What is psoriasis?
Psoriasis is a non-allergic, chronic skin condition that has a genetic predisposition and can affect anyone at any age. It is characterised by red scaly patches of skin ranging from mild, with a few patches usually at the backs of the knees and elbows, and minimal discomfort, to severe with psoriatic lesions covering large areas of the body and causing extreme itching, pain and discomfort. Psoriasis is thought to be an automimmune disease, where certain cells of the immune system (T lymphocytes) are triggered to overproduce inflammatory chemicals, particularly TNF alpha, a cytokine that stimulates excessive growth and proliferation of keratinocytes (epidermal skin cells), causing thickening and scaling of the skin as well as inflammation.
Treatment for psoriasis
Calcipotriol is a derivative of calcitriol or Vitamin D (also known as 1,25 dihydroxycholecalciferol or 1,25(OH)2D3). Vitamin D is primarily involved regulating calcium metabolism but has other actions including inhibition of cell proliferation, stimulation of cell differentiation and immunomodulation. Calcipotriol binds to the same receptor in skin cells as Vitamin D and has the same activity in regulating cell growth and differentiation but is less effective in terms of calcium metabolism. Calcipotriol is used as a topical treatment for psoriasis and helps to prevent over production of hardened keratinocytes and restores normal cell growth and behaviour to the epidermal skin cells.
Tazarotene is a retinoid pro-drug of Vitamin A that affects skin cell behaviour and helps reverse abnormal changes in keratinocyte behaviour; it also has anti-inflammatory properties.
Both medications reduce the inflammation, scaling and thickening of psoriatic plaques and relieve symptoms of psoriasis.