Tailoring a patient’s acne regimen with the knowledge of the pathogenesis of acne and the mechanism of action of the available acne treatments will ensure maximum therapeutic response. Treatment regimens should be initiated early and be sufficiently aggressive to prevent permanent sequelae. Often multiple treatments are used in combination so as to combat many factors in the pathogenesis of acne (Table 80-1). The mechanism of action of the most common treatments for acne can be categorized in the following categories as they relate to the pathophysiology:1. Correct the altered pattern of follicular keratinization.2. Decrease sebaceous gland activity.3. Decrease the follicular bacterial population, particularly P. acnes.4. Exert an anti-inflammatory effect.

LOCAL THERAPYCleansing. The importance of cleansing in the treatment of acne is generally intuitive. Twice daily washing with a gentle cleanser followed by the application of acne treatments may encourage a routine and therefore better compliance. Overcleansing or using harsh alkaline soaps are likely to increase the skin’s pH, disrupt the cutaneous lipid barrier, and compound the irritancy potential of many topical acne treatments. Use of a syndet (synthetic detergent) will allow cleansing without disruption of the skin’s normal pH. Antibacterial soaps, containing agentssuch as triclosan, inhibit Gram-positive cocci but may increase Gram-negative rods; their overall affect on acne is unclear. Medicated cleansers, containing benzoyl peroxide or salicylic acid, offer convenience as a wash and are excellent for hard to reach areas like the back.

Topical Agents. (See Table 80-2)Sulfur/Sodium Sulfacetamide/Resorcinol. Products containing sulfur, sodium sulfacetamide, and resorcinol, once favored treatments for acne, are still found in severalover-the-counter and prescription niche formulations. Sulfonamides are thought to have antibacterial properties through their inhibition of para-aminobenzoic acid (PABA), an essential substance for P. acnes growth.52 Sulfur also inhibits the formation of free fatty acids and has presumptive keratolytic properties. It is often combined with sodium sulfacetamide to enhance its cosmetic tolerability due to sulfur’s distinctive odor. Resorcinol is also indicated for use in acne for its antimicrobial properties. It is generally found in 2% concentration in combination with 5% sulfur.Salicylic Acid. Salicylic acid is a ubiquitous ingredientfound in over-the-counter acne preparations in concentrationsranging from 0.5% to 2%. This lipid soluble-hydroxy acid has comedolytic properties, thoughsomewhat weaker than those of a retinoid. Salicylicacid also causes exfoliation of the stratum corneumthough decreased cohesion of the keratinocytes. Mildirritant reactions may result.Azelaic Acid. Azelaic acid is available by prescriptionin a 20% cream or 15% gel. This dicarboxcylic acid hasboth antimicrobial and comedolytic properties.53 It isalso a competitive inhibitor of tyrosinase and thus maydecrease postinflammatory hyperpigmentation.54 It isgenerally well tolerated, though transient burning canoccur, and is safe in pregnancy.Benzoyl Peroxide. Benzoyl peroxide preparations areamong the most common topical medications prescribedby dermatologists and are also readily availableover-the-counter. Benzoyl peroxide is a powerfulantimicrobial agent through decreasing both the bacterialpopulation and the hydrolysis of triglycerides.Benzoyl peroxide preparations are available in creams,lotion, gels, washes, and pledgets. Products that areleft on the skin, such as a gel, are generally consideredmore effective. Benzoyl peroxide can produce significantdryness and irritation. Allergic contact dermatitishas been uncommonly reported. Of significance,bacteria are unable to develop resistance to benzoylperoxide, making it the ideal agent for combinationtherapy.55

Topical Antibiotics. (See Chapter 218). Erythromycin

and clindamycin are the most commonly used topicalantibiotics for the treatment of acne. These two agentshave also been used in combination preparations withbenzoyl peroxide. Increased levels of P. acnes resistancehave been reported in patients who are being treatedwith antibiotics. However, the development of resistanceis less likely in patients who are treated with acombination of benzoyl peroxide/erythromycin orclindamycin.56 Therefore, the combination of these twoproducts is preferable over monotherapy with topicalantibiotics. Topical dapsone is the most recentlyapproved topical antibiotic for acne. With twice dailyapplication topical dapsone has shown better efficacyin controlling inflammatory lesions (58%) versus noninflammatorylesions (19%).57,58 Unlike oral dapsone,topical dapsone is safe for use even in patients witha G6PD deficiency.59 It is generally well tolerated butshould not be applied concomitantly with benzoyl peroxideor it may impart an orange color on the skin.60

Retinoids. (See Chapter 217). Retinoids are definedby their ability to bind to and activate retinoic acidreceptors (RAR) and in turn activate specific gene transcriptionresulting in a biologic response. Some havechemical structures similar to tretinoin (all-trans-retinoicacid), but they may be entirely dissimilar, suchas adapalene or tazarotene, and still potentiate a retinoideffect. In general, the binding of these agents tonuclear RAR affects the expression of genes involvedin cell proliferation, differentiation, melanogenesis,and inflammation.61,62 The result is modification ofcorneocyte accumulation and cohesion, and inflammation.Thus, retinoids have both comedolytic and antiinflammatoryproperties.62

Tretinoin is commercially available in severalstrengths and formulations. Having both potent comedolyticand anti-inflammatory properties, it is widelyused. In general, all retinoids can be contact irritants,with alcohol-based gels and solutions having the greatestirritancy potential. Some newer formulations utilizea microsphere delayed-delivery technology (RetinA Micro® 0.04% or 0.1% gel) or are incorporated withina polyolprepolymer (PP-2) (Avita® cream) to decreasethe irritancy potential of tretinoin while allowinggreater concentration of medication. Advising patientsto apply tretinoin on alternate nights during the firstfew weeks of treatment can help ensure greater tolerability.Patients must also be cautioned about sunexposure due to thinning of the stratum corneum,especially those with any irritant reaction. Regular useof a sunscreen should be advised. The comedolytic andanti-inflammatory properties of topical retinoids makethem ideal for maintenance therapy of acne. Generictretinoin is inactivated by concomitant use of benzoylperoxide and is photolabile. Therefore, patients shouldbe counseled to apply tretinoin at bedtime.Adapalene is a synthetic retinoid widely marketedfor its greater tolerability. It specifically targets theRARreceptor. It is both photostable and can be usedin conjunction with benzoyl peroxide without degradation.Adapalene 0.1% gel has been shown in clinicaltrials to have greater or equal efficacy to tretinoin

0.025% gel with greater tolerability.63,64 It is availableat a 0.1% concentration in both a nonalcohol gel and

ACNE CONGLOBATAThis severe form of nodular acne is most common inteenage males, but can occur in either sex and intoadulthood. Acne conglobata (conglobate means shapedin a rounded mass or ball) is a mixture of comedones,papules, pustules, nodules, abscesses, and scars. It canbe on the back, buttocks, chest, and, to a lesser extent,

on the abdomen, shoulders, neck, face, upper arms,and thighs (Fig. 80-6). The comedones often have multipleopenings. The inflammatory lesions are large, tender,and dusky-colored. The draining lesions dischargea foul-smelling serous, purulent, or mucoid material.Subcutaneous dissection with the formation of multichanneledsinus tracts is common. Healing resultsin an admixture of depressed and keloidal scars. Themanagement of these patients is very difficult and theeffect of treatment is often temporary. Several medicationshave been used, including intensive high-dosetherapy with antibiotics, intralesional glucocorticoids,systemic glucocorticoids, surgical debridement, surgicalincision, and surgical excision. The use of isotretinoinhas produced dramatic results in some of thesepatients. In severe cases, dosages as high as 2 mg/kg/day for a 20-week course may be necessary. However,because severe flares may occur when isotretinoin isstarted, the initial dose should be 0.5 mg/kg/day orless, and systemic glucocorticoids are often requiredeither before initiating isotretinoin therapy or as concomitanttherapy.