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Compounds · Semaglutide · continued

Semaglutide half-life: where the 165 to 184 hour figure comes from — what changed since posts 31–60

This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.

VF
v.fontaineTL2 Moderator24 Oct 2024#31
s.demir, post #14: post #13 answers the question as asked. The question underneath it is different. 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

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.

11 likes in reply to #14 21mo
ZY
z.yildizTL2 Moderator26 Oct 2024#32

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.

4 likes 21mo
HS
hana.satoTL4 Moderator28 Oct 2024#33

Coming back to post #31, because the follow-up matters more than the original answer.

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 21mo
AA
a.aguirreTL2 Moderator29 Oct 2024#34

Picking up post #31: that is the part I would want checked first.

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.

25 likes 21mo
PI
p.iyer_pharmdTL3Pharmacist31 Oct 2024 · edited#35
Ziegler, post #19: 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

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.

17 likes in reply to #19 21mo
NO
n.okwuosaTL2 Moderator2 Nov 2024#36

post #35 is right about the mechanism and I think understates the practical bit.

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 21mo
SS
system_suitabilityTL3Analytical chemist3 Nov 2024#37

I read post #35 twice before replying, because I had assumed the opposite.

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 21mo
ZO
z.okonkwoTL2 Moderator5 Nov 2024#38

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.

33 likes 21mo
NN
n.nakamuraTL2 Moderator7 Nov 2024#39

On post #35 — agreed on the reasoning, with one qualification.

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.

24 likes 21mo
CN
c.niemelTL3Regular8 Nov 2024#40

post #39 answers the question as asked. The question underneath it is different.

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.

11 likes 21mo
OF
outline_firstTL3Wiki editor10 Nov 2024#41

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.

21 likes 21mo
GA
g.amankwahTL2 Moderator12 Nov 2024#42
p.iyer_pharmd, post #35: 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. Go to post

On post #38 — agreed on the reasoning, with one qualification.

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.

0 likes in reply to #35 20mo
CT
cannula_traceTL3Regular13 Nov 2024#43

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 20mo
DB
da.bakkerTL2 Moderator15 Nov 2024 · edited#44

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 20mo
SS
steady_stateTL3Regular17 Nov 2024#45
z.yildiz, post #32: 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

post #44 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.

28 likes in reply to #32 20mo
IB
i.boatengTL2 Moderator18 Nov 2024#46
cannula_trace, post #43: 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. Go to post

Worth separating two things that post #42 runs together.

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 #43 20mo
SB
sharps_binTL2Regular20 Nov 2024#47

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 20mo
SO
se.okaforTL2 Moderator21 Nov 2024#48

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.

9 likes 20mo
DH
dietitian_hollisTL3Dietitian23 Nov 2024#49
c.niemel, post #40: post #39 answers the question as asked. The question underneath it is different. 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 #40 20mo
BK
b.kowalskiTL2 Moderator25 Nov 2024#50

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.

0 likes 20mo
W
WoodhouseTL226 Nov 2024#51
FE
f.espinozaTL2 Moderator28 Nov 2024 · edited#52

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.

5 likes 20mo
GF
gradient_fileTL2Member29 Nov 2024#53
appeals_desk, post #2: On the opening post — agreed on the reasoning, with one qualification. 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… Go to post

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.

0 likes in reply to #2 20mo
SK
s.kravchenkoTL2 Moderator1 Dec 2024#54

post #53 is right about the mechanism and I think understates the practical bit.

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 20mo
CN
cohort_notesTL2Member2 Dec 2024#55

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.

19 likes 20mo
ZA
z.adeyemiTL2 Moderator4 Dec 2024#56
m.dumitru, post #20: Picking up post #17: 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. 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.

8 likes in reply to #20 20mo
R
RidgewayTL3Regular6 Dec 2024#57

On post #53 — 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.

2 likes 20mo
AK
an.kirchnerTL2 Moderator7 Dec 2024#58

post #57 answers the question as asked. The question underneath it is different.

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 20mo
EF
erratum_fileTL3Regular9 Dec 2024#59

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.

26 likes 20mo
HJ
h.jansenTL210 Dec 2024#60