How a metered nasal spray pump works: filling and priming.
A metered nasal pump delivers a fixed volume each time it is pressed fully. Priming fills the pump's metering chamber with liquid instead of air, so until a pump is primed its first presses deliver air, a sputter, or a partial spray.
This page explains the device, plainly and only the device. It is not a suggestion to put any peptide in one. Most peptides are not formulated or approved for nasal use. Only a small number of peptide drugs, calcitonin salmon and nafarelin among them, have been approved as nasal sprays, and each was developed as a complete formulation in a specific pump with testing that a solution mixed from a vial and poured into a generic bottle has never had.
If you have an approved nasal product, its label and Instructions for Use are the manual. Read on for why its instructions say what they say.
Reviewed October 14, 2026
This tutorial does not suggest an amount, a number of sprays, or how often to use one, and it does not describe how to use a spray in the nose.
What you need.
- The spray bottle and its documentation or label
- A label or marker
- A way to count sprays (a tally card or a log in an app)
- A clean, damp cloth for the outside of the pump
Step by step.
Find out what your pump delivers per press
Every metered pump has a fixed actuation volume, set by the size of its metering chamber. Many nasal pumps deliver around 0.1 mL per full press, but there is no standard. The nafarelin (Synarel) label states about 100 microliters (0.1 mL) per actuation; the calcitonin salmon label states 0.09 mL; and FDA's nasal spray guidance mentions pumps as small as 20 microliters. Find the figure in your pump's documentation or the product's label. Do not assume it.
Everything downstream depends on that number. The amount in one spray is the solution's concentration multiplied by the volume per spray, which is the arithmetic the intranasal calculator runs on numbers you enter.
Fill and assemble the bottle (only if it is not prefilled)
Approved nasal sprays arrive filled, sealed and assembled, and should not be opened or refilled. An empty pump bottle is a different situation: filling one is a compounding step done outside a cleanroom, with no testing of what results.
If a pharmacy prepared the spray, it was filled for you. If a bottle is being assembled, it is done with washed hands on a clean surface, without touching the inside of the neck or the dip tube, and with the pump screwed down fully so the dip tube reaches near the bottom. Note the volume that went in: that volume, minus priming and the liquid the tube cannot reach, is how many sprays the bottle can actually deliver.
Prime it until you get a full spray
A new pump is full of air. Priming replaces that air with liquid so the metering chamber holds a full measure. Hold the bottle upright, point the nozzle away from your face and away from anyone else, and press fully and firmly. The first presses deliver air or a weak spurt. Keep going until you see a full, even mist. Partial sprays do not count as anything.
Labels set the method. The calcitonin salmon instructions say to let the bottle reach room temperature and then press until a full spray appears; the Synarel label describes pumping until a fine spray appears and says priming is needed only once for a new bottle. Approved products work this out in testing: FDA's guidance asks manufacturers to establish how many sprays it takes to prime the pump and how long it can sit before it needs priming again.
- Actuator and nozzle. Each full press delivers one fixed volume.
- Metering chamber. Sets that volume. Priming fills it with liquid instead of air.
- Dip tube. Draws liquid up from the bottle. The last of the liquid sits below its reach.
Priming pulls liquid up the dip tube into the metering chamber. Air first, then a sputter, then a full, even spray. Re-prime after it sits, but not before every use
A pump that sits unused can lose its prime as liquid drains back. The re-priming interval comes from the product's own testing, so it comes from the label. The calcitonin salmon instructions show a sensible pattern: check whether the pump is still primed by pressing once, prime only if a full spray does not come out, and do not prime before every use, because that wastes the medicine.
Count the sprays
A bottle holds more liquid than it can usefully deliver: some goes to priming, and the last of it sits below the reach of the dip tube. That is why approved sprays are labeled with a number of sprays rather than only a volume, and why their instructions say to throw the bottle away after that number. The Synarel label goes further and tells users not to try to use up the leftover amount.
FDA's guidance has manufacturers test the content of sprays from both the beginning and the end of a container for exactly this reason. Keep a tally on a card or in an app, and remember that presses used to check or re-prime the pump come out of the same bottle.
Label the bottle
Write what is in it, the concentration, the date it was prepared or first used, and the volume per spray if you know it. A spray bottle looks the same whatever is inside it.
Understand why sterility and formulation matter
The inside of the nose is not sterile, but the bottle must stay clean, and an ordinary pump lets air back into the bottle to replace each spray. Approved multi-dose sprays manage this deliberately: where a preservative is used, FDA's guidance requires the manufacturer to show that the minimum amount in the product actually works against microbes.
Formulation is the larger issue. An approved nasal product's spray volume, droplet behavior, pH, preservatives and stability were developed and tested together, and FDA's guidance expects individual sprays to stay within 15 percent of their target weight. A peptide solution mixed for injection has none of that work behind it: its diluent was chosen for a vial, not a nose, and how much of it would be absorbed through nasal tissue is generally unknown. That is why most peptides are not formulated or approved for nasal use, and why this page explains the device and stops there.
This tutorial explains the device and ends there. How to use a specific nasal product, and whether to, comes from your prescriber, pharmacist, or the product's Instructions for Use.
Common mistakes.
Assuming every pump delivers 0.1 mL
Approved labels state 0.09 mL and about 0.1 mL for two different products, and smaller pumps exist. Check your own pump.
Counting priming sprays as delivered sprays
Priming sprays go into the air. They still come out of the bottle, so they count against its total.
Priming before every use
Labels that address it say not to. Check the prime with one press and re-prime only if the spray is not full.
Using the bottle past its labeled spray count
The last of the liquid sits below the dip tube and end-of-bottle sprays are not reliable. Labels say to discard at the count.
Taking the pump apart to clean it
Follow the product's cleaning instructions, which wipe or rinse the outside and tip only.
Sharing a pump
The nozzle touches the inside of the nose. It is personal equipment.
Treating an injection solution as a nasal formulation
A spray bottle does not turn a vial's contents into a tested nasal product.
FAQ.
How much liquid is in one spray?
It depends entirely on the pump. Two approved peptide nasal sprays state about 0.1 mL and 0.09 mL per actuation on their labels, and FDA's guidance mentions pumps as small as 20 microliters. The figure for your pump is in its documentation or the product label.
Why does a new spray bottle only puff air?
It has not been primed. The pump's metering chamber and dip tube start full of air, and the first presses push that air out. Keep pressing, pointed away from your face, until a full, even spray appears.
Why throw away a bottle that still has liquid in it?
Because the remaining liquid cannot be delivered reliably. Some of it is below the reach of the dip tube, and end-of-bottle sprays can be incomplete. Approved labels set a spray count for this reason, and at least one tells users not to try to use up the leftover amount.
Can any peptide be used as a nasal spray?
This page does not suggest it, and in general no. Only a small number of peptide drugs have been developed and approved as nasal sprays, each as a tested formulation in a specific pump. Most peptides have no nasal formulation, no approval for nasal use, and little or no human data on how much is absorbed through the nose.
How do I work out the amount in one spray?
Multiply the solution's concentration by the pump's volume per spray. A solution at a given mg per mL, delivered 0.1 mL at a time, puts one tenth of that mg figure in each full spray. The intranasal calculator does the arithmetic on numbers you enter and suggests none of them.
Sources.
- [1]Synarel (nafarelin acetate) nasal spray label · DailyMed, US National Library of Medicine
- [2]Calcitonin salmon nasal spray (metered): label and Instructions for Use · DailyMed, US National Library of Medicine
- [3]Nasal Spray and Inhalation Solution, Suspension, and Spray Drug Products: Chemistry, Manufacturing, and Controls Documentation · FDA guidance for industry, 2002
Cite this page
PepCue. “How a metered nasal spray pump works: filling and priming.” PepCue, reviewed October 14, 2026. https://www.pepcue.app/tutorials/nasal-spray.
All four walkthroughs are on the tutorials hub.