Up to Exam 1

Question 1

Transdermal Drug Delivery Systems

Answer 1

rely on passive diffusion of API molecules across layers of skin to produces therapeutic concentrations in systemic circulation

Question 2

Advantages of Transdermal Drug Delivery Systems

Answer 2

delivery location easily accessible
avoid 1st pass metabolism and variables associated with PO delivery
enables sustained drug delivery; provides constant plasma concentrations
reduced dosing frequency
reduced side effects associated with peaks/troughs in plasma concentrations over time
non-invasive; suitable for long-term treatment
delivery easily stopped by patch removal

Question 3

Disadvantage of transdermal delivery systems

Answer 3

limited to drugs having specific physiochemical properties
API has to be able to penetrate the stratum cornerman
limited to potent drugs
intra- and inter-patient variability skin permeability is affected by disease state/ application site quality
skin irritation and sensitization
api-specific counseling instructions associated with proper use/disposal may be ignored; results in toxic/fatal consequences

Question 4

What 3 routes deal with penetration of the skin?

Answer 4

appendegeal route
intracellular route
transcellular route

Question 5

Surface

Answer 5

mainly local
barriers/repellents
sunscreens
antimicrobials/antiseptics

Question 6

Local

Answer 6

Corticosteroids
cytotoxics
antiviral
antihistamines
anaesthetics

Question 7

Appendegeal

Answer 7

antimicrobials
depilatories

Question 8

Systemic

Answer 8

hormones
antiemetics
opioids
antihypertensives
anticoagulants
antipsychotics
antidepressants

Question 9

NSAIDS are delivered to the

Answer 9

deep tissues

Question 10

Stratum Corneum

Answer 10

2 phase layer of corneocytes surrounded by a lipid matrix
10-15 layers of corneocytes; lipid layer
dry skin: 10-15 um; hydrated skin 40 um

Question 11

What is the hydrous layer of skin?

Answer 11

Dermis
matrix of loose connective tissue, fibrous protein, and collagen embedded in water-containing ground substance
3-4mm
blood capillaries extend into dermis

Question 12

intercellular route

Answer 12

molecule diffuses entirely through lipid matrix at a rate proportional to its lipophilicity

Question 13

Transcellular Route

Answer 13

molecule diffuses mainly through hydrous corneocytes or entirely through overlapping corneocytes

rate is proportional to hydrophilicity

Question 14

Percutaneous diffusion is rate-limited by

Answer 14

the slowest permeation step

Question 15

Stratum cornerman provides the xxxx xxxx to diffusion

Answer 15

greater resistance

Question 16

What are examples of properties that a drug must have to be suitable for transdermal delivery?

Answer 16

predominantly uncharged
low molecular weight and melting point
adequate solubility in both liquid and aqueous environments
high potency

Question 17

How can permeation by an API be improved for transdermal delivery?

Answer 17

Drug-Based
Vehicle-based
stratum corneum modifications

Question 18

Chemical Permeation enhancers

Answer 18

excipients that reversibly decrease the barrier function of the stratum corneum to promote skin penetration

are pharamcologically inactive, non-toxic, non-irritating, non-allergenic, compatible with other formulation components, rapidly enhance permeability, and allow for recovery of the skin after removal

Question 19

Prodrug enhancement

Answer 19

add a functional group to improve solubility in delivery fluid. moiety is metabolized in body to yield api

Question 20

What is an example of a vehicle based approach to modify transdermal delivery?

Answer 20

API enclosed in phospholipid vesicle having a greater affinity for the stratum corneum

Question 21

Hydration modification for transdermal delivery

Answer 21

excess water at to subcutaneous layer by soaking skin, occlusion with ointments/emulsions, dressings etc.

transcellular diffusion enabled by overlap of corneocytes

Question 22

What are some examples of chemical permeation enhancers?

Answer 22

fatty acids
azone
surfactants
terpenes
alcohols
pore-forming peptides

Question 23

microneedle patches

Answer 23

array of micrometer-sized needles that penetrate the stratum corneum into the viable epidermis, producing micro channels

needles can prime to skin and be removed or biodegrade
drug eludes from hollow cores