Dihexa vs DSIP
A neutral, side-by-side comparison of two nootropic & cognitive peptides — their mechanisms, dosing ranges, administration routes, side effects, and research evidence. For research and educational purposes only.
Dihexa
Dihexa is a synthetic hexapeptide derived from angiotensin IV, developed at Washington State University. It is considered one of the most potent nootropic peptides known — in rodent models it outperforms BDNF itself for synaptogenesis and cognitive enhancement, acting through the hepatocyte growth factor (HGF) / c-Met receptor system. Unlike most nootropics, Dihexa is highly lipophilic and can be administered transdermally or orally.
Full profileDSIP
DSIP (Delta Sleep Inducing Peptide) is a nonapeptide (9 amino acids) first isolated from rabbit thalamus in 1974, initially believed to directly induce slow-wave (delta) sleep. Research has since broadened its profile considerably: it modulates the HPA axis (reducing stress-driven cortisol), influences GH and LH release, demonstrates antioxidant properties, and may have cardioprotective effects. Despite decades of research, its precise receptor system remains incompletely characterized.
Full profile| Dihexa | DSIP | |
|---|---|---|
| Category | Nootropic & Cognitive | Nootropic & Cognitive |
| Also known as | PNB-0408, N-hexanoic-Tyr-Ile-(6) aminohexanoic amide | Delta Sleep Inducing Peptide, Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu |
| Evidence | Preclinical only | Research-stage |
| Dosing range | 10mg–20mg mg, Once daily (or every other day — long-lasting effects) | 100mcg–500mcg mcg, Once daily (evening) or every other day |
| Administration | Oral (capsule), Transdermal (cream/lotion — lipophilicity makes this effective), Subcutaneous injection (less common) | Subcutaneous injection, Intranasal, Intravenous (clinical studies) |
| Key side effects | Potential for pro-proliferative effects — HGF/c-Met pathway promotes cell growth (theoretical cancer concern at high doses), Headache (uncommon), Mental fatigue if overdosed, Long half-life means effects accumulate — take every other day initially | Generally well-tolerated, Daytime drowsiness if dosed in morning, Mild headache, Altered dream quality (common) |
| Cited sources | 2 references | 3 references |
Key differences
- Evidence level differs: Dihexa is preclinical only, while DSIP is research-stage.
- Administration: Dihexa — Oral (capsule), Transdermal (cream/lotion — lipophilicity makes this effective), Subcutaneous injection (less common); DSIP — Subcutaneous injection, Intranasal, Intravenous (clinical studies).
- Dosing units differ: Dihexa is dosed in mg, DSIP in mcg — they operate at different scales.
- Frequency: Dihexa is typically Once daily (or every other day — long-lasting effects); DSIP is Once daily (evening) or every other day.
- Research depth: this profile cites 2 sources for Dihexa vs 3 for DSIP.
How each works
Dihexa
Dihexa (PNB-0408) was developed by Joseph Harding and colleagues at WSU as a metabolically stable angiotensin IV analog. It binds hepatocyte growth factor (HGF), potentiating its interaction with the c-Met receptor — a pathway critical for dendritic branching, synapse formation, and synaptic plasticity. In rodent Alzheimer's and scopolamine-impaired models, Dihexa restored cognitive performance at doses ~7 orders of magnitude lower than BDNF. It readily crosses the blood-brain barrier due to its lipophilicity, unlike BDNF itself.
DSIP
DSIP does not directly trigger sleep in the simple sense originally proposed — more recent research indicates it modulates the neuroendocrine environment that facilitates sleep. Key findings: it reduces ACTH-driven cortisol elevation under stress, increases GH secretion in some models, and attenuates withdrawal severity in opioid and alcohol dependence (mechanisms unclear). DSIP demonstrates antioxidant effects and has cardioprotective properties in ischemic preconditioning models in animals. Its unique resistance to most peptidases (attributed to its unusual conformation) gives it a relatively long half-life for a nonapeptide.
This comparison aggregates public research and structured profile data for informational purposes only. It is not medical advice and does not recommend either compound for human use. Consult a qualified healthcare provider before considering any peptide.