microneedles Flashcards

(15 cards)

1
Q

what advantages does drug delivery via microneedles have compared to oral and injection dosage forms

A

oral drugs: may have poor absorption, drug degradation in GI and liver
injection: painful and hard to use for patients themselves
microneedles, painless, ease of use by patients themselves, safer needle disposal eliminate spread of pathogens by reusing needles

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2
Q

how do microneedles deliver drugs

A

penetrate stratum cornerum into viable epidermis
- avoids contact with nerve fibres and blood vessels (in dermal later)
drug delivered here allowing movement from demise into body

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3
Q

4 types of MN

A

solid, coated, dissolving, hollow

MAIN: solid and hollow

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4
Q

what is photolithography

A

method of making silicone microneedles where light is used to etch shape of needles

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5
Q

describe the process of fabrication of solid microneedles

A

combo of photolithography and micro moulding
silicone mould made using photolithography and then this is filled using polymer melt or liquid monomers that are UV cureable

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6
Q

how are hollow microneedles made

A

uisng reactive ion etching or electroplating using master mould (electrochemical decomp of metal)

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7
Q

hollow microneedle fabrictaion:
describe the process in electoplating using a master mould

A
  • tapered holed are laser drilled through polymer to form mould
  • conductive later is deposited on side walls and top of mould
  • metal (usually nickel) electroplated onto seed layer
  • polymer mould removed to release metal hollow microneedles
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8
Q

hollow microneedles:
benefit and drawback of using two photon stereolithography

A

high resolution
more complex geometrical figures can be created

slow process means mass production is difficult

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9
Q

solid microneedles: how do they work

A

insert and remove microneedles to form microneedle pores in skin

drug can be applied to the skin to allow slow diffusion of drug through pores and into body

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10
Q

how do drug coated microneedles work

A

microneedles have been sprayed or dipped into drug needed

microneedles inserted into skin and drug is left behind

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11
Q

what are considerations needed when administering a drug using coated microneedles

A

MNs need sufficuent mechanical strength

controlled wetting and spreading of drug solution on microneedles

adhesion between drug and microneedle for insertion into skin

coating excipients should be safe

compatibility with drug

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12
Q

limitations of coated microneedles

A

small dose
loaded cargo may weaked MNs resulting in low penetration ability

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13
Q

considerations for drug encapsulated MNs

A

sufficient mechanical strength

thermosensitive should be encapsulated at moderate conditions

speed of dissolution determines the time microneedles need to be inserted into skin

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14
Q

what are hydrogel forming microneedles

A

where the drug is loaded into the backing membrane allowing sustained drug release

polymer swells as it takes up inerstitial fluid allowing drug permeation into skin

rate of drug delivery can be tuned by crosslink density in materual

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15
Q

advantaged and disadvantages of using hollow microneedles for infusion of liquid into skin

A

ad:
- control over amount and timing of drug
- separation of microneedles from drug during manufacturing
- use existing liquid formulations

dis:
- required drug reservoir, pump, microfluidic networs = expensive

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