Semaglutide versus liraglutide head to head: reading STEP 8 carefully posts 31–60
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
Nausea is dose-related and adaptation-related, and both are true at once. The pattern most people describe is a return of symptoms at each escalation followed by adaptation, rather than a single course of adaptation at the start.
Post #29 and I disagree about the size of the effect, not about the direction.
If someone has run semaglutide versus liraglutide properly I would rather read that than my own reconstruction of it. Posting mine only because the thread has gone quiet.
Taking post #33 at face value and following it one step further.
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.
That is where I would start, not where I would stop.
Coming back to post #33, because the follow-up matters more than the original answer.
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.
This is the version I would want a new member to read first.
Injection site does not appear to matter much for semaglutide exposure. The published comparisons of abdomen, thigh and upper arm found differences small enough to be clinically unimportant, which is not true of every injectable.
I am aware this is the third time this month I have made this point.
Noted, and I have changed what I was going to do on the strength of it.
This follows post #36 rather than contradicting it.
Reading back through the semaglutide versus liraglutide threads from last year, the same three questions come up every time and only one of them has ever been answered properly. That seems like a documentation gap rather than a knowledge gap.
Solutions of semaglutide can look faintly opalescent without anything being wrong. Visible particulate, fibres or frank cloudiness are a different observation entirely and are worth raising with the supplier rather than reasoning about.
The rule of thumb is fine; the edge cases are where it earns its keep.
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Post #38 is right about the mechanism and I think understates the practical bit.
Discontinuation rates in the trials are worth reading alongside efficacy and almost never are. A large mean effect in a population where a meaningful fraction stopped early is telling you two things, not one.
I would treat the number as indicative rather than as a measurement.
Distinguishing three things in the semaglutide versus liraglutide discussion that keep getting used interchangeably: the observation, the proposed mechanism, and the recommendation that gets attached to both.
Answering the question post #41 raises rather than the one it answers.
The strongest argument against my own position on semaglutide versus liraglutide, stated as well as I can state it, since nobody else has yet.
That is the distinction I keep failing to hold on to. Written down now.
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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.
That holds under the stated conditions and I have stated them.
Adding the measurement that post #42 says would settle 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.
I would be interested in a counterexample if anyone has one.
Answering the question post #45 raises rather than the one it answers.
Appetite effects and gastrointestinal effects are frequently reported together and are not the same mechanism reported twice. Slowed gastric emptying contributes to both, but central satiety signalling accounts for effects that persist after emptying has normalised.
That holds for the case as described. Change the assumptions and it may not.
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.
That has held every time I have looked, which is not the same as always.
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.
Anyone who has looked at this more carefully, please correct the record.
Semaglutide's structure is a modified backbone with a C18 diacid attached through a spacer. The acylation is the reason for the long half-life and it is also the reason a plain sequence comparison against native GLP-1 is misleading about how the molecule behaves.
It is the sort of thing that seems obvious in retrospect and was not at the time.
On the injection-day question: the labelling for licensed semaglutide allows the day to be changed provided at least two days separate the two injections. That interval is not arbitrary — it is what stops two doses stacking inside one absorption window.
That has been true for the cases I have seen and I have not seen many.
Post #47 describes the usual case. This is about the unusual one.
Counter-ion form matters for the arithmetic and is almost never stated. A vial labelled 5 mg of peptide as an acetate salt and one labelled 5 mg as trifluoroacetate do not contain the same quantity of the molecule you are interested in.
Filing a mild objection to the consensus on semaglutide versus liraglutide. Mild because I might be wrong; an objection because nobody has addressed the case that does not fit.
Research-use-only semaglutide is not a licensed medicine, is not manufactured to pharmaceutical standards, and is not approved for human use. That is a statement about what it is, not a coded opinion about anything.
Happy to be corrected if someone holds better data than mine.
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.
A guess, clearly labelled as one.
This is the answer, and the reason it is the answer is the more useful part.
Picking up post #54: that is the part I would want checked first.
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.
On identity confirmation: a mass close to 4113.6 Da on the intact molecule is consistent with semaglutide and is also consistent with several closely related species. Mass narrows the field; it does not close it, and no certificate should be read as though it did.
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.
Adding it because I spent an afternoon working it out and nobody should have to twice.
STEP 1 and STEP 4 are two different questions. The first asks what happens when treatment is added; the second asks what happens when it is withdrawn after a run-in. Quoting the first as evidence about maintenance is the commonest misreading of the programme.
None of the above is medical advice and I am not qualified to give any.
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.
If anyone can point at the primary source I would be grateful.