Provided is a method for producing HPMCP capable of reducing the average particle size of HPMCP particles to an intended range without a pulverization step. Specifically provided is a method for producing hypromellose phthalate, comprising an esterification step of reacting hypromellose with an esterification agent in the presence of a catalyst to obtain a reaction solution containing crude hypromellose phthalate, a precipitation step of mixing the reaction solution with water to precipitate the crude hypromellose phthalate, thereby obtaining a hypromellose phthalate suspension, a liquid removal step of removing a liquid from the hypromellose phthalate suspension with a centrifugal decanter to obtain liquid-removed hypromellose phthalate, and a drying step of drying the liquid-removed hypromellose phthalate.

Provided is a method for producing HPMCAS capable of reducing the average particle size of HPMCAS particles to an intended range without a pulverization step. Specifically provided is a method for producing hypromellose acetate succinate, comprising an esterification step of reacting hypromellose with an esterification agent in the presence of a catalyst to obtain a reaction solution containing crude hypromellose acetate succinate, a precipitation step of mixing the reaction solution with water to precipitate the crude hypromellose acetate succinate, thereby obtaining a hypromellose acetate succinate suspension, a liquid removal step of removing a liquid from the hypromellose acetate succinate suspension with a centrifugal decanter to obtain liquid-removed hypromellose acetate succinate, and a drying step of drying the liquid-removed hypromellose acetate succinate.

Esterified cellulose ethers which comprise (i) groups of the formula C(O)RCOOA or (ii) a combination of aliphatic monovalent acyl groups and groups of the formula C(O)RCOOA, wherein R is a divalent aliphatic or aromatic hydrocarbon group and A is hydrogen or a cation, which have a viscosity of up 50 mPa.Math.s, measured as a 10 wt % solution of the esterified cellulose ether in acetone at 20 C., and a weight average molecular weight M.sub.w of at least 220,000 Dalton, or which have a viscosity of up 100 mPa.Math.s, measured as a 10 wt % solution of the esterified cellulose ether in acetone at 20 C., and a weight average molecular weight M.sub.w of at least 310,000 Dalton are useful for preparing solid dispersions comprising drugs.

Esterified cellulose ethers which comprise (i) groups of the formula C(O)RCOOA or (ii) a combination of aliphatic monovalent acyl groups and groups of the formula C(O)RCOOA, wherein R is a divalent aliphatic or aromatic hydrocarbon group and A is hydrogen or a cation, which have a viscosity of up 50 mPa.Math.s, measured as a 10 wt % solution of the esterified cellulose ether in acetone at 20 C., and a weight average molecular weight M.sub.w of at least 220,000 Dalton, or which have a viscosity of up 100 mPa.Math.s, measured as a 10 wt % solution of the esterified cellulose ether in acetone at 20 C., and a weight average molecular weight M.sub.w of at least 310,000 Dalton are useful for preparing solid dispersions comprising drugs.

Esterified cellulose ethers comprising groups of formula C(O)CHRCHRCOOA, wherein, R and R are hydrogen or (S)m(R.sup.1)n-R.sup.2, wherein R.sup.1 is a hydrocarbon group having 1 to 4 carbon atoms, R.sup.2 is an optionally substituted 5- or 6-membered cyclic group, m and n each independently are 0 or 1, and A is hydrogen or a cation, with the proviso that in each group CHRCHR one of R and R is hydrogen and the other one is (S)m(R.sup.1)n-R.sup.2, are useful as excipients for maintaining the concentration of poorly water-soluble drugs in aqueous liquids at supersaturation levels.

Esterified cellulose ethers comprising groups of formula C(O)CHRCHRCOOA, wherein, R and R are hydrogen or (S)m(R.sup.1)n-R.sup.2, wherein R.sup.1 is a hydrocarbon group having 1 to 4 carbon atoms, R.sup.2 is an optionally substituted 5- or 6-membered cyclic group, m and n each independently are 0 or 1, and A is hydrogen or a cation, with the proviso that in each group CHRCHR one of R and R is hydrogen and the other one is (S)m(R.sup.1)n-R.sup.2, are useful as excipients for maintaining the concentration of poorly water-soluble drugs in aqueous liquids at supersaturation levels.

Provided are hypromellose acetate succinate (HPMCAS) which exhibits high solubility and can suppress generation of undissolved materials when dissolved in a solvent; an HPMCAS-containing composition; and a method for producing the HPMCAS. More specifically, provided are HPMCAS having a ratio of 2-position MS to 3-position MS of 1.2 or less, wherein the 2-position MS means a molar substitution of hydroxypropyl group by which a hydrogen atom of a hydroxyl group on 2-position carbon of each glucose unit of the HPMCAS has been directly replaced, and the 3-position MS means a molar substitution of hydroxypropyl group by which a hydrogen atom of a hydroxyl group on 3-position carbon of each glucose unit of the HPMCAS has been directly replaced; a composition comprising the HPMCAS and a solvent; and the method for producing the HPMCAS.

Provided are hypromellose acetate succinate (HPMCAS) which exhibits high solubility and can suppress generation of undissolved materials when dissolved in a solvent; an HPMCAS-containing composition; and a method for producing the HPMCAS. More specifically, provided are HPMCAS having a ratio of 2-position MS to 3-position MS of 1.2 or less, wherein the 2-position MS means a molar substitution of hydroxypropyl group by which a hydrogen atom of a hydroxyl group on 2-position carbon of each glucose unit of the HPMCAS has been directly replaced, and the 3-position MS means a molar substitution of hydroxypropyl group by which a hydrogen atom of a hydroxyl group on 3-position carbon of each glucose unit of the HPMCAS has been directly replaced; a composition comprising the HPMCAS and a solvent; and the method for producing the HPMCAS.

A process for fractionating an esterified cellulose ether comprising groups of the formula C(O)RCOOH, wherein R is a divalent hydrocarbon group, comprises the steps of a) blending the esterified cellulose ether comprising groups of the formula C(O)RCOOH with an aqueous liquid and setting the temperature of the resulting blend to less than 10 C. to dissolve a portion of the esterified cellulose ether in the aqueous liquid, b) separating the non-dissolved portion of the esterified cellulose ether from the remainder of the blend, and c) recovering or disposing of the esterified cellulose ether that is dissolved in the aqueous liquid.

A process for fractionating an esterified cellulose ether comprising groups of the formula C(O)RCOOH, wherein R is a divalent hydrocarbon group, comprises the steps of a) blending the esterified cellulose ether comprising groups of the formula C(O)RCOOH with an aqueous liquid and setting the temperature of the resulting blend to less than 10 C. to dissolve a portion of the esterified cellulose ether in the aqueous liquid, b) separating the non-dissolved portion of the esterified cellulose ether from the remainder of the blend, and c) recovering or disposing of the esterified cellulose ether that is dissolved in the aqueous liquid.