[PF] DERMATOLOGICAL PHARMACOLOGY Flashcards
Two purposes of dermatological pharmacology:
- To directly treat disorders of the skin
2. To deliver drugs to other tissues
After application of a drug to the surface of the skin (stratum corneum), __________ and __________ may occur that affect the drug’s ultimate bioavailability.
evaporation
structural/compositional alterations
__________ limits drug diffusion into the lower layers and hence into the body
Stratum corneum
between the cells of the stratum corneum
Intercellular
across the corneal cellular layer
Transcellular
across the corneal cellular layer
Follicular
*with its associated sebaceous glandular cells and arrector pili muscle that is innervated by the sympathetic branch of the autonomic nervous system
Permeation to the _____ brings a drug in contact with lymphatics and cutaneous vessels carrying arterial and venous blood.
dermis
*These vessels provide an absorptive route into the general circulation.
Deeper permeation to the _______ may also occur.
hypodermis
Important considerations when a drug is applied to the skin:
- What are the absorption pathways of intact and diseased skin?
- How does the chemistry of the drug affect the penetration?
- How does the vehicle affect the penetration?
- How much of the drug penetrates the skin?
- What are the intended pharmacological targets?
- What host and genetic factors influence drug function in the skin?
- What are the predicted adverse effects?
immunosuppressive and anti-inflammatory properties
Glucocorticoids
measured using a vasoconstrictor assay in which an agent is applied to skin under occlusion, and the area of skin blanching is assessed.
Topical Glucocorticoids
*suppression of erythema and edema and the psoriasis bioassay
selected on the basis of its potency, the site of involvement, and the severity of the skin disease
Topical Glucocorticoids
Often, a more potent steroid is used initially, followed by a less potent agent.
Topical Glucocorticoids
daily application of topical glucocorticoids suffices; more frequent application does not improve response.
Twice
Chronic use of class 1 glucocorticoids:
- Skin atrophy
- Striae
- Telangiectasias
- Purpura
- Acneiform eruptions
________ and _______ develop after the use of fluorinated compounds on the face, therefore should not be used on this site.
perioral dermatitis and rosacea
________ increases the risk of HPA axis suppression
Occlusion
For severe dermatological illnesses and generally is reserved for allergic contact dermatitis to plants (e.g., poison ivy) and for life-threatening vesiculobullous dermatoses
Systemic Glucocorticoids
Daily morning dosing with ________ generally is preferred, although divided doses occasionally are used to enhance efficacy.
prednisone
Most side effects are _____________-.
dose dependent
Natural and synthetic compounds that exhibit vitamin A– like biological activity or bind to nuclear receptors for retinoids.
Retinoids
Retinoids exert their effects on gene expression by activating two families of receptors, ______ and ______, members- steroid receptor superfamily.
RARs and RXRs
*RAR: retinoic acid receptor
RARE: retinoic acid–responsive element
RXR: retinoid X receptor
On binding to a retinoid, RARs and RXRs form heterodimers (RAR-RXR) that bind specific DNA sequences (RAREs) that activate _______ of genes whose products produce both the desirable pharmacological effects
transcription
Retinoids that target _____ predominantly affect cellular differentiation and proliferation.
RARs
_______, _______ and _______ which target RARs, are used in acne, psoriasis, and photoaging (disorders of differentiation and proliferation).
Tretinoin
Adapalene
Tazarotene
Retinoids that target _____ predominantly induce apoptosis.
RXRs
_________ and ________ which target RXRs are used
Bexarotene
Alitretinoin
Retinoid Toxicity is similar to vitamin A intoxication:
dry skin, nosebleeds from dry mucous membranes, conjunctivitis, reduced night vision, hair loss, alterations in serum lipids and transaminases, hypothyroidism, inflammatory bowel disease flare, musculoskeletal pain, pseudotumor cerebri, and mood alterations
Photolabile (susceptible of change under the influence of radiant energy and especially of light)
Tretinoin
Should be applied once nightly for acne and photoaging
Tretinoin
_______ inactivates tretinoin and should not be applied simultaneously.
Benzoyl peroxide
Approved for the treatment of acne, psoriasis, and Cutaneous T Cell lymphoma
Systemic Retinoids
Recalcitrant (unresponsive to treatment) and nodular acne vulgaris (efficacy in severe acne) and may induce prolonged remissions after a single course of therapy.
Isotretinoin
Topical vitamin D analogue for the treatment of psoriasis.
Calcipotriene
Applied twice daily to plaque psoriasis on the body, often in combination with topical corticosteroids.
Calcipotriene
Hypercalcemia and hypercalciuria may develop when the cumulative weekly dose exceeds the recommended ________ limit and resolves within days of discontinuation of calcipotriene
100 g/week
precursor of vitamin A (green and yellow vegetables)
β-Carotene
Dietary supplementation used to reduce skin photosensitivity in patients with erythropoietic protoporphyria
β-Carotene
decreases the production of free radicals or single oxygen
β-Carotene
Maximum recommended therapeutic dose (MRTD) for β-carotene is _________.
0.05 mg/kg/d
UV or visible radiation induce a therapeutic response either alone (__________) or in the presence of an exogenous photosensitizing drug (__________)
phototherapy
photochemotherapy
(340–400 nm)
UVA1
(320–340 nm)
UVA2
(290–320 nm)
UVB
most erythrogenic and melanogenic, major action spectrum for sunburn, tanning, skin cancer, photoaging, and cutaneous vitamin D synthesis
UVB
(100–290 nm)
UVC
almost completely absorbed by the ozone layer and atmosphere so that measurable amounts do not reach Earth’s surface.
UVC
sunburns, photoaging, and skin cancer development, cause photoimmune suppression, an effect that is utilized for therapy of certain dermatological conditions.
UVA and UVB
a thousandth as erythrogenic as UVB but penetrates more deeply into the skin and contributes substantially to photoaging and photosensitivity diseases
UVA
able to penetrate clouds and glass, so exposure may occur even in the shade or while indoors.
UVA
combines UVA light with photosensitizing compounds called ________.
psoralens
Orally administered __________ followed by _______ is FDA approved for vitiligo and psoriasis, off label in several other inflammatory or lymphoproliferative cutaneous disorders
methoxsalen (8-methoxypsoralen)
UVA (PUVA)
stimulate melanocytes and induce antiproliferative, immunosuppressive, and anti-inflammatory effects, between 320 and 340 nm
PUVA: Psoralens and UVA
Oral methoxsalen dose is _____ capsule depending on weight (__________) taken about 1.5–2 h before UVA exposure.
10–70 mg
0.4–0.6 mg/kg
Lotion containing ________ is available for topical application for vitiligo.
1% methoxsalen
Approximately 70%–100% of psoriatic patients have clearing or virtual clearing of skin disease within about 24 treatments
PUVA
Remission typically lasts __________, often require maintenance therapy with intermittent PUVA or other agents.
3–6 months
between 150 and 300 treatments.
VITILIGO
Topical PUVA and more extensive disease with systemic administration.
Localized vitiligo
Risk of __________ dose dependent, greatest risk at more than 200–250 treatments
nonmelanoma skin cancer
Extracorporeal peripheral blood mononuclear cells separated using a leukapheresis-based method then exposed to UVA radiation in the presence of methoxsalen
Extracorporeal photopheresis (ECP)
_________ injected directly into the extracorporeal plasma before radiation and reinfusion
Methoxsalen
Treated lymphocytes are returned to the patient undergoing apoptosis over ________.
48–72 hr
Combines the use of photosensitizing drugs and visible light for the treatment of dermatological disorders, aminolevulinic acid and methylaminolevulinate.
Photodynamic Therapy
Provide temporary photoprotection from the acute and chronic effects of sun exposure
Sunscreens
Comprehensive sun protection approach along with minimizing sun exposure and using photoprotective gear.
Sunscreens
Reduces photocarcinogenesis and photoaging
Sunscreens
Ratio of the minimal dose of incident sunlight that will produce erythema (sunburn) on skin with the sunscreen in place to the dose that evokes the same reaction on skin without the sunscreen.
SPF (Sun protection factor)
Primarily a measure of UVB protection and does not provide information regarding UVA coverage.
SPF (Sun protection factor)
UVA protection assessed using the CW (critical wavelength) method, and products with a CW of 370 nm or greater may be labeled as ___________
“broad spectrum”
Sunscreens broad-spectrum coverage with an ______ or greater may include a claim on their labeling that use “decreases risk of skin cancer and early aging caused by the sun.”
SPF 15
Sunscreens should be applied liberally ________ prior to sun exposure and reapplied every ______.
15–30 min
2 hr
Activities involve swimming or sweating, water-resistant sunscreens are recommended and should be reapplied every _______ depending on their labeling.
40 or 80 min
Potent vasodilator, bronchial smooth muscle constrictor, and stimulant of nociceptive itch receptors
Antihistamines
Human skin mast cells express H1, H2, and H4 receptors but not ________.
H3 receptors