Related Experiment Video
Updated: Sep 2, 2026

Dry Powder and Nebulized Aerosol Inhalation of Pharmaceuticals Delivered to Mice Using a Nose-only Exposure System
Published on: April 6, 2017
Comparing a Fixed and Freely Rotating Capsule in a Dry Powder Inhaler Under Realistic Breathing Conditions
Karan Shrivastava1, Ajit Kumar2, Somashekhar S Hiremath1
1Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, Tamil Nadu, 600036, India.
Purpose:
To investigate the performance of a capsule-based dry powder inhaler (DPI) under two device configurations - free-axis and fixed-axis capsule rotation - across steady-state and transient inhalation profiles.
Method:
Two new research-based transparent capsule-based DPI were developed-one with a fixed capsule rotational axis and another with a floating capsule configuration. High-speed imaging was used to capture capsule motion, and the effects of flow regimes (laminar, transient, and turbulent), capsule rotation, and breathing profiles on capsule RPM, wall collisions, and powder retention were analyzed.
Conclusions:
Fixed-axis rotation significantly outperformed free-axis rotation (~ 6 × higher RPM and lower powder retention). Higher flow rates and faster-accelerating transient profiles increased RPM and collision frequency, enhancing drug release. Fixing the rotational axis of the capsule had the greatest benefit for the slow inhalation profile. The findings offer key insights for the design of future capsule-based DPIs.
Related Concept Videos
Inhaled Medications
Application of Integration: Problem Solving
Pulmonary Ventilation: Inhalation
Boyle's law becomes particularly pertinent when examining respiratory...
One-Compartment Open Model for IV Bolus Administration: Estimation of Clearance
In the one-compartment open model for intravenous (IV) bolus administration, clearance is estimated by dividing the elimination rate by the plasma drug concentration. This equation leverages the elimination rate constant and the apparent...

