Topical Therapies for Psoriasis

Psoriasis is a chronic and recurring inflammatory condition of the skin that affects approximately 2% of the western population (Nestle et al., 2009). The most common form is plaque type psoriasis, the treatment of which is the focus of this chapter. Patients with psoriasis often present with scaly, painful and disfiguring skin lesions (Nestle et al., 2009). Although, it is seldom life-threatening, psoriasis is associated with a high degree of morbidity patients are embarrassed about the appearance of their skin. There are significant psychosocial issues affecting these patients, often they experience social isolation, stigmatization, alcoholism and depression. In addition, patients with psoriasis, like those with other major medical disorders, have reduced levels of employment and income as well as a decreased quality of life (Horn et al., 2007). The combined costs of long-term therapy and social costs of the disease have a major impact on healthcare systems and on society in general. There are several co-morbidities that have been linked to psoriasis and it has been hypothesized that psoriasis as a disease has important systemic manifestations (Nestle et al., 2009). The shared conditions include the metabolic syndrome, depression, and cancer. Psoriasis can also occur in association with inflammatory bowel disease (Wolf et al., 2008), diabetes mellitus (Wolf et al., 2008) and HIV infection (Maurer, 2005). Although cases have been reported, it is unclear whether cancer particularly lymphoma and skin cancer, is related to psoriasis or the long term consequences of its treatment (Gelfand et al., 2006a). The relationship between psoriasis and the risk of cardiovascular disease is of emerging significance (Gelfand et al., 2006b). While patients with mild psoriasis appears to be in no excess risk, the moderate and severe form of the disease is associated with an increase in frequency of myocardial infarction and an increase in mortality, in large part because of cardiovascular events (Gelfand et al., 2006b). If confirmed, these findings would have major implications for future preventive and therapeutic strategies. Further, it is estimated that a significant population of juvenile guttate psoriasis cases are preceded by streptococcal infections (Campalani & Barker, 2005).