1
Q
What is the outermost layer of epidermis?
A
Stratum corneum or horny layer
2
Q
What is the epidermis composed of? (4)
Is it easy or hard to penetrate?
A
- Layers of dead, flattened keratinocytes
- surrounded by a lipid matrix,
- together act as a brick-and-mortar system
- difficult to penetrate.
3
Q
Where is the Stratum germinativum or basal layer?
and what does it have? (3)
A
below stratum corneum having viable dividing cells & Keratinocytes and other specialized cells such as melanocytes and Langerhans cells.
4
Q
What is the basal layer of the epidermis thickness in comparison to the stratum corneum?
A
10x as thick as the stratum corneum.
5
Q
What is the basal layer of the epidermis diffusion like and why?
A
- Diffusion is faster due to the greater degree of hydration in the living cells of the viable epidermis.
6
Q
What is below the epidermis?
A
Dermis.
7
Q
How thick is the dermis in comparison to the stratum corneum?
A
100x the thickness of the stratum corneum.
8
Q
What is the dermis (corium) made of?
4
A
- matrix of connective tissues w/ blood vessels, nerves, sweat glands and origin of hair follicles.
9
Q
What do the blood vessels in the dermis do?
2
A
- Distribute drugs into the systemic circulation
- regulates temp.
10
Q
How thick is the dermis in mm?
A
3-5 mm thick.
11
Q
Are hair follicles a part of skin appendages ?
A
yes
12
Q
What do Sebaceous glands empty into and why?
A
Hair follicles to form pilosebaceous unit.
13
Q
What do Sebaceous glands secrete?
A
They secrete sebum.
14
Q
What does sebum do?
2
A
- Lubricates skin surface
- maintains surface pH 5.0
15
Q
What is the density of Hair follicles?
A
Varies from 50-250 follicles per sq.cm. of skin.
16
Q
What are Eccrine Glands?
location & connection
A
- Coiled and tubular gland
- in the dermal tissue
- connected to a duct that ascends towards the surface.
17
Q
What do Eccrine glands respond to? and how?
2 it responds to
A
- Increased temp
- stress
- by exuding a dilute salt solution (sweat).
18
Q
How many eccrine glands are distributed throughout the body surface?
A
Approximately 3-4 million.
19
Q
Where are the eccrine glands concentrated at?
A
Hands and feet.
20
Q
What are the Advantages of Transdermal Pathways?
7
A
- Controlled release of drug
- Non-invasive
- Bypasses hepatic first pass metabolism
- Reduces side effect - GI incompatibility
- Better patient compliance
- Ease of monitoring and termination
7. Scope of programmable delivery
21
Q
Delete
A
delete
22
Q
What is an example of a drug through the Transdermal Pathway that bypasses hepatic first pass metabolism?
A
Nitroglycerin.
23
Q
What do Transdermal Pathways eliminate?
3
A
- Variation in plasma concentration
- Use of medical personnel and sterile equipment
- Risk associated with needles.
24
Q
What are Transdermal Pathways only feasible for?
3
A
- Moderately lipophilic (logP between 1 – 3.5)
- Molecular weight < 500 Da
- Highly potent.
25
What are the Limitations of Transdermal Pathways?
Can cause skin irritation in some patients.
26
What kind of membrane is the skin?
Heterogeneous membrane.
27
Can the simple diffusion laws be used to describe the transport through the skin?
Yes.
28
For steady-state conditions what can the transport through the skin be EXPLAINED using?
Fick’s first law of diffusion.
29
For Fick’s Law of Diffusion, what does J stand for?
Flux per unit area.
30
What is Fick’s Law of Diffusion equation?
31
For Fick’s Law of Diffusion, what does P stand for?
Stratum corneum-formulation partition coefficient of the active.
32
For Fick’s Law of Diffusion, what does d stand for?
Diffusion coefficient in the stratum corneum of the thickness h.
33
For Fick’s Law of Diffusion, what does C1 stand for?
Concentration inside the skin.
34
For Fick’s Law of Diffusion, what does C0 stand for?
Concentration of active substance applied to the skin surface.
35
What Factors Affect Percutaneous Absorption of a drug?
| 9
1. Drug concentration
2. SA
3. application site
4. **Skin condition**
5. application duration
6. vehicle nature
7. Dissociation constant
8. Partition coefficient and solubility
9. Molecular weight.
36
What is the ideal molecular weight of drugs for TDDS?
400 or less.
37
What kind of solubility allows for a drug via TDDS to be absorbed better from the skin?
Some solubility in both lipid and water.
38
What is the desired Log P for a drug via TDDS?
Log P of 1 to 3.5 desired.
39
Are ionized or un-ionized drugs better absorbed from the skin via TDDS?
Un-ionized.
40
If a drug has a greater attraction toward the skin than to the vehicle, is it likely to be better absorbed?
Yes.
41
Is absorption better in hydrated or dehydrated skin?
Hydrated.
42
What kind of absorption increases with the increase in the concentration of the drug?
Percutaneous absorption.
43
Is maintaining saturation the best approach and is it feasible?
Yes, it’s the best but may not be feasible.
44
How much nicotine do Nicotine patch reservoirs contain?
36 to 114 mg of nicotine per patch.
45
What do Nicotine patch reservoirs exceed?
Exceeds the estimated LD50 for nicotine in humans of 1 mg/kg for most children and many adults.
46
What is the relationship between SA, TDDs, & absorption?
Larger the area of application, the larger the TDDS, the more drug is absorbed.
47
Is absorption better from a thin horny layer or from a thick layer?
Thin horny layer.
48
What is the relationship between total amount of drug absorption and contact time?
Proportional.
49
Does the FDA approve of TDDS?
Yes.
50
What is Scopolamine used to prevent?
Nausea and vomiting associated with travel.
51
What does Scopolamine look like?
Circular patch.
52
How much of the drug is in each Scopolamine patch?
1.5 mg of drug.
53
What is the rate of drug delivery by a Scopolamine patch?
Constant drug delivery rate.
54
What is TransDerm Scop designed for?
Continuous release of scopolamine over 3-day period.
55
Where do you place the TransDerm Scop patch onto?
An area of intact skin on the head, behind the ear.
56
For TransDerm Scop, what is the limiting factor?
Is the MEMBRANE used, not the skin.
57
What controls the rate of absorption for TransDerm Scop?
Membrane.
58
What is the amount of drug released by TransDerm Scop less than?
The skin’s absorption ability.
59
What are the 4 Candidates (criteria) for Transdermal Delivery?
1. Nonirritating and nonsensitizing to skin
2. First pass metabolism
3. Potent
4. IV infusion vs Bolus dose
60
What are the 3 TDDs Formulation/Design Considerations?
Flux desired, Drug loading, Patch design.
61
What are the 7 Basic Components of TDDS?
1. Polymer matrix / Drug reservoir
2. Drug
3. Permeation enhancers
4. Pressure sensitive adhesive (PSA)
5. Backing laminates
6. Release liner
7. Other excipients like **plasticizers and solvents.**
62
What are All TDDS designed to do?
Release the drug from the system to the surface of the skin and deliver the drug into the systemic circulation.
63
What are the 2 types of currently available transdermal patches?
Matrix type, Reservoir types.
64
What controls the rate of release from a reservoir for the Reservoir type of transdermal patches?
the A membrane between the drug and skin
65
What kind of release does the Reservoir type of transdermal patches provide?
zero-order as long as drug solution in reservoir remains saturated.
66
What is drug in the Matrix type of transdermal patches contained in?
Drug is contained in a polymeric matrix.
67
What kind of matrix controls the rate of drug release for Matrix type of transdermal patches?
Polymeric matrix.
68
Do Matrix type of transdermal patches have a controlled release of drugs?
No.
69
What does a reservoir type patch consist of?
| 4
1. impermeable backing
2. reservoir holding active ingredient w/ release controlling materials
3. adhesive
4. A protective liner
70
What does a matrix type patch consist of?
| 3
1. backing layer
2. Drug dispersed in adhesive layer
3. A protective liner.
71
What does Noven’s DOT Matrix technology use?
Adhesive blend of silicone, acrylic, and drug.
72
For Matrix Controlled Transdermal Patch, what is the Drug/Adhesive poured over?
Release liner.
73
For Matrix Controlled Transdermal Patch, what is evaporated?
Mixing solvent evaporated.
74
Matrix Controlled Transdermal Patch, what is laminated?
Backing laminated on patch.
75
What do Chemical Enhancers increase and how?
Increase skin permeability by reversibly altering the physical chemical nature of the stratum corneum.
76
What are 7 examples of chemical Enhancers?
1. Acetone
2. Azone
3. Polyethylene glycol (Polyols)
4. DMSO (Sulfoxides)
5. Dimethyl formamide (Amides)
6. Oleic acid (Fatty Acids)
7. SDS (Surfactants).
77
What is the Proper Usage and Handling of Transdermal Patches specific to?
Drug guidelines.
78
What must you stop when using a Nicotine Patch?
Stop smoking during use of patch.
79
Should you replace nicotine patches on the daily?
Yes.
80
In case of overdosage of Nicotine patches, what should you do?
Remove and flush with water. Do not use soap.
81
What could occur at the Nicotine patch application site for a short while?
Erythema.
82
In case of vivid dreams or sleep disturbances due to Nicotine patches, what should you do?
Remove patch at bedtime.
83
For Duragesic (Fentanyl) Patch Use, where should it be applied to?
Apply to dry, flat area – hair can be clipped but not shaved.
84
For Duragesic (Fentanyl) Patch Use, what may be needed for a day or two in beginning?
Oral narcotics.
85
For chronic pain and use of Duragesic (Fentanyl) Patch Use, what should you be under?
Medical supervision.
86
For Duragesic (Fentanyl) Patch Use, can you use a heating pad?
No.
87
For patches, once the lining is pulled off, what should you not do?
Do not touch the sticky surface of the patch.
88
If you touch the sticky surface of the patch, what should you do?
Wash your hands immediately after application to avoid absorbing the medication.
89
Can you cut the patches?
No.
90
What cannot be used while using patches?
| 5
1. Soaps
2. alcohol
3. oils
4. lotions
5. abrasive devices
91
Where are the 5 most common Patch placements?
Abdomen, upper arm, back, hip and thigh.
92
Delete
delete
93
What areas should be avoided when placing a patch?
Hairy areas.
94
Should you rotate sites when placing a patch?
Yes.
FPS Exam 2
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