Skin Pharm

Question 1

What is the moa of moisturisers?

Answer 1

1) Occlusives
- prevent transepidermal water loss

2) Humectant
- attract water from environment and from deeper epidermal/dermal tissues

3) Emollient
- fills cracks in stratum corneum → smoothen skin

Question 2

What are the parameters affecting skin permeability?

Answer 2

Fick’s law:
Rate of absorption (flux/J) of a substance across a barrier is proportional to its concentration difference across that barrier

Question 3

What are 3 factors that affect a drugs ability to penetrate the skin barrier?

Answer 3

1) Concentration of drug in vehicle
2) Diffusivity (length^2/time)
3) Ability of drug to move form vehicle to skin (partitioning)
4) Thickness of skin

Question 4

True or false:
In singapore, pharmaceutical companies are mandated to have the drug concentration on the label equal to that of the soluble drug in the vehicle.

Answer 4

False.
Drug concentration on the label may not equal to that of the soluble drug in the vehicle. (potency may differ even with differing concentration)

Question 5

What are 4 methods to enhance transdermal drug delivery?

Answer 5

1) Water
2) Solvents, surfactants
3) Microneedles/mechanical abrasion
4) Electroporation /iontophoresis
5) Metabolic inhibitors/peptides
6) US
7) Thermal ablation

Question 6

What are 2 contraindications of topical glucocorticosteroids?

Answer 6

1) Infective considerations
2) Existing steroid-related AEs

Question 7

What are 5 AEs of topical glucocorticoids?

Answer 7

Cutaneous:
1) Atrophy
2) Striae
3) Pseudoscars
4) Hypopigmentation
5) Rosacea-like eruptions
6) Acneiform eruptions

Impaired wound healing (7)

Vascular:
8) Telangiectasias
9) Purpura
10) Facial plethora

Topical steroid withdrawal:
- LT inappropriate use of potent topical glucocorticoids
- erythema, edema, papulopustules, burning sensation on discontinuation

Question 8

What are 3 pharmacological alternatives to topical steroids?

Answer 8

1) Topical calcineurin inhibitors
- eg. Tacrolimus, Pimecrolimus ointment
- inhibit transcription of pro-inflammatory cytokines and T cell activation

2) Topical PDE4 inhibitors
- eg. Crisaborole, Roflumilast
- inhibit PDE4 → ↑intracellular cAMP → anti-inflammation

3) Vitamin D analogues
- Eg. Calcipotriol, calcitriol
- inhibit proliferation + promotes differentiation of keratinocytes + ↓inflammatory mediators

4) Coal tar
- suppress DNA synthesis → anti-inflammatory/ microbial/ pruritic

Question 9

Why are topical calcineurin inhibitors often used as alternatives of topical steroids?

Answer 9

1) No risk of cutaneous atrophy

2) Proactive therapy in atopic dermatitis to prevent flares

Question 10

What are 2 AEs of topical calcineurin inhibitors?

Answer 10

1) Burning, stinging, warm at application

Rare:
2) Rosacea-like granulomatous rxn
3) Allergic contact dermatitis

Question 11

What are 2 indications for topical PDE4 inhibitors?

Answer 11

1) Atopic dermatitis (Crisaborole)

2) Plaque psoriasis (Roflumilast)

3) Seborrheic dermatitis (Roflumilast)

Question 12

What is the main indication of vitamin D analogues (eg. calcipotriol, calcitriol)?

Answer 12

Psoriasis

Question 13

What are 2 AEs of vitamin D analogues (eg. calcipotriol, calcitriol)?

Answer 13

1) Application site discomfort
2) HyperCa and Hypercalciuria (on excessive use)

Question 14

What are 3 AEs coal tar?

Answer 14

1) Acneiform eruptions
2) Folliculitis
3) Irritant contact dermatitis

Question 15

How are topical steroid applications typically measured (units)?

Answer 15

Fingertip unit measurement

Question 16

What is wet wrap therapy?

Answer 16

Application of bandages over skin after application of moisturiser with or without topical steroids