Psoriasis Tx: Pharmacology

[liveonearth]

chronic, noncontagious autoimmune dz affecting skin and joints
red, scaly patches on skin
immune cells move from dermis to epidermis, stimulating keratinocyte proliferation
guttate psoriasis looks like droplets on skin
extensor surfaces

DRUG TX
involves stepwise progression of:
topical corticosteroids
topical vitamin D (calciprotriene)
phototherapy with psoralen
systemic therapy incl oral steroids, chemotherapy agents (methotrexate), and TNF inhibitors (infliximab/remicade)

PHOTOTHERAPY
electromagnetic non-ionizing radiation (ultraviolet A or B
psoralen drugs (ie methoxsalen) added to tx
phytochemotehrapy with psoralen containing plant extracts dates back to 1500 BC
in India and Egypt
what plants contain psoralen??

PSORALEN
aka psoralene
parent compound in a family of natural products known as furocoumarins
structurally related to coumarin
a derivative of umbelliferone
occurs naturally in the seeds of Psoralea corylifolia
Psoralea = tumbleweed genus, Fabaceae family
also in common fig (Moraceae), celery, parsley (Apiaceae) and West Indian satinwood (Rutaceae)
widely used in PUVA tx for psoriasis, eczema, vitiligo, and Cutaneous T-cell Lymphoma
safe to mammals
use with care: many furocoumarins extremely toxic to fish
mb used in streams in Indonesia to catch fish

PUVA
= psoralen + ultraviolet A
psoralen drugs react to UV
mechanism not fully understand
therapy induces anti-inflam rxn, suppresses immune rxn, inhibits DNA synthesis
used for: psoriasis, vitiligo (stims melanocyte prolif), T-cell lymphoma, alopecia areata, urticaria pigmentosa (pt scratches skin off??)
SE: nausea, erythema, blistering, increased risk of skin cancer, advanced skin aging, actinic kerotosis