By Tonya Chalfant, SME Process Engineer


Shelves of pharmacies and grocery stores are filled with liquids, from prescription medications to cosmetics. For consumer products, containers must be functional and visually appealing while pharmaceuticals must meet regulatory requirements and satisfy patients’ needs. To get all of these design aspects into a container and closure, product and user requirements must be identified and well understood. When selecting a container and closure for packaging your liquid product, be sure to keep these three categories in mind:

1. Ease of Use

A patient’s disease state and age range can influence the closure and bottle design. For example, medication targeted at treating arthritis pain needs to be easy to open for patients with decreased dexterity and hand strength. The consumer use case should be evaluated for ease of handling, space needed for storage during use, and increasing the overall consumer experience of the product. To quantify these attributes, market research or human factors studies can be important inputs into the packaging design. Also, spending time looking at similar products on the market can provide useful insights into options or areas for improvement that may give a product a competitive advantage.

2. Materials & Storage

Determining whether the product is sensitive to light, moisture, and oxygen will define the barrier properties required to ensure the quality of the product is maintained throughout the shelf life. Materials of construction for bottles include co-polymers, monolayer polymers, and glass that all can come in different sizes and neck finishes. Product compatibility with the bottle material of construction depends on whether the product is aqueous-based, contains solvents and/or flavorings, and the environmental exposure to temperature and humidity extremes during manufacturing, distribution, and consumer use.

Glass bottles provide an impermeable barrier with no interaction with the product. However, glass bottles are heavier than polymers, do not have as many shape options, and are at risk of breaking during filling and consumer use. Polymers have a large variety of shapes, are break resistant, can be optimized for the needed barrier properties, and, in general, are consumer preferred. For prescription pharmaceutical products, polymers can have challenges when evaluating for extractable components that may contaminate the product and create a patient safety concern. Pharmaceuticals can also have the added concern of maintaining sterility in the case of injectable or ophthalmic products. However, a large portion of consumer products, including many over the counter medications, only need to be considered clean and not sterile.

The size of the container is influenced by pricing, available shelf space, and intended use. In the case of prescription medications, the bottle volume can be determined based on the quantity that will be reimbursed through insurance plans.

3. Functionality in Dispensing

Closures can be child-resistant, include tamper evident bands or drop rings, induction heat seals, and have various foam liners to ensure seal integrity. Closures must be evaluated for thread alignment with the selected bottle neck, compatibility with the product contained, and long term shelf storage and in-use seal integrity. The application torque of the closure after filling in manufacturing will impact the seal integrity, engagement of any child resistance features, and the ease of opening experienced by the consumer. After the initial application torque, the relaxation of this torque will depend on the amount of thread overlap between the bottle neck threads and the closure internal threads. This interference can be determined using 3D modeling and measuring the differences in thread dimensions between bottle and closure. Manufacturing variability for the bottle and closure should be taken into account to ensure that full dimensional differences are analyzed during the design. Ideally, the bottle and closure will be designed in unison and from the same manufacturer to ensure the dimensions of the bottle and closure are optimized together. When a glass bottle must be used, additional leak studies at proposed storage conditions will need to be completed to ensure good seal integrity. Glass bottle threads tend to be rounded and have more dimensional variability when compared to polymer bottles. For these reasons, the plastic closures do not perform as well with glass bottles.

Overall, a well-designed bottle and closure can provide the protection your liquid product needs while improving the consumer experience. For more information, visit our manufacturing and packaging page or reach out to a member of our team for a free consultation on pharmaceutical manufacturing.

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