Dermatologic Therapeutics Flashcards
Drug factors affecting percutaneous absorption of topical medications
Active drug concentration
Composition of the vehicle
Molecular size of the drug or prodrug
Lipophilicity of the drug
Patient factors affecting percutaneous absorption of topical medications
Presence of barrier disruption
Anatomic location (including thickness of the stratum corneum)
Skin hydration
Occlusion
Types of vehicles for topical medications
Ointments: Water in oil emulsion
Creams: Oil in water emulsion
Gels: Semisolid emulsion in alcohol base
Lotions/Solutions: Powder in water (some oil in water)
Foams: pressurized collections of gaseous bubbles in a matrix of
liquid film
Ointment characteristics and sites of use
- strong potency
- hydrating
- very low sensitization; low irritation risk
- good sites: non-intertriginous
- bad sites: face, hands, groin
Cream characteristics and sites of use
- moderate potency
- some hydration < ointments
- significant sensitization risk; low irritation risk
- good sites: most
- bad sites: areas w/maceration
Gel characteristics and sites of use
- strong potency
- drying
- significant sensitization; high irritation risk
- good sites: oral mucosa, scalp
- bad sites: areas w/fissures, erosions, or maceration
Lotions/solutions characteristics and sites of use
- low potency
- variably drying
- significant sensitization; moderate irritation risk
- good sites: scalp, intertriginous regions
- bad sites: areas w/fissures, erosions
Foams characteristics and sites of use
- stable at room temp but melts at body temp
- supersatured solution allows maximal delivery of active ingredients
- strong potency
- good sites: hair-bearing areas
- bad sites: areas w/fissures, erosions
Important factors in selecting appropriate vehicle
- anatomic location
- contact allergy/sensitization
- irritancy
FTU definition
- amount dispensed from 5mm diameter nozzle that fits in the distal third of the index finger
- 1 FTU=0.5g
FTUs required to cover face and neck
2.5 FTU
FTUs required to cover trunk (front or back)
7 FTU
FTUs required to cover arm
3 FTU
FTUs required to cover hand (both sides)
1 FTU
FTUs required to cover leg
6 FTU
FTUs required to cover foot
2 FTU
Mechanism of action of corticosteroids
- bind receptors in cytoplasm of cells –> ultimately alter transcription
- alter mRNA production of several inflammatory pathways:
- cAMP/CREB-binding protein
- nhibits nuclear factor-kb –> decreases cytokines, adhesion mlx, inflammatory enzymes
- interacts w/activating protein 1 (AP-1) which controls trxn of growth factor and cytokine genes
General classes of topical glucocorticosteroids
- Class 1(Superpotent)
- Class 2 (High potency)
- Class 3 (High potency)
- Class 4 (Medium potency)
- Class 5 (Medium potency)
- Class 6 (Low potency)
- Class 7 (Low potency)
Prototypical corticosteroids
- “gentle touch”: Hydrocortisone 2.5% (cream or ointment)
- “almost all-purpose weapon”: Triamcinolone Acetonide 0.1% (cream or ointment)
- “hercules”: Clobetasol Propionate 0.5% (cream or ointment)
Hydrocortisone 2.5% characteristics
- class 7 (lowest potency)
- good for:
- mild eczema in children and adults
- inflammatory dermatoses @ face, intertriginous areas, groin
Triamcinolone Acetonide 0.1%
- class 4 (medium potency)
- good for:
- moderate spongiotic dermatoses (e.g. eczema, atopic dermatitis, allergic contact derm, athropod bites, drug reactions) @ trunk, extremities
- not on face, groin, intertriginous regions
Clobetasol Propionate 0.5%
- class 1 (superpotent)
- acute eruptions that need quick resolution (e.g. contact dermatitis or acute drug eruptions)
- not on face, groin, intertriginous regions
Adverse effects of topical glucocorticosteroids
- more potent = greater adverse effects
- skin atrophy = shiny, thin skin, telangiectasia, striae formation
- systemic side effects=adrenal suppression, Cushing’s syndrome, growth retardation in children
