Method of fabricating microneedle patches
In the preferred embodiment, a method of making microneedles comprises i) providing a microneedle template ( 300 ) having a plurality of microneedles cavities ( 360 ) on one surface, ii) preparing a casting solution ( 320 ) comprising at least one matrix material and its solvent, iii) subjecting said microneedle template ( 300 ) to a vacuum pressure for a length of time to deprive it of air, iv) dispensing the casting solution ( 320 ) over the air-deprived microneedle template, v) allowing the casting solution ( 320 ) to be drawn into the air-deprived microneedle cavities ( 360 ) completely, and vi) allowing the dissolving microneedles to solidify or dry in a controlled environment.
1. A method of making dissolving microneedles, the method comprising:
a. providing a microneedle template comprising a plurality of microneedle cavities wherein the microneedle template is air permeable,
b. subjecting the microneedle template to a vacuum pressure and depriving the microneedle template of air,
c. preparing a casting solution comprising at least one matrix material and its solvent, and
d. removing the vacuum pressure and dispensing the casting solution over the microneedle cavities in the air-deprived microneedle template under atmospheric conditions.
2. A method of making dissolving microneedles in claim 1 , wherein the microneedle template is made of an air-permeable elastomer.
3. A method of making dissolving microneedles in claim 1 , wherein the microneedle template is made of polydimethylsiloxane.
4. A method of making dissolving microneedles in claim 1 , wherein the casting solution further comprising at least one active pharmaceutical ingredient.
5. A method of making dissolving microneedles in claim 1 , wherein the matrix material is selected from the group consisting of sodium hyaluronate and polyvinylpyrrolidone.
6. A method of making dissolving microneedles in claim 5 , wherein the solvent for the matrix material is water.
7. A method of making dissolving microneedles in claim 1 , wherein the matrix material is selected from the group consisting of sodium hyaluronate, polyvinylpyrrolidone, polyethylene glycol diacrylate and carboxymethyl cellulose.
8. A method of making dissolving microneedles in claim 1 , wherein the vacuum pressure subjected to the microneedle template is at least −0.3 bar to at least −1.0 bar relative to atmospheric pressure.
9. A method of making dissolving microneedles in claim 1 , wherein the vacuum pressure subjected to the microneedle template is at least −0.7 bar to at least −1.0 bar relative to atmospheric pressure.
10. A method of making dissolving microneedles in claim 1 , wherein the duration for subjecting the microneedle template to a vacuum pressure is at least 1- to at least 3 minutes.
11. A method of making dissolving microneedles in claim 1 , further comprising
a. a filling step wherein a length of time is allowed immediately after the dispensing step for the casting solution to fill up the microneedle cavities completely, and
b. a drying step wherein the filled microneedle template is placed in a controlled environment for a length of time to allow the dissolvable microneedles to solidify or dry.
12. A method of making dissolving microneedles in claim 11 , wherein the duration of the filling step is at least 1- to at least 3 minutes.
13. A method of making dissolving microneedles in claim 11 , wherein the controlled environment for the drying step has a temperature range of 15° C.-30° C.
14. A method of making dissolving microneedles in claim 11 , wherein the controlled environment for the drying step has a relative humidity of RH35%-RH65%.
15. A method of making dissolving microneedles in claim 11 , wherein the controlled environment for the drying step has a steady air flow.
16. A method of making dissolving microneedles in claim 11 , wherein the controlled environment for the drying step is under vacuum conditions.
17. A method of making dissolving microneedles in claim 11 , wherein the controlled environment for the drying is under pressurized conditions.