2/22/2016

PHARMACOLOGY CHAPTER 12 SKIN MEDICATIONS (DERMATOLOGICS)

INTRODUCTION

 skin is the largest organ of the body  large surface area - many conditions can affect the skin – can be minor (annoyance or discomfort like pruritus) or major (severe burns)  treatment is usually topical or local (applied to affected area)  some skin treatments require systemic treatment (oral / injections)

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 nine classifications of skin preps  antipruritics – relieve itching  cortricosteroids – treat dermatologic disorders associated with allergy  emollients / protectants – soothe irritation  keratolytic agents – loosen epithelial scales  enzymatic agents – promote removal of necrotic / fibrous tissue  scabicides / pediculicides – treat scabies or lice  local anti-infectives – prevent / treat fungal, bacterial and viral infections  burn medications – prevent / treat infections  acne treatments

ANTIPRURITICS

 used short term to relieve discomfort from dermatitis (rashes) associated with allergic rxns, poison ivy, hives and insect bites  relieve itching by use of products (singly or in combination)  local anesthetic (-caines / benzocaine)  dying agent (calamine)  anti-inflammatory agent (corticosteriod) – should be avoided if no inflammation – fewer adverse effects with local vs PO admin  antihistamines – usually PO for systemic effect (topical may cause hypersensitivity) precautions / contraindications • delayed healing – open wounds for corticosteroids • prolonged use (especially corticosteroids) • hypersensitivity rxn to active drug or any component of the formulation

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PATIENT EDUCATION Patients taking antipruritics should be instructed to:

• clean area thoroughly before application • rub in gently until medication vanishes • use caution if they have allergies • avoid contact of the medication with eyes or mucous membranes • avoid covering area with dressings (unless directed by physician) • avoid prolonged use • discontinue fi condition worsens / irritation develops • trim children’s fingernails to reduce possibility of infection from scratching

CORTICOSTERIODS

 used both locally and systemically to treat dermatological disorders associated with allergic rxns  most topical steroids are available in a variety of doses forms and potencies (low to very high) – choice depends on the area affected and condition being treated  topical corticosteroids also used to treat psoriasis and seborrheic dermatitis precautions / contraindications • skin infections (bacteria, fungal, viral) • open wounds • abrupt discontinuation of very high potency after long term use • hypersensitivity to active drug or any component of formulation

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EMOLLIENTS AND PROTECTANTS

 used to topically soothe, soften, protect (create a lipid barier) and seal out wetness in minor dermatologic al conditions (diaper rash, irritation, abrasions and minor burns)

KERACTOLYTICS  like salicylic acid - used to control conditions of abnormal scaling of the skin (dandruff, seborrhea and psoriasis) or to promote peeling of the skin (acne, hard corns, calluses and warts) precautions / contraindications • open areas of the skin • hypersensitivity rxn to active drug or any component of formulation

PATIENT EDUCATION Patients taking keratolyticsshould be instructed to:

• use only as directed and for the entire treatment period (even if condition improves) • avoid contact with eyes and mucous membranes • avoid prolonged use • discontinue and seek medical aid if irritation occurs • avoid contact with surrounding tissues when applied as a caustic agent to warts, corns or calluses

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ENZYME PREPARATIONS

 bedridden pts are prone to decubitus ulcers (bed sores) and diabetic pts are prone to develop foot ulcers  ulcerations produce necrotic (dead) skin) that must be removed in order to promote healing  collagenase (Santyl) – topical enzyme ointment used for the chemical debridement (removal of dead / damaged tissue) of dermal ulcers and burns  should only be used on necrotic tissue  if topical antibiotic indicated, apply before collagenase  avoid using detergents, providone-iodine and heavy metal-containing agents – will inhibit the enzymatic activity of collagenase

SCABICIDES AND PEDICULICIDES

 scabies is caused by an itch mite that burrows under the skin  scabicides (permethrin 5% or lindane lotion) must be applied according to directions on package insert, left in place for required period of time and then rinsed thoroughly

 pediculosis is caused by infestation of lice on the hairs of the scalp, pubic area and trunk  pediculicides (permethrin 1% and lindane shampoo) are used as topical treatment  pyrethrins (RID) are considered safer – need repeated treatment after 7- 10 days

 both are easily transmiited fromone person to another by direct contact or through contact with contaminated clothing or bed linenens

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PATIENT EDUCATION Patients taking scabicides / pediculicides should be instructed to:

• follow directions carefully (read and understand medication guide with lindane prescription) – itching may still occur after the successful killing of lice (not an indication of retreatment) • thoroughly launder (130oF) clothing and bedding using the hot cycle of a dryer for at least 20min • bag large items (pillows) in plastic for two weeks • use caution with infants who might suck thumbs • inform sexual partner if condition is present in the pubic area • alert the school if head lice infestation occurs

LOCAL ANTI-INFECTIVES

 used to treat diseases caused by microorganisms – bacterial, viral and fungal infected skin

ANTIFUNGALS  nystatin - used to treat fungal infections (candidiasis) like thrush, diaper rash and vaginitis  clotrimazole (Lotrimin) – used to treat fungal infections such as athlete’s foot, body ringworm and jock itch

 antifungals can be combined with corticosteroids (Lotrisone – betamethasone/clotrimazole and Mycolog II – nystatin/amcinolone) – not recommended for dermatological use

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 effective treatment with antifungals requires topical administration according to package insert and good hygiene practices (washing, drying and exposure to air) contraindications / caution  Use of vaginal preps during pregnancy – used only under the supervision of a health care provider – some products can cause fetal abnormalities

PATIENT EDUCATION Patients taking antifungals should be instructed to:

• carefully wash and dry affected areas • expose affected areas to air whenever possible (genital fungus – avoid tight undergarments / athletes foot – avoid sneakers) • follow application instructions carefully (use for prescribed amount of time – even if asymptomatic) • consult a physician before vaginal preparations are used during pregnancy • for vaginal infections – refrain from intercourse until treatment is complete – consider treating partner if infection reoccurs • for oral suspensions or lozenges, apply after meals and after thorough rinsing of mouth (no food or liquids for 1h after treatment)

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ANTIVIRALS  acyclovir (Zovirax) – antiviral effect on herpes simplex (cold sores and genital herpes), herpes zoster (shingles) and varicella zoster (chicken pox) viruses  available as oral, parenteral and topical preparations  local therapy is substantially less effective than systemic therapy

 topical acyclovir is not a cure and does not reduce the frequency or delay the appearance of new lesions – generally  the duration of viral shedding, duration of pain and itching and time required for crusting and healing of lesions  effective in first episode genital herpes infection – little effect on recurrent infections  ointment should be applied ASAP following the onset of signs and symptoms of infection – do not get ointment in the eyes  is not effective in preventing infections

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 docosanol (Abreva) is the only OTC med approved by the FDA to shorten healing time and duration of cold sore symptoms – helps to protect against the herpes simplex virus by modifying the cell membrane (makes it difficult for virus to penetrate and combine with cells)  apply as soon as first symptoms appear (tingling, redness, bump or itch

ANTIBACTERIAL AGENTS

 mupirocin (Bactroban) – structurally unrelated to other topical or systemic antibiotics  ointment used topically to treat impetigo (Staphylococcus areas and some species of Streptococcus) and secondarily infected traumatic skin lesions  nasal ointment applied intranasally to reduce the risk of infection in patients of high risk during institutional outbreaks of MRSA (methicillin resistant Staph aureus)

 antibacterial agents have the potential for adverse side effects – hypersensitivity and systemic rxns  overuse / extended use of antibacterial agents can lead to drug resistance

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PATIENT EDUCATION Patients using topical antibacterial agents should be instructed to:

• read an follow directions carefully • check all ingredients carefully for possible allergies • if no improvement, the condition worsens, or other reactions (inflammation, itching, rash, swelling) stop medication and consult a physician

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ANTISEPTICS • substances that inhibit the growth of bacteria (bacteriostatic) • chemicals applied to body tissues – especially the skin • disinfectants are included • bactericidal (kill bacteria) are too strong to be applied to body tissue – usually applied to inanimate objects (instrumentation, furniture, floors)

• two major antiseptics – chlorhexidine(Hibiclens) and povodone- iodine – used in surgical scrubs and as bacteriostatic skin cleansers • prior to surgery, skin cleansing with chlorhexidine is preferred – lower rates of surgical site infections when compared to povodone- iodine • some iodine preps are bactericidal – used to treat superficial skin wounds / disinfect skin preoperatively • Hibiclens should not be used on wounds involving more than superficial layers of the skin – rinse thoroughly after use

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cautions / contraindications chlorhexidine • pregnancy category B • not for frequent use / total body bathing • not for use in eyes or ears povidone-iodine • not for those allergic to iodine • not for use on open wounds • not for use in newborns (risk of iodine absorption)

PATIENT EDUCATION Patients being treated with local anti-infectives should be instructed to:

• rinse chlorhexidine thoroughly • avoid chlorhexidine for total body bathing or frequent use • avoid use of chlorhexidine on open skin, mucous membranes and genital areas • avoid contact with eyes or ears (chlorhexidine or povidone-iodine) • use caution with povidone-iodine in anyone with allergies

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BURN MEDICATIONS

 burns are injuries to the skin and tissues below the skin that are caused by heat from flames, hot liquids, steam, heated objects, chemicals, friction, electricity, radiation or the sun  classified as first degree (superficial), second degree ( partial thickness - into the dermal layer) and third degree (full thickness – into the subcutaneous layers)

 burn treatments include topical application of meds to prevent or treat infections associated with the damaged skin  silver sulfadiazine (Silvadene) and mafenide (Sulfamylon) commonly used to treat 2nd / 3rd degree burns – applied with a sterile gloved hand precautions / contraindications • do not apply to newborns or pts with • impaired kidney or liver fxn (cumulative effects) • hx of allergy – especially to sulfua drugs • do not use silver sulfadiazine with collagenase or trypsin- containing enzymatic debriding agents (silver will inactivate enz activity)

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PATIENT EDUCATION Patients using burn medication should be instructed to:

• use aseptic techniques to prevent infection • watch for allergic reactions • keep careful intake and output records • keep affected area covered at all times with cream and sterile dressings

SUNSCREENS • overexposure to the sun is considered the primary cause of skin cancer – most common cancer in US (1million dx/yr) • UV (ultraviolet) radiation is emitted by the sun – UVA / UVB • sun protection factor (SPF) is a measure of the protection a sunscreen offers – only broad based sun screens (UVA/UVB) with SPF ≥ 30 can claim to reduce the risk of skin ca and early skin aging if used as directed • apply 10-30 min prior to exposure, limit sun exposure b/t 10am-4pm, wear sun protective clothing, use water-resistant sun screen when swimming / sweating and reapply ever 2h (at least) – even on cloudy days

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AGENTS USED TO TREAT ACNE

 acne is a common condition of the skin – seen on face, scalp, neck, chest, back and shoulders  pts with mild acne – nonprescription topical meds – sulfur, salicylic acid and benzoyl peroxide  pts with moderate to severe – prescribed topical therapy with a combo of retinoid (isotretinoin - ↓oil production) and topical antibiotics (clindamycin or erythromycin - ↓ inflammation)  pts with severe acne – prescribes oral antibiotics (tetracycline / erythromycin) with topical products

 for female pts who produce too much testosterone – birth control (systemic female hormones – estrogen / progesterone) may be prescribed  oral retinoids (isotretinoin) are used for only the most severe forms of acne and for pts who fail other treatments (caution – there may be severe side effects) precautions • Accutain (retinoid) prescribed to treat 4 types of acne – pulled off market November 2009 – signs that drug may be linked to inflammatory bowel disease • generic versions still available – may be removed upon further investigation • do not use if pregnant / breastfeeding • do not use in pts with skin disease • hypersensitivity (benzoic acid / paraben) • avoid exposure to the sun / eyes and mucous membranes

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PATIENT EDUCATION Patients taking acne agents should be instructed to:

• use preparations every day as directed ( may take several weeks to become effective – acne may get worse before it gets better) • do not use benzoyl peroxide with other topical acne products or retinoids • avoid prolonged exposure to sunlight (UV light) – use sunscreen and protective clothing – avoid drugs with sulfates (make more sensitive to the sun) • avoid multivitamins or nutritional supplements that contain vitamin A, tetracycline antibiotics, certain antacids (aluminum hydroxide) and certain birth control pills (progestin only) while taking isotretinoin • make sure to receive, read and understand the Isotretinoin Medication guide every time a prescription is filled

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