	S2 peptide hormone category — long-standing prohibition	Growth hormone secretagogue research
Anamorelin	GHS-R1a (ghrelin receptor) agonist	S2 peptide hormone category via shared mechanism	Cancer cachexia / appetite research
MOTS-c	Mitochondria-derived, AMPK pathway	Gray zone — reachable by "similar biological effect" language	Metabolic homeostasis, insulin sensitivity
Semaglutide	GLP-1 receptor agonist	Monitoring-pattern class, not blanket-prohibited	Metabolic / obesity research
Tirzepatide	Dual GLP-1/GIP receptor agonist	Monitoring-pattern class, not blanket-prohibited	Cardio-metabolic-kidney research

Reading WADA's classification distinctions as a researcher

Researchers tracking anti-doping status alongside pharmacology should keep four distinctions in mind. First, mechanism drives classification more reliably than study population or intended use — a ghrelin receptor agonist studied in oncology and one studied in sport can land in the same prohibited category. Second, "monitored" and "prohibited" are not the same status, and a compound generating research interest is not automatically banned. Third, anti-doping classification is independent from other regulatory frameworks, including FDA compounding determinations, and researchers who need a compound-specific compliance answer should consult the current official WADA Prohibited List directly rather than a secondary summary. Fourth, the list itself is a living document — WADA revises it annually, and a compound's category can move between monitoring status, explicit prohibition, or an unlisted gray zone from one cycle to the next as new pharmacological and detection data accumulate.

That last point is easy to underestimate when working from older summaries or from research databases that were compiled before the most recent revision. A peptide's WADA status recorded in a 2024 or 2025 reference does not necessarily hold for 2026, particularly for a compound class as active in current metabolic and longevity research as growth hormone secretagogues and mitochondria-derived peptides have been. Laboratories maintaining internal compliance documentation should treat the official list, not any third-party summary including this one, as the authoritative source, and should re-check compound status at each annual revision rather than assuming continuity. The half-life reference chart is a useful companion tool for researchers cross-referencing pharmacokinetic data against classification questions, since detection-window and half-life data often come up in the same anti-doping literature that discusses classification.

Cited studies

PMID 41880199 — "A new era of doping? Use of peptide and peptide-analog drugs in recreational and professional sport and bodybuilding: a critical review." (2026).
PMID 41950300 — "Pharmacological Treatments for Cancer-Related Anorexia-Cachexia Syndrome: An Umbrella Review of Systematic Reviews and Meta-Analyses." (2026). DOI: https://doi.org/10.1016/S1470-2045(16)00023-2
PMID 41945630 — "Are serum MOTS-c levels and MOTS-c m.1382A>C polymorphism related to polycystic ovary syndrome?" (2026). DOI: https://doi.org/10.1016/j.cmet.2015.01.013
PMID 42027588 — "Unexplained hypercapnia with normal pulmonary evaluation in a patient receiving semaglutide: a diagnostic challenge." (2026). DOI: https://doi.org/10.1056/NEJMoa1607141
PMID 42029986 — "Persistence-Dependent Effectiveness of Tirzepatide on the Cardio-Metabolic-Kidney Syndrome Outcomes in Obesity: Real-World Evidence from the United Arab Emirates." (2026). DOI: https://doi.org/10.1056/NEJMoa2107519

Frequently asked questions

Q: Is MOTS-c on the WADA prohibited list?

A: MOTS-c does not have the same long history of explicit S2 listing that classic growth hormone secretagogues carry, but WADA's broadened language covering substances with a similar chemical structure or biological effect to listed peptide hormones is specifically designed to reach novel compounds like it. Researchers should check the current official Prohibited List rather than assume either inclusion or exclusion.

Q: Are semaglutide and tirzepatide banned for athletes?

A: Research and public discussion of GLP-1/GIP receptor agonists has grown rapidly, but this class has followed a monitoring-oriented pattern rather than the blanket S2 prohibition that applies to classic growth hormone secretagogues. Status can shift with each annual list revision, so current verification against the official list is necessary for any compliance-relevant determination.

Q: What is the difference between WADA's prohibited list and its monitoring program?

A: The Prohibited List names substances and methods banned in competition, out of competition, or in particular sports. A separate monitoring framework tracks substances of research or usage interest without prohibiting them outright, allowing WADA to observe patterns before deciding whether formal prohibition is warranted.

Q: Why are ipamorelin and anamorelin grouped together despite different research uses?

A: Both act on the same ghrelin receptor (GHS-R1a) and fall within WADA's peptide hormone framework because classification tracks mechanism and structural class rather than the specific research application a given study population was investigating.

Q: Does an FDA 503A compounding recommendation change a peptide's anti-doping status?

A: No. FDA compounding determinations, such as the 503A Bulk Drug Substances List review process, evaluate a different question — whether a bulk substance may be used in compounded preparations — using separate criteria from WADA's anti-doping classification. A change in one framework does not automatically change status in the other.

See also:

Anamorelin: Research Profile and WADA 2026 Status Update — a focused profile on anamorelin's WADA S2 listing and cachexia research data.
Ipamorelin Research Profile: GHRP Mechanism, Half-Life & Pulsatile GH Release — deeper mechanism and pharmacokinetic detail on ipamorelin.
MOTS-c: Mitochondria-Derived Peptide and Metabolic Regulator — full mechanism profile and regulatory status tracking for MOTS-c.

For laboratory research purposes only. Not for human or animal consumption. Compounds described are not approved by the FDA for human or veterinary use unless explicitly stated.