5 Things to Consider when Choosing a Vial for Drug Development

What are the challenges when choosing a vial?

Choosing a vial which is right for your product and project can be extremely important and surprisingly complex. This container will have direct contact with your drug formulation throughout its shelf life, so it is important to ensure compatibility at the earliest opportunity.

In our experience many start-ups don’t even consider what container to store their product in until much later in development, and yet this simple oversight can drastically alter the course of their drug discovery project, potentially resulting in costly revalidation work and increased time-to-market. This is why here at Adelphi Healthcare Packaging we specialise in helping you to specify the right packaging for your project from the very earliest stages of development. This includes discussing your product’s properties, sensitivities and fill volume, among other specifications.

Vials come in many materials, shapes and sizes, each serving a different purpose. Variants include neck finish, vial capacity, glass type and special features, such as internal coatings.

Parenteral drugs are typically filled into vials made from Type I glass. Type I is a pharmaceutical grade, borosilicate glass with a high melt point and excellent chemical resistance. However, not all drugs are compatible with standard glass vials, and later we evaluate potential alternatives.

Numerous considerations need to be taken into account, from vial integrity to storage conditions, and it can be a challenging process for any researcher or startup to find the ideal packaging.

In this article we will look at 5 things you need to consider before deciding which container is best suited to your project and why.

Drug composition

One of the first challenges is understanding the composition of your drug and how this might impact its compatibility with the vial. Drug composition refers to the chemical makeup of your formulation. A particularly aggressive formulation, for example, might react with or delaminate the internal surface of the container it is packaged within. For this we need to consider the following factors:

pH Level

pH is a measure of the acidity or alkalinity of a solution. It quantifies the concentration of hydrogen ions (H+) in a liquid, and is used to determine how acidic or basic (alkaline) that solution is. The pH scale ranges from 0 to 14, with 7 being considered neutral.

When it comes to vials, the pH level of your product can impact its compatibility with the container. If your formulation is more alkaline or acidic the wrong container choice could result in potential delamination or damage to the vial’s surface, leading to an unexpected leachables and extractables profile.

Type I, neutral, borosilicate glass is characteristically resistant to chemicals, however, for preparations outside of the 3-7 pH range a standard Type I Glass vial may struggle, making it either entirely unsuitable or dramatically affecting shelf life.

In these cases, we would recommend the use of a vial with an inert internal coating which will minimise interaction between the drug and its container. Products to consider depending on which side of the pH scale your product sits, include the SCHOTT Type 1 Plus® Vials, the SCHOTT EVERIC® care and EVERIC pure vials.

Request samples to test compatibility with your product: Contact Us.

Drug sensitivity

This concerns how reactive your product is to the composition of the glass itself. Glass contains a number of ingredients, and on testing your formulation you may discover sensitivities to some of these elements. Some examples include:

• Metals: these are elements, typically aluminum (Al₂0₃) that can possibly leach into the product depending on the chemical composition of your drug.
• Trace elements: this includes rarer metals such as iron and boron that can be picked up in the forming of the container. This has the potential to transfer into the product, leading to a loss of stability and a change inefficacy and shelf life.

If your product reacts with elements in the glass matrix, there are still suitable options available. These include glass vials with an inert internal coating, such as the SCHOTT Type I Plus® vial which features an internal surface of silicone dioxide (Si02), providing an effective barrier between your product and the potential extractables of the vial. Another benefit of a vial with a silicone dioxide coating is that there is no need for re-registration from a standard Type I glass vial. Alternatively, a pharmaceutical grade polymer vial, like the West/Daikyo Crystal Zenith vials are metal-free by design, have clarity comparable with glass. and provides additional benefits in areas such as cold storage.

Photosensitivity

Exposure to light is a concern to those developing drugs prone to photodegradation. Photodegradation is the process whereby a ray of external light (natural or artificial) changes the chemical composition of a product after a sustained period. This can affect the efficacy of the API and reduce shelf life. If photosensitivity is an issue for your product, it is advisable to use a container with UV blocking properties, such as an amber glass vial.

You’ll find most glass vials on the market are available in both clear and amber glass. Examples include: Standard Injection Vials, which can also be offered in a sterile format.

Drug storage and administration

Other factors to assess when selecting a drug container may include the state in which your product should be stored, as well as considerations relating to optimisation at the point of administration. For example, with high value or low-fill formulations you will want to ensure full extraction is possible, and for products which struggle to remain stable in a liquid state, you may need to consider options such as freeze drying.

Lyophilisation

Lyophilisation (freeze drying) is a process where the state of a liquid drug is changed to a solid, usually resulting in a dry powder. The process is separated into three distinct phases (Annealing, Sublimation, and Absorption) with the aim of drawing out as much water from the drug as possible. The benefit of freeze drying your drug is that it prolongs shelf life and inhibits reactive characteristics. At the time of administration by a medical professional the dried drug is reconstituted into a liquid form, ready for injection.

If you are planning to freeze dry your product, the first thing you need to consider in your container is whether the vial provides good thermal transfer through the shelf of the lyo chamber. Tubular glass vials are preferable to moulded in this instance, as they feature a consistent thin base for optimal heat transfer.

A common challenge when freeze drying a drug product within a vial is product creep. This can happen in the case of proteins which tend to cling to the walls of the vial, affecting the results achieved. To avoid this phenomena you can opt for a container with a hydrophobic internal coating, such as the SCHOTT TopLyo® vial or the EVERIC® care vial. This will ensure all liquid remains at the bottom of the vial, increasing the probability of a neat lyo cake and maximum removal of the reconstituted product.

Visit our Information Centre for more Tips on Freeze Drying in the Vial.

Recoverability of High Value / Low Fill Drugs

Recoverability refers to the ease by which you can remove the entire contents of the container prior to administration. This is especially important for high value drugs, where the need to discard unused residual product could be extremely costly, and for low-fill drug preparations where it is crucial to administer the full dose. Often in cases such as these drug manufacturers are forced, by necessity, to overfill vials in order to ensure sufficient product can be drawn up into a syringe.

Fortunately, solutions do exist to help in these situations. For example vials with a hydrophobic internal coating, such as the TopLyo® or EVERIC® care vial, ensure liquid does not adhere to glass, but instead always runs to the base of the vial. In the case of low-fill drugs of 1ml or less, we recommend the use of a 2ml vial with a hydrophobic coating, which can be tilted to guide all of the liquid drug into the heel of the vial for easiest extraction by needle.

Conclusion

Selecting the right vial for your drug is a critical process with profound implications for your drug discovery project. We’d like to emphasise the importance of early consideration in the selection process to avoid potential setbacks such as increased time-to-market and costly revalidation work. The considerations in choosing a vial involve factors such as drug composition, pH level, sensitivity to elements in the glass matrix, photosensitivity, and suitability for lyophilisation.

Adelphi Healthcare Packaging specialises in guiding clients through these considerations from the earliest stages of development, ensuring compatibility and optimal packaging choices for their specific needs.