How much is left when the next dose lands?
This site’s axis spans three orders of magnitude, from minutes to days, and that is not an abstraction: it is the difference between a molecule that is gone before the next injection and one that is still mostly there a week later. Pick a peptide and a dosing interval and the arithmetic is below, with its working printed beside it.
The calculator
Where a half-life is recorded as a span, the answer is a band, and both ends of it are printed. There is no midpoint in this calculator and no function in the code behind it that could produce one — the spread is the information.
5.8–8.1 days
Recorded from Teichman et al. 2006. The band below is computed from both ends of it.Still present when the next dose lands
88.7% to 91.8%
Between 0.12 and 0.17 half-lives have elapsed by then. The two ends of the answer are the two ends of the recorded half-life: the longer figure leaves more behind.
- Our arithmetic, not anybody’s label
- 0.5 ^ (1 day ÷ 8.1 days) = 0.5 ^ 0.12
0.5 ^ (1 day ÷ 5.8 days) = 0.5 ^ 0.17 - Interval
- 1 day
Every molecule, every interval, in the served HTML
The whole result set, server-rendered, so it is here with JavaScript switched off and it is here for anything that reads this page without running it. The intervals are intervals somebody might be on — they are not a schedule this site recommends, and nothing here computes a dose.
The table scrolls sideways; the first column stays put.
| Molecule | every 8 hours | every 12 hours | once a day | every 2 days | once a week |
|---|---|---|---|---|---|
| Sermorelin10–20 min | below 0.01% | below 0.01% | below 0.01% | below 0.01% | below 0.01% |
| Tesamorelin26–38 min [needs citation] | below 0.01% to 0.016% | below 0.01% | below 0.01% | below 0.01% | below 0.01% |
| Ipamorelin~2 hours | 6.25% | 1.56% | 0.024% | below 0.01% | below 0.01% |
| CJC-1295 (no DAC)~30 min [needs citation] | below 0.01% | below 0.01% | below 0.01% | below 0.01% | below 0.01% |
| CJC-1295 + DAC5.8–8.1 days | 96.1% to 97.2% | 94.2% to 95.8% | 88.7% to 91.8% | 78.7% to 84.3% | 43.3% to 54.9% |
Computed from the half-life recorded for each molecule in this site’s own records, both ends of every range. The documents behind them are on the sources page; 2 of the 5 carry no document and say so.
How this is computed
One line of arithmetic, printed beside every answer: remaining = 0.5 ^ (interval ÷ half-life). That is plain exponential decay — after one half-life half the dose is left, after two a quarter, and so on. The number of half-lives elapsed is the interval divided by the half-life, and it is printed too, because it is the figure that actually explains the answer.
Where the half-life is a range, the sum is done twice, once at each end. The longer end leaves more behind, which is the direction that catches people out, so the band always reads from the short half-life to the long one.
Below 0.01% this page stops printing a percentage and says “below 0.01%” instead. A figure with twenty leading zeros is arithmetic about an exponential rather than something a reader can use, and it implies a precision the underlying half-life — itself a span — does not have. The threshold is printed rather than hidden so it can be checked.
What this does not tell you
It is not a dosing schedule and it does not compute a dose. The output is a fraction of whatever was given, and nothing on this page says how much of anything to inject or how often. This site has no medical reviewer and no clinical review process, and it claims neither — see the medical disclaimer.
It models one dose, not a course. Repeated dosing accumulates, and the arithmetic for that is a different sum from the one printed here. This page answers the narrow question it states in its own title.
3 claims across the 5 molecules are still untraced, two of them half-lives, and every figure computed from those two carries the marker. The count is read from the records rather than typed, so it moves by itself when a citation lands:
Citation status, counted from the records behind this page rather than typed: 3 of 21 pharmacological figures on it are recorded in this site’s data but not yet traced to a published source, and they are marked [needs citation] where they appear. Where the writing below restates one of those figures, it rests on the same unsourced record. The open sourcing work is listed in the repository’s content to-do. This line counts itself down as sources land.
Sources
Every half-life this calculator uses is recorded in this site’s own records and traced to the document below, or marked as untraced.
8 documents are cited on this page, listed in the order the figures above rely on them. Each carries the date printed on the document itself, which is not the date it was read and not the date in its address.
- Esposito P, Barbero L, Caccia P, Caliceti P, D'Antonio M, Piquet G, Veronese FM. PEGylation of growth hormone-releasing hormone (GRF) analogues.Document date: 2003-09-26. PMID 14499707, doi:10.1016/s0169-409x(03)00109-1. Read September 2026.
- Food and Drug Administration, Department of Health and Human Services. Determination That GEREF (Sermorelin Acetate) Injection, 0.5 Milligrams Base/Vial and 1.0 Milligrams Base/Vial, and GEREF (Sermorelin Acetate) Injection, 0.05 Milligrams Base/Amp, Were Not Withdrawn From Sale for Reasons of Safety or Effectiveness.Document date: published 2013-03-04, signed 2013-02-26. 78 FR 14095, FR Doc. 2013-04827, Docket No. FDA-2012-P-1071. Read September 2026.
- Dominikowski A, Rękoś Z, Olejarz M, Szczepanek-Parulska E, Domin R, Ruchała M. The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration.Document date: 2026-06-18. PMID 42395176, PMC13322892, doi:10.3389/fendo.2026.1822475. Read September 2026.
- Theratechnologies Inc., prescribing information approved by the Food and Drug Administration. EGRIFTA SV (tesamorelin) for injection, for subcutaneous use — full prescribing information.Document date: label face date: Revised 03/2024; label version published 2026-07-31. SPL set id 3d783378-b02d-4f19-99dd-0fc91a042224, Initial U.S. Approval 2010. Read September 2026.
- Venkova K, Mann W, Nelson R, Greenwood-Van Meerveld B. Efficacy of ipamorelin, a novel ghrelin mimetic, in a rodent model of postoperative ileus.Document date: 2009-06. PMID 19289567, doi:10.1124/jpet.108.149211. Read September 2026.
- Gobburu JV, Agersø H, Jusko WJ, Ynddal L. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers.Document date: 1999-09. PMID 10496658, doi:10.1023/a:1018955126402. Read September 2026.
- Raun K, Hansen BS, Johansen NL, Thøgersen H, Madsen K, Ankersen M, Andersen PH. Ipamorelin, the first selective growth hormone secretagogue.Document date: 1998-11. PMID 9849822, doi:10.1530/eje.0.1390552. Read September 2026.
- Teichman SL, Neale A, Lawrence B, Gagnon C, Castaigne JP, Frohman LA. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults.Document date: 2006-03. PMID 16352683, doi:10.1210/jc.2005-1536. Read September 2026.