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Pharmacotherapy > Dermatologicals > Flashcards

Dermatologicals Flashcards

1
Q

What is percutaneous absorption equal to?

A

Absorption through the skin

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2
Q

What is percurtaneous absorption?

A

It is the amount of drug that passes form the vehicle into the stratum corneum of the skin

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3
Q

What happens as we increase the concentration of the drug generally?

A

Generally higher concentration sees high rates of diffusion through the lyaers of the ksin

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4
Q

What is the rate limiting step of diffusion?

A

It is the diffusion through the stratum corneum

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5
Q

What does the passive barrier allow?

A

The movement of molecules from the region of higher concentration to a region of lower concentration

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6
Q

What is the Stratum Corneum?

A

Think of the Brick/mortar model, where you can either have intracellular route or intercellular route

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7
Q

What is the fastest route of the drug movement?

A

Depends on the drug composition of the drug and its desired route

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8
Q

What is the first route of percutaneous absorption?

A

Appendages inclusive of the sweat glands sebaceous or hair follicles

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9
Q

Why is the sweat ducts. sebaceous glands or hair follicles negligible in percutaneous abosrption?

A

Since this area is more so promotes the growth of microbrials

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10
Q

With respect the drug factors, what influences percutaneous absorption?

A

Concentration of the drug (The cahnge in concentration gradient across the skin),
Partition coefficent
Drug/Skin barrier

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11
Q

What are factors that influence percutaneous absorption with respect to Vehicle factors

A

PH
Co-Solvents
Release of the drug from vehicle
Penetration enhancers

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12
Q

What is Ph determine?

A

Ionization of the drug thus it affects absorption

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13
Q

What does co-solvents determine?

A

Define the concentration of drug on the skin

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14
Q

What does the release of drug from vehicle determine?

A

Optimize with the appropriate dosage form.

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15
Q

What does penentration enhancers d?

A

Temporarily increase permeability of the skin

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16
Q

What skin factors affect percutaneous absorption?

A

Age of the skin
Skin condition
Thickness of stratum corneum
Skin metabolism
Circulation effects
Species differnces

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17
Q

What is the thickness of stratum corneum?

A

Regional that have difference in permeation (Eye vs foot)

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18
Q

What are the methods for studying percutaneous absorption?

A

We have In vitro mehtods where we can use cell lines to create a temporary membrane.

Helps us to read the diffusion of drugs from ointments creams and gels

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19
Q

What are the limitations of in vivo methods for testing percutaneous absorption?

A

There are different raites of percutaneous absorption between humans and animals

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20
Q

What animals are most predictive of skin absorption/penetration rate as humans?

A

Monkeu, pig and hairless guinea pig

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21
Q

What are bioassays?

A

Where we utilize human volunteers for the usage of testing

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22
Q

What is the blanching test?

A

Utilizes the skin whitening side to estimate the rate and extend of CS diffusion to the dermal vasculature, the intensity of thise whiteness correlating directly with the topical availability of the drug

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23
Q

What is CD?

A

Drug concentration in the donor compartment/vehicle

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24
Q

What is C1?

A

Drug concentration at the vehicle/skin. Where we see the accumulation of drug at the skin/vehicle interface. Leading to an increase in concentration to rise at the interface

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25
Q

What is C2?

A

References the Sink effect where the drug does not stay at the interface partitions into the receiver compartment

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26
Q

What is delta?

A

Thickness of the stratum corneum

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27
Q

What is Cr?

A

Concentration in the receptor compartment/blood

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28
Q

Is movement of the drug form donor to receiver compartment linear?

A

No, since it is driven form the concentration gradient that happens at the interface

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29
Q

Can you measure the amount of drug in interface?

A

No, instead that is why Fick’s law was developed to calculate the partition of the drug at interface to gives us an idea of the amount of drug that should be in the vehicle to drive this gradient

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30
Q

What is the diffusion coefficient of the solute/drug?

A

The amount of a particular drug that diffuses across a unit area of the stratum corneum in 1s under the influence of a concentration gradient

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31
Q

What is partition coefficient iof the solute/drug?

A

The ratio of the concentraiton of the drug in on medium or phase tothe concentration in a second phase when the two concentrations are at equilibrium

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32
Q

What is the permeability coefficient?

A

A quantitative measure other rate at which a molecule can cross a membrane such as a lipid bilayer

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33
Q

What factor defines the rate at which the drug goes in the skin and how long it will take to travel across the membrane?

A

Permeability coefficient

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34
Q

Take this time to review ficks law on the reverse slide

A
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35
Q

what does a larger partition coefficient mean?

A

Better the penetration thus more effective is the formulation

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36
Q

What does the J mean in Ficks law?

A

Solute flux

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37
Q

What does the D mean in Ficks law?

A

Solute diffusion coefficient in the stratum corneum

38
Q

What does the P mean in Ficks law?

A

Solute partition coefficient between skin and vehicle

39
Q

What does the Delta mean in Ficks law?

A

Thickness of stratum corneum

40
Q

What does the Change CV mean in Ficks law?

A

Difference in solute concentration between vehicle and tissue

41
Q

What is the main goal of dermatological preparation?

A

Build high concentration of the drug locally without Systemic exposure

42
Q

What is the difference between dermal and transdermal?

A

Transdermal goes through the skin intentionally

43
Q

What is the epidermis?

A

This is the top of the layer that encapsulates the skin structure

44
Q

What is the Ph of the epidermis?

A

5.5

45
Q

What is the main composition of epidermis?

A

Keratinocytes, dendritic cells

46
Q

What are the 5 distinct layers of the epidermis?

A

Horny Layer
Clear layer
Granular layer
Prickle cell layer
Basal layer

47
Q

What is the stratum corneum?

A

Also the horny layer It is a layer of 10-15 flattened keratinized dead cells

48
Q

What is the role of the stratum corneum

A

Major permeability barrier of the skin
Controls percutaneous absorption

49
Q

What is desquamation?

A

Creates a barrier which enables skin to retain hydration and resist assault

50
Q

What is the stratum lucidum?

A

This is the clear layer where it is responsible for the ability for skin to stretch

Ctonains a protein that is responsible for degeneration of skin cells

Lowers the effects of friciton in skin especially in regions like the soles of feet

51
Q

What is the stratum granulosum?

A

keratinocytes which discharge the cement like substance to bind cells together

Site of biochemical activity

52
Q

What is the stratum sponosum?

A

Prickly layer
Help the skin resist abrasion

Keratinocutes contain bundles of folaments and is subject to constant pressure and friction

53
Q

What is the stratum germinativum?

A

Basal layer where the cells held together by desmososomal cells

Provides the germinal cells necessary for regeneration of the layers of the epidermis

54
Q

What is the dermis mainly?

A

Connective tissues that have vascular supply and neural supply

55
Q

What is the role of the dermis?

A

support
Thermoregulation
Aid in sensation

56
Q

What is the pH of the dermis

A

7.2

57
Q

What is the function of subcutaneous tissue?

A

Storing energy
Connecting the dermis layer of your skin to your muscles and bones
insulating your body
mechanical cushion

58
Q

What is the funciton of the skin (Mechanical)

A

Elasticity, water retention

59
Q

What is the protective functions of the skin

A

Microbiological barrier

60
Q

What is the chemical barrier of hte skin

A

Controls the traffic of compounds in and out of the body

Intact versus disease skin

61
Q

Epidermis

A
  • Major permeability capabilities (Drug absorption)
    • Acidic
    • We have both living and biochemical processes that can be activated and inactivated in that stage
      Macrophages in that layer (depending on active ingredient) it can be a bit of interference where the macrophage can cleave the drugs/active ingredients
62
Q

Epidermis

A
  • Major rate limiting barrier to transdermal drug delivery is stratum (determines the rate of absorption)
    • Overall epidermal layers are packed with cells different morphologies mechanical barrier for transport of drugs
      Bioreactor activity (Enzymatic activation or inactivation of the drug)
63
Q

Dermis

A
  • Drug has blood vessel
    • Vascularize
      Sink Effect where the drug does not accumulate on the skin the concentration gradient exist to partition the drug
64
Q

Hypodermis

A
  • Fatty cells aids in transport of lipophilic drugs
    • Macrophages may impact stability of biomolecular therapeutic entities
    • Injectable drug delivery to subcutaneous tissue is more common than topical therapy
      Factors like aging affect the fatty composition of this layer affecting transdermal drug absorption
65
Q

What is an ointment

A

Contains ≤20% water and volatiles and ≥50% of hydrocarbons, waxes, or polyethylene glycols as the vehicle for external application to the skin

66
Q

What is a cream

A

An emulsion semisolid dosage form that contains >20% water and volatiles and <50% of hydrocarbons, waxes, or polyethylene glycols as the vehicle for external application to the skin

67
Q

What is a paste?

A

A semisolid dosage form that contains a large proportion (i.e. 20-50%) of
solids finely dispersed in a fatty vehicle for external application to the skin

68
Q

What is a gel?

A

A semisolid dosage form that contains a gelling agent to provide stiffness to a solution or colloidal dispersion for external application to the skin. A gel may contain suspended particles

69
Q

What is an oleaginous base?

A

Single phase (Ointments)

Hydrocarbon bases is another name

70
Q

What is the properties of a oleaginous bases?

A

Hydrophobic
Greasy
Non-water washable

71
Q

What is a property of an oleaginous base?

A

formation of an impermeable layer on
the skin to prevent evaporation of water.

72
Q

What are the effects of an oleaginous base?

A

Increased hydration (by preventing evaporation of water from the skin)
* Enhanced percutaneous absorption due to increased retention on skin

73
Q

Advantages of a Oleaginous base?

A
  • Very stable vehicles
  • Non-irritating
  • Non-sensitizing
  • High compatibility with drugs
74
Q

Disadvantages of an oleaginous base?

A
  • Greasiness
  • Stain clothing
  • Difficult to remove
  • Low patient acceptance (&laquo_space;emulsion bases)
75
Q

What are the main ingredients of an oleaginous base?

A

Fats and fixed oils (Can become rancid)

Mineral oil

Petrolatum (USP) and white petrolatum (USP)

Waves

Paraffin

76
Q

What are the properties of ideal penetration enhancers?

A
  • Non-toxic, non-irritating, non-allergenic
  • Immediate and predictable effect and immediate recovery of the barrier property of the skin after removal of the agent
  • Should not cause loss of body fluids, electrolytes or other endogenous materials
  • Compatible with drugs and excipients
  • Good drug solvent
  • Cosmetically acceptable (good spreadability and “feel”)
  • Odourless, tasteless, colourless and inexpensive
77
Q

What are levigating agents?

A

A levigating agent is a liquid used as an intervening agent to aid the incorporation and particle size reduction of a powder into an ointment

78
Q

What is a Absorption bases?

A

Non-water washable bases

79
Q

What is a non-anhydrous base?

A

hydrophilic components provide water-absorbing properties

80
Q

What do absorption bases contain?

A

an oleaginous material and a water-in-oil (w/o) emulsifier so that they can absorb water to form or expand w/o emulsions

81
Q

What are the main components of anhydrous bases?

A

➔Fats and fixed oils
➔Mineral oil
➔Petrolatum (USP) and white petrolatum (USP) ➔Waxes

82
Q

What is Glyceryl monostearate and glyceryl monooleate

A

Very weak emulsifying capacity used in anhydrous base

83
Q

What is Lanolin (wool fat)

A

Take up to two times its weight of water

Acts as W/O emulsifier

84
Q

What is cholesterol used for?

A

Commonly used in absorption bases.

Speciality in compounding like HRT

85
Q

What is the absorption bases Antioxidants?

A

➔ Substances that prevent or inhibit oxidation
➔ Properties of ideal antioxidant
* Effective at low concentrations
* Stable
* Soluble in the vehicle
* Compatible with pharmaceutical excipients and wide range of drugs
* Odourless, tasteless

86
Q

What are emulsifying bases?

A

➔Water washable bases
* Also called water miscible bases
* Anhydrous bases containing O/W emulsifying agents
* Cream-like appearance
* Miscible with water
* Self-emulsifying
* Upon water addition form O/W emulsions
* Emollient

87
Q

What are the main components of an emulsifying base?

A

➔Fats and fixed oils
➔Mineral oil
➔Petrolatum (USP) and white petrolatum (USP) ➔Waxes

88
Q

What are the additional components of an emulsifying base?

A

O/W emulsifiers and surfactants

89
Q

What is the compounding approach for emulsifying base?

A

Fusion method is more commonly applied

90
Q

What is the Pnemonic “Come lets get sun burnt” stand for?

A

Stratum Corneum
Stratum Lucidum
Stratum Granulosum
Stratum Spinosum
Stratum Basale

Pharmacotherapy (6 decks)

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