Psoriasis: General principles section 3

Approximately 80% of patients affected with psoriasis have mild to moderate disease. The majority of these patients can be treated with topical agents which generally provide both high efficacy and safety. Topical agents are also used adjunctively for resistant lesions in patients with more extensive psoriasis who are being concurrently treated with either ultraviolet light or systemic medications. However, the use of topical agents as monotherapy in the setting of extensive disease or in the setting of limited, but recalcitrant disease is not routinely recommended. Treatment should be tailored to meet individual patients’ needs. These needs vary depending on body location, characteristics of the psoriasis being treated including lesion thickness, degree of erythema and amount of scaling, as well as patient preferences. It is important to match patient expectations with practical considerations. Patients who wish for lifetime clearance with no evident lesions will inevitably be disappointed with topical therapy because of the need for a continuous intense topical regimen that will be very difficult to carry out and maintain. Some patients may desire to be free from pruritus and to have a diminution in their most visible lesions. Others may prefer only intermittent treatment with little interest in spending considerable time to care for their psoriasis. It is important to ascertain each patient’s goals and then to develop a strategy to help fulfill his or her expectations while also being practical and realistic. 

The choice of vehicle can significantly alter the use and penetration of the medication and therefore alter the efficacy. Vehicle types are numerous and may include ointments, creams, solutions, gels, foams, tape, sprays, shampoos, oils, and lotions. Different vehicles are indicated for different body sites. The optimal choice is generally the vehicle the individual patient will most likely use. For example, hair-bearing areas including the scalp can be treated with solutions, foams, shampoos, sprays, oils, gels, or other vehicles, with individual patients having different preferences among these options. Some patients may prefer a less greasy preparation, perhaps a cream for daytime use and may be willing to use an ointment, which is more effective but less cosmetically appealing, at night. Cultural preferences may also make one vehicle preferred over others for a given site. Occlusion of topical medications can also alter the penetration, thereby varying the effectiveness. The observation that flurandrenolide 0.1%, which is a class 5 topical steroid when used in the cream or lotion formulation, functions as a class 1 topical steroid when used as a tape and has a higher efficacy than the class 1 steroid diflorasone diacetate ointment in the treatment of psoriasis6 serves as a strong reminder of the impact of occlusion.

Topical medications can sometimes be used concurrently to take advantage of varied mechanisms of action. For example, calcipotriene can be used in combination with topical corticosteroids. However, when using multiple topical agents, it is important to be aware of possible compatibility issues. For example, calcipotriene should not be used concurrently with products that can alter the pH of its base, such as topical lactic acid. When it is desirable to use multiple topical agents to achieve a clinical goal, patients may be instructed to apply the various medications at separate times throughout the day. Along with the option of concurrent use of topical agents, topical agents can be combined with either phototherapy or systemic agents to enhance efficacy in patients who are improving but still have areas of active disease. 

Use of topical agents can be both intermittent and long-term. In general, it is recommended that more potent agents be used on a short-term basis to allow for response, after which patients should be instructed to use these agents intermittently for long-term management. This strategy may confer less risk of side effects than continuous treatment. Alternatively, patients who require continuous topical treatment should be instructed to use the least potent agent that allows for disease control or be transitioned to a topical agent that is associated with the lowest long-term risk. Although topical agents for psoriasis are usually well tolerated without significant side effects,7 it is important that patients receive regular examinations, whether they use medications over the long term or intermittently as unsupervised use of potent topical medications is not recommended. It is generally accepted that approximately 400g of a topical agent is required to cover the entire body surface of an average-sized adult when used twice daily for 1 week.8 Guidance regarding the appropriate amount of topical agents to be applied to affected skin derives from the concept of the fingertip unit (Fig 1, Table I),9 which provides a means for patients to more accurately dose their topical medications.

Use of topical agents: The fingertip unit and how to assess quantity of topical agents needed to cover a given body surface area

Area to be treated
No. of fingertip
units
Approximate
Body surface area (%)
Scalp 3 6
Face and Neck                   2.5 5
One hand (front and back) including fingers
1 2
One entire arm including entire hand
4 8
Elbows (large plaque) 1 2
Both soles 1.5 3
One foot (dorsum and sole), including toes 1.5 3
One entire leg including entire foot
8 16
Buttocks 4 8
Knees (large plaque) 1 2
Trunk (anterior) 8 16
Trunk (posterior) 8 16
Genitalia 0.5 1

 

 

Navigate section 3 of the psoriasis guideline: Topical therapies

Citation note

When referencing this guideline in a publication, please use the following citation: Menter A, Korman NJ, Elmets CA, Feldman SR, Gelfand JM, Gordon KB,et al. Guidelines of care for the management of psoriasis and psoriatic arthritis. Section 3. Guidelines of care for the management and treatment of psoriasis with topical therapies. J Am Acad Dermatol. 2009 Apr;60(4):643-59.



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