Transdermal drug delivery is a convenient method of administering drugs that diffuse through the skin. Ethylene-vinyl acetate copolymers (EVA) can play multiple roles in the design and construction of a transdermal patch or film, and have a long history of use in approved and marketed products, such as patches that delivery nicotine and estradiol.
Transdermal patches are often multi-layer structures consisting of a backing layer, a drug-loaded matrix layer, an optional rate-limiting membrane for controlling drug release, and an adhesive. EVA can be effectively used in the backing, drug matrix, and rate-limiting membrane layers of a transdermal patch.
The drug-loaded matrix of a transdermal patch commonly consists of active pharmaceutical ingredient and additional penetration enhancers dissolved or dispersed in EVA. These systems are frequently put together using solvent-based processes, so working with high vinyl acetate copolymers that readily dissolve in selected organic solvents is important when developing a scalable product; easier dissolution is generally experienced with high (~40% vinyl acetate) copolymers.
In some applications, the rate of drug delivery is controlled by inserting a rate-limiting membrane between the drug-loaded matrix and the adhesive. EVA can be effectively used in this layer as well, where the ability to select different EVA comonomer compositions can be used to tune the system to deliver a drug at the targeted rate.
Celanese has a broad range of Ateva® EVA G-CP and VitalDose® EVA products suitable for transdermal drug delivery – including high vinyl acetate copolymers for drug matrices - and provides a full regulatory support packages to customers seeking regulatory approval.
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