Drug-holding microneedle array and manufacturing method thereof
Inventors
Quan, Ying-shu • Kamiyama, Fumio • Yamada, Tomoya
Assignees
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Publication Number
US-12048824-B2
Publication Date
2024-07-30
Expiration Date
Abstract
The present invention provides a drug-holding microneedle array in which a drug is applied and held only on a tip portion of microneedles for quantitatively holding the drug and for preventing the drug from falling away during insertion of the microneedles.The drug-holding microneedle array comprises: a microneedle array having a microneedle substrate 4 and microneedles, the microneedles being positioned in plural on the microneedle substrate 4 and a tip portion 1 of the microneedles projecting via steps 2; and a drug held on the tip portion of the microneedles and the steps 2.
Core Innovation
The invention relates to a drug-holding microneedle array in which a drug is held on microneedle tip portions and on step regions, but not on the microneedle substrate. The microneedle tip portions project from root portions via steps, and the steps narrow a width of each microneedle from the root portion toward the tip portion at a plane where the tip portion meets the root portion.
The invention addresses a problem in which a drug solution shows a capillary phenomenon such that drug solution moves upward at the steps, causing drug falling away during skin insertion and loss of drug retention. The invention prevents this upward movement at the steps by forming the steps discontinuously while reducing a cross-sectional area, thereby improving drug retention and enabling quantitative drug delivery by holding a drug on the tip portions.
Geometric relationships defining the steps are provided, including defining a first width of the step as a distance along the plane where the tip portion meets the root portion from a center of the microneedle to an outer edge of the tip portion, and a second width as a distance along the same plane from the center to an outer edge of the root portion. A difference between the first width and the second width is set to be more than 10 bcm and less than 100 bcm, and in preferred ranges the difference is more than 14 bcm and less than 50 bcm.
Claims Coverage
The independent claim covers a manufacturing method for a drug-holding microneedle array that quantitatively fixes a drug administration amount by combining step geometry at the tip/root junction with a soaking-then-drying process using a drug aqueous solution. The inventive features include specific step-narrowing geometry constraints defined by first and second widths and their difference range.
Step-arranged tip/root narrowing geometry in a microneedle array
A microneedle array is prepared in which each microneedle has a tip portion projecting from a root portion via a step that narrows a width of the microneedle from the root portion to the tip portion, the step being arranged at a plane where the tip portion meets the root portion.
Quantitative fixation by soaking tip portions and pull-up drying
The tip portions of the microneedles are soaked into a drug aqueous solution, and the tip portions are pulled up and dried in order to hold a drug on the tip portions so that a drug administration amount is quantitatively fixed.
Width difference constraint of the step at the tip/root plane
A first width of the step is defined as a distance along the plane where the tip portion meets the root portion from a center of the microneedle to an outer edge of the tip portion, a second width of the step is defined as a distance along the plane where the tip portion meets the root portion from the center of the microneedle to an outer edge of the root portion, and a difference between the first width and the second width is more than 10 bcm and less than 100 bcm.
Drug aqueous solution including water-soluble polymer and/or low molecular weight saccharides
The soaking is performed using a drug aqueous solution that includes a water-soluble polymer, or a mixture of a water-soluble polymer and low molecular weight saccharides.
Preferred width difference range for the step
The difference between the first width and the second width is more than 14 bcm and less than 50 bcm.
Overall, the claim coverage centers on a drug-holding microneedle array manufacturing method that uses step-based narrowing at the tip/root plane, a soaking-then-drying process to quantitatively fix a drug administration amount on the tip portions, and a specified constraint on the difference between step-related first and second widths.
Stated Advantages
Prevents drug solution from moving upward at the steps during skin insertion, thereby preventing drug falling away.
Improves drug retention and enables quantitative drug delivery by holding a drug on the tip portions so that a drug administration amount is quantitatively fixed.
Documented Applications
Transdermal administration using the drug-holding microneedle array, with quantitative dosing and dissolution/administration observations on a parfilme skin model and pig skin.
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