| 摘要 |
Capsules formed by coating particulate materials with a substance comprising a gelable hydrophilic colloid by a process involving liquid-liquid phase separation are rendered less permeable by spray drying a dispersion of the coated material in a liquid having a pH between 4 and 6. The coating material may be a single gelable colloid, e.g. gelatine or it may additionally comprise other colloid material, e.g. partially or completely hydrolysed styrenemaleic anhydride copolymer, gum acacia, sodium alginate, sodium carboxymethyl cellulose or carbohydrate acetate phthalates. The particulate material may be a lipophilic solid, an oil, or an oil-in-hydrophilic liquid or hydrophilic liquid-in-oil emulsion. Prior to spray drying, the capsules may be hardened, e.g. by treatment with formaldehyde, a dicarbonyl compound, tannic acid or an alum. Specific examples refer to the spray-drying of capsules including those containing: (a) an aqueous suspension of caffeine-in-mineral oil emulsion (sustained action oral stimulant), (b) aqueous sulphanilamide solution-in-lanolin emulsion (ointment ingredient); (c) particles of mercuric oxide coated with glyceryl mono-stearate (veterinary anthelmintic), and (d) aqueous chloral hydrate-in-mineral oil (sustained action sedative). Specifications 751,600, 911,483, 929,402, 929,404, 929,405, 929,406, 929,407, 929,408 and 929,409 are referred to. |
