Psoriasis



Psoriasis


Shelly Schneider



Psoriasis is a debilitating disease characterized by recurrent exacerbations and remissions. It affects between 2% and 3% of the U.S. population, with a higher incidence in whites and an equal distribution between the sexes. Approximately 36% of patients with psoriasis have a positive family history. The cost of outpatient treatment for psoriasis averages $1.6 to $3.2 billion annually.

There appear to be two peak ages of onset: between ages 16 and 22 and between ages 57 and 60. Psoriasis has an element of physical discomfort, with pain, itching, stinging, cracking, and bleeding of the lesions. In approximately 10% of patients with psoriasis, the disease develops into psoriatic arthritis.

Psoriasis affects almost all aspects of life, including sexual relationships and emotional well-being. In addition, patients with psoriasis spend 1 or more hours a day caring for their skin. Of a survey group of patients with psoriasis, up to 25% felt at some point in their life that they would rather be dead than alive with psoriasis.

Psoriasis affects approximately 2.5% of Whites and 1.3% of Blacks in the United States, with approximately 150,000 newly diagnosed cases every year. The incidence of psoriasis is somewhat lower in Asians (0.4%). Generally, it is more common in individuals living at higher latitudes or in colder locales and less common in individuals who have greater sun exposure. There seems to be a genetic factor associated with psoriasis. Based on population studies, the risk of psoriasis in children is estimated to be 41% if both parents are affected, 14% if one parent is affected, and 6% if one sibling is affected, and a family history can be found in 5% to 10% of patients who have psoriasis.


CAUSES

A definitive cause for psoriasis is unknown, although there are several possible etiologic factors: abnormal epidermal cell cycle, hereditary factors, and trigger factors, including trauma, infection, endocrine imbalance, climate, and emotional stress.

Physical trauma, such as rubbing, scratching, or sunburn, is a major exacerbating factor in psoriasis, and this is referred to as Koebner phenomenon. A precipitating event, in some cases of guttate psoriasis, is a streptococcal infection. Stress plays a role in as many as 40% of psoriasis flares in adults and children. Exacerbations of psoriasis may develop from the use of certain drugs (Box 15.1).




PATHOPHYSIOLOGY

Psoriasis is an autoimmune-mediated process driven by abnormally activated helper T cells. Activation of these T cells can occur through specific interactions with antigen-presenting cells (APCs) or via nonspecific superantigen interactions (i.e., guttate psoriasis is triggered by streptococcal antigens). APC activation requires costimulatory signals. Once activated, psoriatic T cells produce a type 1 helper T cell-dominant cytokine profile that includes interleukin-2 (IL-2), tumor necrosis factor-alpha (TNF-α), interferon-γ, and IL-8. These cytokines act to attract and activate neutrophils, which are responsible for much of the inflammation seen in psoriasis. Other factors leading to neutrophil recruitment and activation are complement split products and leukotrienes (arachidonic acid metabolites from the 5-lipoxygenase pathway).


DIAGNOSTIC CRITERIA

Psoriasis is diagnosed by observation of characteristic, well-demarcated, erythematous papules or plaques surrounded by silvery or whitish scales. The lesions are symmetric and usually
found on the face, extensor joints, anogenital area, palms and soles, intertriginous areas (known as inverse psoriasis), trunk, scalp, ears, and nails.



BOX 15.1
Drugs Known to Exacerbate Psoriasis

Systemic corticosteroids (when dose is decreased or stopped)

Lithium carbonate

Antimalarials

Beta-blockers

Systemic interferon

Alcohol

The varieties of psoriatic disease include plaque, guttate, erythrodermic, and pustular. The plaque type is the most common form. The guttate type is characterized by small, scattered, teardrop-shaped papules and plaques. In many cases, psoriasis begins as the guttate form. The erythrodermic form is characterized by generalized intense erythema and shedding of scales. Finally, the pustular type has three additional forms: generalized, localized, and palmar-plantar. All share a similar characteristic: 2- to 3-mm sterile pustules on specific body regions.

Clinical presentation of the plaque type of psoriasis consists of sharply demarcated, erythematous papules and plaques with marked silvery-white scales. Bleeding may follow removal of the scales (Auspitz sign). The elbows, knees, and scalp are the most common areas for psoriatic plaques. Pitting and discoloration of the nails also characterizes psoriasis. In some cases, the nail may separate from the nail bed—referred to as onycholysis.


INITIATING DRUG THERAPY

Before beginning drug therapy, the patient is usually counseled to avoid precipitating factors. Cigarette smoking is discouraged since this can exacerbate the condition.

There are three treatment modalities available: topical agents, phototherapy, and systemic agents. To select the most appropriate treatment, the prescriber must determine whether the patient has localized or generalized psoriasis. Patients with 10% or less of body involvement can usually be successfully treated in a primary care setting with topical agents, whereas those with greater body surface area (BSA) involvement usually require treatment by a dermatologist with phototherapy or systemic therapy. In estimating BSA involvement, the prescriber keeps in mind that the palm represents 1% BSA; this can be used as a tool to estimate total BSA involvement.


Goals of Drug Therapy

The goals of therapy are to:



  • Decrease the size and thickness of the plaques


  • Decrease pruritus


  • Improve emotional well-being and quality of life


  • Put the patient in remission


  • Have minimal side effects from treatment

It is imperative to use a management strategy that has the least possible toxicity and that is acceptable to the patient. Sequential therapy is thought to be effective because psoriasis is a chronic disease requiring long-term maintenance therapy and treatment of exacerbations. The three phases of sequential therapy are the clearing, transitional, and maintenance phases. Table 15.1 identifies topical and systemic preparations used in psoriasis treatment.









TABLE 15.1 Overview of Selected Agents for Psoriasis


































































































Generic (Trade) Name and Dosage

Selected Adverse Events

Contraindications

Special Considerations


Topical Agents


Emollients (Eucerin, Lubriderm, Moisturel, CeraVe, Cetaphil) Apply to affected skin three or four times daily.

Folliculitis, maceration, miliaria


Avoid applying near eyes.


Tar Preparations


Coal tar

Irritation, photoreactions, unpleasant odor, folliculitis

Open or infected lesions

Preparation may stain skin and clothing.


With emulsion, immerse affected area for 10 to 20 min three to seven times a week.


Shampoo should be massaged into wet scalp and rinsed, then applied a second time and left on for 5 min.

Apply at bedtime and allow to remain on skin.


Emulsion: 15-25 mL dissolved in bath water


Shampoo


Antipsoriatics


anthralin (Drithocreme, Micanol) Apply for 30-60 min, and then remove.

Irritation

Renal disease, acute psoriasis

Preparation may stain skin, towels, sinks, and tubs.


Avoid applying near eyes and mucous membranes. Irritation can be avoided by applying emollients to unaffected skin.


Vitamin D Analogs


calcipotriene (Dovonex) Apply bid.

Burning and stinging, skin peeling, rash

Hypercalcemia, vitamin D toxicity

Do not use on face.


Vitamin A Derivatives


tazarotene (Tazorac) Once a day at bedtime

Pruritus, erythema


Avoid vitamin A.


Topical Corticosteroids


hydrocortisone (Cortisporin)

Burning, folliculitis, hypothalamic-pituitary-adrenal axis suppression

Primary bacterial infections or fungal infections

Use lowest effective dose.


Avoid prolonged use.


Use occlusive dressing.


Systemic Agents


apremilast (Otezla)

GI upset, diarrhea

Known hypersensitivity

Starter kit to minimize side effects.


cyclosporine (Cyclosporine A, Sandimmune)

Tremor, gingival hyperplasia, GI upset, hypertension, Trenal dysfunction, acne

Pregnancy and lactation; caution in impaired renal and hepatic function

Increased risk of digoxin toxicity.


Interacts with lovastatin, diltiazem, ketoconazole.


Decreased therapeutic effect with use of hydantoins, rifampin, sulfonamides.

Maximum dose 2-5 mg/kg/d


etretinate (Acitretin) 25-50 mg daily

Elevation in lipid levels, abnormal liver function, alopecia, rash, dry skin, pruritus

Alcohol use, pregnancy, and lactation

Perform pretreatment lipid and liver function tests.


Advise female patients not to become pregnant while taking this medication.


Take with meals.


methotrexate (MTX, Rheumatrex) 12.5-25 mg/kg/wk

Headache, blurred vision, fatigue, malaise, GI distress, gingivitis, hepatotoxicity, chills, bone marrow depression, rash alopecia, fever

Pregnancy and lactation; caution inpatients with renal and hepatic compromise, leukopenia

Drug decreases the level of digoxin.


Increased risk of toxicity with salicylates, phenytoin, sulfonamides.


Take folic acid 1 mg on nontreatment days.


Biologics


adalimumab (Humira) 80 mg subcutaneously initially then 40 mg every other week

Headache, nausea, rash, reaction at injection site

Concurrent live vaccine, active infection; caution in pregnancy

Used for psoriatic arthritis.


etanercept (Enbrel) 50 mg twice a week for 3 mo, then 50 mg weekly by subcutaneous injection

Infection, injection site pain, localized erythema, rash, upper respiratory infection, abdominal pain, vomiting

Concurrent live vaccine, active infection; caution in pregnancy, impaired renal function, asthma, blood dyscrasia, central nervous system demyelinating disease, history of recurrent infections

A maximum of 25 mg can be given in each site, requiring two injections.


It is given subcutaneously.


Not to be given with live vaccines.


infliximab (Remicade) IV 5 mg/kg

GI upset, headache, fatigue, cough, congestive heart failure


Nasopharyngitis, upper respiratory infection


Infection

Severe congestive heart failure


Infection


Malignancy, infection

Not to be given with live vaccines.

Secukinumab (Cosentyx) 150-300 mg


Ustekinumab (Stelara)




Emollients

Emollients are useful for all cases of psoriasis as an adjunct therapy. These agents hydrate the stratum corneum, decrease water evaporation, and soften the scales of the plaques. They are available in lotions, creams, and ointments. The thicker the preparation, the more effective it is. Commercially available agents include Eucerin cream/lotion, Lubriderm, and Moisturel. In addition to preserving moisture, emollients have a mild antipruritic effect. Newer products include CeraVe and Cetaphil.


Topical Corticosteroids

The foundation of topical treatment is topical corticosteroids. They play an important role in treating psoriasis by decreasing erythema, pruritus, and scaling. They promote vasoconstriction. They are fast acting but not intended for long-term use. Topical corticosteroids are classified into several categories based on potency and vasoconstrictive properties. Low-potency corticosteroids are safer for long-term use and for use at thin-skinned sites such as the face and groin. The most effective topical treatment is a medium- or high-potent agent used for a limited time, followed by a less potent agent for maintenance. Occlusion of the area where the topical steroid is applied is recommended. Saran wrap can be used, or Cordran tape is also effective. This method increases the absorption (hence the potency) of the topical preparation.

Topical corticosteroids may be used for longer periods on thicker skin because thicker skin does not absorb medication as well as thinner skin. Topical corticosteroids have a rapid onset of action. They decrease erythema, inflammation, and pruritus. For more information on topical corticosteroids, see Chapter 11.

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Nov 11, 2018 | Posted by in PHARMACY | Comments Off on Psoriasis

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