Dose Counting Inhalers

Inhalers are common for treatment of respiratory illnesses. They deliver steroids (e.g. prednisone) to treat inflammation and/or bronchodilator, to open up the airways.

Modern asthma inhaler designs have adapted to include dose counting features. This information is crucial to the user as it indicates if a medicine is being under- or over-used (which can pose respiratory health challenges), as well as indicating when an inhaler needs replacing.

The counting mechanism relies on a mechanical action that indexes when the asthma cylinder is depressed. Upon depression, a series of Delrin® SC acetal gears are rotated and this increases the count number. The devices need to be compact for handheld usage, which makes Delrin® SC an ideal polymer material due to its ability to perform with smaller and thinner parts. In addition, some dose counting inhaler designs have suffered from high friction issues, making it harder to both activate the inhaler and operate the counting mechanism. With Delrin® SC’s advanced low wear and friction properties (e.g. Delrin® SC 698), these forces are reduced and the product’s mechanisms can work more efficiently.

Delrin® SC is a medically approved portfolio of homopolymer acetal. Compared to acetal copolymer, Delrin® acetal homopolymer offers higher tensile strength, stiffness, creep and fatigue resistance, and significantly higher impact resistance. The extra mechanical properties of Delrin® allow for parts to be made thinner and smaller, whilst delivering the same performance of a thicker, less compact copolymer acetal moulding.

Spotlight on Delrin® SC:

• High rigidity / modulus
• Mechanical properties enable thinner wall sections
• Low wear and friction
• Excellent spring-like properties
• Medically approved

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