Injection & Absorption
Route of administration shapes how a research peptide enters circulation, how quickly it reaches peak concentration, and how long it persists in observable form.
Diagram 01 — Tissue Depth
Where each route deposits the compound
Cross-section showing relative needle depth for subcutaneous and intramuscular routes against the body's tissue layers.
Diagram 02 — Route Comparison
Three primary research delivery routes
| Route | Deposit Site | Onset | Duration | Profile |
|---|---|---|---|---|
| Subcutaneous | Below dermis, into fat | 30–60 min | Long | Slow, steady release. Most common research route. |
| Intramuscular | Into muscle tissue | 10–20 min | Moderate | Faster absorption via richer vascular bed. |
| Intranasal | Nasal mucosa | 5–15 min | Short | Bypasses first-pass metabolism. Used for cognitive peptides. |
Diagram 03 — Absorption Profile
Plasma concentration over 12 hours
Theoretical first-order absorption + elimination model, normalised so each route's peak = 100%. Visual model only — not dosing guidance.
Why It Matters
Route of administration is one of the strongest variables in any peptide research design. Subcutaneous delivery produces the flattest, longest curves — ideal for compounds requiring sustained presence. Intramuscular sharpens the peak. Intranasal bypasses first-pass metabolism entirely, making it the route of choice for cognitive peptides like Semax and Selank where rapid central action matters more than systemic exposure.