clinical Flashcards
characteristics of topical steroids
lipophilic - allows passive diffusion across plasma membrane where they combine with cell receptors + bind to steroid responsive elements in DNA
anti-proliferatives
anti-inflammatory
vasoconstrictive
why are creams more likely to cause contact sensitisation than ointments?
creams contain preservations - ointments do not
patients prefer creams but ointments are better for very dry, hyperkeratotic areas.
how much ointment is required for a typical adults all over application?
30g
2 hands areas = 1/2g, 1 fingertip unit
investigation for bacterial infection
swab for bacteriology
- staph aureus
- impetigo
investigation for viral infection
swab of vesicular fluid for virology
- herpes labialis - cold sore
investigation for fungal infection
scraping of edge for mycology
- athletes foot (tineas pedis)
investigation for infestations
scraping for microscopy
- scabies - lift out mite on needle
when would you use immunofluorescence as an investigation?
skin diseases with an immune basis - lupus, vasculitis, blistering diseases
- localises antibodies, complement
- small biopsy of perilesional skin (skin just beside lesion)
Ix for type 4 h/s
(delayed) patch test
- > possible allergens prepared in Finn chambers + applied to back under occlusion for 48hrs
benefits of foams as base/vesicle
increases penetration of active agents - steroids, vit D
spreads easily over large areas with no grease
side effects of topical steroids
thinning of skin purpura stretch marks poor wound healing rosacea, fixed telangectasia can mask/worsen infections
are adults or kids more at risk of topical steroid side effects?
kids due to larger surface area to volume ratio
give an example of a mild + potent topical steroid
mild = hydrocortisone 1%
potent = clobetasol propionate
what systemic effects can vit D analogues cause?
hypercalcaemia
hypercalcuria
