Vial Adapter: What It Is and How It Works
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[Glossary · Mixing and measuring]

Vial adapter

Also called vial access device, needle-free vial adapter, transfer adapter · Reviewed

Definition: A vial adapter is a small plastic piece that snaps onto the top of a vial and lets a syringe screw on, so liquid can move in and out without a needle. Some come packed with a drug and a prefilled liquid syringe as a needle-free mixing system. Some have a filter built in.

How the Kovaltry label describes one

Kovaltry, a clotting factor sold as a powder, comes with a sterile vial adapter that has a 15 micrometer filter, and a prefilled syringe of liquid. Its label calls this a needleless reconstitution system and says it was usability tested with 60 people.

  1. Clean the rubber stopper with a sterile alcohol swab and do not touch it after.
  2. Set the vial on a firm, non-skid surface.
  3. Holding the adapter by its plastic housing, press it down until it snaps over the vial cap.
  4. Lift off the housing, then screw the syringe onto the adapter.

Those steps belong to that product; other adapters differ.

Adapters with filters

A 2015 lab study by authors from an adapter maker tested a filter-integrated vial adapter with silica particles of 0.5-10 μm, used to stand in for glass flakes that can come off the inside of vials. It reported high filter efficiency. It was a bench test, not a study in people.

Why it matters when you track doses

An adapter changes how the liquid moves, not the math. The strength of the mixed vial is still the amount of powder divided by the amount of liquid added. Dose Track's reconstitution helper works from those two numbers whatever device you mix with.

Read more on Dose Track: Using the reconstitution helper · Tracking vials and supplies

General education drawn from labels and published studies, not personal medical advice. Your prescriber, pharmacist and the label that came with your product are the final word.
ReconstitutionReconstitution is adding a liquid, called a diluent, to a powdered drug so it dissolves into a solution… DiluentA diluent is the liquid used to dissolve a powdered drug or thin a liquid one before it is injected. The… Filter needleA filter needle is a needle with a small built-in filter, used to draw liquid into a syringe while holding… Lyophilized (freeze-dried)Lyophilized means freeze-dried. The drug solution is frozen and the water is then removed, leaving a dry… Concentration (mg/mL)Concentration is how much drug is in each unit of volume, usually written as mg/mL, mcg/mL or units/mL. It…

Frequently asked questions

What does a vial adapter do?+
It snaps onto a vial so a syringe can screw on and move liquid in and out without a needle. Some come with a prefilled liquid syringe as a needle-free mixing system.
Does a vial adapter change the concentration?+
No. The strength of the mixed vial is still the amount of powder divided by the amount of liquid added, however the liquid gets in.

Sources

  1. Kovaltry (antihemophilic factor, recombinant) US label with vial adapter instructions, DailyMed
  2. Zarour-Shalev et al. PDA J Pharm Sci Technol 2015 (filtration of glass particles with filter vial adapters; manufacturer authors). PMID 26659100

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