Polymethacrylates

• BPMethacrylic Acid–Ethyl Acrylate Copolymer (1:1)
• JPMethacrylic Acid Copolymer L
• JPMethacrylic Acid Copolymer S
• JPMethacrylic Acid Copolymer LD
• JPAminoalkyl Methacrylate Copolymer E
• Ph. Eur.Methacrylic Acid–Ethyl Acrylate Copolymer (1:1)
• Ph. Eur.Methacrylic Acid–Methyl Methacrylate Copolymer (1:1)
• Ph. Eur.Methacrylic Acid–Methyl Methacrylate Copolymer (1:2)
• Ph. Eur.Ammonio Methacrylate Copolymer (Type A)
• Ph. Eur.Ammonio Methacrylate Copolymer (Type B)
• Ph. Eur.Basic Butylated Methacrylate Copolymer
• USP–NFMethacrylic Acid and Ethyl Acrylate Copolymer
• USP–NFMethacrylic Acid and Methyl Methacrylate Copolymer
• USP–NFAmmonio Methacrylate Copolymer
• USP–NFAmino Methacrylate Copolymer

Acryl-EZE; Eastacryl 30D; Eudragit E 100; Eudragit E PO; Eudragit L 100; Eudragit L 100-55; Eudragit L 30 D-55; Eudragit S 100; Eudragit FS 30 D; Eudragit RL; Eudragit RS; Eudragit NE 30 D; Kollicoat MAE 30 DP; methacrylic acid copolymers; E1205 (basic methacrylate copolymer); E1206 (neutral methacrylate copolymer); E1207 (anionic methacrylate copolymer)

Synthetic cationic, anionic or neutral copolymers of dimethylaminoethyl methacrylate, methacrylic acid and methacrylic or acrylic acid esters, in varying ratios · [—]

Polymer, mixture or material of variable composition — no single molecular formula applies.

Coating agent, film former, Release-modifying polymer

Typical concentrations: — · Dosage forms: Solid

Used mainly as film coatings for oral tablets, capsules, pellets and granules: the aminoalkyl (basic) copolymer for taste masking, moisture protection and immediate-release coats; the methacrylic acid copolymers for enteric and colon-targeted coatings; and the insoluble ammonio methacrylate and neutral ester copolymers for pH-independent sustained-release coats. They are also used as matrix formers and binders and in hot-melt extrusion and solid dispersions. Coating levels typically correspond to a weight gain of a few percent up to about 10–20%, with plasticisers such as triethyl citrate commonly added at about 10–25% of the dry polymer.

A family of synthetic polymers based on methacrylic acid, its esters and acrylic esters. Their solubility behaviour is set by the functional groups: free carboxyl groups make them dissolve in intestinal fluid, dimethylaminoethyl groups make them dissolve in gastric acid, and quaternary ammonium or purely ester groups give insoluble, permeable films. The solid grades are white powders or granules with a faint characteristic odour; the dispersions are milky-white liquids of low viscosity.

Dissolution pH (anionic types)

methacrylic acid–ethyl acrylate (1:1) above about pH 5.5; methacrylic acid–methyl methacrylate (1:1) above about pH 6.0; (1:2) above about pH 7.0

Dissolution pH (cationic type)

basic butylated (amino) methacrylate copolymer dissolves in gastric fluid up to about pH 5 and swells above this

Permeability (insoluble types)

ammonio methacrylate copolymers and neutral ester dispersions are insoluble and swell independently of pH; type A (RL) is more permeable than type B (RS)

Supply forms

powders, granules, organic solutions (12.5%) and aqueous dispersions (about 30% solids)

Solubility (solid grades)

soluble in acetone and in alcohols such as isopropanol; the ionisable types dissolve in water only in the appropriate pH range

Solid grades are stable when stored below about 30 °C in a well-closed container. Aqueous dispersions must be protected from freezing and from high temperatures (typically stored at about 5–25 °C), since freezing or overheating causes irreversible coagulation; they also need protection from microbial contamination.

Aqueous dispersions can be coagulated by electrolytes, pH changes, some organic solvents and extremes of temperature. Some types interact with ionic drugs (for example anionic drugs with the cationic types), which can change film permeability or drug release, and excessive amounts of certain pigments or talc can destabilise dispersions.

Made by free-radical emulsion or solution polymerisation of the chosen monomers. Emulsion polymerisation gives aqueous latex dispersions directly; solid grades are obtained from these by spray drying or by solution polymerisation followed by drying and granulation, and some powders are redispersible after partial neutralisation.

Polymethacrylate copolymers are widely used in oral products and are regarded as non-toxic and non-irritant; the polymers are not absorbed from the gastrointestinal tract. Residual monomers are limited by the pharmacopoeias because the monomers themselves are irritant.

Observe normal precautions for the quantity handled. Avoid inhalation of dust and contact with the eyes; organic solutions are flammable and need explosion-proof equipment and good ventilation.

Included in the FDA Inactive Ingredient Database (oral capsules and tablets, including delayed- and extended-release forms, and transdermal systems) and in non-parenteral medicines licensed in Europe. In the EU, basic, neutral and anionic methacrylate copolymers are authorised for coating food supplements (E1205, E1206 and E1207).

Cellulose acetate phthalate; hypromellose phthalate; polyvinyl acetate phthalate; shellac.

The pharmacopoeial names, the old 'Type A/B/C' labels and the Eudragit codes do not map one to one, so the exact grade should always be specified. Aqueous dispersions need a plasticiser and coating temperatures above their minimum film-forming temperature, and coated products often require curing to give stable release; mixing the RL and RS types lets the permeability of sustained-release films be adjusted.