Transdermal

Question 1

what are the main layers in the skin?

Answer 1

dermis and hypodermis

Question 2

what’s the main role of hypodermis?

Answer 2

insulation and protect against mechanical strength

Question 2

what’s the main components of dermis? & why may that be significant?

Answer 2

its made out of collagen and elastin dispersed in a gel, Maintaining the strength

Question 3

what environment does the dermis sit in?

Answer 3

hydrophilic environment

Question 4

what happens when mechanical strength isn’t absorbed by the hypodermis?

Answer 4

causes the capillaries to burst = blood accumulation = bruising

Question 5

what is the hypodermis also known as?

Answer 5

subcutaneous layer

Question 6

what is the major barrier for absorption in the skin?

Answer 6

hypodermis

Question 7

what are some main components found within the skin?

Answer 7

• eccrine sweat gland
• muscle
• hair follicles with Sebaceous glands
• meissner corpuscle
• pacini corpuscle
• blood vessels found in the dermis

Question 7

what does the eccrine sweat gland do?

Answer 7

release sweat to regulate heat to control body temperature

Question 8

what is the function of the blood vessels in the skin?

Answer 8

vasodilation to dissipate heat to control body temperature; vice versa.

Question 9

what is the function of the muscles in the skin?

Answer 9

responsible for goose bumps

Question 10

what is the function of the sebaceous glands?

Answer 10

formation of sebum

Question 11

what is the function of the meissner corpuscle in the skin?

Answer 11

sensing touch

Question 12

what is the function of the pacini corpuscle in the skin?

Answer 12

sensing pressure

Question 13

what does the epidermis protect you from?

Answer 13

• trauma
• chemicals
• sun rays
• too much water / heat

Question 14

what’s the difference between the epidermis and dermis in relation to size?

Answer 14

epidermis thinner than the dermis

Question 15

what are the main layers of the epidermis (from young/bottom to old/top)?

Answer 15

base layer, prickle cell layer, granular layer, horny layer

Question 16

how long does it take for the base layer to mature and migrate to the horny layer?

Answer 16

a month

Question 17

what happens to the shape and structure of the cells as the base layer migrates and matures into the horny layer?

Answer 17

loses general shape of the cell,

cell loses it nucleus as the out layer is composed of dead cells

Question 18

what cell types are found within the base layer? and what do they do?

Answer 18

keratinocytes (main type); melanocytes (produce melanin) and langerhan cells (T cell response for an immune response)

Question 19

what cell types are found within the prickle cell layer? and what do they do?

Answer 19

mainly keratinocytes and some langerhan cells (for immune response) and some desmosome junctions to hold cells together

Question 20

why may regeneration for the epidermis take longer? and where may this take place?

Answer 20

if it recieves a lot of friction;

palms of the hand/ soles of the feet

Question 21

under what conditions does the regeneration of the epidermis occur at a faster rate?

Answer 21

dandruff and psoriasis

Question 22

what are the two layers of the horny layer ? what environment do they have?

Answer 22

lipid based ‘mortar’ - lipophilic
protein based ‘brick’ - hydrophilic (formed by keratin)

Question 23

when are medicated plasters used?

Answer 23

for local effect to mainly target nerve endings in the dermis, must still be able to pass through the dermis

Question 24

what are some examples of medicated plasters?

Answer 24

Question 25

what are the features of nails?

Answer 25

keratinised tissue (80% hard keratin)

Question 26

what are some examples of topical treatments used for the nail?

Answer 26

- fungal infections - nail psoriasis

Question 27

what problems are associated to nail topical treatment?

Answer 27

difficult to drug deliver, therefore weeks of treatment may be necessary in order to see any results

Question 28

what is the first barrier for drug formulations crossing the skin?

Answer 28

epidermis - stratum corneum (outer layer of the epidermis)

Question 29

what are the advantages of transdermal drug administration?

Answer 29

Avoids all the disadvantages of the oral route! Non-invasive and ease of administration Controlled release Low frequency of administration Drug administration can be stopped quickly Easy to identify in cases of emergency self administration without training needed

Question 30

why can the drugs effects still be felt after the removal of the transdermal patch?

Answer 30

as the drug accumulates and forms a reservoir within the stratum corneum which allows drug absorption to continue

Question 31

what are the disadvantages of transdermal drug administration?

Answer 31

Not suitable for “bolus’’ Only suitable for potent drugs -active at doses < 10 mg/day ...with the right properties! Skin sensitisation/irritation Skin first-pass effect still possible for some drugs -Pre-systemic metabolism -Less extensive than from GIT - Likely minor role in drug elimination from patch -Mostly in the viable epidermis - CYT P450 and other metabolic enzymes - not used in emergencies big portion of the drug remains within the patch

Question 32

why can't non-potent drugs be used for transdermal use?

Answer 32

due to the drug being non-potent, a large volume of drug would be needed to reach therapeutic effects, this will cause the drug packaging to become too large = a low patient compliance

Question 33

what do conditions such as psoriasis do?

Answer 33

increase a thickness of stratum corneum affecting the drug permeation

Question 34

what's the anatomical variation of skin thickness (from the highest permeability to the lowest)?

Answer 34

Epigenital region Scalp, head and neck Trunk (chest, belly, back) Arms/Legs Palms/soles

Question 35

what are the physicochemical properties that are desired for transdermal drug delivery?

Answer 35

MW 100-800 Da (ideal <400-500) 1

Question 36

what does ethanol do within transdermal formulations?

Answer 36

permeation enhancement leaves a film on the skin upon evaporation

Question 37

label the following

Answer 37

Question 38

how is inter patient variability minimised within reservoir patches?

Answer 38

by the rate controlling polymer membrane

Question 39

why may there be drug present on the adhesive layer of a reservoir patch? what is the importance?

Answer 39

due to the diffusion/saturation to the adhesive layer during storage causes dose dumping = overdose as the drug is absorbed instantly

Question 40

what is the release rate typically like for a reservoir patch?

Answer 40

zero order due to being controlled by changing the properties of the membrane

Question 41

label the following

Answer 41

Question 42

what are features of a matrix layered patches?

Answer 42

have one or more layers drug may be dissolved or suspended in a polymer matrix

Question 43

what is the release rate typically like for a matrix patch?

Answer 43

drug dissolved in a polymer matrix - first order drug suspended in a polymer matrix - zero order

Question 44

what is the release rate typically like for drug in adhesive layer?

Answer 44

typically first order - patient variability

Question 45

what advice would you give to your patient who is using transdermal patches?

Answer 45

Instructions provided in the PIL - Alternate sites of application - May need to cut hair (do not wet-shave or use hair-removal cream) - Skin should be clean, not too oily, not irritated, broken or callused Do not cut or modify the patch Remove carefully, taking care not to touch the adhesive Press firmly against the skin, hold in place for a few seconds Place where it won’t be rubbed off by friction Can generally be left while bathing/swimming/showering Sensitivity/intolerance/irritation can happen After removal, fold in half so that the adhesive layers stick together Residual drug may be toxic to children and pets Provide advice if patch falls off or was not replaced in time Lag time to onset Remove before MRI - Backing layer may contain metal

Question 46

what are the ways we can physically enhance permeation of transdermal patches?

Answer 46

Iontophoresis sonophoresis micro- and nanoparticles micro needles

Question 47

how does iontophoresis enhance permeation?

Answer 47

using a small electric current to support drug transport

Question 48

how do ionised drugs move in iontophoresis?

Answer 48

by electrostatic repulsion drug reservoir is placed under the electrode with the same charge as the drug - the repulsion drives diffusion of the drug through the skin

Question 49

how do neutral drugs move in iontophoresis? and when is it used?

Answer 49

by electro-osmosis movement of water and neutral molecules with migrating ions - used for glucose monitoring 'reverse' iontophoresis

Question 50

how does sonophoresis work?

Answer 50

using ultrasound enhanced drug transport by causing vibrations in the skin and temporarily increasing the pore size between cells allowing an increase in drug absorption

Question 51

what are some examples where sonophoresis works?

Answer 51

lidocaine salicylic acid - gels, creams and lotions

Question 52

how does micro and nanoparticles work for enhancing permeation?

Answer 52

Targeted delivery through hair follicles thru Microparticles: reservoir effect and sustained drug release Liposomes and derivatives - increase permeation