GLP-1 half-lives and level curves, medication by medication
Peptrend ships a preset for each of these medications: a half-life, a time to peak, a bioavailability and a dosing interval. Each page below sets those four numbers beside the FDA label, names the source the app cites, and draws the curve the app's dose model makes from them.
- InjectionSemaglutide (injection)7 days half-life · peaks at 48 h · every 7 days
- OralSemaglutide (tablet)6.5 days half-life · peaks at 1.5 h · daily
- InjectionTirzepatide5 days half-life · peaks at 24 h · every 7 days
- InjectionDulaglutide5 days half-life · peaks at 48 h · every 7 days
- InjectionLiraglutide13.2 hours half-life · peaks at 10 h · daily
- OralOrforglipron38.4 hours half-life · peaks at 6 h · daily
Each small curve is four weeks at the preset's own interval on the same clock, scaled to its own highest point, so the shapes compare and the heights do not.
All six, side by side
Every figure in this table comes from the app's model, run on the preset's constants. The last column is a share of one logged dose once the level has settled, at its highest and lowest point in the dosing interval.
| Preset | Half-life | Tmax | Absorbed | Interval | 4 to 5 half-lives | Settled peak / trough |
|---|---|---|---|---|---|---|
| Semaglutide (injection) | 7 days | 48 h | 100% | 7 days | 28 to 35 days | 172.7% / 107.4% |
| Semaglutide (tablet) | 6.5 days | 1.5 h | 0.8% of each dose | 1 day | 26 to 32.5 days | 7.9% / 7.1% |
| Tirzepatide | 5 days | 24 h | 100% | 7 days | 20 to 25 days | 143.1% / 63.7% |
| Dulaglutide | 5 days | 48 h | 100% | 7 days | 20 to 25 days | 129.6% / 68.7% |
| Liraglutide | 13.2 hours | 10 h | 100% | 1 day | 2.2 to 2.75 days | 95.1% / 54.8% |
| Orforglipron | 38.4 hours | 6 h | 77% of each dose | 1 day | 6.4 to 8 days | 203.0% / 146.4% |
What these curves are
Each curve is a decayed-milligram estimate: the amount term of a one-compartment model with first-order absorption and first-order elimination, built from a published half-life and time to peak. The model has no volume of distribution, so it cannot give a blood or plasma concentration, and the app says as much beside its own chart. The curves describe each drug as its preset models it. None of them is a measurement or a forecast for anyone, and none describes an effect of the app.
No page here gives a dose or any dosing guidance. The curves are scaled to one logged dose, so they carry no dose amount at all. Every constant is editable in Settings › Medication, and the app asks before a preset overwrites them.
Where a preset departs from its label, the page says so and by how much. Some carry a single number for a label range: the orforglipron preset in 1.4.0 is built from midpoints throughout, 1.6 days for a 29-to-49-hour half-life and 6 hours for a 4-to-8-hour peak. Its curve is the middle of that range rather than a measured value.
The app also carries five research-compound presets, which it marks "Not FDA approved, research use only." They are not covered here.
The arithmetic behind them
- How long until a GLP-1 reaches steady state? Four to five half-lives
- When does a GLP-1 peak after injection? Tmax and the absorption curve
- Does oral semaglutide have the same half-life as the injection?
- The fifteen weight-trend methods, which apply the same kind of published arithmetic to weigh-ins