What is psoriasis?

Psoriasis is a common condition where there is inflammation of the skin. It typically develops as patches (plaques) of red, scaly skin. Once you develop psoriasis it tends to come and go throughout life. A flare-up can occur at any time. The frequency of flare-ups varies. There may be times when psoriasis clears for long spells. However, in some people the flare-ups occur often. Also, the severity of psoriasis varies greatly. In some people it is mild with a few small patches that develop and which are barely noticeable. In others, there are many patches of varying size. In many people the severity is somewhere between these two extremes.

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 treatment 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.

What are vitamin D analogues?

Vitamin D analogues are creams, ointments and lotions that contain medicines related to vitamin D. They are used to treat psoriasis. Three vitamin D analogues are currently available in the UK - calcipotriol, calcitriol and tacalcitol.

Vitamin D analogues are popular and often work well to clear chronic 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 other commonly used treatments. They seem to work by slowing the rate at which skin cells divide. (The skin cells in patches of psoriasis divide faster than normal.)

This leaflet is just about vitamin D analogues used to treat psoriasis. The following are some general points that aim to complement (not to replace) the instructions that come with the preparation that you are prescribed. You should follow the instructions carefully, which come with the brand that you are prescribed. Also, persevere with the treatment, as success often takes several weeks.

Note: see separate leaflet called 'Psoriasis', which discusses psoriasis in general. See also other separate leaflets called 'Dithranol & Psoriasis - Short Contact' and 'Coal Tar for Psoriasis', which discuss some other common treatments for psoriasis.

Calcipotriol

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

There is usually an improvement in the skin within two weeks after the start of treatment with calcipotriol. The improvement then usually continues for at least eight weeks. At this point, the psoriasis is cleared in some people. However, 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.

How do you use calcipotriol?

The cream or ointment is commonly applied once- or twice-daily. Generally, calcipotriol is thought to be safe, provided that you follow the manufacturer's instructions. The instructions include that you should not exceed the maximum dose. This is:

• 100 g of cream or ointment per week for adults.
• 75 g per week for children aged over 12 years.
• 50 g per week for children aged between 6 and 12 years.
• For a scalp preparation, no more than 60 ml of scalp lotion weekly.

But note: if you are using calcipotriol as a cream or ointment for your body and you are using a scalp lotion that contains calcipotriol, you need to consider both of these. In this situation, the maximum amount of each is less than stated above. You should follow the instructions given by your doctor.

If you are also using an emollient (a moisturiser) for your skin, you should make sure that you use this first. Then, wait for 30 minutes before you apply calcipotriol or one of the other vitamin D analogues.

You should wash your hands after applying calcipotriol. This prevents you from inadvertently transferring the cream or ointment to other areas of your body.

Are there any problems with calcipotriol?

Calcipotriol may cause skin irritation which can lead to 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. Because of the risk of skin irritation, you should not use calcipotriol on your face and flexures (skin creases, such as the front of elbows, behind knees, armpits, groins, etc).

Is there anyone who should not use calcipotriol?

Calcipotriol is not recommended for children under six years old.

There is little experience of using calcipotriol in pregnant women. Therefore, the manufacturer advises that you should avoid using calcipotriol when you are pregnant (which also means if you are trying for a baby) if possible. It is also probably best not to use it when breast-feeding.

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 only be used by people with the more severe forms of psoriasis - erythrodermic and pustular psoriasis - under the close supervision of a specialist.

Also, people with calcium metabolism disorders should not use calcipotriol, as there is a risk of causing a high blood level of calcium.

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 30 g of 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 10 g of tacalcitol ointment per day.

Calcitriol and tacalcitol have not been licensed in children. Also, they have not been adequately assessed for use during pregnancy. The manufacturer advises avoiding them during pregnancy unless there is no safer alternative. This also includes if you are trying for a baby. You should not use either of these treatments if you are breast-feeding.

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 on a long-term basis. Therefore, one treatment strategy that is sometimes used is to use calcipotriol combined with a steroid for four weeks and then use calcipotriol alone for four weeks. The combination treatment may then be started again after this.

Another example is that some people continue to use a vitamin D analogue in addition to light therapy - ultraviolet B (UVB) or psoralen with ultraviolet A (PUVA), sometimes used to treat psoriasis.

Acitretin

Acitretin is a vitamin D analogue that is taken by mouth. It is indicated for severe extensive psoriasis resistant to other forms of therapy. Acitretin is only moderately effective in many cases and it is therefore usually combined with other treatments. Women taking acitretin should avoid pregnancy and use effective contraception for at least one month before, during, and for at least three years after treatment.

Further sources of information

Psoriasis Association

Dick Coles House, 2 Queensbridge, Northampton, NN4 7BF
Tel (helpline): 0845 676 0076
Web: www.psoriasis-association.org.uk
Founded in 1968, the Association has three fundamental aims: to support those who have psoriasis; to raise awareness about psoriasis; to fund research into the causes of and treatments for psoriasis.

PAPAA - The Psoriasis and Psoriatic Arthritis Alliance

PO Box 111, St Albans, Hertfordshire, AL2 3JQ
Tel: 01923 672837
Web: www.papaa.org
Provides support and information for people with psoriasis and psoriatic arthritis.

References

• Psoriasis, Prodigy (May 2010)
• Diagnosis and management of psoriasis and psoriatic arthritis in adults, Scottish Intercollegiate Guidelines Network - SIGN (October 2010)
• Psoriasis - General Management, British Association of Dermatologists (BAD), 2008
• Lui H et al, Plaque Psoriasis, Medscape, Mar 2011
• British National Formulary
• Guidelines on the efficacy and use of acitretin in dermatology, British Association of Dermatologists (2010)