Selank and Semax are the two compounds in our library that are primarily used as nasal sprays in research literature. The math is different from injection peptides — here’s everything you need: which compounds are intranasal-suitable, how the absorption works, the exact dose-per-spray maths, and how to actually use the spray.
Why some compounds go up the nose
Three things make intranasal delivery worth the awkwardness:
- The blood-brain barrier. The nasal mucosa has direct routes to the central nervous system — the olfactory and trigeminal nerve pathways. Peptides that target brain receptors (like Selank and Semax) can reach the CNS faster intranasally than via the bloodstream.
- Avoiding first-pass metabolism. Oral peptides get destroyed in the stomach. Intranasal bypasses the gut entirely.
- It’s a needle-free route. For protocols where the compound works well intranasally, skipping the injection is just easier and lower-friction.
The trade-off: intranasal bioavailability is lower than injection (typically 5–40% vs 60–90% subQ), so doses are usually somewhat higher. But for compounds that act on CNS targets, the direct CNS routing more than compensates.
Which compounds in our library are intranasal
| Compound | Primary route | Notes |
|---|---|---|
| Selank | Intranasal | Almost always nasal in research. Targets serotonergic and GABAergic systems via CNS. |
| Semax | Intranasal | Same. BDNF / NGF modulation studied via direct CNS route. |
| Oxytocin | Both | Intranasal in social-cognition research (BBB limits IV efficacy); injection in obstetric research. |
| PT-141 (Bremelanotide) | Both | Originally developed as intranasal, switched to subQ due to BP variability. Both forms still studied. |
| DSIP | Injection | Subcutaneous is standard. Some intranasal research exists but it’s not the primary route. |
For this guide, we’ll focus on the two that are primarily intranasal — Selank and Semax. The same maths and technique apply to any peptide you choose to use intranasally.
The per-spray maths
This is where intranasal research differs from injection. You can’t measure 250 mcg in a syringe and “inject” 250 mcg into your nose. Instead, you reconstitute the peptide, decant the solution into a nasal sprayer, and let the sprayer’s calibrated dose define your per-spray mcg.
The maths comes in three stages:
Step 1: mg/mL = vial mg ÷ BAC water mL
Step 2: mg per spray = mg/mL × spray volume (mL)
Step 3: sprays per dose = target mg ÷ mg per spray
Sprayer mechanics
A standard pharmaceutical-grade nasal spray bottle delivers a calibrated volume per actuation. The most common is 0.1 mL per spray (≈ 10 sprays per mL of solution). Some smaller sprayers deliver 0.05 mL (≈ 20 sprays per mL); some larger ones 0.14 mL. Check your specific sprayer — it should be marked on the bottle.
Worked examples
Selank, 10 mg vial, reconstituted with 1 mL BAC water, decanted into a 0.1 mL/spray sprayer:
| Stage | Calculation | Result |
|---|---|---|
| Concentration | 10 mg ÷ 1 mL | 10 mg/mL (10,000 mcg/mL) |
| Per spray | 10 mg/mL × 0.1 mL | 1 mg per spray (1000 mcg) |
| 250 mcg target dose | 250 ÷ 1000 | 0.25 sprays — too concentrated |
That last row exposes a common gotcha — you can’t deliver a quarter of a spray. So the recommended reconstitution is more dilute to land the typical research dose on a clean 1–2 spray draw. Let’s redo it:
| Stage | Calculation | Result |
|---|---|---|
| Concentration | 10 mg ÷ 4 mL BAC water | 2.5 mg/mL (2500 mcg/mL) |
| Per spray | 2.5 mg/mL × 0.1 mL | 250 mcg per spray |
| 250 mcg target dose | 250 ÷ 250 | 1 spray ✓ |
| 500 mcg target dose | 500 ÷ 250 | 2 sprays ✓ |
Result: reconstituting a 10 mg vial of Selank with 4 mL BAC water gives clean 1- or 2-spray doses for the standard 250 mcg or 500 mcg research dose. That’s the sweet spot.
Reconstitution → spray bottle workflow
- Get a pharma-grade nasal sprayer. Empty 5 mL or 10 mL bottle with a calibrated 0.1 mL pump. Available from research-supply vendors. Sterilise before use.
- Reconstitute the peptide vial with BAC water as you would for injection. For a 10 mg Selank vial targeting 250 mcg/spray, use 4 mL of BAC water. Swirl gently — don’t shake.
- Decant into the sprayer. Draw the reconstituted solution out of the vial using a luer-lock syringe (no needle, just the barrel), then transfer into the sprayer bottle. Reseal the sprayer.
- Prime the sprayer. Pump 3–5 times into a tissue until you see a fine mist. Until it primes, the first sprays won’t be dosed correctly — they’re partially air.
- Label the bottle. Compound name, concentration in mcg/spray, reconstitution date.
Spray technique
- Blow your nose gently first. Clearing mucus improves absorption.
- Tilt your head slightly forward, not back. Tilting back sends the spray down your throat where it doesn’t get absorbed by nasal tissue.
- Insert the sprayer just inside one nostril. Aim toward the outside wall of the nostril (away from the septum). The septum has less absorptive surface and is more easily irritated by repeated sprays.
- Press the pump once, breathing in gently through the nose. A hard sniff drives the spray past the absorption zone into the throat. A gentle inhale just keeps it in place.
- Alternate nostrils for multi-spray doses. Two-spray dose? One per nostril. Distributes the compound over more mucosal surface and reduces local irritation.
- Don’t blow your nose for at least 10 minutes after spraying — the compound is still being absorbed.
Storage & shelf life
A reconstituted peptide in a nasal sprayer follows the same rules as a reconstituted vial:
- Refrigerate at 2–8°C between uses.
- Stable for 28 days if reconstituted with bacteriostatic water (the standard).
- Stable for only 24–48 hours if reconstituted with sterile water (no preservative).
- Never freeze a reconstituted nasal sprayer — ice crystals damage the peptide and may crack the sprayer pump.
The sprayer itself can be reused across reconstitutions if cleaned properly between uses (rinse with sterile water, dry inverted). Most researchers replace the sprayer every 2–3 reconstitutions to avoid contamination buildup in the pump mechanism.