Nasal sprays

Why nasal at all

The nasal mucosa is thin, vascular, and sits right next to the brain. Two things follow:

• Small molecules can absorb directly into the bloodstream without going through the gut or liver — this skips the first-pass metabolism that destroys most orally-taken peptides.
• There’s a plausible direct nose-to-brain pathway via the olfactory nerve. For peptides targeting the central nervous system, this is theoretically attractive — though the clinical relevance is debated for most molecules.

The catch is molecular size. The nasal mucosa is permeable to small peptides; it’s a barrier to large ones. Bioavailability falls off sharply as molecules get bigger.

Which peptides are nasally absorbable

Generally suitable (small enough for meaningful nasal absorption)

• Oxytocin (9 amino acids). Has an FDA-approved clinical IV form; nasal forms are studied for autism, social cognition, and pair-bonding contexts. Off-label community use is widespread.
• Selank and Semax (Russian-origin nootropics, both ~7 amino acids). Specifically formulated as nasal sprays in their countries of origin. Not FDA-approved in the US.
• DSIP (delta sleep-inducing peptide, 9 amino acids). Sometimes administered nasally in community protocols.
• Insulin (51 amino acids, but on the borderline). Intranasal insulin is well-studied for cognitive applications.
• Melanotan II (7 amino acids). Sometimes used nasally; off-label and unregulated.

Generally NOT suitable (too large or wrong target)

• Tirzepatide (~39 amino acids), semaglutide (~31), tesamorelin (44), BPC-157 (15 — borderline but typically used SubQ), TB-500 (17 — same), most peptides over 30 amino acids.
• Why: nasal bioavailability for these is poor (typically <5%) — you’d need 20+ pumps to approach a SubQ-equivalent dose, which is impractical, expensive, and irritating to the mucosa.
• GHK-Cu, CJC-1295, ipamorelin — also typically not nasal. Topical (GHK-Cu) or SubQ (the others) is the studied route.

Rule of thumb: peptides under ~10 amino acids are nasal candidates; peptides over ~30 amino acids generally aren’t. The 10–30 range varies — depends on the specific molecule.

What to dilute with — the two-stage approach

The cleanest workflow is two-stage: reconstitute the source vial in BAC water (preservative protects the stock), then transfer a small portion of stock into a separate nasal bottle and dilute heavily with sterile saline. The saline dominates the final mix so the spray is mucosa-friendly; the residual benzyl alcohol is a small fraction of a percent.

• BAC water in the vial. Bacteriostatic water (0.9% benzyl alcohol) keeps the stock stable across many withdrawals. Plain sterile water has no preservative — the stock would spoil faster.
• Sterile 0.9% saline in the bottle. Isotonic with nasal mucosa, pH-friendly, no preservative needed (the ampule is sterile and the bottle is consumed within a few weeks). Preservative-free single-dose ampules — sold for nasal irrigation and contact lens use — are the cleanest source.
• Why not BAC water all the way through? Spraying full-strength 0.9% benzyl alcohol on the nasal mucosa is irritating with daily use. Diluting with saline-dominant volume drops the residual benzyl alcohol below the irritation threshold.
• Why not pure sterile water? Hypotonic — never use as a final vehicle. Stings and causes mucosal damage with repeated use.

See the step-by-step prep guide for the full procedure and the nasal-spray calculator for picking the stock-to-saline ratio that lands the residual benzyl alcohol below ~0.2% (the practical threshold for daily use).

What each pump delivers

Standard nasal spray pumps dispense ~0.1 mL (100 microliters) per actuation. This is true for most clinical and consumer nasal sprays. So:

• Bottle volume: 5–15 mL is typical → 50–150 pumps per bottle.
• Concentration math: if your bottle is 5 mL and you reconstituted 5 mg of peptide into it, that’s 1 mg/mL → 100 mcg per pump (0.1 mL × 1 mg/mL × 1000 mcg/mg).
• Multi-pump dosing is common — “2 pumps per nostril, daily” would deliver 0.4 mL (4 × 0.1 mL). Verify the pump’s spec before assuming 0.1 mL.

Priming, technique, and rotation

• Prime the pump on first use by spraying several pumps into a tissue until a fine mist comes out consistently. The first few pumps from a fresh bottle are typically air or partial liquid.
• Tilt your head slightly forward, not back — this keeps the spray on the nasal mucosa rather than running down your throat (where it won’t absorb).
• Sniff gently while pumping. Don’t inhale hard — that pulls the spray past the absorption zone.
• Alternate nostrils across doses. Each nostril’s mucosa needs recovery time; chronic single-nostril dosing causes local irritation.
• Don’t share bottles. Nasal pumps are single-user devices.

Storage of nasal-spray solutions

Once the peptide is in saline, the same shelf-life rules as any reconstituted peptide apply (see the storage guide): refrigerated, away from light, 4–6 weeks of efficacy. Saline-based formulations may degrade slightly faster than BAC-water formulations because there’s no bacteriostatic agent — though the saline itself is sterile to start.

What to discuss with your clinician

• Whether the peptide you’re considering has any published evidence for nasal administration — for many it doesn’t.
• Whether a clinical-grade compounding pharmacy can prepare the formulation properly — they have access to sterile fill equipment and pH-correct vehicles.
• Whether nasal absorption variability matters for your goal (it often does — therapeutic-window peptides like insulin need predictable absorption).

Reminder: Juno is an educational reference. Nasal administration of peptides is a niche, mostly community-practice space — most of the information above is general principle plus published data on the few molecules with real nasal evidence. Talk to a qualified clinician before adopting a nasal protocol.