Ethylcellulose Controlled-Release Coatings Without Post-Curing
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Solution Overview
Problem
Existing controlled release dosage forms using ethylcellulose coatings require additional processing steps like high humidity and heat treatment, which increase production time and equipment requirements, and organic solvent-based coatings pose environmental and safety concerns.
Innovation Solution
A method using an aqueous suspension comprising ethylcellulose, an ionic surfactant, and a coalescing agent with an HLB value of 3 to 8, eliminating the need for high humidity and heat treatment, and employing organic esters like propylene glycol monolaurate or sorbitan monooleate to form a controlled release coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If organic solvent-based coatings are used to form controlled release dosage forms, then coating stability is improved, but environmental pollution and safety concerns increase
Solution Approach 1:
The patent changes the solvent parameter from organic to aqueous, transforming the coating formulation from organic solvent-based to water-based. This parameter change eliminates the harmful environmental and safety issues associated with organic solvents while maintaining coating stability through the use of latex or pseudolatex dispersions and appropriate coalescing agents.
2Stability of the object's composition
If additional processing steps like high humidity and heat treatment are employed, then storage stability of ethylcellulose coatings is improved, but production time and equipment requirements increase
Solution Approach 1:
The patent extracts and eliminates the need for separate high humidity and heat treatment steps by incorporating the necessary components directly into the coating formulation. The aqueous dispersion contains ethylcellulose, plasticizer, and coalescing agent in a single formulation that forms a stable coating upon application without requiring subsequent specialized processing steps.
Solution Approach 2:
The patent merges the coating formulation and curing process into a single step. The aqueous dispersion with ethylcellulose, plasticizer, and coalescing agent is applied and forms a stable coating directly, combining what were previously separate processes (coating application, humidity treatment, and heat treatment) into one integrated operation.
3Ease of manufacture
If coalescing agents with HLB value of 3 to 8 are used in aqueous dispersions, then controlled release coating is formed without additional curing steps, but this is unexpected and may affect coating impermeability
Solution Approach 1:
The patent specifies a particular HLB value range (3 to 8) for the coalescing agent, which is a parameter change that enables the aqueous dispersion to form a stable coating without additional curing steps. This specific parameter range balances the hydrophilic and hydrophobic properties needed for proper coating formation while maintaining controlled release characteristics.
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
The method achieves effective controlled release without specialized equipment or additional processing steps, maintaining stability and reducing environmental impact, while providing consistent drug release profiles.
Implementation Method 1
the coatings resulting from such formulations are generally designed to be impermeable... U.S. Pat. No. 4,629,753 (Quinn) discloses compositions suitable for forming impermeable coatings or films based upon aqueous polymeric dispersions (including ethylcellulose), which dispersions may optionally contain coalescing agents
Implementation Method 2
aqueous suspension comprising (i) water; (ii) ethylcellulose; (iii) an ionic surfactant; and (iv) a coalescing agent
Data Source
AI summary
In one aspect, the present invention is directed to a method of making a controlled release solid dosage form having an ethylcellulose coating layer, which layer comprises a coalescing agent which is an organic ester having an HLB Value of from 3 to 8. The use of such coalescing agent permits the formation of an effective controlled release coating without the need for a further curing step after the coating process. In other aspects, this invention relates to an aqueous dispersion useful in such method; as well as to the coated dosage form produced.