Acne vulgaris is a common skin disorder with a peak incidence around 18 years of age. The condition should not be underestimated in terms of its negative psychosocial consequences. Brown and Shalita review the range of treatment options and stress the importance of individualizing patient therapies.
Patients with acne have high rates of sebum secretion, providing a lipid-rich growth medium for Propionibacterium acnes. High sebum production may reflect increased production of adrenal and gonadal androgens. In most women with acne, serum androgen concentrations are not higher than normal; however, some women may respond to antiandrogen therapy. Patients with acne also have abnormally adherent desquamated cornified cells that may plug the follicular canal instead of shedding from the skin surface. The combination of plugged follicular canals and excessive sebum production leads to the development of comedones. As P. acnes proliferates in this medium, it contributes to the inflammatory process, leading to the typical papules, pustules and nodules of acne vulgaris.
In patients with mild to moderate acne or noninflammatory comedones, topical therapy is indicated. Tretinoin reduces the formation of comedones by reversing the abnormal keratinization process. Because topical tretinoin is irritating and photosensitive, therapy usually begins with the lowest-strength cream or gel, increasing the formulation strength until the desired result is achieved. Other topical agents include salicylic acid, adapalene, azelaic acid and isotretinoin, but not all of these preparations are currently available in the United States. Topical benzoyl peroxide targets P. acnes and is available in gels, lotions, creams and soaps. Local irritation may be reduced by using the lower-strength preparations or by applying the product less frequently. Topical bacteriostatic antibiotics such as clindamycin, tetracycline and erythromycin are effective in acne vulgaris but may induce resistant strains of P. acnes. Combination topical therapy is commonly used in the treatment of acne, because concurrent therapy with several agents has a synergistic antimicrobial effect. Benzoyl peroxide, topical antibiotics and tretinoin may be used concurrently. Several agents may be combined in one preparation, but an alternating schedule of application of individual agents may be less irritating. The choice of vehicle depends on the patient's skin type. Non-greasy gels and solutions tend to dry the skin and may be preferred by patients with oily skin. Creams and lotions may be more cosmetically acceptable.
Oral antibiotics such as tetracycline, doxycycline, minocycline, erythromycin and cotrimoxazole are used in patients with mild to moderate disease, those with affected areas that cannot be adequately covered with topical medications and those with a high potential for scarring or substantial pigmentary changes. These medications act primarily by inhibiting bacterial growth, although some also have anti-inflammatory properties. The potential benefits and side effects should be weighed when choosing an agent. Treatment with oral antibiotics should generally be continued for four to six months; maximal clinical improvement may not be apparent before three months of therapy. If acne worsens during antibiotic therapy, bacterial resistance may have developed.
Severe nodular acne is best treated with isotretinoin. Therapy usually continues for 20 weeks. About 15 percent of cases relapse after a single course, but most patients who relapse show enhanced results from a second course of treatment. Further courses of isotretinon are seldom necessary. Clinical improvement may continue for up to five months following a course of therapy, so retreatment should not be attempted within six months. Isotretinoin has several serious potential side effects, particularly spontaneous abortion and congenital malformations. Stringent methods of contraception are mandatory when this drug is used in women with childbearing potential.
Other possible therapies for acne include hormonal manipulation to reduce androgens and spironolactone, which blocks androgen receptors and has antiandrogenic effects.