Sec 36 Topical Therapy and Sec 38 Physical Treatments Flashcards
The rate-limiting barrier to percutaneous drug delivery.
Stratum corneum
This cornified layer is composed of ceramides, free fatty acids, and cholesterol in a 1:1:1 molar ratio
Stratum corneum
Composition: Stratum corneum
50% ceramides (acylceramides being the most abundant)
35% cholesterol
15% free fatty acids
Two main routes for permeation through the stratum corneum
- Transepidermal pathway
2. Transappendageal pathway
Involves the flow of molecules through the eccrine glands and hair follicles via the associated sebaceous glands
Transappendageal, or shunt route
Molecules pass between the corneocytes via the intercellular micropathway, or through the cytoplasm of dead keratinocytes and intercellular lipids
Transepidermal route
Considered the most important route for cutaneous drug delivery
Intercellular pathway
Difference in penetration (from most to least penetration)
- Mucous membrane
- Scrotum
- Eyelids
- face
- chest and back
- Upper arms and legs
- lower arms and legs
- Dorsa of hands and feet
- Palmar and plantar skin
- Nails
Occlusion increases drug delivery by
10-100x
Associated with adherence to a treatment regimen
Female gender
Employment
Being married
Low prescription costs
Decrease in drug response when used over a prolonged period of time
Tachyphylaxis
Worsening of preexisting dermatoses
Rebound effect
Emulsifying agents
Cholesterol Disodium mono-oleamidosulfosuccinate Emulsifying wax Polyoxyl 40 stearate Polysorbates Sodium laureth sulfate Sodium lauryl sulfate
Auxiliary emulsifying agents/emulsion stabilizers
Carbomer Catearyl alcohol Cetyl alcohol Glyceryl monostearate Lanolin and lanolin derivatives Polyethylene glycol Stearyl alcohol
Stabilizers
Benzyl alcohol Butylated hydroxyanisole Butylated hydroxytoluene chlorocresol Citric acid Edetate disodium Glycerin Parabens Propyl gallate Propylene glycol Sodium bisul te Sorbic acid/potassium sorbate
Solvents
Alcohol Diisopropyl adipate glycerin 1,2,6-Hexanetriol Isopropyl myristate Propylene carbonate Propylene glycol Water
Thickening agents
Beeswax Carbomer Petrolatum Polyethylene Xanthan gum
Emollients
Caprylic/capric triglycerides cetyl alcohol Glycerin Isopropyl myristate Isopropyl palmitate Lanolin and lanolin derivatives Mineral oil Petrolatum Squalene Stearic acid Stearyl alcohol
Humectants
Glycerin
Propylene glycol
Sorbitol solution
Absorb moisture and decrease friction; adhere poorly to the skin; use is mainly limited to cosmetic and hygienic purposes; used in the intertriginous areas and on the feet
Powders
Also referred to as a cataplasm; a wet solid mass of particles, sometimes heated; used as wound cleansers and absorptive agents in exudative lesions such as decubiti and leg ulcers
Poultice
Semisolid preparations that spread easily; petrolatum-based vehicles, capable of providing occlusion, hydration, and lubrication
Ointments
Also called oleaginous bases; often referred to as emollients because they prevent the evaporation of moisture from the skin; composed of a mixture of hydrocarbons of varying molecular weights; greasy and can stain clothing
Hydrocarbon bases
Contain hydrophilic substances that allow for the absorption of water-soluble drugs; these are lubricating and hydrophilic, and they can form emulsions; greasy to apply; do not contain water; examples: anhydrous lanolin and hydrophilic petrolatum
Absorption bases
Contains <25% water, with oil being the dispersion medium with the two phases separate unless shaken; less greasy, spread easily on the skin, and provide a protective film of oil that remains on the skin as an emollient, while the slow evaporation of the water phase provides a cooling effect
Water-in-oil emulsion
Contains >31% water with the aqueous phase may comprise up to 80% of the formulation; one most commonly chosen to deliver a dermatologic drug; spread very easily, are water washable and less greasy, and are easily removed from the skin and clothing
Oil-in-water emulsion
Consist either primarily or completely of various PEGs; water soluble, will not decompose, and will not support the growth of mold, and therefore require no preservative additives; much less occlusive than water-in-oil emulsions, nonstaining, greaseless, and easily washed off of the skin
Water-soluble bases
Made from water-soluble bases by formulating water, propylene glycol, and/or PEGs with a cellulose derivative or carbopol; consists of organic macromolecules uniformly distributed in a lattice throughout the liquid; suitable for facial or hairy areas
Gels
Incorporation of high concentrations of powders (up to 50%) into an ointment such as a hydrocarbon base or a water-in-oil emulsion; function to localize the effect of a drug that may be staining or irritating; also function as impermeable barriers that serve as protectants or sunblocks; less greasy than ointments, more drying, and less occlusive
Pastes
Involves the dissolution of two or more substances into homogenous clarity. The liquid vehicle may be aqueous, hydroalcoholic, or nonaqueous
Solutions
A hydroalcoholic solution with a concentration of alcohol of approximately 50%
Tincture
A nonaqueous solution of pyroxylin in a mixture with ether and ethanol, and is applied to the skin with a soft brush
Collodion
Nonaqueous solutions of drugs in oil or alcoholic solutions of soap; can be used as counterirritants, astringents, antipruritics, emollients, and analgesics
Liniments
Two-phase system consisting of a finely divided, insoluble drug dispersed into a liquid in a concentration of up to 20%; easier to apply and allow for uniform coating of the affected area; more drying than ointments, and preparations with alcohol tend to sting eczematized or abraded skin
Suspension or lotion
Lotions to which a powder is added to increase the surface area of evaporation; effectively dries and cools wet and weeping skin; tend to sediment
Shake lotions
Triphasic liquids composed of oil, organic solvents and water, which are kept under pressure in aluminum cans; formulated with a hydrocarbon propellant
Foams
Involve formulating the drug in a solution within a pure propellant which is a blend of nonpolar hydrocarbons; allow for the ease of application and high patient satisfaction but expensive and potentially ecologically damaging
Aerosols
Compound that is able to promote drug transport through the skin barrier
Penetration enhancer
Application of crystals (generally aluminum oxide) on the skin and the collection of such crystals and skin debris under vacuum suction
Microdermabrasion
Nontherapeutic ingredients and include the preservatives, antioxidants, and chelating agents
Stabilizers
Increase the viscosity of products or suspend ingredients in a formulation
Thickeners
Patients may detect burning or stinging sensations without any signs of cutaneous irritation after applying a topical medication
Sensory irritant contact dermatitis
Reported with the long-term use of nitrogen mustard
Keratoacanthomas
Basal and squamous cell carcinomas
Lentigo maligna
Primary melanoma
Factors that modulate absorption also influence toxicity
Concentration of the drug Vehicle Use of occlusion Body site and area treated Frequency of use Duration of therapy Nature of the diseased skin
Parameters that Affect Drug Amounts in Skin Compartments
- Formulations may undergo drastic changes in composition and structure
- Drug or formulation may affect the skin barrier, resulting in time-dependent changes of the barrier function
- Skin barrier may be affected by the type and progression of a disease
- Regional variations in the barrier properties of the skin
- Skin may respond to topical drug, enhancing or retarding percutaneous absorption
- Metabolic capacity of skin may lead to exposure of skin or systemically to both parent drug and pharmacologically active metabolite(s)
Highly responsive dermatoses to topical application of corticosteroids
Psoriasis (intertriginous)
Atopic dermatitis (children)
Seborrheic dermatitis
Intertrigo
Moderately responsive dermatoses to topical application of corticosteroids
Psoriasis Atopic dermatitis (adults) Nummular eczema Primary irritant dermatitis Papular urticaria Parapsoriasis Lichen simplex chronicus
Least responsive dermatoses to topical application of corticosteroids
Palmoplantar psoriasis Psoriasis of nails Dyshidrotic eczema Lupus erythematosus Pemphigus Lichen planus Granuloma annulare Necrobiosis lipoidica diabeticorum Sarcoidosis Allergic contact dermatitis, acute phase Insect bites
The amount of an active ingredient that is still in contact with the nonvolatile constituents of its formulation after the latter had been massaged into the skin surface
Reservior
Microscopic spheres comprising a bilayer that encloses an inner aqueous core
Liposomes
Potential sites of discontinuity in the integrity of the skin barrier
Appendages
The uptake of compounds by the cutaneous microvasculature; directly related to the surface area of the exchanging capillaries as well as their blood flow
Resorption
MOA: Blockage of DNA synthesis by inhibition of thymidylate synthetase
5-fluorouracil
MOA: Alkylating activity, immune stimulation
Mechlorethamine (nitrogen mustard)
MOA: Alkylation agent: inhibits DNA, RNA, and protein synthesis
Carmustine
MOA: Antimitotic agent: acts by disrupting microtubules, blocking cell division in metaphase
Vinblastine
MOA: Disrupts DNA synthesis and causes scission of DnA strands
Bleomycin
MOA: Antimetabolite: interferes with DNA synthesis (inhibition of dihydrofolate reductase)
Methotrexate
MOA: Binds tubulin, disrupting the cellular cytoskeleton
Podophyllin
MOA: Cytotoxic - promotes phospholipid turnover
and modulates membrane signal transduction by inhibition of protein kinase c
Miltefosine
Indications: 5-fluorouracil
Actinic keratoses
Superficial basal cell carcinomas
Indications: Mechlorethamine (nitrogen mustard)
Mycosis fungoides Stages IA, IB
Indications: Carmustine
Mycosis fungoides Stages IA, IB
Indications: Vinblastine
Kaposi sarcoma
Indications: Bleomycin
Viral warts
Hemangiomas
Keloids
Hypertrophic scars
Indications: Methotrexate
Keratoacanthoma
Indications: Podophyllin
Anogenital warts
Facial angiofibromas
Indications: Miltefosine
Cutaneous metastases of breast cancer
Cutaneous lymphomas
Cutaneous mastocytosis
Indications: Tacrolimus and Pimecrolimus
Second-line therapy for atopic dermatitis
Children older than 2 years
Adults
Short-term, noncontinuous chronic therapy
Indications: Imiquimod
External anogenital warts Actinic keratosis Superficial BCC smaller than 2 cm on trunk, neck, extremities Immunocompetent adults When surgical options less appropriate Biopsy confirmed
Contraindications: Tacrolimus and Pimecrolimus
Immunocompromised
Netherton syndrome
Active bacterial or viral infection
Phototherapy
Contraindications: Imiquimod
Immunocompromised
Refractory, thicker, actinic keratoses
Dosing of Imiquimod for Anogenital warts
3x/week
Max: 16 weeks
Dosing of Imiquimod for Actinic keratosis
2x/week for 16 weeks
Dosing of Imiquimod for Superficial BCC
5/week for 6 weeks
Complications: Tacrolimus and Pimecrolimus
Elevated blood levels and risk of systemic immuno- suppression
Unclear long-term risk of lymphoproliferative disease
Unclear long-term malignancy risk
Eczema herpeticum
Complications: Imiquimod
Irritant contact dermatitis
Ulceration
Incomplete treatment of malignancy
Bisbiguanide which (1) binds to negatively charged bacterial cell wall and cytoplasmic components leading to altered osmotic equilibrium and (2) precipitation of cytoplasmic components; for gram-positive, gram- negative bacteria, enveloped viruses, and fungi; can cause keratitis, ototoxicity; used for antiseptic surgical hand B scrub and surgical site preparation
Chlorhexidine
Dye with unknown MOA; for some vegetative gram- positive bacteria and yeast; can cause potential skin necrosis at high concentrations or when occluded, stains skin and clothing, tattooing when applied over granulation tissue and mutagenic; used for impetiginized eczema, mycotic skin infections, oral candidiasis and superficial skin infections
Gentian violet
Dye with unknown MOA; for some vegetative gram- positive bacteria and yeast; can cause potential skin necrosis and stains skin and clothing; used for impetiginized eczema, mycotic skin infections, oral candidiasis and superficial skin infections
Brilliant green
Peroxide which oxidizes microbial molecules and is a broad spectrum antimicrobial; can cause bleaching of hair; used for cleansing of wounds, suppurating ulcers, and local infections
Hydrogen peroxide
Iodophor which oxidizes and releases of free iodine; for gram-positive, gram-negative, enveloped viruses, fungi, sporicidal, Mycobacterium tuberculosis; can cause potential systemic toxicity in neonates or when applied to large body surface area, neutralized by blood, serum proteins, and sputum; used as antiseptic surgical hand c scrub, prevention or treatment of topical site
infection associated with surgery, burns, minor cuts/ scrapes
Povidone-iodine
Iodophor which oxidizes and releases free iodine, chelates bacterial surface and trace metals needed for bacterial growth; for gram-positive, gram-negative, enveloped viruses, fungi, sporicidal, M. tuberculosis; may have possible irreversible optic atrophy and peripheral neuropathy (oral), contraindicated in children <2 years of age, contraindicated for diaper rash, stains skin yellow and neutralized by blood, serum proteins, and sputum; approved for fungal — infections; also used for pyoderma, folliculitis, and impetigo
Clioquinol
Imidazole which acts by creation of reduced intermediate compounds and free radicals on anaerobes, protozoa, and microaerophilic bacteria used in Rosacea; contraindicated during 1st trimester of pregnancy
Metronidazole
A fermentation product of Pseudomonas fluorescens which acts by inhibiting bacterial isoleucyl-t- RnA synthetase on gram-positive, some gram-negative, but spares normal flora; used in non-bullous impetigo, B eradication of nasal carriage of S. aureus; potentially toxic amounts of polyethylene glycol contained in vehicle may be absorbed in patients with extensive burns or open wounds
Mupirocin
Pleuromatilin which acts by inhibits 50S subunit of prokaryotic ribosome on Gram + bacteria; used in nonbullous impetigo
Retapamulin
Dicarboxylic acid which acts by inhibition of microbial respiratory chain of Propionibacterium acnes and S. epdermidis; used in Acne; may cause hypo pigmentation
Azaleic acid
Peroxide which oxidizes microbial molecules; used in Acne; bleaches dark clothing
Benzoyl peroxide
Astringent which acts by coagulation of proteins used for weeping, impetiginized skin disorders; should not be used under impervious material to prevent evaporation
Aluminum salts
Astringent which acts by oxidation microbial molecules used for weeping, impetiginized skin disorders; can cause skin discoloration and caustic at high concentrations or with contact of undissolved crystals
Potassium permanganate
Astringent which acts by precipitation of bacterial proteins by free silver ions used for eeping, impetiginized skin disorders, cauterization
of wounds, removal of granulation tissue and aseptic prophylaxis of burns; can cause black skin discoloration, caustic at high concentrations and potential methemoglobinemia
Silver nitrate
Agents that cause contraction of the tissues, arrest of secretion, or control of bleeding or a drug product that is applied to the skin or mucous membranes for a local and limited protein coagulant effect
Astringent
Synthetic pyrethroid which inhibits nerve cell sodium ion influx used in lice and scabies and used on clothing as an insect repellant; may cause itching and stinging
on application and contraindicated for infants <2 months of age
Permethrin (1% or 5%)
Natural botanical which inhibit nerve
cell sodium ion influx or inhibits cytochrome P450; used for lice; can cause itching and stinging on application and ragweed or chrysanthemum allergy
Synergized pyrethrins
Organophosphate which is a cholinesterase inhibitor used in lice; flammable; not approved for children <6 years of age
Malathion (0.5%)
Crotonyl-N-ethyl- O-toluidine with unknown MOA; used in Scabies
Crotamiton (10%)
Organochlorine which is a cholinesterase inhibitor used in lice and scabies; may cause seizures, muscle spasms, aplastic anemia; not for use in children <3 years, pregnant or breastfeeding women, patients with underlying neurologic disorders, or over broken skin
Lindane (1%)
Fermentation product which acts by generalized central nervous system excitation leading to paralysis in lice
Spinosad (0.9%)
Topical antipruritic has local anesthesia and histamine antagonism
Diphenhydramine
Tricyclic antidepressant with antipruritic effects through histamine antagonism, interference with neuronal synaptic communication; decreased awareness through production of drowsiness
Doxepin
Cyclic terpene alcohol which acts as a counter-irritant; cooling sensation may be the result of a direct interaction of menthol with cold receptors and/or nerve fiber
Menthol
In low concentrations (0.5% to 2.0%) acts as an antipruritic agent through its anesthetic effect; percutaneously absorbed and should be avoided in pregnant women and infants. In higher concentrations, it is caustic and is used for deep chemical peels
Phenol
Effective in cases of mild to moderate pruritus; inhibits conduction of nerve impulses by altering the cell membrane permeability to ions; onset of action: 2-5 minutes
Pramoxine Hydrochloride
A vitamin D analog which inhibits epidermal proliferation, induces epidermal differentiation, and exerts anti-inflammatory effects
Calcipotriol
Keratolytic (available at concentrations up to 12%); increases ceramide production by keratinocytes improving water barrier function
Lactic acid
Humectant that is proteolytic at high concentrations; added to some topical glucocorticoid preparations to increase penetration; used for dry skin and nail plate destruction
Urea
In concentrations of 3% to 6%, it causes shedding of scales by softening the stratum corneum, dissolving the intracellular matrix, and loosening connections between corneocytes. In concentrations > 6%, it is destructive to tissue.
Salicylic acid
Humectant, occlusive, and keratolytic agent, often combined with other medications to enhance their penetration used in patients with lamellar ichthyosis and n various other hyperkeratotic diseases
Propylene glycol
Reduce the thickness of hyperkeratotic stratum corneum by an incompletely understood mechanism wherein the acids may directly solubilize the protein components of desmosomes or activate endogenous hydrolytic enzymes by changing the pH of the stratum corneum, resulting in keratolysis
A-Hydroxy acids
UVB filter most commonly used PABA derivative and is photounstable
Padimate O
Cinnamate most widely used UVB filter and is photounstable; rarely a photoallergen
Octinoxate
Weak UVB absorbers which improves photostability of other filters
Octisalate
Weak UVB absorbers. good substantivity: used in water-resistant sunscreens and hair-care products
Trolamine salicylate
Photostable UVB filter and improves photostability of photolabile filters
Octocrylene
Water soluble UVB filter and enhances sun protection factor of the final product
Ensulizole
Most commonly used UVA filter; most common cause of photoallergic contact dermatitis to UV filters
Oxybenzone
A weak UVA filter with no sensitization reaction reported.
Meradimate
Photounstable UVA1 filter which enhances the photodegradation of octinoxate
Avobenzone
Factors affecting sun protection of garments
Style of garment Number of layers Fabric thickness Type of fibers (polyester > wool, silk, nylon > cotton, rayon) Stretching Laundering Wetness Chemical treatments
Ratio of the minimal erythema dose (MED) of a subject’s sunscreen-protected skin over the MED of the unprotected skin
Sun protection factor (SPF)
Most widely used method to evaluate protection against UVA
Persistent pigment darkening (PPD)
Quantifies the ability of the sunscreen to prevent immunosuppression
Immune Protection Factor (IPF)
Narrowband UVB by MED
1-cm2 areas on the lower back or inner aspect of the forearm: 200, 400, 600, 800, 1,000, 1,200 mJ/cm2 read at 24 h initial: 50-70% of MED 2–5 times per week Increase by 10%–20%
Narrowband UVB by Fitzpatrick Skin Phototype
I - 130 - 2,000 II - 220 - 2,000 III - 260 - 3,000 IV - 330 - 3,000 V - 350 - 5,000 VI - 400 - 5,000
Broadband UVB by MED
1-cm2 areas on the lower back or inner aspect of the forearm:
20, 40, 60, 80, 100, 120 mJ/cm2
read at 24 h
initial: 50-70% of MED
2–5 times per week
Increase by 25% x 10 treatments then 10% thereafter
Broadband UVB by Fitzpatrick Skin Phototype
I - 20 II - 25 III - 30 IV - 40 V - 50 VI - 60
Oral PUVA by MPD
1-cm2 areas on the lower back or inner aspect of the forearm:
0.5, 1.0, 2.0, 3.0, 4.0, 5.0 mJ/cm2 UVA
read 72 h after UVA
initial: 50-70% of MPD
2-4 times per week
Increase UVA dose per table entries each week
Oral Psoralen dose
8-MOP micronized 0.6 mg/kg; 120 minutes before UVA 8-MOP dissolved 0.4-0.6 mg/kg; 90 minutes before UVA
Oral PUVA by Fitzpatrick Skin Phototype
I - 0.5 - 0.5 II - 1.0 - 0.5 III - 1.5 - 1.0 IV - 2.0 - 1.0 V - 2.5 - 1.5 VI - 3.0 - 1.5
Bath Psoralan dose
8-MOP dissolved in bath water for a final concentration of 1.0 mg/l
Bath water is at body temperature (98.6°F)
Duration of bath is 15–20 minutes
Modification of Phototherapy Dose: No erythema
Increase by 25%
Modification of Phototherapy Dose: Erythema with no pain
No increase
Modification of Phototherapy Dose: Erythema with pain
Hold treatment until symptoms subside
Modification of Phototherapy Dose: Erythema with pain and blistering
Hold treatment until symptoms subside and then reduce dose by 50% from last dose
Modification of Phototherapy Dose: Missed <1 week
No increase in dose
Modification of Phototherapy Dose: Missed 1–2 weeks
Decrease dose by 50% (BB-UVB) or 25% (NB-UVB or PUVA)
Modification of Phototherapy Dose: Missed 2–3 weeks
Decrease dose by 75% (BB-UVB) or 50% (NB-UVB PUVA)
Modification of Phototherapy Dose: Missed >3 weeks
Restart at initial exposure dose
Diseases amenable to UVA1
Atopic dermatitis Cutaneous T-cell lymphoma Localized and systemic scleroderma Chronic GVHD Lymphomatoid Papulosis Telangiectasis macularis eruptiva Perstans Urticaria pigmentosa Granuloma annulare Chronic hand eczema
Phototherapy-Responsive Diseases for therapy
Psoriasis Palmoplantar pustulosis Mycosis fungoides (stages IA, IB) Vitiligo Atopic dermatitis Generalized lichen planus Urticaria pigmentosa Cutaneous graft-versus-host disease Generalized granuloma annulare Pityriasis lichenoides Lymphomatoid papulosis Pityriasis rubra pilaris Localized scleroderma
Phototherapy-Responsive Diseases for prevention
Polymorphous light eruption Hydroa vacciniformea Solar urticaria Erythropoietic protoporphyria Chronic actinic dermatitis
Indications for Photopheresis (with sufficient evidence)
Erythrodermic cutaneous T-cell lymphoma
Chronic graft-versus-host disease
Acute graft-versus-host disease
Organ transplant rejection
Indications for Photodynamic Therapy - Oncologic
Actinic keratosis
Bowen disease
Superficial BCC
Off label: Actinic Cheilitis Nevoid BCC syndrome Keratoacanthoma Superficial SCC Kaposi sarcoma Cutaneous metastases Cutaneous T-cell lymphoma
308 nm Excited dimer molecules (Xe-Cl) Different gases Gas Pulsed μs–ms
Excimer laser
532 nm Nd Crystal: Yttrium- aluminum Garnet (Y3Al5O12) Solid state Pulsed μs–ms
“KTP” laser (Nd:YAG laser) frequency doubled with KTP crystal
585–600 nm Dyes (e.g., Rhodamines) Organic solvents Liquid Pulsed ms
Dye laser
694 nm Cr Al2O3 Solid state Pulsed μs–ms
Ruby laser
755 nm Cr Chrysoberyl (BeAl2O4) Solid state Pulsed μs–ms
Alexandrite laser
Different wavelengths (e.g. 810, 940) InGaAs, AlGaAs Semiconductor material Solid state Pulsed μs–ms
Diode laser
1,064 nm Nd Crystal: Yttrium-aluminum Garnet (Y3Al5O12) Solid state Cw, Pulsed μs–ms
Nd:YAG laser
2,940 nm Er Crystal: Yttrium-aluminum Garnet (Y3Al5O12) Solid state Pulsed ms
Er:YAG laser
10,600 nm CO2 Different gases Gas Cw, Pulsed ms
CO2 laser
Power × Time
W x s
Energy (J)
Power / Area
W / cm2
Intensity
Power x Time / Area
Radiant exposure (“Fluence”)
Target - DNA, proteins
Effect - Photochemical reactions
Application - Comparable to narrow band UVB 311nm
Excimer (XeCl) (308)
Target - Vascular lesions; Tissue
Effect - Semiselective coagulation; Coagulation
Application - Telangiectases, spider nevi, venous lakes;
Syringoma, xanthelasma, epidermal nevi
Argon (488/514)
Target - Vascular lesion
Effect - Selective coagulation (“KTP” laser)
Application - Telangiectases, spider nevi, venous lakes
Frequency-doubled Nd:YAG (532)
Target - Pigmented lesions
Effect - Selective and fast heating Nd:YAG (explosion)
Application - Benign melanin-containing lesions, tattoos (red)
Frequency-doubled Nd:YAG (532)
Target - Vascular lesions; Tissue
Effect - Selective Coagulation
Application - PWS, telangiectases, rosacea, spider nevi; Scars, keloids, warts, photoaging
Flashlamp pulsed dye (585–600)
Target - Pigmented lesions
Effect - Selective and fast heating (explosion)
Application - Benign melanin-containing lesions, tattoos (black, blue, green)
Ruby (694)
Target - Vascular lesions; Tissue; Pigmented lesions
Effect - Selective coagulation; Selective and fast heating (explosion)
Application - large vessels (leg veins, hypertrophic PWS) Hair removal; Benign melanin-containing lesions, tattoos (black, blue, green)
Alexandrite (755)
Target - Vascular lesions; Tissue
Effect - Selective coagulation
Application - large vessels (leg veins, hypertrophic PWS); Hair removal
Diode (810)
Target - Vascular lesions, Tissue, Pigmented lesions
Effect - Unspecific coagulation, Selective coagulation, Selective and fast heating (explosion)
Application - Vascular malformations, tumors; Large vessels (leg veins, hypertrophic PWS), Hair removal; Benign melanin-containing lesions, tattoos (black, blue, green)
Nd:YAG (1,064)
Target - Tissue
Effect - Selective coagulation (nonablative)
Application - Skin remodeling, photoaging
Diode (1,450)
Target - Tissue
Effect - Selective and fast heating (ablation)
Application - Skin resurfacing, epidermal ablation
Er:YAG (2,960)
Target - Tissue
Effect - Unspecific coagulation (vaporization); Selective and fast heating (ablation)
Application - Vaporization of tissue; Skin resurfacing, epidermal ablation
CO2 (10,600)
Refers to the delivery of specified radiation dose in temporally separate treatments
Fractionation
A phenomenon describing a cutaneous reaction in the area of previous radiation exposure, in response to specific systemic agents
Radiation recall
Faint erythema
Dry desquamation
Radiation Dermatitis Grade 1
Moderate-to-brisk erythema
Patchy moist dequamation (mostly confined to skin folds and creases)
Moderate edema
Radiation Dermatitis Grade 2
Moist desquamation (other than skin folds and creases) Bleeding induced by minor trauma or abrasion
Radiation Dermatitis Grade 3
Skin necrosis
Ulceration of full thickness of dermis
Spontaneous bleeding
Radiation Dermatitis Grade 4
Death
Radiation Dermatitis Grade 5
Delivers 20% less energy to melanin and proportionally more to oxyhemoglobin thus, reducing the epidermal damage, especially for dark skin. The epidermis is further protected by cooling during the procedure. The spot size can be varied from 5–12.5 mm and makes possible the rapid treatment of larger areas.
Alexandrite Laser (755 nm)
At this wavelength, the energy is well absorbed in the follicle but less absorbed by competing chromophores like oxyhemoglobin or water. In addition, a penetration depth of 3 mm can be reached. The laser light is scarcely absorbed by the epidermis, making the device well suited to dark skin. The long impulse duration (up to 50 ms) and high fluences make epidermal cooling mandatory.
Diode Laser (800/810 nm)
This laser penetrates very deep (5-7 mm), so that even deep-lying follicles receive enough energy for epilation. There is also very little epidermis absorption, making the device well suited for dark skin. Surface cooling is essential to reduce pain and side effects. This has the fewest side effects but is most painful.
Pulsed Nd: YAG Laser (1,064 nm)
These sources have a broad emission spectrum extending into the near infrared region, which allows for excellent depth of penetration and have the largest spot sizes (around 5 cm2) of all the photoepilation units, which make rapid treatment possible. In the epilation mode, a cut-off filter at 600 nm is usually employed in order to filter out shorter wavelengths destined to be absorbed in the epidermis. The impulse durations are 0.5–25 ms, while 20 ms is usually chosen. A cooling gel is used to improve the coupling of light into the skin, cool the epidermis, and reduce pain. This is a method well suited for all skin types and with few complications.
High-energy Flashlamps (590–1,200 nm).
