How to prevent vial coring

What is vial coring? And what are the risks?

Vial coring is when a small piece of a vial's rubber cap breaks off and gets into the vial itself and/or the fluid inside. This is generally caused by repeat insertion of needles through the vial cap.

There is not much clear evidence about the risks of vial coring but potential issues include the possibility of drawing up and injecting small pieces of rubber. This is not necessarily dangerous but probably best avoided.

Another issue is that the hole in the vial cap may be large enough that it stays permanently open and allows air, dust and other contaminants to enter the vial. It may also allow fluid to leak out if the vial is not kept upright.

Overall, while the risks associated with vial coring are not entirely clear, there are safeguards which are helpful and relatively easy to implement.

How to prevent coring

Approaches to reducing vial coring

People use a range of approaches when drawing medication from multi-dose vials. Practices often vary depending on needle type, needle gauge, medication viscosity, and individual technique. None of these methods completely eliminate coring, but they are used to reduce the likelihood of it happening.

Using thinner needles

One approach is to use narrower gauge needles, such as 25 gauge (thin) needles, when drawing medication. Whether this is possible depends on the carrier oil and viscosity of the medication.

When thinner needles are used, most people rotate puncture sites, while others reuse the same hole. Thinner needles create smaller punctures, which can help reduce the amount of rubber displaced and allow for more room on the stopper for multiple new punctures than a typical 18 gauge (thick) drawing needle.

Switching to blunt drawing needles

Another approach is to use a sharp needle for the first puncture of a new vial, then switch to blunt needles for later draws.

In this method, blunt needles would be reinserted through the same puncture site. They are commonly used to reduce the risk of accidental needle-stick injuries and can help keep the rubber at the puncture site taut, which some people find reduces coring.

45°-90° puncture technique

When inserting needles through the vial cap, you can use the 45°-90° puncture technique. This involves inserting the needle at a 45–60° angle with the opening of the needle tip facing up (i.e. away from the stopper). As the needle enters the vial, a small amount of pressure is applied as you slowly increase the needle to a 90° angle. The needle should be at a 90° angle just as the needle bevel passes through the stopper.

Check out the video below for a step-by-step tutorial on the above method: