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Compounds · Semaglutide · continued

Molecular mass of semaglutide and why the figure differs between sources — does this still hold? posts 31–60

This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1 · go to the accepted answer.

GR
g.radichTL2 Moderator20 Dec 2024#31
a.iyer, post #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. 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.

0 likes in reply to #28 19mo
TY
two_year_lineTL3Regular20 Dec 2024#32
m.steiner, post #22: 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

post #31 is right about the mechanism and I think understates the practical bit.

Thank you for the correction. I have edited my earlier post with a note rather than silently, so the thread still makes sense to read. The error was mine and it was the kind that comes from remembering a figure instead of looking it up.

28 likes in reply to #22 19mo
YA
y.adeyemiTL2 Moderator20 Dec 2024#33

I read post #31 twice before replying, because I had assumed the opposite.

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.

9 likes 19mo
JR
j.rasmussenTL2Regular20 Dec 2024#34

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.

2 likes 19mo
DF
d.ferreiraTL2 Moderator20 Dec 2024#35
a.iyer, post #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. Go to post

Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing.

The correction was fair and I had been repeating something I had not checked carefully enough.

0 likes in reply to #28 19mo
BV
bias_varianceTL4Biostatistician20 Dec 2024#36
bias_variance, post #21: This follows post #18 rather than contradicting it. Thank you for the correction. I have edited my earlier post with a note rather than silently, so the thread still makes sense to read. The error was mine and it was the kind that comes from remembering a figure instead of looking it up. 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.

21 likes in reply to #21 19mo
CC
c.chowdhuryTL2 Moderator20 Dec 2024#37

Coming back to post #35, because the follow-up matters more than the original answer.

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.

5 likes 19mo
B
batchlogTL3Regular21 Dec 2024 · edited#38

Picking up post #35: that is the part I would want checked first.

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.

0 likes 19mo
IN
i.norgaardTL2 Moderator21 Dec 2024#39

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
CR
compounding_ruthTL4Pharmacist21 Dec 2024#40
a.reyes, post #19: 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. 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 #19 19mo
EC
e.coelhoTL2 Moderator21 Dec 2024#41

post #40 is right about the mechanism and I think understates the practical bit.

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.

25 likes 19mo
FA
f.abrahamsenTL2Member21 Dec 2024#42
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

Worth separating two things that post #38 runs together.

Is there a ceiling dose beyond which the effect plateaus? The trials did not study that because they stopped at 2.4 mg. Some people report trying higher doses, but trial data is absent and off-label dosing enters territory this site does not advise on.

0 likes in reply to #2 19mo
CH
ca.haddadTL2 Moderator21 Dec 2024#43

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.

1 like 19mo
G
GDashwoodTL3Regular21 Dec 2024#44

Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing.

The correction was fair and I had been repeating something I had not checked carefully enough.

7 likes 19mo
MY
m.yilmazTL2 Moderator21 Dec 2024#45

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.

18 likes 19mo
GI
g.ibarraTL2 Moderator21 Dec 2024#46

On post #42 — agreed on the reasoning, with one qualification.

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.

0 likes 19mo
SC
s.cardosoTL2 Moderator21 Dec 2024#47
m.ekstrom, post #8: 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. 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 #8 19mo
BP
b.petrovTL2 Moderator21 Dec 2024 · edited#48

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.

4 likes 19mo
NZ
n.zielinskiTL2 Moderator21 Dec 2024 · edited#49
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

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.

12 likes in reply to #1 19mo
M
MJayawardenaTL3Regular21 Dec 2024#50
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

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.

26 likes in reply to #12 19mo
OO
orbitrap_olaTL3Mass spectrometrist22 Dec 2024#51

Coming back to post #49, because the follow-up matters more than the original answer.

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.

17 likes 19mo
NB
n.brobergTL2 Moderator22 Dec 2024#52

Picking up post #49: that is the part I would want checked first.

Is there a ceiling dose beyond which the effect plateaus? The trials did not study that because they stopped at 2.4 mg. Some people report trying higher doses, but trial data is absent and off-label dosing enters territory this site does not advise on.

6 likes 19mo
PW
PharmNotes_WhitfieldTL4Pharmacist22 Dec 2024#53
g.ibarra, post #46: On post #42 — agreed on the reasoning, with one qualification. 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

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.

1 like in reply to #46 19mo
JF
j.fonsecaTL2 Moderator22 Dec 2024#54

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.

0 likes 19mo
CL
customs_ledgerTL3Regular22 Dec 2024#55

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.

11 likes 19mo
RF
ro.friskTL2 Moderator22 Dec 2024 · edited#56

This follows post #53 rather than contradicting it.

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.

3 likes 19mo
DS
dr_seongTL3Physician22 Dec 2024#57
GDashwood, post #44: Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing. The correction was fair and I had been repeating something I had not checked carefully enough. 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.

0 likes in reply to #44 19mo
PM
p.mwangiTL2 Moderator22 Dec 2024#58
two_year_line, post #32: post #31 is right about the mechanism and I think understates the practical bit. Thank you for the correction. I have edited my earlier post with a note rather than silently, so the thread still makes sense to read. The error was mine and it was the kind that comes from remembering a figure instead of looking it up. Go to post

Thank you for the correction. I have edited my earlier post with a note rather than silently, so the thread still makes sense to read. The error was mine and it was the kind that comes from remembering a figure instead of looking it up.

32 likes in reply to #32 19mo
NN
n.nybergTL2 Moderator22 Dec 2024#59

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.

7 likes 19mo
CL
c.lundgrenTL2 Moderator22 Dec 2024#60

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.

1 like 19mo