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Pharmaceutics Spring 2016 > Transdermal Delivery (2) > Flashcards

Transdermal Delivery (2) Flashcards

1
Q

The epidermis and the dermis both sit on the ______ which is a ________ fat layer.

A

hypodermis; subcutaneous

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2
Q

______ is the rate limiting step of the skin. Why?

A

stratum corneum; because it is very compact and hard to permeate

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3
Q

T/F There IS blood in the epidermis.

A

FALSE: NO BLOOD

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4
Q

______ are the major antigen-presenting cells of the skin

A

langerhan

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5
Q

______ contains blood vessels

A

Dermis

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6
Q

The stratum cornuem is about _____ microns

A

10 (dry)-20

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7
Q

Transdermal patch acts in the ______ while ointments, cream act _____

A

bloodstream (use the skin as a route of administration); on the skin (localized)

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8
Q

Drugs only need to pass the ____ to the into the blood

A

epidermis

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9
Q

What do sebaceous glands secrete?

A

oil

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10
Q

What is the purpose of the sebum secreted by the sebaceous glands?

A

to lubricate the skin surface and maintain the pH around 5

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11
Q

_____ disrupts the stratum corneum

A

shaving

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12
Q

The resistance of the skin includes: (3)

A
  • Rsc (stratum corneum: rate limiting)
  • Re (epidermis)
  • Rd (dermis)
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13
Q

Transdermal patches help to maintain….

A

the amount of drug in the blood

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14
Q

When does it make sense to make a patch? (4)

A
  • moderately lipophilic
  • short half life
  • wide therapeutic index
  • dose is low (potent)
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15
Q

What mechanism does transdermal patches use? What does that mean?

A

passive delivery; drug goes in by diffusion

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16
Q

If a drug is extremely lipophilic? hydrophilic?

A

lipophilic: it will go into the skin, but not into the blood
hydrophilic: not go into the skin

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17
Q

What are some benefits of transdermal patch? (5)

A
  • absence of first pass metabolism
  • sustained release effect (drug concentration goest up–> maintained)
  • non-invasive
  • ease of self administration
  • reduced adverse effects/systemic exposure
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18
Q

The skin is ____ degrees Celsius. (used in Franz diffusion cells)

A

32

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19
Q

FACTORS AFFECTING SKIN ABSORPTION:
Drug concentration/solubility
If you _____ the drug concentration: ____ the amount that will cross the skin

A

increase; increase

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20
Q

FACTORS AFFECTING SKIN ABSORPTION:

Partition coefficient?

A

how drug balance between hydrophilic and lipophilic parts

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21
Q

What is the desired LogP for Skin absorption?

A

1-3.5

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22
Q

If the LogP is negative then?

A

hydrophilic: not cross the skin

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23
Q

If the LogP is greater than greater than 3.5?

A

lipophilic: will cross the skin–> not go into the blood

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24
Q

FACTORS AFFECTING SKIN ABSORPTION:
Surface Area
When you ____ the surface area, you _____ the strength

A

increase: increase

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25
Q

FACTORS AFFECTING SKIN ABSORPTION:

If you ____ the temperature: _____ the amount of drug going into the body

A

increase: increase

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26
Q

For transdermal patches the ideal saturation is around…

A

90%

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27
Q

What is the driving force for the delivery of the transdermal patch for increasing concentrations?

A

thermodynamic activity, which also depends on the vehicle

28
Q

flux?

A

amount of drug that crosses the skin in a defined area (ug/sq cm/h)

29
Q

What is the ideal permeant flux for a transdermal patch?

A

1 mg/sq cm/day= 10 mg/day

30
Q

What are the types of transdermal systems? (2)

A
  • reservoir membrane-modulated system

- drug-in-adhesive diffusion controlled system (matrix)

31
Q

T/F With an adhesive(matrix) patch you remove the backing membrane.

A

FALSE: you remove the protective liner NOT the backing membrane

32
Q

Where is the drug in an adhesive match?

A

inside the adhesive which is revealed after the protective liner is removed

33
Q

The type of patch used depends on ……

A

the solubility

34
Q

Acrylate based
Silicone based
Polyisobutylene based are examples of what type of transdermal patch

A

matrix (adhesive) patch

35
Q

T/F You SHOULD use an acrylate patch for controlled substances

A

FALSE: should not

36
Q

In a reservoir patch, the drug is suspended, so how is the release of the drug controlled?

A

by the membrane

37
Q

Where is the loading dose found in reservoir patches?

A

in the adhesive

38
Q

What is the reason why reservoir patches are used less commonly?

A

leaking from the patches

39
Q

What was the first transdermal product?

A

transderm-scop (used for motion sickness)

40
Q

T/F Nicotine patches ONLY have nicotine

A

TRUE

41
Q

Using ____ with nicotine patches may act like an enhancer

A

soap

42
Q

When are oral narcotics okay to be used with duragesic patches?

A

for breakthrough pain (immediate release)

43
Q

One should avoid…. when using a patch (2)

A
  • hairy areas

- placing the patch in the same place over and over

44
Q

T/F One should touch the sticky surface of the patch?

A

FALSE: drug will start to go in the blood from fingers–>adhesive gets compromised

45
Q

T/F It is okay to cut a patch

A

FALSE: DO NOT cut the patch

46
Q

After a patch has been applied for the desired time, does it have any drug remaining? If yes, how much?

A
  • the drug does have excess drug because that is required to drive the gradient
  • 10-90% remaining depending on the patch design
47
Q

What could happen if the drug concentration in a patch is supersaturated?

A

matrix is unstable–> crystallization will occur over time

48
Q

If a patch falls off, can it be placed back by putting a tape around it? How about an overlay wrap that is included with some patches?

A

-No for both the tape and the overlay wrap because the adhesive is compromised

49
Q

What is the surface area of patches on the market?

A

5-40 sq cm

50
Q

What are some enhancement technologies for skin microporation? (4)

A
  • microneedles
  • thermal ablation
  • radiofrequency ablation
  • laser ablation
51
Q

_____ works for drugs that are charged or neutral. use low electric current to push the drug into the skin(via anode)

A

iontophoresis

52
Q

_______ uses high voltage for a short period of time

A

electroporation

53
Q

_____ uses ultrasound (tested to enhance the transdermal delivery–> drives molecules into and across skin)

A

phonophoresis , sonophoresis

54
Q

_______ is creating microscopic pores in the skin

A

skin microporation

55
Q

skin ONLY allows ____ and ____ drugs to come across

A

small and moderately lipophilic

56
Q

Why can’t proteins pass into or through the skin?

A

Large molecular weight and hydrophilic

57
Q

Type of Skin Microneedle:

Needle goes in makes the pores then comes out. Then the patch is applied

A

SOLID

58
Q

Type of Skin Microneedle:

  • Needle has the drug coated on it
  • Needle goes in, drug is left in the skin and then the needle comes out
  • No Patch involved
  • Not a lot of drug ~1mL
A

COATED

59
Q

Type of Skin Microneedle:

Drug is the needle and the needle dissolves in the skin? example

A

DISSOLVING: maltose

60
Q
  • Which of the following is more likely to be easily delivered through microchannels from a patch applied after microporation?
    • IgG (MW 150,000 Da)
    • Terbinafine (MW 291.4)
A
  • IgG (MW 150,000 Da) ANSWER

- Terbinafine (MW 291.4): not needed because it is already moderately lipophilic and small

61
Q

_____ is the defined as the measurement of the quantity of water that passes from inside a body through the epidermal layer (skin) to the surrounding atmosphere

A

transepidermal water loss

62
Q

Pores remain open under ____ conditions

A

occluded

63
Q

Maltose micro needles treated skin open to the environment?

A

NO pores (pores close within 15 hours)

64
Q

Maltose micro needles occluded by plastic film or by any solution

A

OPEN pores (up to 72 hours)

65
Q

How can you determine the drug concentration in the skin? (2)

A

microdialysis (probe)

tape stripping

Pharmaceutics Spring 2016 (20 decks)

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