Derm Flashcards
The efficacy of a topical applied drug depends on…
its potency & on its ability to penetrate skin
What are factors that affect penetration?
- Concentration of med
- Thickness & integrity of stratum corneum
- Frequency of application
- Occlusiveness of the vehicle
- Compliance
Topical formulations are meant to…
enhance the beneficial effects of the med
What can cause local toxicity?
The vehicle or its active ingredients
Topical meds can induce…
systemic toxicity
Penetration w/ regards to regional differences
1 = most penetration 10 = less penetration
- MM
- Scrotum
- Eyelids
- Face
- Chest/back
- Upper arms & legs
- Lower arms & legs
- Dorsa of hands/feet
- Palmar & plantar skin
- Nails
Is the epidermis thicker in acral skin or eyelid skin?
Acral
What all determines the response to topical drugs?
- Regional variation in drug penetration
- Concentration
- Dosing schedule
- Vehicles
- Occlusion
What are the goals of derm therapy?
- Counteract disease
- Reduce inflammation
- Relieve sx
- Promote epithelial healing
- Restore integrity of cutaneous barrier
- Prevent complications
Topical therapy considerations
- Vehicle selection
- Class selection
- Appropriate quantity for BSA involved
- Enhance absorption
- Tachyphylaxis: diminishing response to doses of a drug, rendering it less effective
1 palm area = ….
1% BSA
2 FTUs = …..
1 g of topical steroid
How can you enhance absorption w/ topical therapy?
- Cover area to increase effectiveness & absorbency into skin
- Apply topical to skin & cover w/ plastic wrap, cellphane, waterpoof dressing, cotton socks, or nylon.
How can topical therapies be delivered?
- Powders
- Liquids: foams, solutions, lotions, gels
- Combo of liquid & oil: creams, ointments
What is an example of a nonocclusive dressing? What are they used for?
- MC = gauze
- Allow air to reach wound
- Allow the lesion to dry
What are wet-to-dry dressings? What are they used for?
- Nonocclusive dressing wetted w/ saline
- Cleanse & debride lesions
What are occlusive dressings? What are they used for?
- MC = transparent films or transparent semi-permeable dressings
- Increase absorption & effectiveness of topical
What are characteristics of topical corticosteroids?
- Antimitotic effects on epidermis
- Minimally absorbed
- Occlusion enhances penetration (10x increase in absorption)
- Penetration increases in inflamed skin
When are super high potency (Class I) corticosteroids used?
For severe dermatoses over nonfacial areas:
- Scalp, palms, soles, thick plaques over extensor surfaces
When are medium-high potency (class II-V) steroids used?
Mild-mod nonfacial areas
When are low potency steroids (Class VI, VII) used?
Large areas & thinner skin:
- Face, eyelid, genital, intertriginous areas
How long are corticosteroids used for depending on potency?
High: < 3 wks
Med-high: < 6-8 wks
Low: side effects rare, 1-2 wk intervals
What is an example of a class I (high potency) topical corticosteroid?
Clobetasol propionate .05% cream or ointment
What are 2 examples of class II (med-high potency) topical corticosteroids?
- Betamethasone .05% cream
- Fluocinonide .05% cream
What are 3 examples of class III (med-high potency) topical corticosteroids?
- Betamethasone diproprionate .05% cream or lotion
- Betamethasone valerate .1% ointment
- Triamcinolone acetonide .1% ointment
What are 2 examples of class IV (med-high potency) topical corticosteroids?
- Fluocinolone acetonide .025% ointment
- Tramcinolone acetonide .1% cream or ointment
What is an example of a class V (med-high potency) topical corticosteroid?
Flucinolone acetonide .025% cream
What is an example of a class VI (low potency) topical corticosteroid?
Triamcinolone acetonide .1% cream
What is an example of a class VII (low potency) topical steroid?
Hydrocortisone 1%
What are systemic effects of topical steroids?
- suppresion of hypothalamic-pituitary-adrenal axis
- Cushings syndrome
- pseudotumor cerebri
- growth retardation
- Na retention & edema
What are ocular effects of topical steroids?
- cataracts
- glaucoma
- retarded healing of corneal abrasion
- extension of herpetic infection
- increased susceptibility to bacterial & fungal infection
What are cutaneous effects of topical steroids?
- atrophy
- striae
- telangiectasias, purpura, ecchymosis
- hypopigmentation
- retardation of wound healing
- contact allergic derm
- “habituation”
What are 4 categories of antibacterial agents?
- Bacitracin
- Mupirocin
- Polymyxin B, neomycin, gentamicin
- Topical/oral abx in acne
What are characteristics of bacitracin?
- Active against gram + (s. aureus, strep)
- Used alone or in combo w/ neomycin, polymyxin B, or both
- Poorly absorbed
- Contact derm is common
What is mupirocin active against? What are ADEs? What forms is it available in?
- Gram+
- Stinging, burning, pruritis, HA
- Cream or ointment
What is polymyxin B active against?
Gram - (pseudomonas, enterobacter, e.coli)
*All gram+ are resistant
What is neomycin active against? What is an ADE?
- Aerobic gram+ & gram- bacilli (s. aureus, e.coli)
- sensitization
What is important to know about gentamicin?
Has greater activity against pseudomonas than neomycin
How do you classify acne severity?
- Mild: < 20 comedones
- Mod: 20-100 comedones
- Severe: > 100 comedones
What are 4 factors involved in acne vulgaris?
- Increase in sebum via androgens
- Keratin & sebum plug hair follicle –> hyperkeratosis w/ comedone formation
- P. acnes proliferates in follicle
- Inflammatory response
What are 2 actions of retinoids?
- Normalize desquamation
- Reduce inflammation
What are 2 actions of abx?
- Reduce microorganisms
- Reduce inflammation
What are 4 actions of oral isotretinoin?
- reduce sebum
- normalize desquamation
- inhibit p. acnes growth
- reduce inflammation
What is the action of hormones?
Reduce sebum
What is the action of benzoyl peroxide?
Reduce microorganisms
How do you tx mild acne?
Topical retinoid OR topical benzoyl peroxide
How do you tx moderate acne?
Topical retinoid & benzoyl peroxide +/- topical abx
How do you tx severe acne?
Topical retinoid & benzoyl peroxide +/- topical abx & oral abx
How do you tx comedones?
topical tretinoin
How do you tx cystic acne?
intralesional triamcinolone
What is the preferred oral antibiotic for acne?
Tetracyclines
- Doxy = best
Why should topical & oral abx not be used as monotherapy for acne?
Risk of resistance
What 2 topical abx are used for rosacea?
- Metronidazole
- Sulfacetamide
What 2 topical abx are used for acne?
- Clindamycin
- Erythromycin
- Both combined w/ benzoyl peroxide
What are the ADEs of metronidazole gel form?
Dryness, burning, stinging
Can you use topical metronidazole in pregnancy or breastfeeding?
Not recommended
Sodium sulfacetamide MOA
Inhibits p-aminobenzoic acid
Sodium sulfacetamide contraindication
Sulfonamide sensitivity
What are other tx options for rosacea?
- Sunscreen daily
- Clindamycin & erythromycin
- Imidazoles, ketoconazole
- Azelaic acid
- Tetracyclines
What can you use to tx stage III rosacea w/ rhinophyma & fulminans?
Isotretinoin
What local reactions of erythromycin solution?
Burning, drying, irritation
What are characteristics of retinoic acid (vit A)?
- Tx for acne vulgaris
- increases cell turnover
- expulsion of open comedones
- transformation of closed comedones to open
- can induce erythema & peeling
What are ADEs of tetracycline?
- slate gray hyperpigmentation
- drug-induced lupus
- minocycline –> dizziness
What are ADEs of erythromycin & clindamycin?
Erythro = GI upset Clinda = C. difficile
What are the guidelines for isotretinoin?
- Women MUST use 2 forms of contraception (1 month before, through tx, & for 1 cycle following tx)
- Pregnancy test MUST be obtained within 2 wks prior to tx
What are the side effects of isotretinoin (oral retinoid)?
- Dry MMs, xerosis, cheilitis
- joint pain
- thinning hair
- HA
- nausea
- mood swings, suicidal ideations, sleep disturbance
What is the required duration of tx for topical antifungals?
4-6wks
What are 2 actions of imidazoles?
- inhibit enzyme –> mem leaking
- alter cell mem –> fungal cell death
Do not use topical imidazoles for…
subcutaneous, nail or hair infections
What is the box warning for immunomodulators?
- malignancy
- avoid long-term use
- apply to limited areas
- don’t use in < 2 yo
How do you tx pruritis?
- tx underlying cause
- cool skin, light clothes
- AC, humidifier
- Avoid allergens
- Tepid shower before bed or cool compresses
- Apply cream/ointment within 3 mins after bathing
What is a side effect of antipruritic agents? What is a contraindication?
- Drowsiness
- Contraindicated in urinary retention or glaucoma
What is the MC med used for scabies?
Permethrin
What is an alternative drug used for scabies in pregnancy or infants?
Sulfur
What 3 agents affect pigmentation?
Hydroquinone
Mequinol
MBEH
What is the action of trioxsalen & methoxypsoralen?
Repigmentation of depigmented macules of vitiligo
Sunscreen vs sunblock
- Suncreen: chemical compounds that absorb UV
- Sunblock: opaque materials that reflect light
What drug is used for actinic keratoses?
Fluorouracil
How do you tx psoriasis?
- Initial = high potency topical steroid
- phototherapy
Acitretin (retinoid metabolite) guidelines for the tx of psoriasis?
- DON’T use in pregnancy (must wait to get pregnant 3 yrs after tx)
- Avoid Etoh (during tx & for 2 months after)
- MUST NOT donate blood during tx or for 3 yrs after
