TG 227 ea Propellant Suspension Stability
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Solution Overview
Problem
Existing pharmaceutical metered-dose aerosol propellants, such as chlorofluorocarbons, have ozone-damaging potential, necessitating the development of alternative propellants that can stabilize suspensions of active substances for inhalable aerosols effectively.
Innovation Solution
The use of 1,1,1,2,3,3,3-heptafluoropropane (TG 227 ea) or 1,1,1,2-tetrafluoroethane (TG 134 a) as propellants, optionally mixed with other gases, in combination with chemically bound water, to stabilize suspensions of active substances like anticholinergics and steroids for inhalable aerosols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chlorofluorocarbons are used as propellants, then suspension stability is achieved, but ozone layer damage occurs
Solution Approach 1:
The invention changes the chemical composition parameters of the propellant from ozone-damaging chlorofluorocarbons to environmentally friendly alternatives (TG 227 ea and/or TG 134 a). This parameter change maintains suspension stability through careful formulation while eliminating the harmful ozone layer impact, directly resolving the technical contradiction between reliability and environmental harm.
Solution Approach 2:
The invention adopts alternative propellants that are environmentally acceptable substitutes for depleting ozone-layer chemicals. These alternative propellants provide the necessary functional performance for a limited period (the product lifecycle) without causing long-term environmental damage, effectively replacing harmful substances with benign alternatives.
2Object-affected harmful factors
If alternative propellants TG 227 ea or TG 134 a are used, then environmental harm is reduced, but suspension stability is compromised
Solution Approach 1:
The invention introduces water as an intermediary substance in the propellant formulation. Water acts as a mediator that enables the alternative propellants TG 227 ea and/or TG 134 a to stabilize suspensions effectively. This intermediary component facilitates the interaction between the alternative propellant and the active substance suspension, resolving the stability issue while maintaining environmental benefits.
Solution Approach 2:
The invention creates a composite propellant system combining alternative propellants (TG 227 ea and/or TG 134 a) with water and other compatible substances. This composite formulation leverages the synergistic effects of multiple components to achieve suspension stability that neither the alternative propellant nor water could achieve alone, while maintaining environmental compatibility.
3Reliability
If water is added to alternative propellant formulations, then suspension stability is improved, but formulation complexity increases
Solution Approach 1:
The invention optimizes the water content parameter within specific ranges (0.1-10% by weight) to achieve maximum suspension stability. By carefully controlling this parameter and combining it with alternative propellants, the formulation achieves reliable performance without requiring overly complex formulation strategies, balancing stability improvement with formulation simplicity.
Data Source
AI summary
Disclosed are propellant gas formulations containing at least one suspended active substance which contains chemically bound water, water and the propellant TG 227 or TG 134 a.