Topical and Systemic Therapeutics in Derm

Question 1

Define pharmacokinetics

Answer 1

the effect of the body on a medication, including its absorption, distribution, metabolism, and excretion

Question 2

What layer serves as a barrier for the absorption of topical antibiotics

Answer 2

stratum corneum, varying thickness based on body location.

Question 3

What body surfaces lack stratum corneum, therefore highly permeable to topical steroids?

Answer 3

Mucosal surfaces, like the eyes, genitals, especially vulnerable to adverse side effects.

Question 4

What structures aid in absorption of topical agents?

Answer 4

Hair follicles and sebum, or areas w/ inflammation or abrasion.

Question 5

How are oral corticosteroids put into body

Answer 5

absorbed in jejunum, about 50% of ingested gets absorbed.

Question 6

Compare distribution of oral steroids vs. topical steroids.

Answer 6

Oral: diffuse, throughout body, bind to cortisol-binding globulin, and can increase levels with higher doses.
Topical: significantly limited distribution. High potency discouraged in infants b/c of increased body surface leading to adverse side effects.

Question 7

How are steroid metabolized and excreted

Answer 7

Hepatic metabolism inactivates first, modification and excretion renally.

Question 8

Define pharmacodynamics

Answer 8

how medications bind to receptors and signal intended response. Topical as primary tx for skin diseases for their anti-inflammatory effects

Question 9

Effects of steroids

Answer 9

Stabilize cell and lysosomal membranes, reduce vascular smooth muscle sensitivity to histamine, inhibit release of histamine, decrease adherence and migration of neutrophils, decrease production of the pro-inflammatory cytokines IL-1

Question 10

Composition of topical steroids

Answer 10

active ingredient, vehicle (base to deliver active ingredient), preservatives, and humectant (to facilitate penetration)

Question 11

Why is it important to know the full name of a medicine

Answer 11

side effects vary, concentration varies.

Question 12

What is lotrisone

Answer 12

topical agent that combines an ultrapotent steroid (clobetasol) with an antifungal agent (clotrimazole). use cautiously because of side effects.

Question 13

Define potency and the its classes

Answer 13

Ability of a medication to have the desired clinical effect, historically tested with a vasoconstriction assay to determine potency. Seven classes: 1 (ultrapotent), 2 and 3 (high potency), 4 and 5 (mid potency), and 6 and 7 (low potency)

Question 14

List the four common topical agents of varying potency classes

Answer 14

Ultra: clobetasol propionate 0.05%
High: fluocinonide 0.05%
Mid: triamcinolone acetonide 0.1%
Low: hydrocortisone cream 1%

Question 15

Reasons a disease may not be responding to a topical steroid:

Answer 15

inaccurate diagnosis, inadequate steroid potency, poor patient compliance, barrier to proper application, infection impeding healing.

Question 16

Pros and cons of lotion as a vehicle

Answer 16

powder in water, low potency, drying effect, high patient preference.

Question 17

Pros and cons of cream as medication vehicle

Answer 17

oil in water, moderate potency, moderate hydration

Question 18

Pros and cons of ointment as medication vehicle

Answer 18

water in oil, strong potency, hydrating, greasy

Question 19

Pros and cons of solution as medication vehicle

Answer 19

liquid-based, good for hair-bearing areas, messy, irritancy risk

Question 20

Pros and cons of gel as medication vehicle

Answer 20

alcohol base, strong potency, drying effect, may cause burning sensation

Question 21

Pros and cons of foam as vehicle

Answer 21

minimal residue, good for hair-bearing areas, expensive

Question 22

What is propylene glycol and its effects?

Answer 22

a humectant and solvent, may cause irritant contact dermatitis

Question 23

Formaldehyde and its effects

Answer 23

a preservative with high incidence of allergic contact dermatitis.

Question 24

What factors should prescribing amount reflect?

Answer 24

body surface involved, ease disease responds to therapy, and risk of side effects.

Question 25

Amount of topical medication required to cover entire body at one time

Answer 25

30 g

Question 26

How much topical agent is typically prescribed?

Answer 26

30-60 g for rashes

Question 27

Oral steroid dose

Answer 27

1 mg/kg/day, take in the morning to mimic cortisol peak

Question 28

Risk factors for cutaneous atrophy

Answer 28

high potency steroids, occulsion, sites with thin or absent stratum corneum, young patient age.

Question 29

Risk factors for systemic side effects

Answer 29

Young age, renal insufficiency, hepatic insufficiency, steroid potency, amount of application, use of occlusion.

Question 30

Common medication side effects

Answer 30

acne, atrophy (thinning of epidermis or dermis), contact dermatitis, HPA axis suppression (higher risk in children, manifest fatigue, fever, hypotension, shock, sometimes death), infection (fungal or viral), irritant dermatitis, occular side effects (cataracts, glaucoma, infection), rebound (eyelid classic example), systemic effects (more common with oral, hyperglycemia, cataracts, osteoporosis, agitation/psychosis, growth retardation, myopathy, others), tachyphylaxis, telangiectasia

Question 31

When should a patient discontinue use of topical steroid?

Answer 31

When the issue is resolved. Chronic conditions (psoriasis, atopic dermatitis) need periodic drug holidays.

Question 32

What is the longest a pt can use high potency topical steroids?

Answer 32

2 weeks, unless on palms or soles.

Question 33

When does natural cortisol taper off when patient is on an oral steroid?

Answer 33

3 weeks, so use carefully. Taper off to ameliorate side effects of steroid withdrawl.

Question 34

What are two common calcineurin inhibitors?

Answer 34

tacrolimus and pimecrolimus synthesized from streptomyces, have anti-inflammatory effects

Question 35

Topical calcineurin inhibitors are structurally similar to:

Answer 35

cyclosporine, have same anti-inflammatory effects but small enough to absorb through the skin

Question 36

How do calcineurin inhibitors work?

Answer 36

passive diffusion into skin, binds intracell protein FK506-binding protein, complex binds calcineurin, inhibiting ability to dephosphorylate transcription factor NFAT, inhibiting release of pro-inflammatory cytokine IL-2.

Question 37

Indications for calcineurin inhibitor use

Answer 37

atopic dermatitis as a second line therapy or on rotational basis with topical corticosteroids. Have improved psoriasis, seborrheic dermatitis, lichen planus, vitiligo, and others.

Question 38

Side effects of calcinerin inhibitors

Answer 38

burning sensation with application, contact dermatitis, infection, non-melanoma skin cancer, lymphoma