Current Therapies for Psoriasis, Part 1
The rapid changes in the treatment of psoriasis have provided many new options for the approximately 7.5 million Americans who live with psoriasis, of whom 30% may also develop psoriatic arthritis (PsA).1 The tremendous variation in psoriasis—with common, guttate, inverse, pustular, and erythrodermic variants as well as variation in the parts of the body affected by the disease—complicates the treatment decision. Psoriasis not only has a large direct effect on patients’ quality of life; psoriasis is associated with many comorbidities such as obesity, cardiovascular disease, diabetes, and depression.
The development of new targets for psoriasis treatments have paralleled our growing understanding of immunological pathways involved in the pathogenesis of psoriasis. Our improved understanding of the human factors that contribute to how well people use their medications has also led to major improvements in our ability to control the disease. With new evolving information, both topical and systemic medications, have been developed to selectively take advantage of these developments.2
There are a few basic steps in the treatment of psoriasis. First is to address the psychosocial and educational needs of patients with psoriasis. A straightforward way to do this is to encourage patients to join and make use of resources from the National Psoriasis Foundation. This Foundation offers patients a host of materials on how to manage the disease and the social implications of having psoriasis.
The next step in psoriasis treatment is to assess for comorbidities that affect treatment choices. Assessment for PsA is essential, as the skin involvement typically occurs before joint disease, and early identification and treatment of joint involvement may help prevent the occurrence of irreversible joint destruction.
Finally, a key step in psoriasis treatment is to define whether the patient has mild to moderate psoriasis that can be treated with topical treatments alone or whether the patient has moderate to severe disease that will require phototherapy or systemic treatments. In clinical trials, when 10% or more of the body surface area is involved, the patient is generally considered to have moderate to severe disease. In clinical practice, a functional definition is typically used: Can patients reasonably and effectively use topical treatment to treat the psoriasis? If so, then they are treated with topical treatments (and/or localized UV treatments), and if not, then they can be started directly on phototherapy or systemic treatment (Figure).
Figure. Psoriasis Treatment Algorithm
Topical treatments are indicated for mild to moderate psoriasis and for localized resistant areas of disease in patients concomitantly using phototherapy or taking systemic medications. There are many options available (Table 1), and the majority of topical medications work by decreasing the amount of inflammation and/or modulating keratinocyte differentiation. Topical medications work well for patients who are compliant and willing to apply their medication on a regular basis. The main topical medications utilized are corticosteroids with or without a concomitant vitamin D3 analog. Topical calcineurin inhibitors are also valuable, particularly for the face and intertriginous involvement.3
Corticosteroids are the mainstay of topical therapy for psoriasis. They come in many vehicle formulations including ointments, creams, lotions, solutions, foams, shampoo, oil, and sprays. Traditional dogma was that ointments are generally preferred for dry, scaly psoriasis lesions because ointments are more potent than other vehicles and because moisturizing the plaque with an ointment vehicle has direct benefits; but due to the greasy, messy nature of ointments, patients may prefer a cream or lotion that is easier to use. The ability to find a formulation the patient will actually use is critical when selecting any topical agent.
Different vehicles and different strengths of corticosteroid may be used for different parts of the body. Sprays and solution vehicles are normally prescribed for lesions on the scalp because they are able to penetrate past the hair. Potent corticosteroids—such as clobetasol proprionate, fluocinonide, and betamethasone diproprionate—are commonly prescribed for thick plaques located on the trunk and extremities, while moderate potency corticosteroids, like triamcinolone acetonide, are used for thinner and more sensitive areas of involvement. For the most sensitive areas, such as the face and intertriginous areas, mild to moderate potency steroids, such as hydrocortisone, can be effective. The use of different vehicles and different strengths of corticosteroids allows physicians to tailor the treatment to the needs of different lesions, but giving patients too many treatments may complicate the regimen and adversely affect patients’ use of the treatments. Where possible, choosing a single vehicle and corticosteroid that can be used for all the lesions (for example, using a high-potency agent and just reducing the duration of use in sensitive areas) may be best.
These medications can be used once or twice daily for 2 to 4 weeks continuously at a time, followed by intermittent use as needed. Patients can experience rapid improvement with topical corticosteroids, but using them continuously for an extended period of time can have unwanted side effects, including skin atrophy, striae, hypopigmentation, steroid acne, and miliaria.3,4
Intralesional corticosteroid injections can also be used for very localized, recalcitrant plaques, particularly when there is a superimposed prurigo component caused by extensive picking, scratching, or rubbing the lesion. Triamcinolone acetonide (Kenalog) suspension (at 10 mg/mL diluted with sterile saline to 2.5-5 mg/mL) can be injected directly into a plaque at 1 month intervals in order to decrease the thickness.4
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