What Is the Difference Between a Vial & an Ampule?

Ampules and vials rest on the shelves of pharmacies or chemical laboratories. Both types of containers play an active role in storing chemical fluids or solids that will be mixed with others or delivered to a patient. Although both refer to glass or sometimes plastic vessels, they benefit from different designs and serve different purposes.

Ampule

An ampule typically indicates a sealed glass container that holds some pharmaceutical compound. This device is sealed to protect its content from air or humidity. The closure of the small container results from melting the tip of the ampule. Its opening requires breaking the neck of the bottle.

Vial

Vials come in all forms and sizes.

A vial represents a broader term than an ampule. It includes any small container that holds pharmaceutical or chemical compounds. Typically made of glass, the vial can be sealed or not sealed. The vessel closes with a screw on cap, or a rubber plug. Sometimes, its top includes a dropper to measure the liquid to retrieve. The vial tends to have a flat bottom so that it can rest on a counter.

Potency Protection

Ampules are often purged from air before being sealed.

Chemical elements that tend to be unstable in the presence of air or another compound remain intact and keep their potency when stored in an ampule. Frequently, drug manufacturers will pull the air out of an ampule before sealing it to prevent the medication from degrading within the container. A vial is typically not hermetic and best contains stable compounds.

Reuse

An ampule opens by breaking its neck.

Since the ampule opens with a break of its shell, this container is not reusable. At times, snapping off of the ampule may be challenging and at times present risk of injury according to Ron Stoker, Executive Director of the International Sharps Injury Prevention Society. In contrast, a vial can be cleaned and reused several times and presents less risk of injury.

Volume Measurement

Accurate measurements from an ampoule is performed with a syringe.

The container of an ampule experiences slight variations in its internal volume. This results from the sealing process that melts the glass. Typically, a syringe with volume indicators pulls some fluid from the ampule to size the required amount of medication. In contrast, a vial can provide accurate volume markings that become visual indicator of the remaining volume of product.

Mixing

Vials lend themselves to the mixing of compounds.

Vials act as convenient containers to mix several chemical compounds together. Through their glass walls, the resulting compounds feature their consistency and colors. The broken glass edge of opened ampules presents the risk of introducing small glass debris into a mixture of chemical elements and therefore do not lend themselves to mixing products.

References

• Innovation in Pharmaceutical Technology; Glass: Applications in Pharmaceutical Packaging (.pdf); Jochen Alberstetter and Claudia Roth; Mar. 15, 2010
• Managing Infection Control: Safety in the Hospital Pharmacy; Ron Stocker; Jun. 2007
• The Glass Museum:Apothecary Glass: David W. Barker
• Managing Infection Control: Preventing Injuries from Glass Ampoule Shards; Ron Stocker; Oct. 2009

Resources

• "Pharmaceutical Packaging Handbook"; Edward Bauer; 2009