Vitamin D Analogues for Psoriasis

What is psoriasis?

Psoriasis is a common skin condition which commonly develops as patches ('plaques') of red, scaly skin. There is no 'once and for all' cure for psoriasis. Treatment aims to clear the rash as much as possible. However, as psoriasis tends to come and go, you may need courses of treatment on and off throughout your life. There are various treatments. There is no 'best buy' that suits everybody. The treatment advised by your doctor may depend on the severity, location and type of psoriasis. Also, one treatment may work well in one person, but not in another.

This leaflet is just about creams and ointments that contain drugs related to vitamin D (vitamin D analogues) that are used to treat psoriasis. Three vitamin D analogues are currently available in the UK - calcipotriol, calcitriol and tacalcitrol. There are separate leaflets on psoriasis in general, and on the other common topical treatments for psoriasis - dithranol, coal tar, steroid creams and tazarotene.

Some notes about the Vitamin D analogues

Vitamin D analogues are popular and often work well to clear plaque psoriasis. They are easy to use, are less messy, and have less of a smell than coal tar or dithranol creams and ointments which are also commonly used treatments. They seem to work by slowing the rate that skin cells divide. (The skin cells in patches of psoriasis divide faster than normal.)

Follow the instructions carefully that come with the brand you are prescribed. Also, persevere with the treatment as success often takes several weeks. The following are some general points that aim to complement - not to replace - the instructions that come with the preparation that you are prescribed.

Calcipotriol

Calcipotriol cream or ointment has become one of the most commonly used 'first-line' treatments for plaque psoriasis - the common form of psoriasis. There is also a scalp preparation of calcipotriol which is used to treat scalp psoriasis.

The cream or ointment is commonly applied once or twice daily. There is usually an improvement in the skin within two weeks, and improvement then usually continues for at least eight weeks. At this point, the psoriasis is cleared in some patients, but in others there is just an improvement which plateaus and the psoriasis does not clear completely. Any improvement can usually be maintained by continuing treatment.

Generally, calcipotriol is thought to be safe, provided that you follow the manufacturer's instructions. (There are some cautions mentioned below.) The instructions include that you should not exceed the maximum dose. This is 100g or cream or ointment per week for adults, 75g per week for children over 12, and 50g per week for children of 6-12. It is not recommended for children under six years old. If you are using a scalp preparation, the maximum use is 60ml of scalp lotion weekly.

But note - if you are using calcipotriol as a cream of ointment for your body, and a scalp lotion, the total dose needs to be balanced between the two. In this situation, the maximum amount of each is less than stated above. You should follow the instructions given by your doctor.

Wash your hands after applying to avoid inadvertent transfer to other body areas.

Calcipotriol may cause skin irritation which may cause redness, soreness or itch in around 1 in 5 users. Any skin irritation that does develop usually settles, but sometimes a break in treatment is needed. Occasionally, treatment needs to be stopped because of skin irritation. However, because of the risk of skin irritation, you should not use calcipotriol on the face and flexures (skin creases such as the front of elbows, behind knees, armpits, groins, etc).

There is little experience of using calcipotriol in pregnant women. Therefore, the manufacturer advises that you should not use calcipotriol when you are pregnant (which also means if you are trying for a baby). It is also probably best not to use it when breastfeeding. Also, people with calcium metabolism disorders should not use calcipotriol as there is a risk of causing a high blood level of calcium.

Rarely, psoriasis has been reported to get worse in a few people after using calcipotriol. There have also been isolated reports of more serious side-effects when a large quantity of calcipotriol was used by people with the more severe forms of psoriasis - erythrodermic and pustular psoriasis. Therefore, it should be used by people with the more severe forms of psoriasis - erythrodemic and pustular psoriasis - only under the close supervision of a specialist.

Calcitriol and tacalcitol

Calcitriol and tacalcitol ointments contain different vitamin D analogues to calcipotriol. An advantage of calcitriol and tacalcitol is that they are less irritant than calcipotriol. Therefore, one or other may be suitable for use on the face and flexures if advised by your doctor. You should not use more than 30g calcitriol ointment per day and it should not be applied to more than a third of your body surface each day. You should not use more than 10g tacalcitol ointment per day.

Calcitriol and tacalcitol have not been licensed in children and have not been adequately assessed for use during pregnancy. So, do not use when you are pregnant or trying for a baby. You should not use either if you are breastfeeding.

Combination treatments

A vitamin D analogue is sometimes used in combination with another treatment for psoriasis if either treatment alone is not sufficient. For example, an ointment that contains calcipotriol combined with a steroid may be prescribed when calcipotriol alone has not worked very well. However, it is not usually wise to use a steroid long-term. Therefore, one treatment strategy that is sometimes used is to use calcipotriol combined with a steroid for four weeks, alternating with calcipotriol alone for four weeks.

Another example is that some people continue to use a vitamin D analogue in addition to light therapy (UVB or PUVA) which is sometimes used to treat psoriasis.

Further sources of information

Psoriasis Association

Dick Coles House, 2 Queensbridge, Bedford Road, Northampton NN4 7BF
Tel (helpline): 0845 6 760 076
Web: www.psoriasis-association.org.uk