Dermatopharmacology Flashcards
Using antibiotics in derm for
Anti-inflammatory effects, not infectious*
Occlusion
Cover the skin to decrease transepidermal water loss, which hyperhydrates the epidermis, which allows it to heal faster and medication can now easily penetrate the skin.
Epidermal disorder therapy vs dermal disorder therapy
Topical medications vs. systemic medications like oral steroids/intralesional steroids to get into dermis without systemic effects
The classification system for corticosteroids is based on
Their bioassay vasoconstrictor effects- which correlates directly to anti-inflammatory effectiveness
Class I topical corticosteroids and prototype
Very high potency- clobetasol proprionate, 0.05%
Many side effects- atrophy of epidermis, starts to break open=ulcer/erosion, brings BV’s in there to cause redness, etc
Class II
High potency- betamethasone diproprionate, 0.05%
Don’t want to use this for an extended period of time
Class III
Medium potency- triamcinolone 0.1%, flucticasone proprionate, 0.05%
Can use in chronic conditions
Class IV
Medium-low potency- triamcinolone, 0.025%
Can use chronically
Class V
Low potency- hydrocortisone, 2.5%
Topical formulations of corticosteroids: Hairy bearing areas- Cosmetically more elegant option or forSeborrheic dermatitis- Oral mucosa- Gold standard-
Aerosols, foams, solutions, lotions, gels (not for all races/genders)
Creams
Gel or paste
Ointment
*tape can also be used with any of these to increase adherence and increase delivery without patient having to administer corticosteroid medium
Topical corticosteroids are effective treatments for relief of
Inflammatory dermatoses
Pruritic dermatoses
NOT appropriate monotherapy for primary infections
Infection usually drives a concomitant dermatitis- corticosteroid WITH anti-infectious agent
Topical corticosteroid risks
All topicals are potentially teratogenic (Pregnancy category C)
They should be used with caution in children since absorption is greater than in adults and may lead to HPA axis suppression and may induce Cushing’s syndrome.
Skin atrophy at the site of application can also occur in 3-4 weeks use of potent preparations
Lindane (Kwell)
Ovicide and ectoparasiticide- stimulates parasite nervous system resulting in paralysis
Pediculicide for lice- pediculosis capitis or pediculosis pubis: lotion/shampoo
Scabicide for mites- cream or lotion
Systemic preparation- peak levels at 6 hrs, residual in fat and brain, seizure risk (higher in premature neonate and children due to excessive absorption and poor liver function)
Permethrin (Elimite, Nix)- MOA, uses
Pharmacokinetics and ADME
Adverse reactions
Scabicide, pediculocide, and ovicide: MOA disrupts nerve membrane sodium channel current, delays repol, paralyzes ectoparasite. USE- lice, ticks, mites, fleas
Single topical application, <2% absorbed systemically, metabolized by ester hydrolysis, excreted in urine
AE’s: pruritus and temporary burning/stinging
Retinoids and others (acne and anti-psoriatic prep)
Acne:
Retinoids acid- tretinoin; trans-retinoids acid; Vit A acid any skin problem that has to do with messed up keratogenesis
Isotretinoin- 13-cis-retinoic acid (acutane) Class X teratogen (topical isotretinoin is class C)
Acetretin- etretinate metabolite
Adapalene- retinoid-like, milder form
Tazarotene- new generation
Benzoyl peroxide- not a retinoid
Psoriasis- calcipotriene: synthetic Vit D3 analog (regulates the differentiation of keratinocytes)
Acne grading
Grade 1- comedones (clogged hair follicle- keratin skin debri combines with oil to block follicle)
Grade 2- comedones and papules
Grade 3- comedones, papules, and pustules
Grade 4- comedones, papules, pustules and nodules
Retinoids MOA- tretinoin and isotretinoin
Retinoic acid nuclear receptors
Decreases cohesiveness of follicular epithelial cells; decreased microcomedone formation
Stimulates mitotic activity of follicular epithelial cells; extrusion of comedones
Topical- tretinoin, Retin-A, category C
Oral- isotretinoin, Accutane, Category X (avoid concomitant Vit A)
Isotretinoin uses and cautions
Indications- recalcitrant acne, severe grade 4 acne
Side effects- teratogenic, lipid abnormalities, dry lips and skin, arthralgias/myalgia, hepatotoxic, mood, pseudotumor cerebri (intracranial hypertension)
Topical tretinoin cautions
Red, dry, painful skin
Consider combination therapy side effects- other topical acne medications augment these side effects
Want to put it on dry skin- wet skin will enhance its effects, enhancing its side effects
Topical treatments for acne- 3 categories
Comedolytic- grade 1 and >
Antibacterial- grade 2 and >
Antiinflammatory- grade 2 and >
Treatment that is comedolytic, antinflammatory and antibacterial
Benzoyl peroxide
Comedolytic and antiinflammatory treatments
Tretinoin, adapalene, Azelaic acid, tazarotene
Antiinflammatory and antibacterial
Clindamycin and erythromycin
Systemic therapy for grade 3 and 4 acne
Tetracycline family: doxycycline and minocycline
Topical anti-pruritic agents
Doxepin (topical, Zonalon)
MOA is unknown, but it is a potent H1+H2 (histamine rec) antagonist (systemic use as anti-anxiety med)
Hepatic metabolism to active desmethyldoxepin, renal excretion, up to 10% incidence of poor metabolizers (P450IID6 enzyme def)
Warnings- drowsiness in >20% using topical cream, systemic adverse events are related to BSA covered or areas used
Minoxidil
Rogain
MOA= presumably linked to K+ channel activation of hair follicles, promotes blood vessel dilation, stimulates vertex hair growth in ~4 months.
PK and ADME- not significantly absorbed through skin
AE- skin irritation
