Table 1.

Characteristics of commercially available EC *.

Organic EC products

Ethocel™

Available in many varieties that differ in grade and viscosity (e.g., Ethocel™ Standard Grade 4 Premium, 7 Premium, 10 Premium, 20 Premium, 45 Premium, 100 Premium). Ethocel™ are white to light-tan granular powders in physical appearance with bulk density and specific gravity of about 0.4 g/cm3 and 1.12–1.15 g/cm3 respectively and glass transition temperatures range between 129 and 133 °C. They dissolve in a wide range of solvents such as aliphatic alcohols, chlorinated solvents, and natural oils. They are practically insoluble in glycerin, propylene glycol, and water. Films made from Ethocel™ are tough, with high tensile strength and high flexibility even at low temperatures. They can be combined with water soluble polymers such as methylcellulose and hypromellose (HPMC) in aqueous coating liquids. They are characterized by thermoplastic nature and ability to soften at 135–160 °C which makes them versatile in pharmaceutical hot melt extrusion processes. They ensure desired drug release properties and improved bioavailability of especially poorly soluble drugs [12].

Aqualon™ ethylcellulose

During preparation, the substitution of ethoxyl groups is controlled to obtain commercially useful range of 48–52% ethoxyl (or 2.3–2.6 ethoxyl groups out of a theoretical maximum of 3.0) per anhydroglucose unit. Over this ethoxyl range, Aqualon™ ethylcellulose is classified into three ethoxyl types: N (low substitution), T (mid substitution), and X (high substitution). The improved compressible grade (Aqualon™ T10) was developed with optimized compactability (high ethoxyl content and low viscosity) and good powder flow. The grades of Aqualon™ ethylcellulose are compliant with the monograph requirements of the United States Pharmacopoeia (USP) and the European Pharmacopoeia (Ph. Eur.) [24].

Aqueous dispersion of ethylcellulose

Surelease®

Surelease® is a family of fully formulated, aqueous dispersion products which constitute plasticized aqueous dispersions of EC with 25% (w/w) solid content available in four types: E-7-19029, E-7-19030, E7-19040, E-7-19050. They are plasticized (depending on type) with dibutyl sebacate (3.5%-E-7-19029, E-7-19030) and oleic acid (1.9%-E7-19040). Surelease® is produced in the following steps: EC is blended with plasticizer, then extruded and melted. The molten plasticized EC is then directly emulsified in ammoniated water in a high-shear mixing device under pressure. Ammonium oleate is formed in situ in order to stabilize and form the dispersion of plasticized EC particles. Then, purified water is added to achieve the final solids content. Applications of Surelease® include beads and particles coating, matrix granulation (the dispersion can be used as a binder in wet granulation for the production of free-flowing granules, which can subsequently be compressed into tablets), taste-masking coating, or nutritional enteric coating [25].

Aquacoat® ECD

It contains primarily EC with a surfactant and a stabilizer from the emulsion stage (sodium lauryl sulfate (SLS) and cetyl alcohol (CA)). Depending on type it consists of EC (24.5–29.5%), CA (1.7–3.3%), and SLS (0.9–1.7%). Traces of dimethylopolysiloxane to enhance foaming during distillation may also be present. EC is dissolved in a water-immiscible organic solvent with CA addition as a dispersion stabilizer. The solution is then emulsified into an aqueous SLS solution. The resulting crude emulsion is homogenized to yield a submicron emulsion which is then distilled to remove the organic solvent and water to yield a solid dispersion. EC is present in the dispersion as spherical particles in the size range of 0.1–0.3 μm. It exists as a milky white liquid with the characteristic odor of EC. Product does not contain plasticizer. Recommended plasticizers include dibutyl sebacate, acetylated monoglycerides, triacetin or glyceryl triacetate, acetyltriethyl citrate, and triethyl citrate. It is used for the aqueous film coating of solid dosage forms to extend drug release, taste mask, or to protect against moisture [26].

* The table presents examples of selected, most commonly used, products.