ROUTE · ADMINISTRATION
Sermorelin injection: administration in the research
The route the studies used, the timing rationale, and the pharmacokinetics — described from the record, never prescribed.
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Almost everything known about sermorelin in humans was learned through sermorelin injection — specifically the subcutaneous (under-the-skin) route. This page describes how injection appears in the published studies: the route, the timing researchers used, and the short half-life that shapes both. It is a research summary, not instructions, and it contains no recommended dose or technique.
The reason injection dominates is simple: sermorelin is a peptide that is poorly absorbed by mouth or nose, so the bloodstream-delivering route in the trials was injection [3]. The bedtime timing seen in studies tracks the body's own tendency to release growth hormone during early, deep sleep — a rationale, not a rule. The sermorelin tablets page covers why non-injected forms are criticized.
The subcutaneous route in the studies
The primary route across the human record is subcutaneous injection. Children in the pediatric efficacy study received once-daily subcutaneous sermorelin at bedtime, which accelerated growth [1]. Older men in the aging study received subcutaneous GHRH(1-29) twice daily for 14 days, producing dose-related GH and IGF-1 increases [2]. The intravenous route appears in diagnostic and pharmacokinetic studies — for example, intravenous doses of 0.25-2 mcg/kg used to characterize GH release — rather than in routine administration [3].
Why is bedtime dosing so often described? Growth hormone is secreted in pulses, especially during slow-wave (deep) sleep, so studies commonly timed administration to align with that natural rhythm [1]. That is the rationale reported in the literature; it is context for reading the studies, not a personal schedule.
Half-life, handling, and the compounding context
Sermorelin's plasma half-life is short — roughly 10-12 minutes after intravenous administration — yet a single dose keeps serum GH elevated for about 3 hours, because the downstream GH pulse outlasts the peptide itself [3]. This short native half-life is exactly why longer-acting analogs were engineered (D-Ala2 substitution and the DAC albumin-binding technology behind a multi-day GHRH analog) [3].
On handling, lyophilized sermorelin acetate is reconstituted with sterile diluent and then typically refrigerated, because aqueous peptide solutions are susceptible to degradation [3]. Compounded injectable preparations are prepared under USP <797> sterile-compounding standards, and the regulatory standing of that compounding is covered on the legal status page [9]. Nothing on this page is a route, dose, or technique recommendation — it is the administration record as the studies and standards describe it.
Why bedtime, and why pulses matter
The bedtime timing seen across studies is not arbitrary. Growth hormone is released in discrete bursts rather than continuously, and the largest natural pulses occur during early, slow-wave (deep) sleep [1]. Sermorelin works by amplifying the body's own pulsatile release rather than flooding the system with a steady level of hormone, so dosing was generally aligned with that natural rhythm in the research [6].
This is also the mechanistic argument an editorial makes in sermorelin's favor: because the peptide acts on the pituitary and leaves the feedback brakes (somatostatin and IGF-1) in place, it preserves the pulsatile pattern rather than overriding it — which the editorial frames as a potentially more physiologic approach to adult GH insufficiency than supplying recombinant growth hormone directly [4]. The point for reading the injection record is that the timing in studies reflects biology, not a one-size schedule for any person.
What the injected route does not establish
It is as important to mark the limits of the injected record as its strengths. The controlled injection studies measured GH/IGF-1 movement and, in children, growth [1][2]; they were not long-term adult anti-aging or body-composition trials. The clearest body-composition and cognition signals in the literature come from a related, longer-acting analog over 20 weeks — not from sermorelin itself [7]. And the cautionary editorial on using GH secretagogues for aging applies regardless of route [5].
So a reader should not read "sermorelin injection" as a validated long-term protocol for adult goals. The injected route is simply the route with the published pharmacology and the historical efficacy data behind it; what that data does and does not cover is laid out study by study on the sermorelin research page, and the regulatory standing is on the legal status page.