Sermorelin half-life and steady state
12 min modelled half-life, peaking 6 min after a dose. What that means for how long it lasts, how much it builds up, and when bloodwork is worth drawing.
- Also known as
- GHRH(1-29)
- Class
- GH Secretagogues
- Modelled half-life
- 12 min
- Time to peak
- 6 min
- Formulation
- Aqueous (reconstituted powder)
- Cleared per dosing interval
- 100% gone, 0% still present after 24 h
- Time to steady state
- ~1 h (about five half-lives)
- Accumulation at that cadence
- 1× — effectively none; each dose clears before the next
- Peak-to-trough at steady state
- Not meaningful — the level returns to zero between doses, so there is no trough to divide into a peak
- Regulatory status
- Research compound — no FDA approval for general use. Used in anti-aging medicine.
- Monitoring panel
- IGF-1 at baseline and every 3 months. Fasting glucose.
- Before mixing
- Sealed powder tolerates room temperature in transit, but keep it refrigerated at 2–8 °C (36–46 °F) for anything beyond a few weeks, or frozen for months. Keep it dark — the carton it shipped in is doing a job.
- After mixing
- Once reconstituted with bacteriostatic water: refrigerate at 2–8 °C and use within about 28 days. The benzyl alcohol in bacteriostatic water is what buys that window — plain sterile water has no preservative, so a vial mixed with it should be treated as one sitting only. Kits are usually ten vials: only the one you mixed is on that 28-day clock — the sealed ones keep their own, much longer shelf life, so store them as powder, not as solution.
- What ruins it
- Do not freeze a reconstituted vial. Repeated freeze–thaw is one of the more reliable ways to degrade a peptide.
- Handling caveat
- General handling practice for this formulation. Your supplier’s own insert or COA overrides anything here.
Sermorelin's twelve-minute half-life is the shortest on this site by an order of magnitude, and it is not an approximation of a longer-acting drug — it is native biology. Sermorelin is simply the first twenty-nine amino acids of human GHRH, the fragment that carries all the receptor activity, with nothing added to protect it. The enzyme DPP-4 begins dismantling it almost immediately, exactly as it does the body's own GHRH.
Every other GHRH analogue on this site is an attempt to lengthen that number. Tesamorelin adds a group at the N-terminus and buys tens of minutes; CJC-1295 without DAC substitutes four amino acids and reaches half an hour; CJC-1295 with DAC binds albumin and reaches a week. Sermorelin is the unmodified baseline they are all measured against, which makes it the most physiological of them and the most demanding to use — a compound with a twelve-minute half-life is entirely dependent on timing.
There is no accumulation to discuss and no steady state: a dose is a single pulse, gone within the hour. What makes that a feature rather than a limitation is the pituitary's feedback loop, which stays intact — GHRH signalling this brief cannot override somatostatin, so the growth hormone response remains self-limiting in a way exogenous growth hormone is not. That is the argument for a secretagogue over the hormone itself, and the short half-life is the mechanism behind it. Sermorelin's monitoring in the app is IGF-1 quarterly plus fasting glucose, which reflects that the marker worth watching moves over weeks even though the drug is measured in minutes.
One dose
pkCurve function — a
one-compartment absorption-and-elimination model with the absorption rate fitted so the
peak lands at the published time to peak.Dosed once daily
Charted at once daily because that is the once-daily pre-bed schedule in the app's own dosing rows. It is what the numbers below are indexed to, not a recommendation about frequency — that is a prescribing decision.
The arithmetic behind those numbers
fraction left after one interval = 2^(−120.00) = 0.000
accumulation ratio = 1 ÷ (1 − 0.000) = 1
time to steady state ≈ 5 × half-life = 1 h
peak-to-trough = not meaningful; the trough is 0 of a single dose's peak, i.e. cleared
The accumulation ratio is a closed form; the peak-to-trough figure is not. The generator adds up enough repeated curves for the total to stop changing, then reads the highest and lowest points of the last interval — which is what steady state means in practice. The vertical axis is relative, not a concentration: the shape and the ratios carry across people, the absolute levels do not.
The dosing rows this cadence came from
Off-label or community practice Reproduced from the app's entry so you can see what the chart above is indexed to. Which row applies to a particular person, if any, is a clinical decision this page does not make.
| Label | Amount | Route and frequency |
|---|---|---|
| Standard | 200-300mcg | Once daily before bed SubQ fasted |
| With GHRP | Sermorelin 200mcg + Ipamorelin 200mcg | Once or twice daily fasted |
When to draw bloodwork
The panel the app records for Sermorelin is: IGF-1 at baseline and every 3 months. Fasting glucose.. The pharmacokinetic point is the timing rather than the list: after any change, a level takes about 1 h to settle, so a panel drawn sooner measures something still moving. And because this compound clears completely between doses, a serum level says only what the last few hours did — which is why the marker worth following here is a downstream one measured over weeks, not the compound itself. Whether a result means anything is a question for the clinician who ordered it, read against the reference range your own lab printed. The lab-marker pages cover what the individual analytes measure.
Related: the interactive half-life calculator to try other cadences.
The app draws this curve from the doses you actually logged — your dates, your cadence — and projects seven days forward from the last one.
Save this dose to your log