Vitamin D analogues

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Vitamin D analogues, such as calcipotriol, calcitriol and tacalcitol, should not be confused with the vitamin supplements that you may take; they’ve been modified to have a completely different effect.

They slow down the overproduction of skin cells and stimulate differentiation of keratinocytes, a type of cell in the upper layer of the skin correcting the abnormally fast cell turnover that characterises psoriasis. Unlike naturally occurring vitamin D, they have less effect on calcium metabolism (the mechanism which regulates the calcium levels in the body), so the risks of high levels of calcium in the blood (hypercalcaemia) or in the urine (hypercalciuria) are reduced. Nevertheless there are limits to how much can be used at any one time (100g per week) to limit the possibility of these side effects happening.

The ease of use and low side effect levels have made these agents popular with medical professionals and people with psoriasis.

One of these agents has been combined with a topical potent corticosteroid to help reduce skin inflammation as well. These products have a time limitation of use of four weeks before stopping and another four weeks before starting again. This allows the skin to recover. The preparation comes in an ointment or a less greasy gel and can be used on body and scalp.