Dermatology Pharmacology and Prescribing

Question 1

What are some reasons for patients not adhering to their prescribed drug cycles?

Answer 1

Psychiatric co-morbidities
Slower acting agents
Multiple applications per day
Lack of patient education
Cosmetic acceptability of treatments
Unintentional non-adherence

Question 2

What are the two components of a topical drug?

Answer 2

Vehicle + drug

• Vehicle: pharmacologically inert, physically and chemically stable substance that carries the active drug

Question 3

What are some factors that affect the absorption of a topical drug?

Answer 3

Concentration
Base/vehicle
Chemical properties of the drug
Thickness and hydration of stratum corneum
Temperature
Skin site
Occlusion

Question 4

What are some examples of drugs that are commonly administered topically?

Answer 4

Corticosteroids
Antibiotics
Anti-inflammatories
Antivirals

Question 5

What are some common functions of topical steroids?

Answer 5

Anti-inflammatory and immunosuppressive

• Regulate pro inflammatory cytokines
• Suppress fibroblast, endothelial, and leukocyte function
• Vasoconstriction
• Inhibit vascular permeability

Question 6

What is a finger tip unit in regards to topical drugs?

Answer 6

• Enough of the formulation (paste etc.) to cover one fingertip
• generally a safe dose, tends to treat an area double the size of one hand

Question 7

What are some potential side effects of topical steroids?

Answer 7

Thinning /atrophy
Striae
Bruising
Hirsutism
Telangiectasia (spider veins)
Acne/rosacea/perioral dermatitis (red bumps on skin)
Glaucoma
Systemic absorption
Cataracts

Question 8

What are the main systemic treatments used in dermatology?

Answer 8

• Retinoids
• Immunosuppressants
• Biologics

Question 9

What are retinoids analogues of? What is their general function?

Answer 9

Analogues of vitamin A
Function to:
- Normalise keratinocyte function
- Anti inflammatory and anti cancer effects

Question 10

What conditions are retinoids effective in? Example of retinoid used in each condition?

Answer 10

Acne isotretinoin

Psoriasis acitretin

Cutaneous T cell lymphoma bexarotene

Hand eczema alitretinoin

Question 11

What are some side effects of common retinoids?

Answer 11

• Can be teratogenic (cause malformation in embryo)
• Cheilitis(dry lips) and xerosis (dry skin)
• ↑transaminases, ↑triglycerides
• Rarely: psychiatric, eye, bone side effects

Question 12

What class of skin disorders are immunosuppressants used to treat?

Answer 12

Inflammatory skin disorders

• Suppress immunity = suppress inflammation

Question 13

Potential serious side effects of immunosuppressants? How are these avoided?

Answer 13

Serious risk of malignancy / infection

Avoided with routine blood tests:

• FBC (esp in methotrexate and azathioprine)
• Renal function (esp ciclosporin)
• Liver function (esp methotrexate)

Question 14

What are biologics? What are they used for?

Answer 14

• Genetically engineered proteins derived from human genes

- Designed to inhibit specific components of the immune system

Question 15

What are some of the potential side effects of biologics?

Answer 15

• Risk of infection (Avoid live vaccines)
• Risk of malignancy
• TNF inhibitors – risk of demyelination

Question 16

What condition have biologics proven particularly effective at treating? List a couple biologics used

Answer 16

Melanoma

If BRAF 600 mutation: Vemurafenib, Dabrafenib

Immunotherapies: Ipilumumab, Pembrolizumab