Skin

Question 1

What is the function of skin?

Answer 1

-thermal, electrolyte, metabolic and immune regulation

Question 2

What is on/in the epidermis?

Answer 2

• melanocytes
• langerhans cells
• keratinocytes
• hair follicles, sebaceous and eccrine glands
• P450 enzymes (degradation, activation)

Question 3

Describe the dermis

Answer 3

• 90% of the skin
• supportive function
• high content of collagen and elastin
• fibroblasts

Question 4

Rate of Cutaneous Drug Reactions

Answer 4

0-8%

Question 5

What drugs are most likely to cause cutaneous drug reactions

Answer 5

antibiotics (penicillins very common)

Question 6

What skin reactions can happen?

Answer 6

• Maculopapular rash (morbiliforme): 91%
• Urticaria (hives): 6%
• SJS
• Toxic Epidermal Necrolysis

Question 7

Two forms of contact dermatitis

Answer 7

• Irritant

- Allergic

Question 8

Describe presentation of contact dermatitis

Answer 8

• erythema (redness)
• induration (increase in tissue, can cause a hardened mass, making it thick)
• scaling
• vesiculation

Question 9

Irritant contact dermatitis:

-Intensity of rxn is proportional to the ____ applied

Answer 9

dose

Question 10

Irritant contact dermatitis:

Non-______ mechanism

Answer 10

immunologic

Question 11

Allergic contact dermatitis is what?

Answer 11

a delayed (type 4) hypersensitivity reaction
*have to be previously exposed

Question 12

Allergic contact dermatitis:

Describe the response

Answer 12

within 12 hours of sensitization, peaks at 48-72 hours

Question 13

How much of contact dermatitis does allergic make up and irritant make up?

Answer 13

Irritant: 75%
Allergic: 25%

Question 14

List some topical medications that can cause allergic contact dermatitis

Answer 14

• bacitracin
• neomycin
• polymyxin
• aminoglycosides
• sulfonamides
• benzocaine
• corticosteroids
• vitamin E

Question 15

What is Contact Urticaria?

Answer 15

• Transient, pruritic, oedematous, pink papule or wheals

- Due to histamine release

Question 16

What type of immune reaction is contact urticaria?

Answer 16

type 1 immune reaction (IgE mediated)

Question 17

What drugs can cause the IgE mediated reaction for contact urticaria?

Answer 17

• bacitracin
• ASA
• ampicillin
• neomycin
• phenothiazines
• latex

Question 18

What can cause a non-immunologic contact urticaria ?

Answer 18

• benzocaine
• capsaicin
• nicotinic acid esters
• jellyfish venom
• no need for previous exposure
  i. e. first time you get stung by jelly fish you get the reaction

Question 19

What is photo toxicology??

Answer 19

• skin is exposed to radiations

- solar radiation most capable of inducing skin changes ranges from 290-700nm

Question 20

What does absorption of light depend upon?

Answer 20

chromophores, epidermal thickness and water content

Question 21

What absorbs UV-B?

Answer 21

• melanin
• amino acids

(290-320nm)

Question 22

What is photosensitivity?

Answer 22

abnormal sensitivity to UV and visible light

Question 23

What can cause photosensitivity?

Answer 23

Endogenous: lupus or porphyrias

Exogenous: tanning booths, chemicals in cosmetics, drugs

Question 24

Phototoxicity can occur at the ____ exposure

Answer 24

first

Question 25

What is most commonly involved in phytotoxicity?

Answer 25

UV-A (320-400nm)

Question 26

When do chemicals absorb UV light

Answer 26

In a higher energy excited state: - oxygen-dependent - free radicals (cell death) - immunomediators from keratinocytes and WBC

Question 27

What are acute reactions of phytotoxicity?

Answer 27

- red skin - blister within minutes to hours (sunburn) - desquamation, peeling

Question 28

What are chronic reactions of phytotoxicity?

Answer 28

- hyperpigmentation | - thickening

Question 29

What drugs can cause phytotoxicity?

Answer 29

- amiodarone - fluoroquinolones - captopril - TCAs - fluorouracil - furosemide - nalidixic acid - naproxen - NSAIDs - phenothiazines - tetracycline - vinblastin - warfarin

Question 30

What is photo allergy?

Answer 30

- True Type 4 delayed hypersensitivity reaction | - Requires prior sensitization

Question 31

How does photo allergy occur?

Answer 31

UV light is necessary to convert a potential photosensitizing chemical into a happen that binds to a tissue antigen = allergic response at subsequent exposures

Question 32

What drugs cause photo allergy?

Answer 32

- antihistamines - barbiturates - TCAs - diltiazem - glyburide - griseofulvin - NSAIDs - PABA - phenothiazines - procaine - quinidine - quinine - sulfonamides - thiazides

Question 33

What is the most common dermatosis induced by systemic drugs?

Answer 33

maculopapular eruptions

Question 34

Describe the clinical presentation of maculopapular eruptions

Answer 34

- morbilliform - exanthematous - rubellaform eruptions - initially appear on truck and pressure areas and spread to entire body - flat or raised erythematous lesions symetrically distributed - few mm size to confluent large areas - itchy macules and papules

Question 35

When do maculopapular eruptions occur?

Answer 35

within first week of therapy

Question 36

maculopapular eruptions occurs in 3-7% of patients receiving what drugs

Answer 36

ampicillin or amoxicillin

Question 37

What are some other drugs that can cause maculopapular eruptions?

Answer 37

- cephalosporins - gentamicin - gold - isoniazid - phenylbutazone - phenytoin - sulfonamides - thiazides

Question 38

Clinical presentation of urticaria

Answer 38

- pink or red - edematous - raised papule and plaques - localized vasodilation and small transudations f fluid from small cutaneous blood vessels - angioedema (usually noticeable on face and around eyes)

Question 39

What are the mechanisms of urticaria?

Answer 39

- Type 1 hypersensitivity reactions - Type 3 immune reactions - Direct effects on mast cell (opioids) - Inhibition of prostaglandins (ASA, NSAIDS)

Question 40

What drugs can cause urticaria?

Answer 40

- ASA - NSAIDs - gold - heparin - opioids - penicillins - sulfonamides

Question 41

Describe fixed-drug eruptions

Answer 41

slide 29