Trust Signals
All cited evidence is real and sourced from PubMed, PMC, or peer-reviewed journals. Speculative claims are labeled as such. No affiliate rankings. Updated 2026-10-03.Quick Answer: The primary records reviewed below do not establish a best peptide for lowering cortisol in people. Anxiety scores, rodent stress behavior, growth-hormone selectivity and measured cortisol responses are different outcomes. A useful comparison keeps those outcomes separate.
On this page
- What each source measured
- What the Selank records show
- Check the cortisol units
- What ipamorelin selectivity means
- How to compare a result
- Frequently asked questions
The endpoint matters more than a peptide ranking
| Source | Population or model | Measured endpoint | What it does not establish |
|---|---|---|---|
| Selank anxiety study, 2008 | 62 patients with generalized anxiety disorder or neurasthenia; 30 Selank, 32 medazepam | Psychometric scales and serum enkephalin activity | The abstract does not report a numerical cortisol-reduction effect |
| Selank adaptive-stress study, 2003 | Rats and mice | Behavioral responses to a conflict situation | Human cortisol outcomes |
| Hexarelin endocrine study, 1997 | 12 normal subjects and 17 patients with Cushing's syndrome; intravenous exposure | ACTH, cortisol and growth-hormone responses | A treatment that lowers cortisol; the normal-subject cortisol response increased |
| Ipamorelin selectivity study, 1998 | Rat pituitary cells, rats and swine; hormone selectivity assessed in swine | Growth-hormone release and other hormone responses | A human cortisol-lowering trial |
The two Selank records cannot support the same claim
The clinical abstract reports similar anti-anxiety effects with Selank and medazepam, assessed with Hamilton, Zung and CGI scales. The measured blood marker was enkephalin activity. An improvement in anxiety scores does not supply a measured cortisol percentage.
From the FormBlends catalog
Semax / Selank Blend
Focus and calm support in one cognitive peptide blend · From $229/mo · compounded by a licensed 503A pharmacy, dispensed only after provider review.
View Semax / Selank Blend →The 30 versus 32 participant counts describe allocation: 30 / 62 x 100 = 48.4% received Selank. They are not response rates. The adaptive-stress paper cited in the earlier version used rats and mice, despite the page's human-cortisol framing. These distinctions do not prove that no other study exists; they identify what these sources actually support.
Decode the human hexarelin result before comparing it
The hexarelin study administered 2 micrograms/kg intravenously and compared responses with human CRH. In the normal subjects, mean cortisol rose from 110.0 to 135.9 micrograms/L. The Cushing's subgroups responded differently; the normal-subject numbers should not be presented as a pooled result for all 29 participants.
| Quantity | Reported micrograms/L | Calculated micrograms/dL |
|---|---|---|
| Baseline | 110.0 | 11.00 |
| Peak | 135.9 | 13.59 |
| Peak minus baseline | 25.9 | 2.59 |
One liter contains ten deciliters, so divide by ten. The relative increase from the displayed means is (135.9 - 110.0) / 110.0 x 100 = 23.5%, rounded. This is an acute within-session change, not a placebo-adjusted effect, a long-term benefit or a dose recommendation.
No significant stimulation is not measured suppression
The ipamorelin paper assessed hormone specificity in swine. ACTH and cortisol responses were not significantly different from those following GHRH stimulation, even at amounts above 200 times the growth-hormone ED50. That is a comparison of stimulation responses in that model, not evidence of lower human baseline cortisol.
The same paper reports ACTH and cortisol increases with GHRP-2 and GHRP-6 in the swine experiments. Peptides grouped together as growth-hormone secretagogues therefore cannot be assigned one shared cortisol effect. A statistically nonsignificant difference also does not prove that every dose produces exactly zero change.
A practical cortisol-result comparison
For each record, write down the specimen, collection time, unit, baseline, comparator and follow-up. Keep blood and saliva results distinct. Compare a peak with a peak, or a baseline with a baseline, rather than treating an acute stimulation test as a chronic stress-treatment trial.
A claim about cortisol reduction needs an actual cortisol endpoint. A behavior score or another circulating peptide is not a substitute. The four records above do not yield a justified rank order or a universal cortisol-management schedule.
Clinical context
Anyone with a known cortisol disorder (Cushing's syndrome, Addison's disease, or HPA axis suppression from exogenous steroid use) should not use these compounds without endocrinologist supervision.
Frequently asked questions
Does the named human Selank study prove cortisol reduction?
Its abstract reports anxiety scales and enkephalin measurements, not a numerical cortisol-reduction result. The full claim requires a source that measured that endpoint.
Is ipamorelin selectivity the same as lowering cortisol?
No. The named study's selectivity comparison was performed in swine and concerns the hormone response to stimulation.
Can different units make the same concentration look different?
Yes. A value of 110 micrograms/L equals 11 micrograms/dL. Keep the original unit visible before comparing numbers.
Primary references
- Selank clinical anxiety study
- Selank animal adaptive-stress study
- Human hexarelin endocrine-response study
- Ipamorelin selectivity study
Related peptide guides
Ready when you are
Semax / Selank Blend
Focus and calm support in one cognitive peptide blend · From $229/mo · compounded by a licensed 503A pharmacy, dispensed only after provider review.
View Semax / Selank Blend →