Modeling cavitation bubble dynamics in an autoinjector and its implications on drug molecules

Area of Science:

• Fluid dynamics
• Biophysics
• Materials science

Background:

• Protein aggregation in drug delivery devices is a significant concern.
• Cavitation bubble collapse is an identified mechanism for inducing protein aggregation.

Purpose of the Study:

• To investigate the dynamics of cavitation bubbles in autoinjectors.
• To understand the role of bubble collapse in protein transport and aggregation.

Main Methods:

• Axisymmetric, three-dimensional simulation.
• Use of passive tracers to model protein molecule transport.

Main Results:

• Bubble collapse concentrates proteins in a re-entrant jet, leading to wall adsorption and aggregation.
• Bubble dynamics (radius, jet velocity, pressure) are influenced by parameters like distance from wall, air pressure, liquid height, and nucleus size.
• Bubble breakup generates smaller bubbles with high protein concentration, promoting bulk aggregation.

Conclusions:

• Cavitation bubble collapse is a critical factor in protein aggregation within autoinjectors.
• Controlling bubble dynamics is essential for preventing protein adsorption and aggregation in drug formulations.