TABLE 16.1 Medications That Cause Acneiform Rash | ||||||||||||
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TABLE 16.2 Classification of Acne Vulgaris | ||||||||||
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TABLE 16.3 Overview of Topical and Oral Acne Preparations | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Acne Vulgaris and Rosacea
Acne Vulgaris and Rosacea
Virginia P. Arcangelo
ACNE VULGARIS
Acne vulgaris is viewed by many as a rite of passage during the adolescent years. Up to 90% of all teenagers report having some form of acne. Adults suffer from the effects of acne as well: between 30% and 50% of adult women report experiencing acne. Consumers spend millions of dollars annually on prescription and over-the-counter (OTC) acne preparations.
The psychosocial costs of acne are great. Adolescents are particularly affected by physical defects, no matter how minor they appear to others. The health care practitioner must be particularly sensitive to the perceived seriousness of the acne in addition to the clinical picture. What may seem inconsequential to the practitioner may be devastating to the patient. No matter how minor the acne may appear to the provider, it is important to ask patients if they are concerned about their acne and whether they would like treatment.
CAUSES
Historically, numerous theories of the cause of acne vulgaris have been proposed, yet the exact cause remains unknown. Foods, stress, and dirt, although not causative, may exacerbate existing acne, which is why it is important to obtain a complete health history to ascertain precipitating factors. For example, a variety of drugs, physical occlusants, and conditions may exacerbate acne. Certain drugs used to treat tuberculosis, seizure disorders, or steroid-dependent chronic illness or depression may cause a drug-induced acneiform rash (Table 16.1). Drug-induced acne should be suspected when all lesions are in the same stage (e.g., the lesions are uniformly all pustules or all open comedones), covering the face, chest, trunk, arms, and legs.
Acne may be exacerbated in teenagers and adults whose skin is exposed to oily agents, such as makeup, oil-based sunscreen, and oil-based hair products that come in contact with the forehead and temporal regions of the face (referred to as pomade acne). Friction acne from tight-fitting clothes, such as football helmets and hatbands, is found over the skin rubbed by the clothes. Exposure to animal-, vegetable-, and petroleum-based oils used in workplaces such as fast food restaurants and automotive garages may also exacerbate acne. Thus, although eating French fries may not cause acne, cooking them may make the acne worse. Emotional stress may contribute to acne exacerbations in persons prone to breakouts, but studies have not consistently proven the correlation.
Women with a history of menstrual irregularities, hirsutism, and treatment-resistant acne should be evaluated for androgen excess associated with polycystic ovarian disease.
PATHOPHYSIOLOGY
Acne usually begins 1 to 2 years before the onset of puberty, when androgen production increases. Excess androgen causes increased sebum production. For unknown reasons, abnormal keratinization causes retention of sebum in the pilosebaceous follicle. This produces open comedones (blackheads) and closed comedones (whiteheads).
When closed comedones continue to produce keratin and sebum, the pilosebaceous follicle ruptures and inflames the surrounding tissue. If the inflammation is close to the surface, a papule forms. If it is deeper in the dermis, a larger papule or nodule forms. These deeper, nodular acne cysts cause permanent scars.
Although Propionibacterium acnes, an anaerobic gram-positive bacterium, is present as normal flora in the pilosebaceous follicle, acne vulgaris is not an infectious entity. Rather, it is believed that P. acnes produces lipolytic enzymes that in turn produce biologically active extracellular products. These in turn attract polymorphonuclear leukocytes and monocytes, which increase inflammation.
DIAGNOSTIC CRITERIA
Acne vulgaris is diagnosed from the clinical presentation of the patient’s skin. It is classified and subsequently treated depending on its severity.
The mildest form of acne is comedonal. Both open and closed comedones may be present. Mild inflammatory acne is manifested by papules. Moderate inflammatory acne consists of pustules and some cysts. Severe cystic acne consists of cysts, nodules, and scarring (Table 16.2).
INITIATING DRUG THERAPY
Skin care is the most important nonpharmacologic tool in the management of acne vulgaris. The patient should be instructed to wash the face gently two or three times a day with a mild soap such as Basis, Cetaphil, Neutrogena, or Purpose. Care should be taken to avoid harsh, drying cleansers. Washing should be gentle because scrubbing the skin may exacerbate the acne. Comedo removal, although therapeutic, should be undertaken only by someone skilled in the proper technique. Picking or popping pimples may increase tissue damage and infection. The health care provider should advise the patient to avoid manipulating the acne with the fingers.
In general, use of personal care products should be minimized. Moisturizers and cosmetics should be water based, noncomedogenic, and fragrance free. If hair preparations are used, they should also be water based. The patient should be instructed to apply hair products so that they do not come in contact with facial skin.
The practitioner also needs to stress that ingestion of specific foods, such as chocolate, greasy foods, colas, and iodide-containing foods, does not cause acne. Elimination diets are not considered therapeutic unless the patient reports an exacerbation associated with a certain food. In that case, the food must be avoided for 4 to 6 weeks and then gradually reintroduced to see what effect that food has on the acne.
Goals of Drug Therapy
The goal of pharmacotherapy is to minimize the number and severity of new lesions, prevent scarring, and improve the patient’s appearance. The patient must be counseled that improvement of acne vulgaris takes time—usually 4 to 6 weeks. Some form of therapy will probably need to be continued throughout adolescence and even into young adulthood.
Pharmacotherapy choices are based on the severity of the acne. Currently, successful therapy usually relies on a combination of medications. The synergistic effect of two or more drugs from different classes produces the best results. See Table 16.3 for a summary of acne medications.
Comedolytics
Retinoic Acid (Tretinoin)
Marketed under the trade names Retin-A and Avita, retinoic acid is the acid form of vitamin A. When applied topically, retinoic acid acts on the epidermis with little systemic absorption to decrease cohesion between epidermal cells and increase epidermal cell turnover. The result is expulsion of open comedones and the conversion of closed comedones to open ones.
When used properly, retinoic acid causes mild erythema and peeling of the skin. Some patients cannot tolerate daily use or prolonged contact at the initiation of therapy. For example, fair-skinned patients should be advised to start out using the product every other day. Alternatively, the patient may be instructed to apply retinoic acid to the face for 15 to 30 minutes each night and then wash off the medication. Gradually, the length of time the medication remains on the face is increased until it can be tolerated overnight. It is best to apply the medication on clean, thoroughly dry skin to avoid excessive irritation. Side effects of retinoic acid include erythema, local skin irritation, and photosensitivity. Patients should be advised to avoid prolonged exposure to the sun or to wear a noncomedogenic sunscreen formulated specifically for use on the face.
Retinoic acid is available in cream (0.025%, 0.05%, and 0.1%), gel (0.01% and 0.025%), liquid (0.05%), and microsphere (0.04% and 0.1%) formulations. The microsphere formulation encapsulates the active ingredient in microspheres, which act as a reservoir that slowly releases the retinoic acid. Although the microsphere product contains a higher percentage of medication, the slow-release formulation produces less irritation, making it one of the mildest dosage forms.
Adapalene Gel
Adapalene (Differin), a topical medication for treating noninflammatory acne, is a derivative of naphthoic acid, which binds to retinoid receptors. It is considered less irritating than retinoic acid. Up to 40% of patients report irritation, but it subsides during the first month of treatment. Adapalene is applied in the same way as retinoic acid. A small amount is applied either every other day or for short periods in the evening until the drug can be tolerated overnight. Side effects of adapalene include hyperpigmentation and photosensitivity.
Tazarotene Gel
A retinoid prodrug, tazarotene gel (Tazorac) is effective against both comedonal and inflammatory acne as well as psoriasis. Despite being a topical drug, tazarotene is considered teratogenic (pregnancy category X) and should be used only by women who take systemic contraceptives and who have a negative pregnancy test.
Care should be taken when using the medication with tetracycline because it potentiates the photosensitivity reaction. Other side effects include dry skin, erythema, and pruritus.
Comedolytic Bactericidals
Benzoyl Peroxide
Benzoyl peroxide is both a comedolytic and bactericidal agent specific to P. acnes. It has a role in inflammatory acne because of its antibacterial qualities. By decreasing P. acnes levels, it decreases the inflammation caused by leukocytic and monocytic attraction to the pilosebaceous follicle.
The major side effect of benzoyl peroxide is irritation. Like all comedolytics, benzoyl peroxide is applied initially in a low-percentage formulation in a nonirritating base. The patient increases the dosage strength and frequency. Because benzoyl peroxide may bleach colored items, the patient should be instructed not to let the product come in contact with brightly colored towels, pillowcases, or clothing. If used with retinoic acid, benzoyl peroxide should be applied in the morning and retinoic acid before bedtime.