Pharmacology in the skin Flashcards Preview

Dermatology > Pharmacology in the skin > Flashcards

Flashcards in Pharmacology in the skin Deck (29)
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1
Q

What are the major routes for drug adminstration via the skin?

A

Topical
Transdermal
Subcutaenous

2
Q

What are the advantages of topical drug administration?

A

Used for local, achieves a high drug concentration at the intended site of action minimising the adverse affects which might occur through systemic absoprtion of the drug

3
Q

What is the most important layer of skin in regards to pharmacology?

A

Stratum corneum - important barrier to drug penetration into the skin or across it

4
Q

What makes up the stratum corneum?

A

Corneocytes, intracellular lipids

5
Q

Where do drugs go when they move thorugh the trancellular route?

A

Corneocytes - aggregated keratin filaments embedded in a filaggrin matrix surrounded by a cornified cell envelope

6
Q

Where do drugs move when they go thorugh the intercellular route?

A

Lamellar structures of intercellular lipids (cholesterol, free fatty aicds)
Highly hydrophobic, acts as a resovoir for lipid-soluble drugs such as topical corticosteroids

7
Q

What are the chemical properties of an ointment?

A

Very highly hydrophobic

8
Q

What are the chemical properties of lotions and pastes?

A

Highly hydrophilic

9
Q

When are topical treatments used in dermatology?

A
Treatment of superficial skin disroders such as psoriasis, eczema
Skin infections
Itching
Dry skin
Warts
10
Q

What is used to treat superficial skin disorders?

A

Glucocorticoids

Retinoids

11
Q

What is used to treat skin infections?

A

Antivirals
Antibacterials
Antifungals
Anti-parasitics

12
Q

What is used to treat pruritus?

A

Antihistamines

13
Q

What is used to treat dry skin?

A

Moisturising agents

14
Q

What is used to treat warts?

A

Keratolytic agents

15
Q

What are the different types of vehicles?

A
Ointments
Creams
Gels 
Lotions
Pastes
Powders
16
Q

What dictates the type of vehicle?

A

Physiochemical properties of the drug

Clinical condition

17
Q

What factors infleunce the absoprtion of topically applied drugs?

A

Permeability coefficient

Concentration of drug in the vehicle

18
Q

What will determine the permeability coefficient?

A

Properties of the drug

Properties of the barrier `

19
Q

What are important factors in how the vehicle affects the rate and extent of absorption of a topically applied drug?

A

Dissolved conc of drug in vehicle

Maximising movement of drug from vehicle into the strateum corneum

20
Q

What are the basic rules of coefficient partitioning?

A

A lipophilic drug in a lipophilic base is soluble in vehicle and the skin and partitions between the two
Lipophilic drug in hydrophobic base is more solube in skin so will partition readily
Hydrophilic drug in hydrophobic base will partiton to a limited extent
A hiydrophilic drug in a hydrophilic vehicle will remain on the surface of the skin

21
Q

What is the function of excipients?

A

Enhances solubility and enhances absorption

22
Q

What is an example of an excipient and its related drug?

A

Propylene glycol in hydrophobic glucorticoids

23
Q

Why do transdermal patches provide a constant rate of delivery of drug?

A

As the dissolved frug is removed into the skin, the conc on the patch decreases and therefore the undissolved drug will dissolve creating a stady stream of drug

24
Q

What factors can improve partitioning?

A

Hydration of the skin by occulsion

Inclusion of excipients which also increase solubility of hydrophobic drugs

25
Q

What factors will influence the absorption of topically applied drugs?

A

Nature of the skin - site of application, hydration of skin, integrity of the epidermis
Drug preperation - drug concentration, drug salt, the vehicle

26
Q

What are the effects of glucocorticosteroids?

A

Anti-inflammatory
Immunosuppressant
Vasoconstricting effects
Anti-proliferating action upon keratinocytes and fibroblasts

27
Q

What will glucocorticosteroid penetration, potency and clinical effect vary with?

A
Body site
State of skin
Occlusion 
Vehicle 
Conc of drug
Form of drug
28
Q

What are the side effects of long term use of high potency steroids?

A
Steroid rebound
Systemic effects
Spread of infection 
Steroid rosacea
Production of stretch marks
29
Q

What receptor do glucorticosteroids signal via?

A

Nucleur receptors class 1