Light therapy Flashcards
PUVA - when do you dose and how? oral and bath?
Food reduces absorption (take fasting), Large inter-individual variations; 1st pass effect through liver
Give 1-2 hours prior to UVA careful photoprotection until after sundown
DOSE -
1. Methoxsalen (8-methoxypsoralen) – on empty stomach = 10mg capsules: 0.6mg/kg 2hr prior to UVA
Oxsoralen Ultra (dissolved 8-MOP) 0.4mg/kg 1hr prior to UVA
Bath (approved only for vitiligo) = 8-MOP lotion diluted 1:10 parts with ethanol 0.1% solution
OR 0.5-5mg 8-MOP/L of bath water = 0.05-0.5% applied 15 min prior + 0.5J/cm2 increasing by 0.25 J/cm2
MOA for light therapy?
- Suppression of DNA synthesis – mechanism for PsO
- Photoimmunologic effectives (selective immunosuppression) – mechanism for PsO
- Selective cytotoxicity
- Stimulation of melanocytes
light therapy c/i?
PUVA - hypersensitivity to Psoralen
LACTATION
relative: PPPPPs
pregnancy, photosensitivity/photo meds Pemphigus, Pemphigoid LE with Photosensitivity Pemphigus and pemphigoid LE with photosensitivity XP
also prior ionizing rad, arsenic MM hx chronic photo damage severe cardiac, liver or renal dz very young
UVA dose? when to do reading? drugs to avoid?
UVA Dose Induction – 3x/w - either by FST (below) or find minimal phototoxic dose (analgous to MED) = minimal dose of UVA (following psoralen) that produces barely perceptible but well defined erythema
READ = 72 hrs
I 1.5 0.5 5 II 2.5 0.5 8 III 3.5 0.5-1 12 IV 4.5 1.0 14 V 5.5 1.0 16 VI 6.5 1.0-1.5 20
avoid cytotoxic drugs: FAINTED and worried sick
furosemide, amio, Nsaids, Thiazide,s tetras
cipro, vori
s/e of PUVA phototherapy?
short term: erythema, edema, pain, pruritis, KOEBNER, HSV recurrence
HYPERTRICHOSIS
photosensitivity eruption
long term: phtoodamage, PUVA lentigines, NMSC, MM
8 mop (.6/kg) - GI, CNS, hepatic tox, drug hypersensitivity
baseline investigations for PUVA?
FBSE, CR, LFTs, ANA PRN, OCULAR EXAM!!!!!
what are instructions post PUVA?
PROTECTION
In unit: eye goggles, face protection (sunscreen or pillow), male genitalia (jock)
Post exposure: Wrap-around UV-opaque glasses until sunset, skin protection (clothing, sunscreen, avoid)
Ø treatment days: avoid sun and use sunscreens
UVB nm? nb and bb? MOA?
311-313 nm, 290-315/20 bb
MOA nb UVB?
UVB Chromophore = DNA Pyrimidine dimers
1. Reduces DNA synthesis suppresses accelerated DNA synthesis of PsO (most import for PsO)
2. Induces expression of p53 cell cycle arrest + apopostosis prevents photocarcinogenesis
3. Releases prostaglandins and cytokines: IL-6 (systemic symptoms), IL-1 (immune suppression)
Psoriasis action spectrum = 304 & 313nm(B), 300-320nm(W) KC and TC targeted Th17
nbUVB advantages (vs bbUVB) = NMSC, erythema (both < 300nm), closer to PsO action spectrum
c/i UVB
Absolute:
Pemphigus and pemphigoid
LE with photosensitivity
XP
Relative:
Photosensitivity/photosensitizing medications
PMH/FHx melanoma
Skin cancer or chronic photodamage
NOT PREGNANCY OR LACTATION UNLIKE UVA
s/e UVB?
short term: erythema, xerosis, pruritis, edema, bullas, PMLE, etc
mucosa: blepharitis, infectious, HSV
AI: LE, pemphigus, pemphigoid
long term : photoaging, MNMSCa
can pred be combined with UVB?
no, reduces remission time, discouraged
can do anthralin, calcipqotriol, emolients
UVB dosing?
note mJ and 20, 40, 60 for BB and x 10 for nB
vs UVA 72 hrs, J unit
Exposure doses for minimal erythema dose (MED – minimum dose of UVB to achieve barely perceptible but well-defined erythema) assessment (measured @ 24h):
bbUVB = 20, 40, 60, 80, 100, 120 mJ/cm2
nbUVB = 200, 400, 600, 800, 1000, 1200 mJ/cm2
70% of MED for first dose Treat M, W, F – increase dose 10% each treatment if erythema –
asymptomatic = hold dose,
symptomatic but subsides = reduce by 20%,
symptomatic and still present = HOLD then reduce dose 20%
whats the fig plant mnemonic for phytotoxic drugs?
Phototoxic drugs = FiG PLANT = Furosemide, Griseofulvin, Plaquenil, Levofloxacin, Amiodarone, Accutane, NSAIDs, Tetracyclines, Thiazides
