An adapter cap goes on or in the top of the prescription bottle for a manufacturer’s/compounded liquid, and allows the slip tip of a syringe to fit into its small opening and the bottle to be inverted without creating bubbles or air. Adapter caps should be supplied with the manufacturer’s/compounded liquid, but if they aren’t, they may also be ordered online or purchased at most pharmacies. There are three types of adapter caps available; the first two may require asking the pharmacist what size the opening of the bottle is to get the right fit.
Press-in adapter caps
These push into the neck of a bottle and fit snugly. They are not reusable, so a new one is needed for each bottle of the drug.
Screw-on adapter caps (Adapta-Cap™)
These are reusable and screw on and off. It’s been reported that the small opening for the syringe can sometimes break after repeated use, so it’s good to have extras on hand.
Universal adapter caps
These fit just about any size bottle opening, since they’re graduated in size. They can be convenient in cases where pharmacies don’t supply drugs in the same size bottles every time they fill a prescription.
To learn more about adapter cap sizing, visit this page at the Abundant Health website.
Layperson tip: There are certain tips of slip tip syringes that are reported to not fit the adapter cap hole. In the event that a 1mL syringe is required with an adapter cap, it can be helpful to do an online search to find a particular brand that does fit, or to ask a well-informed pharmacist.