Pharmacology

Question 1

Immunologically-mediated skin reactions are dose-dependent. True/False?

Answer 1

False

All or nothing!

Question 2

Non-immunologically-mediated skin reactions can be dose-dependent. True/False?

Answer 2

True

Question 3

How do urticarial drug eruptions usually arise?

Answer 3

IgE-mediated hypersensitivity or drug-induced mast cell degranulation

Question 4

Which drugs tend to cause pustular/bullous drug reactions?

Answer 4

Glucocorticoids
Androgens
Hypertensives

Question 5

Fixed drug eruptions are well-demarcated and round. Which drugs are commonly associated with this?

Answer 5

Tetracycline antibiotics
Paracetamol
NSAIDs
Carbamazepine (anti-epileptic)

Question 6

What are the 3 major routes of drug administration through the skin?

Answer 6

Topical
Transdermal
Subcutaenous

Question 7

What is the single most important barrier to drug administration?

Answer 7

Stratum corneum (made up of corneocytes)

Question 8

The stratum corneum is made up similar to a “bricks and mortar” model. What are the bricks?

Answer 8

Corneocytes embedded in filaggrin that are held together by corneodesmosomes

Question 9

The stratum corneum is made up similar to a “bricks and mortar” model. What is the mortar?

Answer 9

Hydrophobic layer made up of intercellular lipids

Question 10

Is the stratum corneum hydrophilic or lipophilic?

Answer 10

Lipophilic

Absorbs lipid-soluble (hydrophobic drugs)

Question 11

The principle mechansim of drug penetration of the stratum corneum is transcellular (across the stratum corneum). True/False?

Answer 11

False

Principle mechanism is intercellular (tortuous course between corneocytes)

Question 12

Drug vehicles are normally used in topical administration of drug (for local effect). What are vehicles?

Answer 12

Pharmacologically inactive substances that “carry” the drug

Question 13

List some examples of drug vehicles

Answer 13

Ointments
Creams
Gels
Lotions
Pastes and powders

Question 14

Rate of absorption of a topically administered drug = ?

Answer 14

J =  Kp x Cv
Kp = permeability coefficient
Cv = concn of drug in vehicle

Question 15

A drug must exit its vehicle if it is to penetrate the stratum corneum. True/False?

Answer 15

True

Question 16

The bigger the Km of a drug, the better it will enter the skin. True//False?

Answer 16

True

Question 17

Lipophilic drug in a hydrophilic vehicle absorb poorly in skin. True/False?

Answer 17

False

They absorb very well

Question 18

Lipophilic drug in a lipophilic vehicle absorb very well in skin. True/False?

Answer 18

False
While they will absorb, the drug will want to remain in the lipophilic vehicle at the same time, so absorption is not great

Question 19

Hydrophilic drug in a lipophilic vehicle don’t absorb very well. Why?

Answer 19

They will make it out of the vehicle but cannot penetrate the stratum corneum because they are hydrophilic

Question 20

Hydrophilic drug in a hydrophilic vehicle absorb the best of all. True/False?

Answer 20

False

They ain’t going nowhere

Question 21

What can enhance the absorption of a drug in skin?

Answer 21

Excipients

Question 22

What are creams?

Answer 22

Semi-solid emulsion of oil and water containing emulsifier and preservative

Question 23

Creams are cooling and greasy. True/False?

Answer 23

False

They are cooling but not greasy

Question 24

What is the danger of the preservative in creams?

Answer 24

Allergic reaction

Question 25

What are ointments?

Answer 25

Semi-solid mix of grease and oil containing soft paraffin

Question 26

What is the benefit of ointments?

Answer 26

Effective at restricting transepidermal water loss

Question 27

What is the downside of ointments?

Answer 27

Not cosmetically attractive (very greasy)

Question 28

What are lotions?

Answer 28

Suspension of medication in water/alcohol/other liquid

Question 29

What are gels?

Answer 29

Thickened aqueous solutions containing high molecular weight polymers

Question 30

What is the downside of pastes?

Answer 30

Stiff and difficult to apply

Question 31

What is the function of emollients?

Answer 31

Enhance hydration of epidermis

Question 32

For what type of conditions are emollients used?

Answer 32

Dry, scaly conditions | Mainstay for eczema

Question 33

When are wet wraps frequently used? How are they applied?

Answer 33

For very dry skin | Wrap around previously moisturised skin to lock in moisture

Question 34

What are the 3 actions of topical steroid upon skin?

Answer 34

Anti-inflammatory Anti-proliferative Vasoconstrictive

Question 35

Name a mild steroid for skin disease

Answer 35

Hydrocortisone

Question 36

Name a moderate steroid for skin disease

Answer 36

Modrasone

Question 37

Name a potent steroid for skin disease

Answer 37

Mometasone

Question 38

Name a very potent steroid for skin disease

Answer 38

Clobetasol

Question 39

How many grams of steroid are equvalent to 1 fingerprint unit?

Answer 39

0.5g

Question 40

1 fingertip unit = how many hand areas?

Answer 40

2

Question 41

What is meant by tachyphylaxis to steroid?

Answer 41

Steroid becomes less effective despite maintained dosage

Question 42

What conditions is potassium permanganate rinse/soak/bath useful for?

Answer 42

Exudative eczema | Pompholyx

Question 43

What is pompholyx?

Answer 43

Exudative eczema restricted to hands and feet | Forms watery blisters + severe itch

Question 44

Name topical antibiotics used for acne

Answer 44

Tetracycline Clindamycin Erythromycin

Question 45

What is the main antibiotic used for rosacea?

Answer 45

Metronidazole

Question 46

List some antipruritics

Answer 46

Menthol Capsaicin Camphor/phenol Crotamiton

Question 47

What are keratolytics used for? Name one

Answer 47

``` Softening keratin (e.g. viral warts, hyperkeratotic disease) Salicylic acid ```

Question 48

Emollients can be used for psoraisis along with what other options?

Answer 48

Coal tar Vitamin D analogues Keratolytic Topical steroid

Question 49

Which cream has been shown to be effective for pre-cancerous and cancerous skin lesions?

Answer 49

Aldara cream | Imiquimod