Abstract: Provided is a core-shell structure having an excellent immediate effect in transdermal absorption of an active ingredient. A core-shell structure comprising a core portion containing an active ingredient, and a shell portion containing a surfactant having an HLB value of 4 to 14, the core portion being solid, and the surfactant containing a saturated hydrocarbon group having 7 to 15 carbon atoms or an unsaturated hydrocarbon group having 7 to 17 carbon atoms.

Abstract: A particle comprising a first fraction containing an active ingredient and a second fraction containing a surfactant, and having a number average particle diameter of from 1 to 100 nm.

Abstract: The present invention provides a core-shell structure having high skin permeability. The core-shell structure includes a core portion containing a hydrophilic drug having a molecular weight of 400 or more; and a shell portion containing a surfactant, and the core portion is a solid, the hydrophilic drug has a water-octanol partition coefficient of ?3 or more and 6 or less, the surfactant has an alkyl group or an alkenyl group having 10 to 20 carbon atoms, and a mass ratio between the hydrophilic drug and the surfactant (hydrophilic drug:surfactant) is 1:5 to 1:20.

Abstract: Problem to be Solved There is provided a formulation including a particle containing an active ingredient and a surfactant, wherein morphological stability is excellent. Solution A particle containing an active ingredient, a surfactant and a pH adjuster.

Abstract: Provided are an active ingredient-containing particle with improved shape retainability. The particle includes a first fraction containing an active ingredient, a second fraction containing a surfactant, and at least one water-soluble polymer selected from the group consisting of a polysaccharide and a polymer having 2-methacryloyloxyethyl phosphorylcholine as a constituent unit.

Abstract: Provided is a core-shell structure having an excellent immediate effect in transdermal absorption of an active ingredient. A core-shell structure comprising a core portion containing an active ingredient, and a shell portion containing a surfactant having an HLB value of 4 to 14, the core portion being solid, and the surfactant containing a saturated hydrocarbon group having 7 to 15 carbon atoms or an unsaturated hydrocarbon group having 7 to 17 carbon atoms.

Abstract: An object is to provide a formulation that includes a particle containing an active ingredient and a surfactant, and a base, and is more excellent in storage stability. For solution, a formulation including a particle containing an active ingredient and a surfactant, and a base, in which the surfactant is contained in a ratio of 5 to 100 parts by weight based on 1 part by weight of the active ingredient, is provided.

Abstract: Provided are an active ingredient-containing particle with improved shape retainability. The particle includes a first fraction containing an active ingredient, a second fraction containing a surfactant, and at least one water-soluble polymer selected from the group consisting of a polysaccharide and a polymer having 2-methacryloyloxyethyl phosphorylcholine as a constituent unit.

Abstract: An object of the present invention is to prevent a particle including a first fraction containing an active ingredient and a second fraction containing a surfactant from bleeding out from the base phase of an external preparation. The external preparation comprises a particle including a first fraction containing an active ingredient and a second fraction containing a surfactant, and a base phase containing a gelatinous liquid component.

Abstract: The present invention provides a core-shell structure having high skin permeability. The core-shell structure includes a core portion containing a hydrophilic drug having a molecular weight of 400 or more; and a shell portion containing a surfactant, and the core portion is a solid, the hydrophilic drug has a water-octanol partition coefficient of ?3 or more and 6 or less, the surfactant has an alkyl group or an alkenyl group having 10 to 20 carbon atoms, and a mass ratio between the hydrophilic drug and the surfactant (hydrophilic drug:surfactant) is 1:5 to 1:20.

Abstract: A particle comprising a first fraction containing an active ingredient and a second fraction containing a surfactant, and having a number average particle diameter of from 1 to 100 nm.

Abstract: An object is to provide a formulation that includes a particle containing an active ingredient and a surfactant, and a base, and is more excellent in storage stability. For solution, a formulation including a particle containing an active ingredient and a surfactant, and a base, in which the surfactant is contained in a ratio of 5 to 100 parts by weight based on 1 part by weight of the active ingredient, is provided.