Psoriasis is a chronic, inflammatory papulosquamous disease clinically characterized by erythematous, sharply demarcated, indurated papules and rounded plaques covered by silvery, micaceous scales [1]. Recently there is increase in a number of population-based studies providing a global prevalence estimate of psoriasis. It has been found that the prevalence of psoriasis varies considerably in different parts of the world. Psoriasis affects approximately 3.5% of the world population [2]. Psoriasis vulgaris is identified as the most prevalent autoimmune disease which is caused by an inappropriate activation of the cellular immune system. The genetic basis of psoriasis has been known since many decades. The incidence of psoriasis in siblings has been found to be as high as 68% [3].

Psoriasis is characterized by hyperproliferation and abnormal differentiation of epidermal keratinocytes, infiltration of mostly T lymphocytes and various endothelial vascular changes in the dermal layer, such as angiogenesis, dilatation and high endothelial venule (HEV) formation [4]. The exact role of T-cells in the pathogenesis and development of lesions can be explained in 3 events that are initial activation of T lymphocytes, the migration of T lymphocytes into the skin, and the various roles played by cytokines released from T lymphocytes and other cells [5]. The typical psoriatic plaque is characterized by well demarcated, elevated, erythematous plaque with dry, loosely adherent silvery-white scales which preferentially involves extensors of the body. The various clinical variants of psoriasis are chronic plaque psoriasis, guttate psoriasis, exfoliative psoriasis, pustular psoriasis, psoriasis unguis and regional variants.

Topical therapies remain the mainstay of treatment for mild psoriasis and in combination with other modalities for patients with moderate to severe psoriasis. The main groups of topical therapies for psoriasis are emollients, keratolytics, corticosteroids, coal tars, dithranol (anthralin), vitamin D3 analogues (Calcipotriol), tazarotene, tacrolimus and pimecrolimus. Calcipotriol (calcipotriene) is already established to be effective topically in the treatment of psoriasis [6]. It has a high binding affinity to the vitamin D receptor (VDR) for the biologically active form of vitamin D3 (1,25-dihydroxy vitamin D3). VDR have been demonstrated in epidermal keratinocytes, melanocytes, dermal fibroblasts and many other cell types [7]. Calcipotriol reduces epidermal cell proliferation and enhances differentiation in the skin lesion by binding to the VDR located in the nucleus of keratinocytes which is found to be increased in number in psoriatic skin. Its advantage over corticosteroids is that it does not cause atrophy, so can be used for longer period. Recently calcipotriol, a synthetic vitamin D3 analogue, has become one of the most widely used treatments for psoriasis. To assess the effectiveness of calcipotriol compared with the more traditional topical treatments for psoriasis we under­took a study to compare 0.005% calcipotriol and 0.1% mometasone furoate ointment.

The study was conducted as double blind, randomized comparative trial on 70 patients of psoriasis attending the outpatient department of dermatology at a tertiary care hospital.

In our study maximum patients were presented in group A between 31 – 40 years (28.5%) and in group B between 21 – 30 years (25.7%) with mean age of presentation being 36.1 years in group A and 37.2 years in group B (Tabl 1). The overall male to female sex ratio was found to be 9:1. Disease exacerbation due to seasonal variation was observed by 26 patients (37.14%) and 4 patients (5.71%) in winter and summer respectively. In group A patients the mean PASI at baseline was 5.54 and it was reduced after 1^st, 2^nd, 4^th and 6^th by 19.4%, 36.9%, 50.5% and 73.1% respectively (Tabl. 2) and in group B patients the mean PASI at baseline was 5.13 and it was reduced after 1^st, 2^nd, 4^th and 6^th by 8.5%, 12.3%, 52.8% and 78.6% respectively (Tabl 3). The reduction of mean PASI score on each follow up in both the group were found to be statistically significant as compare to baseline PASI score.

After comparing both the groups the difference in mean PASI score was observed to be 4.05 in group A and 4.03 in group B on 6^th follow up. From the above data we observed that there was no statistically significant difference between the reductions in PASI score of both the groups (Tabl 4). More than 75% reduction in PASI score is shown by 54.3 % and 68.6 % of patients in group A and group B respectively (Tabl 5). Adverse effect in the form of irritation and burning were experienced by 2 patients using calcipotriol.

Psoriasis is a common, chronic and relapsing inflammatory skin disease. Topical treatment is the mainstay of management for mild to moderate psoriasis and often the initial treatment for severe psoriasis. Despite the availability of several treatments, psoriasis is usually difficult to treat because of its sporadic course, variable response to treatments and adverse effects. Approximately 80% of the patients having psoriasis are treated by the topical therapy [10]. Topical corticosteroids and vitamin D3 analogue are the treatment of choice for mild to moderate psoriasis [11]. Bruce S et al and Queille-Roussel et al found that topical calcipotriol was effective in patients of psoriasis [12,13].

Topical corticosteroids are the oldest, effective and most commonly used treatment modality for mild to moderate psoriasis. Apart from its good effectiveness, topical corticosteroid failed to maintain the effect and showed decreased response, tolerance and tachyphylaxis [14]. They are also known to cause local adverse effects such as striae, hypopigmentation, atrophy, telangiectasis and contact dermatitis. According to the studies conducted by Gulam Kazem Ali Ahmad et al, a medium potent (class 4 and 5, American system classification) topical corticosteroid has been found to be effective in treatment of psoriasis [15]. Our study is consistent with the above studies in showing the effectiveness of mometasone furoate 0.1% (class 4 and 5, American system classification) ointment in treatment of psoriasis.

In our study both the topical agents were found to be effective in clearance of psoriatic lesions, but on comparing the effectiveness of calcipotriol with mometasone furoate ointment, we found at the last follow up of 6^th week that there was no significant difference between the effectiveness of the two drugs (P > 0.05). Our study is consistent with a comparative study by Gulam Kazem Ali Ahmad et al which revealed that calcipotriol ointment was as effective as medium potent corticosteroid (class 4 and 5, American system classification) ointment [15].

Therefore the result of our study showed, topical calcipotriol can be used in treatment of mild to moderate psoriasis involving less than 20% of the body surface area as an alternative to topical corticosteroid, as it is equally effective and safe.

The calcipotriol and mometasone furoate were equally effective in clearance of the disease, Therefore from the current study we conclude that 0.005% calcipotriol ointment can be used in the treatment of psoriasis involving less than 20% of the body surface area as a replacement of the very commonly used topical corticosteroid ointment which are known to be associated with tolerance and many adverse effects.