General Derm Pharm

Question 1

What are some variables that affect cutaneous absorption?

Answer 1

1. Region - axilla more permeable than forearm 2. Concentration gradient - increased conc. increases drug mass/unit time 3. Dosing schedule - long local t1/2 of skin reservoir may permit once daily dosing 4. Vehicles/occlusion

Question 2

Cream vs. Ointment?

Answer 2

Creams: -half water, half oil with emulsifier (makes it thicker so packaged in tube or tub) -Spreads easily, well absorbed, washes off with water -Better for oozing/wet skin conditions Ointments: -20% water, 80% oil from mineral oil or petroleum jelly -Greasy and occlusive (stays on skin surface and isn’t well absorbed but does provide more complete absorption of active ingredient) -Good for dry skin since traps moisture -less likely to cause allergic reaction

Question 3

Importance of hand washing

Answer 3

Single most important measure to reduce transmission of microorganisms to other areas of body/patients (need to wash for 15-30 sec with plain soap and keep clean nails)

Question 4

When should you wash your hands?

Answer 4

-Before touching pt. -Before clean/aseptic procedures -After body fluid exposure/risk -After touching a pt. -After touching pts surroundings

Question 5

What specific organism is alcohol-based hand disinfectant not effective against?

Answer 5

C. difficile

Question 6

What are components of moisturizer?

Answer 6

-Emollients: form oily layer on top of skin that traps water -Humectants: draws water into outer layer of skin -Horny substance (keratin) softeners: loosens bonds between top layer of skin which helps dead cells fall off, helps retain water, and keeps smooth/soft feeling

Question 7

What are some common emollients?

Answer 7

1. Petrolatum
2. Lanolin
3. Mineral oil
4. Dimethicone

Question 8

What are some common humectants?

Answer 8

1. Glycerin
2. Lecithin
3. Propylene glycol

Question 9

What are some common keratin softeners?

Answer 9

1. Urea
2. Alpha hydroxy acids (lactic, citric, glycolic acids)
3. Allantoin

Question 10

What compounds in sunscreen absorb UV light?

Answer 10

1. P-aminobenxoic acid (PABA) - UVB range

2. Benxophenones - wider UVB range than PABA

3. Dibenxoylmethanes - UVA range, useful for drug-induced photosensitivities and cutaneous lupus erythematosus

Question 11

What does SPF tell you?

Answer 11

Ratio of minimal erythma dose with sunscreen to minimal erythema dose without sunscreen