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Microneedle Transdermal Patch

microneedle
TEST PRINCIPLE
Determination of the mechanical strength of needles in microneedles transdermal patch by compression using a TA44 probe fitted to the CTX Texture Analyser.


BACKGROUND
Microneedle transdermal patches (Fig. 1) are the latest in drug delivery systems. They comprise hollow needles of micron size placed perpendicularly on a base plate. The drug or medicine is delivered through hollow needles. They can be directly placed at the site of injury or inflammation to induce faster and site-specific absorption of the drug or medicine. The test was conducted using the CTX Texture Analyser with a 5000 gm Load Cell. A TA44 probe (4 mm) was attached to the load cell to compress the probe into the microneedle patches to a set distance.

The amount of force required to break the needles is then measured. The needle patch is placed on the Fixture Base Table (TA-BT-KIT) (Fig. 2). As the probe slowly lowers onto the sample, it will compress the patch and break the microneedles. In this way, we will obtain the mechanical strength data of the microneedles in the microneedle transdermal patch
 

METHOD
Equipment:           CT3
  CTX Texture Analyser with a 5000 gm Load Cell (XCTX)
  Fixture Base Table (TA-BT-KIT)
  Standard Probe (TA44)
  Texture Pro Software (SWL-02-111)

Settings:
Test Type: Compression
Target Type:  Distance
Go to trigger value (Down):  1.0 mm/s
Go to target value (Down): 0.1 (mm/s)
End test (Up): 0.1 (mm/s)
Trigger load 1.00 g
Distance: 0.60 mm 


SAMPLE PREPARATION

Study samples included five batches of 6X6 mm transdermal patches with a needle height of about 0.6 mm. They were placed individually in the center of the Fixture Base Table (TA-BT-KIT) with the needles pointing upwards, aligned with the TA44 probe.


PROCEDURE
1. Attach the TA44 probe to the CTX Texture Analyser
2. Insert two table bolts into slots on the analyser base.
3. Place the Fixture Base Table on CTX and lightly screw the bolt nuts.
4. Adjust the table, so the probe is centered on the table.
5. Once the alignment is complete, secure the base table by tightening the bolt nuts.
6. Place the sample on the table and align the sample under the probe at the centre (Fig. 3)
7.Position the probe to about 5 mm above the sample.
8.Set the test parameters using the Texture Pro software.
9.Commence test
10.Repeat steps 1-9 for both patches.

Note: When optimizing the test settings, the hardest sample is best tested first in order to predict the maximum testing range for subsequent samples.

OBSERVATIONS
When a trigger load of 1.0 g is detected at the sample surface, the probe compresses the microneedles at a test speed of 0.1 mm/s over a specified distance of 0.6 mm. The probe returns to the starting position once the 0.6 mm distance is met