Pharmacology—Derm Preps - Josh Corwin



Pharmacology—Derm Preps

Dermatology

The rule of thumb for dermatological conditions:

1) If it’s wet or oozing, make it dry

2) If it’s dry, make it wet or moist

Diaper Rash

Diapers act like occlusive dressings. The primary reason for diaper rash is urine and feces in the diaper. Ammonia in urine will increase the pH, which will increase fecal lipases and proteases. This causes skin damage. Systemic antibiotics may also predispose the child to diaper rash due to superinfection. A yeast type infection is the most common (candida albicans). Bacterial type infection is the 2nd most common cause and is usually due to S. aureus and group A S. pyogenes

How can we prevent diaper rash?

1) Keep the area clean and as dry as possible

a) Use powder or cornstarch

b) Frequent diaper changes

c) Diaper should be loose fitting and ventilated

d) Change to cloth, if necessary

e) Remove diaper and leave off as time permits

f) Wash with water or mild cleanser like Cetaphil

g) Use cool air to dry buttocks

2) Protective Barrier

a) A & D ointment—emollients (protective)

b) Vaseline—emollients (protective)

c) Zinc oxide—drying agent

d) Desitin—contains zinc oxide and emollient

e) Some contain protectant, drying, anti-microbial, and vitamins

3) Topical steroids are used to mask symptoms

a) Do little to treat rash – only for anti-inflammatory

b) Cause adrenal suppression

Treatment

Candidiasis:

Use a topical antifungal. Nystatin (Mycolog) comes in a cream, powder, or ointment. There is also a combination of Nystatin and Triamcinolone (Mycolog II), which also comes as a cream or ointment. Clotrimazole (Lotrimin) comes as a cream. Clotrimazole and Betamethasone (Lotrisone) comes as a cream.

Bacterial:

Usually caused by S. aureus. Use systemic antibiotics to treat, such as oral antibiotics, penicillins, macrolides, and cephalosporins.

Butt Paste

Butt paste contains zinc oxide and can contain aquaphor, A & D ointment, or Vaseline. The name of this is called Cholestryamine (Questran). This binds to uric acid and keeps the pH at normal levels. The zinc and A & D provide a protective barrier. This is not for prevent but for treatment.

Poisons

Poisons include poison ivy, poison sumac, and poison oak. They are an example of type IV hypersensitivity. If you are sensitive to one, you are sensitive to all three.

Rhus dermatitis is a delayed hypersensitivity reaction that occurs 12-72 hours after exposure. 10-15% of the population is immune to this. Urushiol is the chemical secreted by bruised plants and causes the reaction.

There are two types of exposure:

Primary Exposure: occurs with direct contact to bruised portion of the plant that exudes the urushiol.

Secondary Exposure: occurs with contact to exposed pets, contaminated clothing, and smoke from burning plants.

It is not transmitted via fluid vesicles or blisters. It is self-limiting, usually resolving with 14-20 days. It subsides on its own in 90% of patients. The symptoms are severe itching, irritation, and a burning sensation. Secondary infection can be caused by scratching because bacteria enter the broken skin.

Treatment Goals

We must protect damaged skin and relieve pain and itching to prevent secondary infection. Wash the area immediately with soap and alcohol to remove the urushiol. Solvents can be poured on the affected area but are not favorable because they can possible remove the skin and cause a secondary exposure. Tecnu is an outdoor skin cleanser that can be used. An alcohol pad should not be used.

Barrier products such as Betoquatam (Ivy Block) can be used, which will decrease dermatitis. Zanfel, an OTC wash, is not recommended because it is not proven.

Treatment of Mild and Moderate Cases

Can use soaks, baths, and mild dressings. Colloidal oatmeal (Aveeno) can be used as a bath and provides transient relief. Aluminum acetate (Burrow’s solution) is used in the form of moist dressings and it reduces itch. It is a mild astringent. It is a drying agent and compresses vesicles and blisters. The aluminum acetate absorbs the resin of the urushiol. For facial lesions, you can use wet dressings. You should not use lotions because they are difficult and painful to remove once dry.

Topicals can also be used. These include Calamine (calamine, Fe oxide, Zn oxide). The calamine is an astringent and the Fe/Zn oxides are drying agents. Local anesthetics (Caladryl = calamine + pramoxine) can be used. This is a mild, local anesthetic and is taken orally. Antihistamines, such as Benadryl, may sensitize skin. Topical Benadryl is generally not effective. Diphenhydramine is another topical antihistamine that does not penetrate the skin and may irritate even further. If you need to relieve itch, you must take an oral antihistamine. Camphor, menthol, phenol, and EtOH promotes the drying of vesicles. Camphor and menthol are cooling agents, while the phenol and EtOH are antibacterial. Aluminum acetate solutions can also be used. You do not want to use ointments while vesicles are present and weeping. They form a barrier sealing the moisture in. The vesicles must be able to dry. Ointments should only be used for very dry lesions. You might want to use a mild-moderate potent topical steroid for a localized area.

Treatment for Severe Cases

Severe cases are for widespread or eye involvement. Antihistamines are used for anti-itch and must be taken orally. Diphenhydramine should be taken 25-50mg, four times a day, as needed. Adverse reactions can be sedation and there can be anticholinergics side effects. Glucocorticosteroids are anti-inflammatory and are used for severe Rhus dermatitis. The drug of choice here is Prednisone, which should be taken orally for 7-21 days and must be tapered off if taken for more than two weeks. Antibiotics should be used if the scratch becomes infected. You must treat for staph, which is the most common skin disease. Cephalosporins and penicillins are the best for this because they provide increasing resistance to MRSA. Steroid injections can also be used.

Acne

Acne is stimulated by testosterone and metabolite dihydrotestosterone, which cause sebaceous glands to grow and produce sebum, leading to white heads and black heads. Its pathogenesis is multi-factorial and bacterial (P. acnes). Irritants that cause it can be touching your face, makeup (lanolin and emollients trap dirt), and foods (certain individuals). It is the one of the most common dermatological conditions that people seek clinical help for.

General Treatment Guidelines

You must cleanse the skin twice a day with a mild cleanser and pat dry. Use a coarse cloth or other sponges to exfoliate the skin. An astringent can close pores and helps prevent dirt from entering. You can use medication as necessary.

Treatment

Benzoyl Peroxide (Benzac, Benzagel, Clearasil, and Stridex) is category C. It causes desquamation, increasing cell turnover and promoting healing. It may be bacteriostatic or cidal. It can cause drying because of its alcohol base, more so in the gel preparations. Drying could cause an enhanced therapeutic response. The cleansers and washes may have decreased therapeutic effects. Peeling can also occur. You should not apply this around the mouth, eyes, or lips. Stinging and bleached clothing (use white pillow cases) can also occur. 2% of the general population is hypertensive, so you must start with a low dose and increase as tolerated.

Salicylic Acid (Clearasil pads) has 0.5-2% potency. It is a keratolytic, which helps remove the upper layer of dead cells. It is a drying agent and also causes peeling.

Retinoids – Vitamin A Derivatives increase epithelial cell proliferation and reduces comedo formation. ADRs include photosensitivity, erythema, scaling, dryness, itching, crusting, and pigmentation changes (bleaching). People who take these should avoid the sun by using SPF 30-45 and also use sunscreens that prevent against UVA.

Adapalene (Differin) (C) is a retinoid-like compound that binds to different retinoid type receptors. ADRs – similar to other retinoids, local skin irritation, not show to be tertaogenic in rodents but also no human studies have been performed.

Erythromycin (Eyderm), Erythromycin + benzoyl peroxide (Benzamycin), and Clindamycin (Cleocin T) are the most common topical antibiotics used for acne. Clindamycin can come as a gel, cream, lotion, solution, or disposable pads. When combined with benzoyl peroxide it is Duac Gel. ADRs for all include burning, stinging, drying, peeling, and erythema.

Oral antibiotics can also be used. However, there is an increased risk of resistance due to the chronic usage. Tetracyclines include Doxycycline and Minocycline. These are the most popular and are the best for acne. Erythromycin can also be used. ADRs include N/V/D, vertigo (minocycline), and contraceptive failure of birth control pills. Oral antibiotics are reserved for more severe acne. They must be used for at least one month.

Estrogen drugs should only be used in females. Increased estrogen helps counterbalance the high testosterone levels which cause acne. Estrogen can be taken alone or in an estrogen/progesterone combination. When using the combination, we prefer to have high estrogenic activity and low androgenic activity. Tricycline brands are good for this. ADRs include PMS-like symptoms, bloating, and weight gain. They can be used for women over 18 years old and those not planning pregnancy.

Isotretinoin (Accutane)

Oral retinoids can also be used. Isotretinoin (Accutane) is the main drug in this group. It is in category X. Taken 0.5 – 0.75 mg/kg/day, twice daily divided dose for 15-20 weeks. Accutane reduces the size of the sebaceous gland and regulates cell proliferation/differentiation.

ADRs include dry skin and mucous membrane, headache, depression, hyperlipidemia, increase LFT’s, alopecia, myalgia, hematologic ADRs, ocular ADRs, photosensitivity, and increased suicide risk. The patient’s CBC and cholesterol levels should be monitored. It is the best treatment for severe cases. Patients need to sign informed patient consent prior to receiving and cannot be/get pregnant and need to undergo two negative pregnancy tests prior to treatment and continue to use two forms of birth control while they are taking the drug. There is decreased night vision and a risk of cataracts.

Photosensitivity is also common, occurring in 5-10% of patients. They should stay out of the sun for prolonged periods of time and use UVA protection. Phototoxicity is common in patients. The UVA light rays are absorbed and cause skin damage. There is a rapid onset and the patients get exaggerated sunburns.

Drugs that Cause Acne

A) Hormones:

1) Gonadotropins

2) Anabolic steroids

3) Corticosteroids

B) Anti-Epileptic drugs

C) TB drugs

1) INH

2) Rifampin

D) Miscellaneous

1) Lithium

2) Cyclosporine

3) Iodine

Psoriasis

Psoriasis has no cure. Treatment is aimed to reduce severity. Palliative treatment is aimed to reduce the risk of secondary infection. Comes in acute and chronic phases

Acute psoriasis is characterized as severely erythematous lesions. The treatment aims to soothe irritation and use non-medicated topicals like Aquaphor, Cold Cream, Lac-hydrin, and Eucerin.

Treatment for chronic psoriasis is topical glucocorticoids. They produce anti-inflammatory, anti-pruritic, vasoconstriction, and immunosuppressive results.

Chronic Psoriasis Treatment

Topical Glucocorticoids – start with super high potency (class one or two) twice a day for 2-3 weeks. After high potency treatment, change to pulse treatment (2 days on then 5 days off) or change to lower potency steroid. Halogenated steroids improve absorption and should not be used on the face, perineum, or mucous membranes. Non-fluorinated steroids can be used on the face, eyelids, perineum, and mucous membranes.

Several ADRs involve thinning of the skin, tearing of the skin (due to thinning), bruising, acne, hypopigmentation – blanching due to vasoconstriction, infection – immune system suppressed, and contact dermatitis.

Super potent steroids should not be used on children or elderly due to increased systemic absorption. In children, the skin is not keratinized and in the elderly the skin is thin. Super potent steroids should be avoided in the flexural areas like the groin, axilla, popliteal, and antecubital fossa. These areas tend to be warm and moist, therefore there is added absorption. If super potent steroids are used, minimize them to less than two weeks or switch to a lower potency. These steroids can also inhibit the HPA axis.

Coal Tar (Zetar, Neutragena T) – comes as an ointment, lotion, soap, or shampoo. It can be used alone or with low potency steroids. Preferably applied at night and washed off in the AM. May be used with UVB light therapy. There are many non-compliance problems because it is cosmetically non-appealing. It stains the clothes, bedding, and hair.

ADRs include irritation, photosensitivity, folliculitis, scaling, itching, and inflammation.

Psoralens – Included in this group is Methoxsalen (Oxsoralen). It comes PO or lotion. UVA light treatment is followed two hours after it is applied. This combination is referred to as PUVA therapy.

ADRs include pruritus, dry skin, and loss of pigmentation, nausea in 10% of patients, blistering, and painful erythema. There is a very potent drug-food interaction so patients should avoid furocoumarin-containing foods, such as limes, figs, parsley, celery, cloves, lemon, mustard, and carrots.

Psoralen treatment is not used alone. They are believed to inhibit DNA synthesis so it will suppress cell division. Lotion is given in a bath prior to UV light. There are extremely photosensitive effects. Patients should stay away from the sun for 24 hours before and 48 hours after. Specifically, patients should avoid sunlight for 8 hours after oral treatment and 12-48 hours after topical treatment.

Retinoids - Etretinate (Tegison)is taken orally. It normalizes the expression of keratin and suppresses chemotaxis. It decreases stratum corneum cohesiveness. The half-life for this drug is 100 days (can be found in plasma 2-3 years after discontinuation.

ADRs include LFT abnormalities, alopecia, exfoliation, hyperlipidemia, myalgia, and arthralgia. Birth control should be utilized 1 month before and during therapy. Birth control must also be used for 3 years after. When combined with PUVA, it is called RE-PUVA.

Acitretin (soriatane) is taken orally. It is very much like etretinate. Its half-life is 49 hours.

Tazarotene (tazorac) is topical.

Miscellaneous – Methotrexate is taken orally and is an anti-metabolite. It is a chemo drug. It affects metabolism, therefore decreasing cell proliferation and suppresses inflammation. It is used orally 1 week in low doses. ADRs include GI, liver, and pulmonary toxicity, hematologic disorders, and cytotoxic.

Cyclosporine A (Neoral) is an immunosuppressant and prevents rejection after transplants.

Topical immune modulators are very commonly used. They include Tacrolimus (Protropic) and Pimecrolimus (Elidel). There are indications for atopic dermatitis and eczema, but not psoriasis. Recently, the FDA added a black box warning – potential cancer risk and should be reserved for after topical steroids fail or other treatments don’t work and should not be used for children under two years old. Should also not be used chronically.

Non-FDA Approved – IV immune modulators, like Etanercept (enbrel), are used for rheumatoid arthritis and juvenile rheumatoid arthritis. Sirolimus (Rapamune) is an immunosuppressant that is used for organ transplants.

Miscellaneous – Cacliprotriene (Dovonex) is topical and is good for mild to moderate psoriasis. Its effects equal class II and III steroids. It is a vitamin D analog; therefore it has no steroid SE. SEs it does have, however, include local skin irritation and skin reactions. Should not be used on the face, eyelids, perineum, or skin folds.

Anthralin (Drithocreme) is topical and is used for short term treatment. It is applied for one hour or less and then washed off. SEs include staining and irritation on un-involved skin. There is permanent brown color staining of clothing and bathroom fixtures with this product. It is also used for alopecia areata (non-FDA). Has an irritant property, so may stimulate the follicle to grow hair.

Keratolytics soften the keratin layer of skin. Also enhances absorption of other agents. Phenol and Salicylic acid are used and are mixed with Aquaphor, cold cream, emollients, and coal tar.

Phototherapy – Sunlight, photochemotherapy (PUVA) and phototherapy (UVB light therapy) can be used to treat psoriasis.

Rosacea

Rosacea is chronic, long-term, inflammatory skin disease. It is characterized by redness/swelling on the face due to swelling of the blood vessels.

Treatment is usually topical, coming in the form of creams, lotions, ointments, and gels. They consist of antibiotics, sulfur lotions, Azelaic acid, and benzoyl peroxide.

Treatment

Topical Antibiotics – Metronidazole (Metrogel, Metrocream) is the treatment of choice for rosacea. It is also an anti-protozoal agent.

Clindamycin (Cleocin T) and Erythromycin can also be used but are not as effective as other topical antibiotics.

Sulfur products such as Novacet and Sulfacet can be used but should be avoided in sulfa allergy.

Topical Azelaic Acid – this is an antibacterial, comdeolytic, and anti-inflammatory drug. A small study showed that it is as effective as Metrogel. It consists of two parts: Finacea Gel 15%, which is used to treat the rosacea; Azelex or Finevin 20%, is used to treat the acne. Finacea is less acidic, so it is used for rosacea.

ADRs include local skin irritation.

Oral Antibiotics – These are better for moderate to severe rosacea. They are used if topicals fail. Treatment can be combined with topical treatment.

Tetracyclines are the most commonly used. Erythromycin is preferred for pregnancy because tetracyclines are category D.

Other oral antibiotics used are Clarithromycin (Biaxin), Sulfamethoxazole/ Trimethoprim (Bactrim, Septra), Metronidazole (Flagyl).

Miscellaneous Treatments – Glycolic Acid comes as either peels or washes and creams. It helps shrink thickened facial skin and diminish nodular rosacea. The peels are put on the skin for 5min. and the skin will be red for a few hours. The washes and creams enhance the peel’s effect.

Topical Tretinoin (Retin-A) can be used. Isotretinoin (Accutane) is used for severe cases but is not FDA approved for rosacea.

Eye Problems associated with rosacea – Oral Doxycycline, Minocycline, and Tetracycline are taken for any eye problems the patient may have.

For Redness and Flushing – For this, anti-inflammatory meds, such as steroid creams, are the preferred choice. Other treatment available includes electrosurgery, intense light therapy, and vascular lasers.

Rhinophyma – Rhinophyma is an enlargement on the nose and is more common in men than in women. Treatment for this includes dermabrasion, electrosurgery, or laser surgery

Overall Treatment Approaches

The overall goal is to minimize flare-ups. Rubbing, scrubbing, and massaging the face should be avoided because it irritates the skin. Moisturizers and sun screen should be used. SPF 15 or greater and protective clothing should also be worn. The patient should avoid hot drinks, spicy foods, and EtOH. Skin should be protected from extreme heat or cold because these extreme temperatures will irritate the skin and causes flare-ups. Cosmetics, soaps, and moisturizers that contain EtOH and fragrances should be avoided. Medication should be used as appropriate.

Eczema

The most common symptoms of eczema are dry, red, extremely itchy patches on the skin. They can occur on any part of the body and usually appears during infancy. Incidence is more common in males than females.

Prevention of eczema is very important. Techniques include moisturizing, avoiding rapid temperature changes, reduced stress, avoiding scratchy materials (wool), avoiding harsh soaps and detergents, avoiding triggers like allergens, and being aware for foods that cause outbreak.

Treatment

The overall treatment of eczema is to prevent the scratching. Creams and lotions should be used to moisturize. Cold compresses relieve the itching. Corticosteroids (OTC or Rx) are anti-inflammatory and can assist. Antibiotics, either topical or oral, can be used for infected skin. Antihistamines (OTC or Rx) will to reduce itch.

Coal tar and phototherapy can be used for eczema. Cyclosporine A (Neoral, Sandimune, Restasis) is only for resistant eczema. Topical immune modulators like Tacrolimus (Protropic) and Pimecrolimus (Elidel) can also be considered.

Treatment options for children include keeping the bedroom and play area dust free, mild soaps (Cetaphil), breathable clothing (cotton), and low potency hydrocortisone.

Actinic Keratosis

Actinic Keratosis is the beginning stage of skin cancer. Common lesions are found on the epidermis and are caused from long sun exposure. Seen most commonly in 40-50 y.o that are exposed to chronic sun exposure. Areas of Florida and Southern Cal also have high incidences of teenagers and people in their 20s. There is an increased risk in fair skin people. Can progress to SCC. It is defined as cutaneous dysplasia of the epidermis.

Treatment

Cryosurgery is the most common treatment. Surgical excision and biopsy should be performed is SCC is suspected. Retinoids, topical or oral, have also be proven effective. 5-Fluorouracil (Efudex, Fluoroplex) is topical chemotherapy that can be useful. Chemical peels are another option. Dermabrasion, laser skin resurfacing, and electrosurgical skin resurfacing can also be performed.

Melanoma

Melanoma is skin cancer of the melanocytes. It occurs when melanin produces too much brown pigmentation. It is potentially lethal.

Treatment

Localized melanoma should be treated with surgical excision. For higher stages of melanoma, interferon injection, interleukin injection, and combination chemotherapy are used.

See Drug-Induced Photosensitivity List

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