Dermatology Lecture # 2 pharm.txt

• Mucocutaneous
• Mucous membrane
• Glabrous
• Hairy

At the junction of the mucous membrane, hairyskin, lips, and tongue

Lining the inside of body orifices

• Skin without hair
• Epidermal layer 1.5 mm; dermis 3 mm

• Skin with hair
• Epidermial layer 0.07 mm; dermis 1.5 mm

Penetrate stratum corneum, enter remaining epidermis / dermis

• Drug molecular weight, particle size, solubility – if they are lipiphilic they are likely to get absorbed
• Drug concentration in the vehicle
• Vehicle
• Chemical / physical properties of vehicle
• Thickness/hydration of epidermis
• Occlusion
• Disease/damaged skin

Lipiphilic

This is what the active agent is placed in, it is important in how something is absorbed, petroleum based is absorbed quickly

The more hydrated, the better absorption

Occlusive dressings will cause the drug to be absorbed better, you may not always want this

Absorbed faster

Ointments, emulsions, liquids

• Lipophilic drug in a vehicle
• Vehicle: petrolatum, mineral oil, wax, organic alcohol
• High release of drug into skin

Mixture of two immiscible substances

Creams and foams

• An emulsion
• Oil in water: more cosmetic
• Water in oil: more occlusive
• O/W cannot be washed off with water while W/O can

• An emulsion
• Liquid and gas
• Easy to apply to hairy areas

Lotions, gels, oils

• Chronic inflammatory pruritic condition
• Genetically predisposed individuals

• Acute phase - Erythema, papulovesicular lesions, oozing, crusting
• Chronic phase - Lichenified skin, pigmentary alteration, < exudative, vesicular lesions than acute, thickened skin, more prone to fissures

Hypersensitivity to environmental allergensOverproduction of IgE by helper T cellsTriggers immune response and release of cytokines

Infant - Extensor parts of extremities (knuckles); cheeks of face

Flexural areas: neck, antecubital & popliteal spaces

Forehead, periorbital areas; hands/wrists; feet/ankles

Control itching and scratchingTreat any inflammation or infectionRestore normal skin barriermaintain skin integrity; limit discomfort

No cure; most children outgrow symptoms

• Hygiene - Literature varies on frequency of baths
• Agree on lukewarm water, gentle soap & shampoo (Dove, Tone, Caress, Aveenobar, Neutrogena)
• Moisturizers - Applied frequently
• Check labels: avoid alcohol containing products
• Avoid fragrances and dyes ***hypoallergenic***

• You do not want a lotion with the first ingredient as water because the water will evaporate very quickly
• Need petroleum based products

• AD worse during dry winter, hot humid summer
• Avoid occlusive clothing, irritating fabrics (wool)
• Wear cotton

• Discourage food introduction prior to 4 months of age
• Avoid known allergens
• tree nuts, peanuts, shellfish, fish, eggs, orange juice, cow’s milk

• UV light (sunshine) may offer some benefit
• Avoid sunburn

To treat secondary infections

Topical Corticosteroid Usage - Relieve inflammation and itchingApplication Immediately after the bath before moisturizersApply sufficient amount to cover lesion only

• Systemic absorption proportional to duration of use and surface area covered
• permeability: scalp, axilla, face, eyelids, neck, perineum, genitalia, inflammed skin
• permeability: back, palms, soles, intact skin

• Ointments are more potent than creams because of their occlusive nature
• Occlusiveness increases effect 10-fold
• Occlusive dressing enhance effect

• Classified from less to more potent
• Some resources list classes I – VII, others list by potency (low, intermediate, high, very high)
• Using resources, in your peripheral brain create a chart with 1 – 2 meds of each category for future reference

• Use least potent product which is effective
• Use low potency products for face, genitalia, axillae
• Prolonged usage results in hypopigmentation
• Adults 2 weeks, children < 6yo 1 week

• Percent of concentration is not equivalent
• 0.05% betamethasone dipropionate is high potency while 2.5% hydrocortisone is low potency

Viral infections of the skin

Antihistamines relieve itching from hives caused by histamine releaseCause of the itching from atopic eczema is quite different from that of hives and involves mechanisms other than histamine

• Classical antihistamines can cause some drowsiness, use of these at bedtime for short period may be useful to help the child sleep when they are itchy, but the sedative effects of these antihistamines do not persist with continued usage
• No indication for the newer generation of antihistamines such as Claritin, Allegra, or Zyrtec since they provide little or no sedation

• Given at bedtime to limit scratch - itch cycle by inducing drowsiness and promoting sleep
• Hydroxyzine (Atarax)
• 0.6 mg/kg/dose q6h prn
• Diphenhydramine (Benadryl)
• 0.5-1.0mg/kg/dose Q4-6h prn

Currently indicated for atopic eczema that does not respond to conventional therapy with skin care and low potency topical corticosteriodsNot a replacement for skin care but may provide an alternative to topical corticosteroids when those are not effective or require excessive use

• Atopic dermatitis
• reduces T cell response = less inflammation

• No risk of the cosmetic changes associated with prolonged usage of topical corticosteroids
• Not required continuouslywhere corticosteroids are required continuously

• Promote shedding of the horny layer of skin
• Effects range from peeling to extensive desquamation of stratum corneum

• For condylomata acuminata: venereal warts
• Only applied by care provider
• Apply on wart surface x 60 minutes; wash thoroughly
• Severe irritation at site of application if not removed
• Repeat weekly up to 4 weeks
• Contraindicated in pregnancy

• For genital and perianal warts
• Can be applied by patient

Scrub to remove dead surface cellsApply on wart surfaceDo not apply to face, genitals, mucous membranes Causes site irritation

diabetes, impaired circulation , children < 2 yo , pregnancy

Dissolves intracellular cement binding scales to stratum corneum

• Forms: disc, gel, ointment, plaster solution, patch
• Apply to wart bid x 7 - 14 days until resolution occurs
• Rub briskly after bath to remove dead surface cells
• Do not apply to face, genitals, mucous membranes

• Contraindicated: diabetes, impaired circulation, children < 2 years of age
• Causes site irritation

Promotes peeling and drying

Forms: lotions, gels, shampoos

Also used to treat acne, dandruff, psoriasis, and seborrheic dermatitis

• Other
• Banana peel
• Duct tape
• Coins, rubbing
• Talking it off

Oxidizes bacterial protein

Benzoyl peroxideSulfur, resorcinol, salicylic acidAzelaic acidTretinoin (retin A, retinoic acid)Antibiotics

Kerolytic and mildly antibacterial

Interfers with DNA synthesis in some bacteria

Comedolytic agent, follicular wall cell turnover

Clindamycin, erythromycin, tetracycline

• Oral antibacterial agents
• Oral contraceptives
• Antiandrogen (androgen receptior blocker)

Clindamycin, erythromycin, tetracycline

Significantly decreases free fatty acids in skin lipids

Decrease androgen levels thus sebum is decreased

spironalactone (Aldactone), flutamide (Eulexin)

• Limited to severe, refractory acne
• Hepatic conjugation, biliary excretion
• Monitor CBC, liver enzymes, TG, cholesterol prior to and weekly to bi-weekly until stable, then monthly
• Stop if liver enzymes x 2 normal or TG >750 mg/dL
• Absolutely contraindicated in pregnancy - Birth control mandatory, Pregnancy tests mandatory

Contact dermatitis immunologically mediatedErythematous, vesicular, pruritic lesions

• Drying lotions, gels
• Antihistamines (hydroxyzine, diphenhydramine)
• Cortisone medications – Topical & Systemic (prednisone)

These trees are deciduous so remember this is child comes in the fall

If child has a rash all over they probably need prednisone because it is a systemic reaction

• Irritation
• Secondary to urine contact with skin

• Change diaper when wet, air dry skin
• Apply barrier cream

Caused by yeast

• Change diaper when wet, air dry skin
• Apply nystatin cream or ointment

• Skin infection at site of skin break caused by streptococcus and staphylococcus
• Contagious

Presentation: Initially small, erythematous papules which enlarge, become moist, develop honey yellow crusts on red base.

Treatment: oral antibiotics, antibacterial soap, antibacterial ointment

Thickened, erythematous, scaling plaques

• Cause unknown but immune system implicated
• Activates disordered growth of keratinocytes
• Also significant genetic component

• Emollients/keratolyticsTopical corticosteroids
• How do topical treatments for psoriasis work?
• Adjunct role: erythema, pruritus, scaling

Cytostatic productsCoal tar / UV light; anthralin, calcipotriene, acitretin, tazarotene

Immune suppression - Cyclosporine and Tacrolimus

• Polysporin, Neosporin, Mupirocin (Bactroban)
• Bacitracin - Gram +
• Polymixin B - Gram –
• Polysporin - Bacitracin and polymixin- gram + and -
• Neosporin - Gram + & - but…no strep, Pseudomonas
• Mupirocin (Bactroban) - Strep & staph but…↑ MRSA resistance