Evaluation of the Importance of Capsule Transparency in Dry Powder Inhalation Devices

Dear Editor,

We would like to express our appreciation for the recent article by Dr. Reinoso et al. [1], which evaluates the impact of transparent capsules on the residual weight after inhalation in patients with chronic airway diseases. This study sheds light on a rarely explored yet clinically relevant topic: the role of visual feedback as a verification mechanism for proper inhaled dose administration.

The finding that transparent capsules achieved a greater reduction in residual weight compared to opaque capsules not only suggests more efficient drug delivery but also potentially improves patient adherence and inhalation technique. However, we believe it would be valuable to expand the discussion on some additional aspects:

1) Patient Training: The study emphasizes the importance of inhalation technique training. Since correct inhaler use is fundamental for treatment efficacy, we are curious if the preference for transparent capsules might encourage patients to pay more attention to their inhalation technique, facilitating education and patient empowerment. It would be interesting to know if, during the retraining process prior to measurement, differences were noted in the ability to learn between patients using opaque versus transparent capsules.

2) Potential Cost-Effectiveness and Accessibility: One interesting aspect worth considering is the potential cost-effectiveness and accessibility of transparent versus opaque capsules. If transparent capsules are shown to enhance drug delivery and inhalation efficacy, it would be helpful to assess whether their use might also result in reduced medication waste, fewer exacerbations, or hospital admissions. Additionally, understanding any cost implications for both healthcare systems and patients would be important to ensure broad accessibility to this potential benefit.

3) Use in Different Populations: We understand the study focused on patients over 35 years old with chronic, non-reversible airway diseases. However, we wonder if these findings would be applicable to other populations, such as younger patients with asthma or intermittent bronchial diseases, who might equally benefit from the visual feedback provided by transparent capsules.

We thought this study offers valuable insight into the importance of inhaler design to optimize dose delivery and improve the management of chronic respiratory diseases. We encourage the authors and other researchers to continue exploring the clinical impact of inhalation technique and feedback mechanisms in various populations.

We are grateful for the opportunity to contribute to this discussion and congratulate Reinoso clinical team for their interesting work.

Reference:

[1] R.Reinoso Arija, R.R.-S. de la Espada, M.D.N. Ollero, L.C. Hernandez, E.Q. Gallego, J.L. López-Campos, Evaluation of the Importance of Capsule Transparency in Dry Powder Inhalation Devices, The Annals of Family Medicine 22 (2024) 417–420. https://doi.org/10.1370/afm.3147.