Ethylcellulose

Ethylcellulose is widely used in oral and topical pharmaceutical

formulations.

The main use of ethylcellulose in oral formulations is as a

hydrophobic coating agent for tablets and granules.. Ethylcellulose coatings are used to modify the release of a drug, to mask

an unpleasant taste, or to improve the stability of a formulation; for

example, where granules are coated with ethylcellulose to inhibit

oxidation. Modified-release tablet formulations may also be

produced using ethylcellulose as a matrix former.

Ethylcellulose, dissolved in an organic solvent or solvent

mixture, can be used on its own to produce water-insoluble films.

Higher-viscosity ethylcellulose grades tend to produce stronger and

more durable films. Ethylcellulose films may be modified to alter

their solubility, by the addition of hypromellose(16) or a

plasticizer; see Section 18. An aqueous polymer dispersion

(or latex) of ethylcellulose such as Aquacoat ECD (FMC

Biopolymer) or Surelease (Colorcon) may also be used to produce

ethylcellulose films without the need for organic solvents.

Drug release through ethylcellulose-coated dosage forms can be

controlled by diffusion through the film coating. This can be a slow

process unless a large surface area (e.g. pellets or granules compared

with tablets) is utilized. In those instances, aqueous ethylcellulose

dispersions are generally used to coat granules or pellets.

Ethylcellulose-coated beads and granules have also demonstrated

the ability to absorb pressure and hence protect the coating from

fracture during compression.

High-viscosity grades of ethylcellulose are used in drug microencapsulation.

Release of a drug from an ethylcellulose microcapsule is a

function of the microcapsule wall thickness and surface area.

In tablet formulations, ethylcellulose may additionally be

employed as a binder, the ethylcellulose being blended dry or wetgranulated with a solvent such as ethanol (95%). Ethylcellulose

produces hard tablets with low friability, although they may

demonstrate poor dissolution.

Ethylcellulose has also been used as an agent for delivering

therapeutic agents from oral (e.g. dental) appliances.

In topical formulations, ethylcellulose is used as a thickening

agent in creams, lotions, or gels, provided an appropriate solvent is

used. Ethylcellulose has been studied as a stabilizer for

emulsions.

Ethylcellulose is additionally used in cosmetics and food

products.

Table I: Uses of ethylcellulose.

Use Concentration (%)

Microencapsulation 10.0–20.0

Sustained-release tablet coating 3.0–20.0

Tablet coating 1.0–3.0

Tablet granulation 1.0–3.0