Semaglutide is a GLP-1 receptor agonist, approved in many countries for type 2 diabetes and chronic weight management. It is given as a weekly subcutaneous injection, and an oral formulation also exists. Published pharmacokinetics describe a half-life of approximately seven days, which is why the weekly cadence works.
By Tessaro Pty Ltd, the maker of Pepti · Last reviewed
This page is a reference, not a protocol. It sets out what the published trials actually report, what a seven-day half-life means for a weekly record, and what a clean log holds. It contains no dose figures and no schedule, and the section further down explains why that is deliberate rather than an omission.
| Property | Value |
|---|---|
| Mechanism | GLP-1 receptor agonist |
| Status | Approved in multiple jurisdictions for type 2 diabetes and chronic weight management; also widely used in compounded form |
| Route and cadence | Subcutaneous injection, once weekly; an oral formulation also exists |
| Half-life | Approximately 7 days (about 168 hours) — per published pharmacokinetics |
| Product form | Approved-product pens are prefilled solution; compounded vials are commonly supplied as lyophilized powder requiring reconstitution |
Published data describe a mean body-weight reduction of 14.9 percent at 68 weeks (Wilding et al., NEJM 2021). That trial is the reference point most later work is measured against, and it is the reason semaglutide became the baseline expectation for the class rather than an outlier result.
For scale, trials report 20.9 percent mean reduction at 72 weeks for tirzepatide, a dual agonist (Jastreboff et al., NEJM 2022), and 24.2 percent at 48 weeks for investigational retatrutide, a triple agonist (Jastreboff et al., NEJM 2023). The comparison has real limits and they are worth stating plainly: these are separate trials, run in different populations, over different durations, with different designs and endpoints. Lining the percentages up in a row is a convenience, not a head-to-head result.
The figure that matters most to a record, though, is not an efficacy number at all. Published data describe one-year persistence on GLP-1 therapy of 64.8 percent (Rodriguez et al., JAMA Network Open 2025), meaning roughly one in three people stop within a year. Whatever drives that in an individual case, it makes the dated history unusually valuable: when the conversation with whoever directs your use turns to whether to continue, a complete record of what was taken, when, and what was observed alongside it is the only evidence in the room that is actually about you.
A half-life is the time taken for half of what is present to clear. At approximately seven days, weekly injections overlap heavily instead of clearing between them: levels build across the early weeks rather than returning to zero, which is why the cadence settles where it does.
Two things follow for record-keeping. A missed week is a much larger gap than a missed day would be on a daily compound, so the log needs to make an absent week obvious at a glance rather than burying it. And because the curve is slow, what you notice in any given week is a product of several preceding weeks, not just the most recent injection, which makes the dated history far more informative than any single entry in it.
Semaglutide differs from the investigational compounds in one important way: an approved product exists, and it has an official label. That label is where approved-product dosing lives, and it is a matter between you and whoever directs your use. Restating label figures on a tracking site adds nothing and risks a good deal, because a number copied out of context loses the conditions attached to it.
Compounded semaglutide is a different situation again. Concentration varies from preparation to preparation, so a figure that was correct for one vial can be wrong for the next one, and no page can tell you what is in the vial in front of you. That is precisely why Pepti computes a draw volume from the figures you already have rather than suggesting any of its own. The measurement is ours; the figure is not, and it never will be.
Because the cadence is weekly, there are relatively few entries in a semaglutide log, which makes each one carry more weight. A record worth keeping holds the following.
The reconstitution calculator converts the figures you already have into a draw volume and a count of doses per vial, the injection site rotation guide sets out the zone system, and how to track peptide cycles covers the record-keeping method in full; you can also see how Pepti compares to other trackers before you choose.
Semaglutide is a GLP-1 receptor agonist. It mimics an incretin hormone the gut releases after eating, acting on appetite signalling in the hypothalamus, slowing gastric emptying, and increasing glucose-dependent insulin secretion. It is given as a weekly subcutaneous injection, and an oral formulation also exists.
Yes. Semaglutide is approved in many jurisdictions for type 2 diabetes and for chronic weight management, which makes it unusual among the compounds people track: an official label exists, and the dosing in it is a matter for whoever directs your use. It is also widely used in compounded form, which is not the approved product and is not covered by that label.
Approximately seven days, about 168 hours, per published pharmacokinetics. That is the value Pepti uses when it draws reference curves. A half-life this long is the reason the cadence is weekly: successive injections overlap substantially rather than clearing between administrations, so levels build across the early weeks rather than returning to zero.
They differ in how many receptors they act on. Semaglutide is a single agonist at the GLP-1 receptor. Tirzepatide is a dual agonist, adding GIP. Retatrutide is a triple agonist, adding glucagon, and is investigational rather than approved. Trials report larger mean body-weight reductions as the number of targets rises, but those figures come from separate trials with different populations, durations and designs, so they are not a head-to-head comparison.
It depends on the form in front of you. The approved product is supplied as a prefilled pen containing solution, already in liquid form and requiring no mixing. Compounded material is commonly supplied as a lyophilized powder, which is inert until a diluent is added, and its concentration varies between preparations rather than being fixed. These are different physical products, and a record that does not say which one it describes is ambiguous later.
No. Pepti supplies no dose figures for semaglutide or for anything else. It records the figure you already have from whoever directs your use, converts it into a draw volume and syringe units, tracks what is left in each vial, and keeps the site sequence. The arithmetic is ours; the figure is not.
This page is a reference on published evidence and record-keeping. It does not recommend semaglutide or any other substance, and it provides no dose figure, no titration amount, and no schedule. Approved-product dosing is a matter for the official label and for whoever directs your use.
Pepti, our iOS peptide tracker, keeps the weekly log, the site sequence, the vial count and the weight trend in one place.
Not medical advice. Pepti is a record-keeping and measurement tool, not a medical device.
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