Photobiology

Question 1

optical radiation

Answer 1

UV
visible light
infrared

Question 2

UV light groups

Answer 2

UVC=200-280 nm, absorbed at ozone layer
UVB=280-320 nm, at/just below skin, burns
UVA1=320-340 nm, deep in skin, photo aging
UVA2=340-400 nm

Question 3

chromophore

Answer 3

molecule in skin that absorbs light energy

Question 4

meds that may result in phototoxic drug eruptions\

Answer 4

amiodarone
doxycycline
furosemide
hydrocholorthiozide
methotrexate
naproxen

Question 5

phytophotodermatitis

Answer 5

follows exposure to caustic plant material w/ UV exposure

patchy or linear erythema, hyper pigmentation

plants may contain furocoumarins (photosensitizer)

Question 6

photoallergy

Answer 6

delayed onset of 24-72 hrs (delayed hypersens)

redness and ITCHING

papular or papulaovesicular lesions

sulfa meds = common cause

Question 7

polymorphous light eruptions (PMLE)

Answer 7

epi: temperate climates, 2nd and 3rd decade onset, DTH to unknown antigen

outbreaks in spring, improved thru summer b/c adaptation

itching, burning, cutaneous lesions, edema, pink papules –> plaques, vesicles

may extend to photo protected sites

treat: min UV, sun block, protective clothing, topical corticosteroids, phototherapy

Question 8

xeroderma pigmentosum (XP)

Answer 8

auto rec

impaired DNA nuc excision repair of UV damage

burn, freckles, xerosis, basal and sq. call carcinoma

some have neurological abnormalities

inc. risk of internal malignancy

Question 9

psoralen

Answer 9

med that inc. absorption of UV light and anti inflam props

commonly combined w/ UVA

oral best results

Question 10

UVA blockers

Answer 10

benzophenones (incl. oxybenzone)
avobenzone (Parsol 1789)
titaniam dioxide/zinc oxide
mexoryl

Question 11

UVB blockers

Answer 11

para-aminobenzoid acid (PABA)
padimate-O (derived from PABA)
salicylates (incl. homosylate) -stabilizer
cinnamates (incl. octyl methoxycinnamate)
titanium oxide/zinc oxide