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Challenges and Development Perspectives of Primary Packaging for Parenteral Drugs

When talking about parenteral drugs, we usually refer to the administration of drugs by injection through the integument or directly into the circulation.

The parenteral route – it could be intradermal, subcutaneous, intramuscular, or intravenous – indeed allows a rapid effect, the administration of orally inactivated drugs, rapid intervention in emergencies, and the administration of nutritional solutions to patients who cannot feed themselves normally.

The most common parenteral drugs are injectables, therapy drugs administered by professional users in healthcare facilities, such as vaccines or IVs, and infusional, mostly complementary solutions used as adjuvants for such therapies.

When it comes to packaging to contain such drugs, it is composed of an integrated system featuring the primary packaging properly said, a vial or a bottle, a rubber stopper, and a basic or tear-off aluminum gear.

Vials are manufactured in glass, with different material specs and manufacturing technologies available, and different features that can better adapt to the drugs’ characteristics and challenges.

Glass specs depend on the characteristics the material should have to better contain drugs: Type I is borosilicate glass, featuring an enhanced mechanical resistance and a high degree of hydrolytic stability, making it ideal to contain all types of injectable products with acid, neutral or slightly alkaline pH.

Type II is a soda-lime glass that achieves the performances required by the international pharmacopeia for parenteral applications through appropriate surface treatment, and it is particularly suitable for packaging injectable and non-injectable preparations with acidic and neutral solutions.

Finally, Type III is a low alkaline sodium calcium glass with good hydrolytic resistance, particularly when it comes to sudden temperature changes. These features make it ideal for non-aqueous or powdered injectable preparations, excluding drugs that must undertake a freeze-drying process.

As said, the glass used to contain parenteral drugs might come from two different manufacturing technologies: premium molded glass and tubing glass.

The first ones are obtained from an improved molding process known as press and blow. Glass is melted into a furnace at over 1600°C, extruded and then blown into a high-precision mold by using mechanical tools (a piston) and a jet of hot air. In just one single process, the melted glass is transformed into a parenteral vial ready to be supplied to pharmaceutical companies or CMOs.

This process is intended for the production of premium borosilicate glass, the golden standard for parenteral and injectable pharmaceutical applications.

On the other hand, tubing glass containers require a two-step process. They are produced by transforming a glass pipe into a vial by means of localised flames and through a number of steps to give the desired shape.

Given these different possibilities, the pharma manufacturer might choose the better option for any application, considering multiple elements such as:

• The heat used when forming the vials directly affects the level of extractable at the surface due to the vaporisation of the more volatile elements of glass and to the condensation of vapors on the inner and colder surface, which produces “rough spots”, chemically different from the rest of the surface

• Premium molded vials are mechanically and chemically superior, while tubing vials perform better in terms of the aesthetic quality of the surface. Differences in other tested aspects are negligible.

• The bigger the format in which the drug must be contained, the more molded glass vials are to be considered as an option due to their mechanical performances; the smaller, the more tubing glass vials are to be preferred