9: Transdermal Delivery Systems Flashcards

1
Q

what is the difference between TDS and topical

A

TDS get into systemic circulation for widespread effects

topical = local effect only

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2
Q

list 3 advantages of TDS drugs

A
  • avoids deactivation
  • noninvasive
  • less frequent application
  • avoids interactions
  • effective for drugs that cause nausea
  • patient compliance
  • ease of removal
  • controlled release property
  • easily recognizable in emergency
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3
Q

what are some limitations of TDS

A
  • absorption of drugs from skin may be limited
  • dermatitis at site
  • lag time
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4
Q

the stratum corneum is made up of _____ ____ cells separated from each other by a _________

A

protein rich cells

thin layer of intercellular lipids

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5
Q

3 ways a drug can pass through the stratum corneum

A
  1. paracellular
  2. transcellular
  3. through hair follicles and sweat glands
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6
Q

what is the most important mechanism of percutaneous absorption

A

diffusion

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7
Q

what are the 3 characteristics that makes the best drug for TDS

A

low MW and melting point, moderate lipophilicity and excretion

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8
Q

3 parts of a TDS

A

backing membrane
adhesive layer
release liner

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9
Q

the backing membrane of a TDS must be

A

occlusive

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10
Q

what can the backing membrane be made of

A

propylene, polyethylene, and polyolefins

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11
Q

where is the drug contained layer located

A

between the backing membrane and adhesive layer

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12
Q

what is commonly used for the adhesive layer

A

polybutyl acrylate

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13
Q

which system is zero order release

  1. membrane controlled system
  2. monolithic system
A

membrane release system

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14
Q

if a membrane controlled patch is used right after manufacturing there will be a ________
if it is expired there may be a _________

A

lay time

dose dumping

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15
Q

what is the only factor we can change of a TDS for release

A

concentration of drug in reservor

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16
Q

the rate limiting membrane of membrane controlled systems are made of

A

polymers that slow down release of drug out of patch

17
Q

describe a monolithic system

A

drug is mixed with rate limiting membrane = no specific drug reservoir
- just backing, adhesive with drug, and release liner

18
Q

why do monolithic systems not have zero order release

A

because as time goes on, the distance of diffusion increases, and rate lowers

19
Q

reservoir systems can form _______ release while monolithic systems usually form _____ release delivery systems

A

controlled release

sustained release

20
Q

list the locations from best for worst for skin penetration

A

abdomen >forarm > instep >heel

21
Q

what are some chemical ways to enhance absorption

A
extraction of lipids
alteration of vehicle/ skin partitioning coefficient
disruption of lipid bilayer structure
displacement of bound water
loosening of horny cells
delamination of stratum corneum
organic solvents
oily structure
surfactant
propylene glycol
other drugs
22
Q

what are some physical absorption enhancers

A

iontophoresis
phonophoresis
electroporation

23
Q

what is iontophoresis

A

generating a constant but low voltage through 2 electrodes to push drug into skin

24
Q

how does phonophoresis/ sonophoresis work

A

forms bubbles inside skin and forms cavities inside lipid structure of stratum corneum = loosens it and drugs get better penetration

25
Q

what is electroporation

A

high voltage pulses in very short durations to help drug get into skin

26
Q

can nanodispersed systems get into skin

A

yes- small size and lipid structure + can change shape

27
Q

nanodispersed systems include

A

liposome
nanoemulsion
lipid nanoparticle

28
Q

name 5 quality control tests

A
  1. peal adhesion test
  2. release liner peel test
  3. tack test
  4. leak test
  5. seal integrity test
29
Q

what is the peal adhesion test

A

measures how well patch sticks to skin and comes off without leaving residue

30
Q

what is the release liner peel test

A

no adhesive sticking to lining + measures force needed to peel sample

31
Q

what is the tack test (rolling ball method and probe tack test)

A

ball = see how far ball rolls on the patch

tip test = see how much force it takes to take the tack off the patch

32
Q

what is the seal integrity test

A

patch is able to withstand a specific pressure without rupturing

33
Q

list 3 points of patient consultation

A
area of application
rotation around rec site of application
avoid wet/ oily sin or immediately after lotion
avoid hair
avoid parts of the body with high frequency of movement/ clothing rubs
don't touch adhesive layer
don't cut TD systems
patch should be folded to be discarded
34
Q

why should we rotate around recc site of application for transdermal delivery

A

Backing membrane of patches can hydrate the skin = structure of skin becomes different = higher absorption over time
Must give some time between applications to avoid tolerance

35
Q

T or F: you can shave the hair in an area to put patch on it

A

F- shaving right before can damage the stratum corneum and increase absorption

36
Q

what is an example of first generation TDS

A

drug loaded patches dependent on diffusion

37
Q

describe second generation TDS

A

noninvasive TDS with actuator

- pepetration enhancers

38
Q

describe third generation TDDS

A

microneedles, ultrasounds, electroporation, microdermbrasion, thermal ablation

stronger disruption of stratum corneum barriers