Term
What are the 3 layers of the skin?
Which is the main barrier to drug absorption? |
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Definition
Epidermis, Dermis, and Subcutaneous
Stratum Corneum in the epidermis |
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Term
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Definition
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Term
| What contents are located in the dermis? |
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Definition
| Blood vessels, collagen and elastin |
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Term
| What role does the subcutaneous layer play in the skin? |
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Definition
Cushion for the dermis and epidermis
Collagen fibers from the dermis thread btwn fat cells |
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Term
| What is percutaneous absorption? |
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Definition
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Term
What are the surface effects of transdermal application?
Give examples |
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Definition
Protective: sunscreen (Zinc Oxide)
Occlusive: Hydrocarbon film to reduce moisture loss or enhance uptake |
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Term
T/F
Local effects of transdermal appl. mean that the drug is absorbed into the blood |
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Definition
FALSE
little or no drug is absorbed into the systemic circulation |
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Term
Surface/Local/Systemic
a) Sunscreen
b) keratolytic agents
c) skin moisturization
d)estrogen patch |
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Definition
a) Sunscreen- Surface
b) keratolytic agents- Local
c) skin moisturization-Local
d)estrogen patch- Systemic |
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Term
What is the slowest step in percutaneous absorption?
Can this be changed? If so how? |
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Definition
Passage through the stratum corneum
Can be moderated by influencing the SC |
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Term
| How do you calculate the diffusion coefficient? |
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Definition
lag time= thickness of membrane
6* D
tl= h2
6*D |
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Term
| What instrument is used to measure drug transport? |
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Definition
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Term
| What factors affect drug absorption? |
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Definition
Skin Hydration and temperature
permiation enhancers
Stratum corneum barrier efficacy and dermal clearance
Cutaneuos biotransformation |
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Term
T/F
Taking water out of the skin causes it to loose its permability |
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Definition
TRUE
Hydration is important for hydrophilic molecules |
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Term
How do permation enhancers affect....
a) hydration
b) lipoprotein matrix
c) driving force of drug molecule |
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Definition
Increase hydration
Decrease consistency of lipoprotein matrix
Increase the driving force of drug molecule |
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Term
| What are the 3 categories f permeation enhancers? |
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Definition
Chemical agents
Iontophoresis
Sonophoresis |
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Term
| How do propylene glycol and dimethyl sulfoxide agents work? |
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Definition
They are chemical agents that increase permeation
Propylene Glycol increases hydration
DMSO decreases the consistency of the lipoprotein matrix |
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Term
What is Iontophoresis?
What are some examples? |
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Definition
Elecrtic field drives a charged molecule into the skin
Lidocaine, dexamethasone, insullin, verapamil, propanolol |
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Term
What is sonophoresis?
Examples? |
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Definition
using high frequency ultrasound to drive molecules across the skin
Hydrocortisone, Lidocaine, Salicylic Acid |
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Term
| What factors affect barrier efficacy and dermal clearance? |
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Definition
Barrier Efficacy- age, skin type and condition
Dermal clearance- dermal blood perfusion, and age |
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Term
| What is dermal clearance and why is it important? |
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Definition
It is drug removal from the skin
It controls the entire system because it is the slowest step |
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Term
| How do vasodilators and Vasoconstrictors affect dermal clearance? |
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Definition
Dilators increace clearance
constrictors lowers clearance |
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Term
| What is cutaneous biotransformation? |
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Definition
| enzymes in the skin that breakdown the drug as it passes through |
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Term
| Why is it important to rotate the site of administration of transdermal systems? |
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Definition
| Clearance eventually gets maxed out and need a new site |
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Term
T/F
Lotions and depilatories should be used before apply transdermal systems to enhance drug absorption |
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Definition
FALSE
they remove the stratum corneum and get more drug than is intended...may be toxic |
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Term
What are the 4 types of Ointment bases?
(Order from hydrophobic to hydrophilic) |
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Definition
| Oleaginous, Absorption, Water-Removable, Water Soluble |
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Term
| What should be considered when selecting a base? |
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Definition
| Degree of occlusion, extent of absorption, time of action, lubrication, removal by washing with water |
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Term
Which type of base?
a) oils, waxes
b) polyethylene glycol
c) o/w emulsions
d) w/o emulsions |
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Definition
a) oils, waxes- Oleaginous
b) polyethylene glycol- Water soluble
c) o/w emulsions- water removable
d) w/o emulsions- abosorption |
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Term
What is the objective for making ointments?
What are the 2 ways to make it? |
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Definition
A uniform, stable, nongritty product
Incorporation and Fusion |
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Term
| What are the steps of making an oinment via fusion method? |
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Definition
Melt component with the highest MP first
add others with constant stirring
add volatile or heat labile componenents at the end |
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Term
T/F
Oleaginous bases can be used for hydrophilic drugs |
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Definition
TRUE
ONLY if used for long term, because they trap moisture in the skin and increase hydration allowing for passage of hydrophilic drugs |
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Term
T/F
Preservatives are essential in gels, why why not
|
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Definition
TRUE
prone to bacterial growth |
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Term
| A suppository that immediately dissolves in a body cavity is what kind of ointment base? |
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Definition
3/4
Water removable or Water soluble
(body cavities are waterbased) |
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Term
| What are examples of suppositories having local action in the rectum? |
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Definition
Relieve constipation
Antihemorrhoidal
Local anaesthetics, vasoconstrictors etc |
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Term
T/F
Rectal suppositories used for relief of N&V have local action |
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Definition
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Term
| What factors affect systemic absorptionof suppositories? |
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Definition
Anorectal physiology (surface area)
Colonic content (feces)
Circulation route (hepatic system)
pH and lack of buffering capacity
Properties of drug and suppository base |
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