Dermatological Agents Flashcards
how are drugs deliver in dermatological diseases
Concentration gradient
Partition coefficient
Diffusion coefficient
what are the physiological factors of drug delivery in dermatological diseases
- thickness of stratum corneum
- degree of hydration
- temperature
what is the equation for Percutaneous Absorption
J=Cveh x K x D/x
what are most dermatological drugs incorporated into
vehicles
what are vehicles
vehicles bring the drug into contact with the skin
the type of vehicle used greatly influences what
drug’s absorption
-vehicles themselves can have a beneficial or harmful effect on the skin
see slide 5
see slide 5
what are the general guidelines for topical therapy
-dosage
-regional anatomic variation
altered barrier function
-hydration
-vehicle
what are topical glucocorticoids
-are grouped into 4-7 classes in order for decreasing potency
modifications of topical glucocorticoids are based on what
hydroxylation, methylation, fluorination or esterificaition are made to increase lipid solubility and potency, and decrease mineralcorticoid effect
relative potency of topical glucocortioics are based on what
vasoconstrictor assay, psoriasis bioassy, or relief of experimentally induced-erythema or inflammation
what is the mechanism of action of steroids
- penetrate cell membrane and bind to a cytoplasmic receptor- heat shock protein complex
- the heat shock protein is released and the hormone receptor complex is transported to the nucleus
steroids interact with —- and regulate their expression
glucocorticoid response elements on various genes and other regulatory proteins
what type of therapeutic use do topical steroids have
anti-inflammatory and immunosuppressive effects
MOA of topical steroids
-decrease adhesion, migration and function of macrophages, PMS and other lymphocytes
topical steroids block production and release of what
- various cytokines and acute phase reactants
- suppress growth factor induced DNA synthesis and fibroblast proliferation
describe the anti-inflammatory effects of topical steroids
-antimitotic; anti-inflammatory; reduce capillary permeability; local vasoconstriction; secondary anti-pruitic effects
how do you choose a topical steroid
ask yourself the following
- what condition are you trying to treat? (acute vs. chronic)
- what potentcy do youw ant to use?
- what part of the body are you treating? (thin vs. thick skin)
- minimize the risk of the SE
- what vehicle/Formulation do you want to use? (ointment, cream, gel, lotion, or foam?)
how are topical steroids strengths classified
classified into 4-7 potency groups
Group 1 = ultra high potency
Group 7 = lowest potency
absorption and potency of topical steroids are increased with what
fluorination, occlusion and application of thinner skin
lower potency are used for
infants, young children; elderly
high skin penetration areas
long-term/chronic therapy
higher potency are used for
Acute lesions/flare-ups
skin penetration poor
short-term control
where can steroids be applied from thickest to thinnest areas
palmar, plantar, nails dorsum of hands & feet lower arms & legs upper arms & legs eyelids*, face*, chest, & back mucous membranes*, scrotum*, submammary area*, axillary & perineal flexures*
*Fluorinated steroids generally avoided on these areas
what are ointments more potent
bc they tend to be more occlusive
what are ointments used for
- dry, fissured & lichenfied skin due to moisturizing effect
- palms and soles
what are creams used for
- weeping lesions due to drying nature
- used in intertriginous areas due to high moisture in these areas
what are gels, locations and foams used for
- suitable for scalp or regions with hair
- little moisturizing benefit
- penetration enhancers (eg. propylene glycol) often used which can be irritating
what is the purpose of occlusive dressings
- increase hydration of skin thus enhancing drug penetration
- increasing drug penetration increases risk of systemic adverse effects
what are occlusive dressings
wrapping medicated areas with occlusive dressings
what are the occlusive dressings commonly used
Saran Wrap, vinyl gloves, cotten gloves
what are the different types of skin infections
- bacterial, fingal, viral or parasitic in origin
- systemic therapy may be required
what drugs are used against surface bacterial infections
topical antibiotics are used
what are the therapeutic uses of topical antibiotics
- prevent infections in clean wounds
- for early treatment of infected dermatoses and wounds
- reduce colonization of the nares by Staphylococci
- to treat acne
what are the different OTC Topical Antibiotics
Bacitracin: Gram (+)
Neomycin: Gram (-), some Gram (+)
Polymixin: Gram (-)
Polysporin® (bacitracin + polymixin)
Neosporin® (all three)
what is the MOA of mupirocin
-inhibits bacterial enzymes necessary for protein and RNA synthesis
what is the spectrum of activity of Mupirocin
- effects gram (+) and some gram (-) bacteria
- broader spectrum of activity that OTC products
what is the functional role of Retinoids
- vision
- cell proliferation and differentiation
- bone growth
- immunity; tumor suppression
what is the MAO of Retinoids
-effects gene expression via 2 families of receptors (RARs; RXRs)
what are the different types of Retinoids
Tretinoin* (acne; photodamaged skin) Isotretinoin# (acne vulgaris) Alitretinoin* (Kaposi’s sarcoma) Acitretin# (psoriasis) Adapalene* (acne) Tazarotene* (acne; psoriasis; photoaging) Bexarotene*# (cutaneous T-cell lymphoma)
Retinoid Toxicity
- acute toxicity similar to Vit. A intoxication
- dry skin, nosebleeds, conjunctivitis, reduced night vision, hair loss, MSK pain, mucocutaneous abnormalities, “retinoid dermatitis” and mood alterations
- oral retinoids are potent teratogens
what is the goal of acne treatment
- correct abnormalities of follicular maturation (unplug pores)
- decrease sebum production
- decrease P.acnes colonization
- decrease inflammation
see slide 28-31
see slide 28-31
what are the Atopic Dermatitis
Glucocorticoids
Antihistamines
Immunosuppressants
what topical agents can be used to treat Pruritus
antihistamines
emollient creams and lotions
menthol
camphor pramoxine; doxepin; capsaicin; tar
what systemic agents are used to treat pruritus
antihistamines; doxepinl glucocorticoids
what physical modalities are used to treat Pruritus
PUVA; acupuncture, electrical stimulation
what immunosuppressants are used for Eczema
Tacrolimus and Pimecrolimus
what is the MOA of Tacrolimus and Pimecrolimus
- inhibits production of interleukins, interferons, other antigen-stimulated products in T cells
- inhibit release of pre-formed mediators from skin mast cells and basophils, breastfeeding
how long should Tacrolimus and Pimecrolimus be used for
short term and intermittent long-term therapy for eczema
what topical agents are used for Psoriasis
Glucocorticoids Calcipotriene (Vit D analog) Tazarotene (retinoid) Anthralin Coal tar
what systemic agents are used to treat Psoriasis
Methotexate
Acitretin
Immunosuppressants (cyclosporine; mycophenlate)
Biologic agents (alefacept; efalizumab; etanercept, adalimumab; infliximab)
