derm Flashcards
SJS vs TEN: which is more extensive?
TEN>SJS
- 30% vs <10% mortalitty
SJS and TEN are
severe mucocutaneous reactions, usually to drugs, characterised by blistering and epithelial sloughing
- widespread epithelial keratinocyte apoptosis and necrosis, initiated by drug-induced cytotoxic T-lymphocytes
how do we categorise SJS and TEN cases?
- SJS: epidermal detachment<10% BSA, with widespread purpuric macules or flat atypical targets
- Overlap SJS-TEN: detachment of 10-30% BSA, with widespread purpuric macules or flat atypical targets
- TEN with spots: detachment >30% BSA, with widespread purpuric macules or flat atypical targets
- TEN without spots: detachment: >30% BSA, with loss of large epidermal sheets without purpuric macules or target lesions
most common drugs causing sjs/ten
- allopurinol
- lamotrigine
- sulfamethoxazole
- carbamazepine
- phenytoin
- nepvirapine
- sulfasalazine
- other sulfonamides
- oxicam NSAIDs: piroxicam, tenoxicam
- phenobarbital
- etoricoxib
likely causative drug was administered how long prior to the onset of the prodrome?
5-28 days
patients with sjs/ten who are immobile in bed should receive
LMWH as prophylactic anticoagulation against VTE
during acute phase of sjs/ten, patients in whom enteral nutrition cannot be established may benefit from
ppi to protect against upper GI stress ulceration
what kind of lubricant eye drops recommended for patients with sjs/ten?
non-preserved
topical corticosteroid drops in sjs/ten
reduce ocular damage in the acute phase, but can mask signs of corneal infection and should be used with caution in presence of a corneal epithelial defect
minoxidil, cannot be used to grow hair if
hair follicles are no longer present
- primary function is to prevent and slow down hair loss
- hair regrowth is more of a side effect
2 types of sunscreen
physical: reflect and scatter light, prevent uv radiation from penetrating the skin
chemical: absorb uv radiation, preventing it from reaching the deeper layers of the skin
examples of common active ingredients of chemical sunscreens
- Cinnamates
- Drometrizole trisiloxane
- Octocrylene
- Oxybenzone
- Avobenzone (butyl methoxydibenzoylmethane)
- Octinoxate
- Salicylates
- Terephthalylidene dicamphor sulfonic acid
common active ingredients of physical sunscreens
zinc oxide and titanium dioxide
if you have oily or acne-prone skin, what type of sunscreen formulation to avoid?
greasy
other ways to maximise sun protection, other than using suncreen
- Avoiding the sun when it is strongest between 11am to 3pm.
- Wearing protective clothes under the hot sun. Even if you are under the shade on the beach, sunrays can be reflected off the sand and cause a burn on your skin.
SPF
Sun Protection Factor: index to indicate the degree of protection from UVB
UVB
type of UV radiation that is more likely to cause sunburn
the higher the SPF
the longer the duration of protection
A sunscreen with SPF ___ or higher should be applied frequently to maintain protection
30
apply the sunscreen at least ____ before going into the sun
half an hour
with a non-water resistant sunscreen, reapply
after every swim or heavy perspiration, but make sure our skin is dry first
with a water resistant sunscreen, reapply
every 2 hours or every hour if you have been swimming
do you have to wear sunscreen on cloudy or overcast days?
yes, the sunrays are as damaging to your skin on hazy days as they are on sunny days
do you have to wear sunscreen at high altitudes?
yes, there is less atm to absorb the sunrays so exposure is higher and risk of sun burning is also higher
oxybenzone in kids
has been found in other studies to be associated with (but not necessarily to cause) lower testosterone levels in adolescent boys
how old must you start using sunscreen adily?
6 months old
sunscreen ingredient to avoid in children
PABA, oxybenzone
- generally go for physical sunscreen: low risk of sensitisation, irritation, and skin peentration potential
reco amt of sunscreen to apply
9 teaspoons
healing wounds should not be treated with
topical antiseptics other than silver (silver nitrate, silver sulfadiazine) because they are irritating and tend to kill fragile granulation tissue
silver preparations have
strong antimcrobial properties
- effective in treating wounds, burns and ulcers
- several wound dressings are impregnated with silver
zinc pyrithione is
an antigunfal and a common ingredient in shampoos used to treat dandruff due to psoriasis or seborrheic dermatitis
iodine indicated for
presurgical skin preparation
keratinolytics
soften and exfoliate epidermal cells
- salicylic acid
- urea
antipruritics
camphor, menthol, EMLA, calamine lotion
antiseptic agents
povidone iodine, clioquinol, gentian violet, silver preparations (silver nitrate, silver sulfadiazine), zinc pyrithione
non-steroidal anti-inflammatory agents
tar (crude coal tar)
TCS group 1
ultra high potency
- clobetasol propionate: ointment, cream, gel, shampoo
TCS group 2
high potency
- bethamethasone dipropionate: ointment
- mometasone furoate: ointment
TCS group 3
high potency
- betamethasone dipropionate: cream
- bethamethasone valerate: ointment
TCS group 4
medium potency
- mometasone furoate: cream, lotion [elomet]
TCS group 5
lower-mid potency
- bethamethasone dipropionate: lotion
- bethametasone valorate: cream
- triamcinolone acetonide: cream
- fluticasone propionate: cream
- desonide: ointment
- hydrodrocortisone 0.1: ointment, cream, lotion, solution
TCS group 6
low potency
- desonide: cream, lotion
- bethamethasone valerate: lotion
TCS group 7
least potent
- hydrocortisone acetate base, betamethasone 0.025/0.5
systemic side effects of TCS
rare due to low percutaneous absorption
- glaucoma
- HPA suppression
- HTN
- hyperglycemia
- Cushing’s syndrome
local SE of TCS
- spread and worsening of untreated infection, if present
- contact dermatitis
- acne
- mild depigmentation
- hypertrichosis
- atrophy/ telangiectasias/ striae
to maintain long term disease control with TCS
intermittent therapy may be effective eg. twice weekly application
TCS withdrawl develop when
- potent TCS are used frequently and for a long time
- within days to weeks after stopping use of TCS
- manifest as a worsening rash that requires stronger and more frequent application of topical steroids to control
2 main types of rash that may develop at sites of application
- erythematoedematous: red, swollen, scaly and peeling
- papulopustular: red, pus-filled bumps without scaling or peeling
FTU
500mg = 0.5g = 2% BSA
it takes ___g to cover an average adult body for one application
30
pathophysiology of tinea presentation
- inoculation -> incubation:
- dermatophytes grow in the stratum corneum, minimal signs of infection - infestation remains within straturm corneum
- allergy and inflammation of skin caused by kertinases and other proteolytic enzymes produced by dermatophytes when they reach the living layer of epidermis
-> tinea presentation
predisposing factors for fungal skin infection
- skin trauma
- warm and moist conditions
- immunocompromised patients
- impaired blood circulation
moa of azoles
destroy fungal infections by inhibiting biosynthesis of ergosterol, incr membrane permeability: fungistatic
2 types of azoles
imidazoles: superficial skin infection, topical
triazoles: systemic
nizoral indicated for
ketoconazole 2%: dandrugg, seborrhoic dermatitis, tinea vesicolor
products contianing clotrimazole
canesten, candazole
products containing miconazole
mycoban, daktarin, zarin
allylamines MOA
inhibit sterol biosynthesis to deficiency in ergosterol to fungal death
is allylamines or imidazoles faster at curing inea?
imidazoles, appox 1-2 week
age restriction for topical imidazoles vs allylamines
<2yo vs 12yo
moa of tolnaftate
Though its exact mechanism unknown, it is believed to prevent ergosterol biosynthesis by inhibiting squalene epoxidase.
pathophysiology of acne
- follicular hyperproliferation and abnormal desquamation
- increased sebum production
- cutibacterium acnes proliferation
- inflammation
acne meds: follicular hyperpproliferation
topical retinoids, oral isotretinoin, azelaic acid, salicylic acid
acne meds: increased sebum production
oral isotretinoin, oral contraceptives, spironolactone, clascoterone
acne meds: c.acnes proliferation
topical/oral abx, bpo, azelaic acid
acne meds: inflammation
oral tetracyclines, topical retinoids, oral isotretinoin, azelaic acid, topical dapsone
how long does acne products take to work?
6-8 weeks
which group of patients have sensitive skins, predisposed to irritation from excessive cleansing or exposure to acids?
old, fair, female, dry skin
