The global market for glass pharmaceutical containers is projected to exceed $10.5 billion within the next three years, solidifying glass as arguably the most widely used primary packaging material for injectable drug products.

In pharma manufacturing, the performance of the primary packaging is critical to ensuring drug product stability, safety and efficacy. Pharmaceutical grade glass vials are widely used for parenteral therapies, however, not all glass vials offer the same performance, especially for small volume parenterals, or SVPs, which are defined as <= 100mL. A primary distinction is whether a vial is made by converting previously produced glass tubing, or whether it is moulded directly from the glass furnace.

SVP Vials

Tubular vials are produced in two separate consecutive manufacturing operations. First, a glass tube with the desired outer diameter (OD) and internal diameter (ID) is drawn from a glass furnace, hardened, and cut into lengths of approximately two metres. Then in a separate operation, usually in a different factory, these tubes are converted into vials by heating and forming the vial opening (known as the finish), the vial shoulder, and then the vial heel, before remelting the glass to close the bottom of the vial. For tubular vials, this remelting process can alter the glass composition in specific areas, particularly at the bottom and heel. Tubular vials are well known for their high optical quality and uniform wall thicknesses, most commonly in the 0.8–1.2 mm range.

In contrast, moulded vials are formed in a single melting process. Molten glass exits the furnace with the consistency of thick honey, but at temperatures exceeding 1,500⁰C. The molten glass flows through a round orifice where the stream is cut into individual “glass gobs”, each equal to the weight of the vial it will form. These gobs are guided by gravity into a two-stage moulding process where the vial takes shape. The glass transitions from a molten state at over 1,000°C to a fully formed vial at around 600°C in under ten seconds. Since moulded vials are not remelted, they exhibit exceptionally high interior surface homogeneity. Moulded vial wall thicknesses are almost always greater than 1 mm, and typically ranging from 1.2–1.8 mm, and they are renowned for strength and lower susceptibility to breakage.