Core Annular Injection Flow for High-Viscosity Drug Delivery
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Solution Overview
Problem
Existing injection devices struggle to deliver high-viscosity fluids, such as high-concentration protein formulations, due to the high molecular weight and viscosity of these fluids, requiring excessive injection force and being unsuitable for subcutaneous delivery by conventional syringes.
Innovation Solution
The use of core annular flow in injection devices, where a high-viscosity fluid is surrounded by a low-viscosity fluid to create an annulus, reducing the injection force required by lubricating the flow and enabling delivery through conventional syringes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional injection devices are used to deliver high-viscosity protein formulations, then the therapeutic can be administered subcutaneously, but the injection force required exceeds the capacity of most devices
Solution Approach 1:
A lubricating fluid with lower viscosity than the protein formulation is introduced between the high-viscosity formulation and the needle/barrel surfaces. This intermediary fluid reduces friction and shear stress, enabling delivery of high-concentration formulations with forces within device capacity.
Solution Approach 2:
The viscosity parameter of the fluid system is modified by introducing a lubricating fluid with different (lower) viscosity characteristics. This creates a viscosity gradient that reduces the overall resistance to flow during injection.
2Ease of operation
If silicone oil is used to lubricate the syringe barrel and plunger interface, then friction is reduced, but the lubricant can migrate into and contaminate the protein formulation
Solution Approach 1:
The lubrication function is segmented into two separate zones: a first lubricant at the plunger-barrel interface and a second lubricant in the flow path. This segmentation prevents the first lubricant from contaminating the formulation while still providing friction reduction.
Solution Approach 2:
A second lubricating fluid acts as an intermediary barrier between the protein formulation and the syringe walls, preventing direct contact and potential contamination while maintaining lubrication function.
3Quantity of substance
If protein concentration is increased to reduce injection volume, then the amount of fluid to be injected is reduced, but the viscosity increases making delivery difficult
Solution Approach 1:
The lubricating fluid serves as a mediator that enables high-concentration formulations to be delivered without requiring excessive injection force, thus allowing volume reduction while maintaining force within acceptable limits.
Solution Approach 2:
The injection system uses a composite fluid system combining the protein formulation with a lubricating fluid, creating a multi-phase system that delivers both high concentration and low resistance to flow.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method significantly reduces the pressure needed for injection, allowing for the delivery of high-viscosity fluids like protein formulations with concentrations up to 500 mg/ml within 30 seconds or less, using existing syringe technologies.
Implementation Method 1
a low-viscosity fluid which surrounds the high-viscosity fluid in an annulus to reduce the injection force required
Implementation Method 2
core annular flow is used to deliver such viscous fluids
Data Source
AI summary
Core annular flow is used to enable the subcutaneous delivery of a viscous fluid such as a protein therapeutic formulation. The high-viscosity fluid is surrounded by a low-viscosity fluid, and the low-viscosity fluid lubricates the passage of the high-viscosity fluid. This allows the use of protein formulations that have a higher concentration and a higher viscosity at comparatively reduced injection forces and reduced injection times. Several different embodiments of injection devices that provide core annular flow are described herein.