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Compounds · Semaglutide

Molecular mass of semaglutide and why the figure differs between sources — does this still hold?

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Solved by l.solberg in post #3
Approved indications differ by jurisdiction and change. As of mid-2026 the weight-management indication is approved in many European jurisdictions but not all, and access is still narrower in others. For your own region, check the regulatory website rather than a forum summary.

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AN
a.norgaardTL2 Moderator17 Dec 2024#1

Molecular mass of semaglutide and why the figure differs between sources — does this still hold? — that is the question, and I have not found it answered plainly anywhere I have looked.

Comparing SURPASS-2 (N Engl J Med, 2021) with STEP 4 (JAMA, 2021) and finding the comparison harder than it looks.

Different populations, different durations, different endpoints defined slightly differently, and in one case a different estimand. People compare the headline percentages anyway, including me until recently.

Is there a defensible way to put these side by side, or is the honest answer that there is not and we should stop?

16 likes 19mo
HM
h.mensahTL2 Moderator17 Dec 2024#2

Two things before anyone answers the substance.

First, the context in the first post is clear and specific. Second, the question is framed so that an answer can actually address it. Both are the norm here and both matter more than they sound.

20 likes 19mo
LS
l.solbergTL2 Moderator Solution17 Dec 2024#3
h.mensah, post #2: Two things before anyone answers the substance. First, the context in the first post is clear and specific. Second, the question is framed so that an answer can actually address it. Both are the norm here and both matter more than they sound. Go to post

Approved indications differ by jurisdiction and change. As of mid-2026 the weight-management indication is approved in many European jurisdictions but not all, and access is still narrower in others. For your own region, check the regulatory website rather than a forum summary.

7 likes in reply to #2 19mo
EV
e.verhoevenTL2 Moderator17 Dec 2024 · edited#4

I read post #3 twice before replying, because I had assumed the opposite.

The C-cell question: semaglutide triggered medullary thyroid carcinoma in rodent toxicology studies. A signal in rodents does not automatically appear in humans, but it is the reason the compound is contraindicated in people with personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2.

2 likes 19mo
T
ThibodeauTL3Regular18 Dec 2024#5

The STEP programme populations were selected: enrollment criteria required baseline body mass index over 30, no recent blood pressure crisis, no recent retinopathy, no renal disease at the time. Applying results from that population to someone well outside it is an extrapolation and should be called one.

13 likes 19mo
MR
m.restrepoTL2 Moderator18 Dec 2024#6

Gastric emptying delay is the mechanism behind most of the gastrointestinal side effects. Slowing the stomach empties it feeds less food into the intestines at a time, which is part of the satiety mechanism but is also why nausea is dose-dependent and titration-dependent.

27 likes 19mo
ME
m.eriksenTL2 Moderator18 Dec 2024#7
m.restrepo, post #6: Gastric emptying delay is the mechanism behind most of the gastrointestinal side effects. Slowing the stomach empties it feeds less food into the intestines at a time, which is part of the satiety mechanism but is also why nausea is dose-dependent and titration-dependent. Go to post

Picking up post #4: that is the part I would want checked first.

I disagree with the reply above, and I think the disagreement is substantive rather than terminological.

The distinction being drawn does not survive when you look at the published data for this specific question. I would be glad to be shown wrong on this, because the version I am arguing against is more convenient.

0 likes in reply to #6 19mo
ME
m.ekstromTL2 Moderator18 Dec 2024#8
a.norgaard, post #1: Molecular mass of semaglutide and why the figure differs between sources — does this still hold? — that is the question, and I have not found it answered plainly anywhere I have looked. Comparing SURPASS-2 ( N Engl J Med , 2021) with STEP 4 ( JAMA , 2021) and finding the comparison harder than it looks. Different populations, different… Go to post

Coming back to post #6, because the follow-up matters more than the original answer.

The mass figure differs between sources because of how the different entities report it. The monoisotopic mass of the bare peptide is one number; the mass including the acylation is another. Different sources emphasise different details.

4 likes in reply to #1 19mo
TS
taper_shiftTL3Regular18 Dec 2024 · edited#9

The SELECT trial changed the positioning because it was the first cardiovascular outcome trial in people without diabetes. That decoupled the cardiovascular argument from glycaemic control, which is why it mattered beyond its own numbers.

0 likes 19mo
RM
r.molnarTL218 Dec 2024#10
HA
h.amankwahTL2 Moderator18 Dec 2024#11

The 165 to 184 hour range: that is roughly 7 to 7.6 days, which is why the weekly schedule works. Below 4 half-lives you are not approaching steady state yet, which is the pharmacological argument for the four-week step interval.

25 likes 19mo
T
ThibodeauTL3Regular18 Dec 2024#12

This follows post #9 rather than contradicting it.

Albumin binding is not a unique structural feature and nothing in the class lacks it, but the reversibility matters. Semaglutide binds albumin covalently through a fatty side chain, which creates a very long half-life at the cost of sequestering the free form. That is a trade-off and it is the trade-off that allows weekly dosing.

12 likes 19mo
LD
l.dialloTL2 Moderator18 Dec 2024 · edited#13

The opalescent appearance in semaglutide solutions is occasionally noted and the mechanism is unclear. It does not appear to correlate with product failure in practice. Visible particles or frank cloudiness is different and would be reason to contact the supplier.

4 likes 19mo
CI
c.inglethorpeTL3Regular19 Dec 2024#14
e.verhoeven, post #4: I read post #3 twice before replying, because I had assumed the opposite. The C-cell question: semaglutide triggered medullary thyroid carcinoma in rodent toxicology studies. A signal in rodents does not automatically appear in humans, but it is the reason the compound is contraindicated in people with personal or family history of… Go to post

For anyone arriving from a search: the marked solution above is the direct answer, and the replies underneath it add the caveats that make it safe to use.

0 likes in reply to #4 19mo
RM
r.molnarTL2 Moderator19 Dec 2024#15

Coming back to post #13, because the follow-up matters more than the original answer.

Practical note that does not fit anywhere else. Whatever you conclude from this topic, write down what you did and when. The single most useful thing in your own records is not any individual result; it is that they are dated and consecutive.

0 likes 19mo
C
CSagredoTL3Regular19 Dec 2024#16

Picking up post #13: that is the part I would want checked first.

On alcohol: the labelling does not contraindicate it, but it raises gastric irritation risk and semaglutide already does that. There is no published interaction study and the conservative position is to limit it if you are titrating or if gastrointestinal symptoms are troublesome.

18 likes 19mo
HR
h.ramosTL2 Moderator19 Dec 2024#17
h.amankwah, post #11: The 165 to 184 hour range: that is roughly 7 to 7.6 days, which is why the weekly schedule works. Below 4 half-lives you are not approaching steady state yet, which is the pharmacological argument for the four-week step interval. Go to post

The mass figure differs between sources because of how the different entities report it. The monoisotopic mass of the bare peptide is one number; the mass including the acylation is another. Different sources emphasise different details.

7 likes in reply to #11 19mo
OA
o.abrahamsenTL3Regular19 Dec 2024#18
m.eriksen, post #7: Picking up post #4: that is the part I would want checked first. I disagree with the reply above, and I think the disagreement is substantive rather than terminological. The distinction being drawn does not survive when you look at the published data for this specific question. I would be glad to be shown wrong on this, because the… Go to post

Albumin binding is not a unique structural feature and nothing in the class lacks it, but the reversibility matters. Semaglutide binds albumin covalently through a fatty side chain, which creates a very long half-life at the cost of sequestering the free form. That is a trade-off and it is the trade-off that allows weekly dosing.

1 like in reply to #7 19mo
AR
a.reyesTL4 Admin19 Dec 2024#19
Staff post. Actions described here are recorded in the public moderation log and may be challenged in Meta.

On alcohol: the labelling does not contraindicate it, but it raises gastric irritation risk and semaglutide already does that. There is no published interaction study and the conservative position is to limit it if you are titrating or if gastrointestinal symptoms are troublesome.

0 likes 19mo
GR
g.rasmussenTL2 Moderator19 Dec 2024#20

The opalescent appearance in semaglutide solutions is occasionally noted and the mechanism is unclear. It does not appear to correlate with product failure in practice. Visible particles or frank cloudiness is different and would be reason to contact the supplier.

24 likes 19mo
BV
bias_varianceTL419 Dec 2024#21
MS
m.steinerTL2 Moderator19 Dec 2024#22
taper_shift, post #9: The SELECT trial changed the positioning because it was the first cardiovascular outcome trial in people without diabetes. That decoupled the cardiovascular argument from glycaemic control, which is why it mattered beyond its own numbers. Go to post

The 165 to 184 hour range: that is roughly 7 to 7.6 days, which is why the weekly schedule works. Below 4 half-lives you are not approaching steady state yet, which is the pharmacological argument for the four-week step interval.

23 likes in reply to #9 19mo
IT
impurity_tableTL3Analytical chemist19 Dec 2024#23
h.ramos, post #17: The mass figure differs between sources because of how the different entities report it. The monoisotopic mass of the bare peptide is one number; the mass including the acylation is another. Different sources emphasise different details. Go to post

Approved indications differ by jurisdiction and change. As of mid-2026 the weight-management indication is approved in many European jurisdictions but not all, and access is still narrower in others. For your own region, check the regulatory website rather than a forum summary.

0 likes in reply to #17 19mo
JM
j.moreauTL2 Moderator19 Dec 2024#24

The C-cell question: semaglutide triggered medullary thyroid carcinoma in rodent toxicology studies. A signal in rodents does not automatically appear in humans, but it is the reason the compound is contraindicated in people with personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2.

3 likes 19mo
RM
r.mcalisterTL3Regular20 Dec 2024#25

The STEP programme populations were selected: enrollment criteria required baseline body mass index over 30, no recent blood pressure crisis, no recent retinopathy, no renal disease at the time. Applying results from that population to someone well outside it is an extrapolation and should be called one.

15 likes 19mo
RN
r.nakamuraTL2 Moderator20 Dec 2024#26

Practical note that does not fit anywhere else. Whatever you conclude from this topic, write down what you did and when. The single most useful thing in your own records is not any individual result; it is that they are dated and consecutive.

31 likes 19mo
FD
f.demirTL2Regular20 Dec 2024#27
impurity_table, post #23: Approved indications differ by jurisdiction and change. As of mid-2026 the weight-management indication is approved in many European jurisdictions but not all, and access is still narrower in others. For your own region, check the regulatory website rather than a forum summary. Go to post

Gastric emptying delay is the mechanism behind most of the gastrointestinal side effects. Slowing the stomach empties it feeds less food into the intestines at a time, which is part of the satiety mechanism but is also why nausea is dose-dependent and titration-dependent.

1 like in reply to #23 19mo
AI
a.iyerTL2 Moderator20 Dec 2024#28

On post #24 — agreed on the reasoning, with one qualification.

The SELECT trial changed the positioning because it was the first cardiovascular outcome trial in people without diabetes. That decoupled the cardiovascular argument from glycaemic control, which is why it mattered beyond its own numbers.

6 likes 19mo
SC
so.cardosoTL2 Moderator20 Dec 2024 · edited#29
Thibodeau, post #12: This follows post #9 rather than contradicting it. Albumin binding is not a unique structural feature and nothing in the class lacks it, but the reversibility matters. Semaglutide binds albumin covalently through a fatty side chain, which creates a very long half-life at the cost of sequestering the free form. That is a trade-off and it… Go to post

Semaglutide versus liraglutide in STEP 8: semaglutide produced greater weight reduction and the discontinuation rates differed. But the trial was open-label for the dosing schedule, which admits expectation effects. Weekly versus daily itself is part of the comparison, not a confounding variable to be removed.

3 likes in reply to #12 19mo
VB
va.baptistaTL220 Dec 2024#30