Lecture 5 - Principles of Topical Therapy PDF

Lecture 5 – Principles of Topical Therapy General: when prescribing topical medications, prescribe appropriate amounts. Topical medications typically come in 30 g, 45 g, 60 g, or 80 g tubes. Some generic topical steroids come in 454 g (one pound) jars. 1. 30 grams = daily application to entire...

Lecture 5 – Principles of Topical Therapy General: when prescribing topical medications, prescribe appropriate amounts. Topical medications typically come in 30 g, 45 g, 60 g, or 80 g tubes. Some generic topical steroids come in 454 g (one pound) jars. 1. 30 grams = daily application to entire face for one month. 2. 60 grams = two applications to entire body. Do not prescribe a 30 gram tube if a patient has a rash over 50% of their body and they need to apply the cream twice daily for two weeks. They will run out after applying it twice. When recommending products, remember that the terms “hypoallergenic”, “unscented”, and “for sensitive skin” are marketing terms, not medical terms. It is very possible for a hypoallergenic product to cause an allergic reaction, an “unscented” product to contain fragrance, and a “sensitive skin” product to be very irritating. In general, these types of products are less likely to cause allergy, contain less fragrance, and are less irritating, respectively, than other products. However, if a patient continues to have problems despite switching products, it is worth further investigation. Moisturizers and Vehicles Ointment Cream Lotion Gel Solution (All oil, no water) (Mainly oil, some water) (Mainly water, some oil) (No oil) (No oil) Very moisturizing Less moisturizing Minimally Moisturizing Drying Drying Very Greasy Less Greasy Minimally Greasy Not Greasy Not Greasy Very Soothing Soothing Not Soothing May Sting May Sting The most effective moisturizing regimen is application of a ceramide-based cream or plain petroleum jelly immediately after bathing and before drying off with towel. Shampoos and Soaps Soaps and shampoos work because they have long chain molecules that are hydrophilic at one end and hydrophobic at the other. These types of molecules are able to bind oily substances (dirt, sebum, etc.) at the hydrophobic end, dissolve these substances in water by binding water at the hydrophilic end, and then be rinsed away. This mechanism of action is inherently drying and somewhat irritating to the skin, as the “natural oils” of the skin are also removed. The fundamental difference between soap and shampoo is that shampoo is formulated to prevent accumulation of residue on the hair shafts. The fact that soaps are not formulated to prevent this is demonstrated by the formation of “soap scum” on bathtubs and showers. If soap is chronically used to wash the hair, the equivalent of “soap scum” will accumulate on the hair shafts, leading to an undesirable appearance. This doesn’t happen on the skin because the stratum corneum is constantly being shed, so any residue on the surface is shed along with the stratum corneum. Conditioners are designed to replace the sebum that is removed by shampooing. Sebum is replaced with synthetic “oil-like” substances that make hair shiny, less prone to tangling, and less susceptible to static electricity. Conditioners or “2-in-1” shampoo/conditioner combinations have no detrimental effects and can be used by all individuals. Anti-dandruff shampoos generally contain zinc pyrithione, selenium sulfide, salicylic acid, sulfur, or tar. Each agent is effective, but patients generally prefer zinc pyrithione or selenium sulfide products. Patients with dandruff will also often have seborrheic dermatitis, and these patients can wash their skin with the dandruff shampoo. In general, for routine daily bathing, patients with dry skin only need to use soap or shampoo to wash their face, groin, and axillary areas. Water alone will effectively clean the rest of the body. Obviously, this does not apply if the individual is excessively dirty or sweaty (following manual labor or exercising). No practical benefit to household use of anti-bacterial soaps has ever been demonstrated. There is concern that continued use of these soaps may lead to increasing bacterial resistance, so these products should be avoided. Deodorant soaps tend to be particularly irritating and drying, so these soaps should be avoided in individuals susceptible to dry skin. Facial cleansers are typically non-lathering cleansers that are less drying and less irritating than regular soaps. They are effective and should be recommended to individuals with dry or irritated facial skin. Sunscreens Sunscreens are designed to block ultraviolet radiation from penetrating the skin. They are often grouped by SPF (Sun Protection Factor). This number is calculated as follows: Time in sun necessary to cause sunburn while wearing product__ Time in sun necessary to cause sunburn while not wearing product For example, if it takes 10 minutes of exposure to get a sunburn on unprotected skin and 3 hours (180 minutes) to get a sunburn on protected skin, the SPF would be 180/10 = 18. Ultraviolet light is broken into three types, based on wavelength: UVC, UVB, and UVA. SPF specifically measures how much UVB is blocked. An SPF tells you nothing about how much UVA is blocked. UVC is absorbed by our ozone layer and does not reach the earth in great amounts, so UVC blockage is unimportant. The calculated SPF depends heavily on how much of the product is applied, and a standard protocol is used when determining the SPF of a given product. An SPF 15 product blocks 93.3% of UVB and an SPF 30 product blocks 96.7%. There are two types of sunscreen ingredients: Chemical blockers: absorb UV light and emit the energy as infrared energy (heat). Physical blockers: reflect and scatter UV light. There are many different chemical blockers, all with different properties (different stability, different absorption spectrum, etc.). There are only two main physical blockers: zinc oxide and titanium dioxide, and both have similar properties – they are extremely stable and they block both UVB and UVA very well. Finally, chemical blockers are often irritating to the skin while physical blockers are non-irritating. In general, it is best to recommend sunscreens that have physical blockers (tell patients to look for the words “titanium” or “zinc”), since we know that they will block both UVA and UVB and will be non-irritating. An SPF of 15-30 is a reasonable minimum. It is MUCH MORE important that the patient actually use the product than that the product has a high SPF. Finally, it is important to note sunscreen cannot completely prevent skin cancer. We assume that it helps to prevent its development, but that assumption may not be true in all instances. If a patient complains that they can’t wear sunscreen because it stings or burns, those symptoms are typically caused by the chemical blockers. Therefore, you should recommend that they find a sunscreen in which the only active ingredients are zinc oxide and/or titanium dioxide. When recommending sunscreens, we should also recommend wearing hats in the sun, avoiding the sun between the hours of 11am and 2pm and trying to stay in the shade when possible. Anti-Fungals Two major classes: Allylamines (Terbinafine; Butenafine) -Excellent for dermatophyte infections: tinea pedis, tinea cruris, tinea corporis. -Not effective for candida infections: intertrigo, diaper rash, balanitis. Azoles (Ketoconazole; Econazole; Clotrimazole) -Good for candida infections. -Less effective than allylamines for dermatophyte infections. Nystatin is good for candida infections, but has no effect on dermatophyte infections. However, there have been recent reports of nystatin resistance among Candida, so you may want to choose an azole antifungal for Candidal infections. Tolnaftate and Undecylenate are over the counter medications that are not as effective as allylamines for tinea pedis. In general, anti-fungals should be used twice daily until the rash clears, then for one more week. If the patient has recurrent infections, consider long term prophylaxis with once weekly applications. Acne Therapy Match vehicle to skin type (if very oily skin, use gel or solution; if normal/dry skin, use cream) Retinoids – use at bedtime, apply to entire face. Start by using every other night, work up to every night (very irritating initially). Tretinoin (Retin-A) – comes in 0.025%, 0.05%, and 0.1% strengths. Can be irritating and drying to skin Adapalene (Differin) – Less irritating, comes in 0.1% and 0.3% strengths. Tazarotene (Tazorac) – comes in 0.05%, and 0.1% strengths. Can also be irritating and drying to skin Topical antibiotics – used in morning to entire face, or both in morning and at bedtime Clindamycin and erythromycin – P. acnes has shown significant resistance to topical erythromycin, so it is used much less frequently than topical clindamycin. Products include: Benzoyl peroxide/clindamycin combination gels (Benzaclin, Duac, Acanya). Benzoyl peroxide – can be prescribed alone as a wash for the face and body. Benzoyl peroxide can be irritating and can bleach fabrics, but there is no bacterial resistance. Metronidazole – Used for rosacea. Strengths include 0.75% and 0.1%. Available in multiple vehicles (gel, lotion, cream). Topical Steroids Class 1 (strongest) through Class 7 (weakest) Recommended use is BID for initial treatment. The same chemical can be class 3 (strong) through class 6 (weak) depending on vehicle and concentration. Ointments are strongest, then creams, then lotions and solutions. Potential side effects: skin thinning, striae, telangiectasia, easy bruising, HPA suppression, glaucoma, cataracts (these two eye problems only if topical steroids are applied to the eyelids). Side effects VERY rare with reasonable usage. If using longer than 2 weeks, should consider “not daily dosing” – either use for two weeks, then take one week off, or use Monday-Friday and take weekends off. This type of dosing is thought to decrease the risk of side effects and to prevent the medication from losing its effectiveness. In general, avoid chronic use on the face, as facial skin can become “addicted” to steroid, and attempts to stop using steroid will lead to SEVERE eruptions. This is unlikely to happen if use is limited to one week on, one week off. Match strength to area being treated: Hydrocortisone 2.5% cream (low strength) – face/groin Triamcinolone 0.1% ointment (medium strength) – trunk/extremities Clobetasol 0.05% ointment (high strength) – thick skin, severe rashes Miscellaneous Protopic (tacrolimus) and Elidel (pimecrolimus): These two agents have the effectiveness of a high to medium strength and a low to medium strength steroid, respectively. The major benefit of these agents is that there is no risk of the local side effects seen with chronic use of topical steroids. The only significant known side- effect is burning with application for the first week, which is more common and severe with Protopic. It is unknown if there are any significant long term side effects. The FDA has placed a black-box warning on these two products, stating that using them may increase the risk of developing lymphoma. However, there is not sufficient data to support this statement at the present time. As previously noted, the side-effects of topical steroids are quite uncommon, except when they are used chronically on the face or in the groin. Steroids come in a wider variety of strengths and vehicles than these two agents, allowing steroids to be better matched to an individual patient’s needs. In general, topical steroids are more effective and are less expensive than these two agents. These two agents should be reserved for patients with facial or groin dermatoses that require chronic treatment. In some instances, they are also useful for dermatoses in other areas, but topical steroids are generally more effective, just as safe, and much cheaper, and are therefore the first line agents. Aldara (imiquimod): This agent is a local immunostimulant, leading to local production of interferon-alpha, IL-12, and other Th1 cytokines. It does not penetrate the skin well, so it must be used in combination with other products if used on thick skin. The primary indication for this medication is on genital warts. Other uses include treating actinic keratoses, regular warts (must alternate applications with salicylic acid), and some skin cancers. Treatment Algorithms: Listed below are some basic treatment plans for common dermatologic conditions. 1. Acne a. Mild i. Tretinoin 0.05% Cream, work up to every night ii. 4% Benzoyl peroxide wash or Neutrogena Oil Free Acne Wash (Salicylic acid wash) b. Moderate i. Tretinoin 0.05% Cream, work up to every night ii. Benzoyl Peroxide wash or combination BP/Clindamycin gel each morning iii. Consider 3 month course of doxycycline/minocycline, 100 mg BID iv. Consider Oral Contraceptive (Ortho-TriCyclen or Yasmin) c. Severe i. Same as moderate ii. Accutane d. Exoriae i. Consider SSRI 2. Rosacea a. Mild i. Metronidazole cream or lotion once daily ii. Sodium Sulfacetamide wash iii. Avoid Triggers b. Severe i. Consider adding intermittent low dose doxycycline/minocycline 3. Seborrheic Dermatitis/Dandruff a. Wash with Head and Shoulders or H&S Intensive Therapy b. Ketoconazole 1% cream once daily c. Hydrocortisone 2.5% cream or desonide lotion alternating with nizoral if necessary (Use each for one week at a time, can continue indefinitely) 4. Perioral Dermatitis a. Topical metronidazole, clindamycin, or topical tacrolimus/pimecrolimus BID b. Consider oral antibiotics  c. Avoid topical steroids 5. Poison Ivy a. Clobetasol 0.05% cream BID if localized b. Prednisone Taper if severe i. Start at 1 mg/kg daily, taper over 3 WEEKS 6. Xerosis a. Ceramide-based creams or petroleum jelly immediately after showering 7. Mild Psoriasis (less than 10% body surface area, no psoriatic arthritis) a. Clobetasol 0.05% Ointment/Solution (for scalp) b. Calcipotriene (Dovonex) 0.005% Ointment/Solution (for scalp) i. Initially use both twice daily (can mix together) ii. Over 1-2 months, decrease clobetasol to 3 times/week max, continue daily dovonex 8. Intertrigo a. Miconazole or econazole cream BID x 2-3 weeks b. After clearing rash, area MUST BE KEPT DRY 9. Thrush a. Mycelex Troches 10. Tinea Corporis/Pedis/Cruris a. Terbinafine or an azole antifungal cream BID until better, then once a week to prevent recurrence. 11. Onychomycosis a. Try not to treat unless patient is diabetic or immunosuppressed b. Terbinafine 250 mg QD for 12 weeks (check LFTs before therapy, at 6 weeks, and at end of therapy). i. Alternate regimen (less expensive, probably safer): Terbinafine 250 mg QD x 1 week, repeat once every 3 months until nails are clear 12. Zoster/Herpes a. Zoster: 1 gm valacyclovir PO TID x 1 week b. Herpes: dose based on whether it is primary HSV infection or reactivation c. Warn about transmissibility, even when no lesions 13. Post Herpetic Neuralgia a. Gabapentin PO, Topical Capsaicin 0.025% or 0.075% TID/QID b. Nerve Block c. TCAs 14. Molluscum a. Scrape off gently with scalpel blade or curette b. Tretinoin 0.05% cream QHS c. Compound W d. Cryotherapy 15. Warts a. Remove dead skin twice weekly b. Soak wart for 20 minutes before applying Compound W QHS under duct tape c. Cryotherapy to lesions every 3-4 weeks d. May alternate using 5-Fluorouracil (5-FU) or Aldara with the compound W (Day 1: Compound W; Day 2: 5-FU or Aldara, Day 3: Compound W, etc.) 16. Genital Warts a. Aldara 3-7x/week b. Increase frequency until mild inflammation occurs, continue until warts gone. c. Comes in boxes of 12 and 24 packets. Packet can be refrigerated after opening. d. Warn about transmissibility, even when no lesions 17. Scabies a. 5% Permethrin i. Apply to entire body, from jaw-line down, before bed ii. Under nails, peri-anal, skin folds, genitalia especially important iii. In the morning, wash bed linens and clothes from last three days iv. Treat everyone who lives in the house v. Repeat in one week b. Alternate: Ivermectin 200 mcg/kg, repeat in one week c. Itching may persist for 6 weeks despite cure d. If you’ve never had scabies before, usually takes at least one month before you start itching after you catch it. e. It is hard to catch, unless you have close personal contact with someone infected 18. Urticaria a. Loratadine, Fexofenadine, Cetirizine i. All are OK to use up to 3-4 times recommended dose b. Benadryl, hydroxyzine are more effective, but more sedating c. Combining multiple antihistamines often more effective d. Prednisone in short term, do not allow to become chronic 19. Stasis Dermatitis a. Compression stockings, knee high, 20-30 mg of pressure at minimum, on in morning, off in evening (assumes arterial circulation is OK) i. Prescribe at least 2 pairs so they can wear one, wash one ii. Replace every 6 months  b. Elevate legs for one hour several times a day (if cardiac can tolerate) c. Triamcinolone 0.1% Ointment BID for up to two weeks at a time 20. Drug Rash a. Check CBC/diff, LFTs (increased LFTs and eosinophilia are worrisome) b. If labs OK, generally OK to treat through if causative medication is necessary and is only going to be used for short term (1-2 weeks). Continue to monitor labs every several days. c. Causative drug usually started 4-14 days prior to rash, may take weeks to months to go away after drug stopped. d. Antibiotics, NSAIDS, diuretics, anticonvulsants very common e. Benadryl and topical steroids for symptomatic relief