Skin external preparation and skin irritation-reducing method
Provided is a skin external preparation including a drug and nanometer-size molecular assemblies. The molecular assemblies contain an amphiphilic block copolymer having a hydrophilic block chain including a sarcosine-derived structural unit and a hydrophobic block chain including a hydroxy acid-derived structural unit. The skin external preparation according to the present invention may reduce skin irritation caused by the drug, be very safe, and have excellent pharmacological effects, even when a drug that is generally difficult to be transdermally administered due to its strong skin irritation is contained therein.
1. A method for reducing skin irritation caused by a drug, comprising:
administering, to a subject in need of the drug, a skin external preparation comprising the drug, and an amphiphilic block copolymer having a hydrophilic block chain including sarcosine monomer units and a hydrophobic block chain including hydroxy acid monomer units,
wherein the drug is one of a statin and an Alzheimer-type dementia treatment drug.
2. The method of claim 1 , wherein the amphiphilic block copolymer forms a molecular assembly.
3. The method of claim 1 , wherein the hydrophilic block chain has 20 or more of sarcosine monomer units.
4. The method of claim 1 , wherein the hydrophobic block chain has 10 or more of hydroxy acid monomer units.
5. The method of claim 1 , wherein a hydroxy acid of the hydroxy acid-derived structural unit is lactic acid.
6. The method of claim 1 , wherein the amphiphilic block copolymer is represented by formula (3),
where R1 is a hydrogen or a methyl group, R2 is a single bond or methylene group, R3 is a divalent hydrocarbon group having 1 to 6 carbons, m is an integer in a range of 20 to 200, and n is an integer in a range of 10 to 100.
7. The method of claim 2 , wherein the molecular assembly and the drug coexist in a mixed state.
8. The method of claim 2 , wherein a region containing the molecular assembly and a region containing the drug are present in the skin external preparation.
9. The method of claim 6 , wherein in the formula (3), m is an integer of 30 to 150, and n is an integer of 15 to 80.
10. The method of claim 1 , wherein the molecular assemblies have an average particle diameter in a range of 15 to 60 nm.
11. The method of claim 1 , wherein the molecular assemblies have an average particle diameter in a range of 20 to 45 nm.