Almost all people with psoriasis can have their skin completely cleared as a hospital in-patient over an average period of three weeks. Clearing the skin may result in a long period of remission. Some people may stay clear for years, yet others may relapse immediately and it is impossible to predict which patient is likely to do which. People with extensive psoriasis and some with severe scalp psoriasis alone, who cannot manage their treatment at home, may benefit from a short stay to get the scalp under control.

There are two standard in-patient regimens employing either dithranol or tar as the active treatment.
They consist of:
• Tar bath – 10-15 minutes and UVB therapy – dosage according to skin type and increasing according to response
• Ingram's regimen – dithranol in Lassar's paste applied carefully to each plaque, sprinkled with talcum powder, then dressed with a gauze suit. This is removed in the bath the following morning. The concentration of dithranol is increased according to the response. When the psoriasis is better the skin will be temporarily stained brown.
or
• Goeckerman regimen – crude coal tar in increasing strengths, applied instead of dithranol.

Ultraviolet therapy
Ultraviolet therapy is a rapid and effective agent for clearing psoriasis. It may be used alone, eg. in widespread thin plaque psoriasis or, more commonly, in conjunction with in or out-patient topical therapy.

Narrow band UVB is the current wavelength of choice. However, it may be inconvenient for the patient to attend a hospital two to three times a week for therapy or impractical if they live far away.

PUVA therapy involves exposure to psoralen, a photosensitiser, either in the form of a tablet or topical preparation and then exposure to increasing doses of UVA, until the psoriasis is cleared or is at an acceptable level to the individual.

The amount of UV exposure should be monitored, in view of the long-term risk of skin cancer. This risk is particularly well established for PUVA therapy, where the number of lifetime treatments should not exceed 200. Thus it is important not to 'use up' all of your UV exposures treating mild, limited disease which may respond to other therapies.

Systemic treatment for psoriasis
For people with very extensive or unresponsive psoriasis, systemic (taken into your system as tablets) therapy may be the treatment of choice. This is usually given to those with psoriasis in hospital out-patient departments. Unfortunately all of the systemic agents have side effects which can be serious. They must all be carefully monitored with blood tests; thus the need for hospital visits.
They include:
• Methotrexate.
• Acitretin.
• Cyclosporin.
• Hydroxyurea.

Methotrexate
Methotrexate inhibits cell division. It is extremely effective and an improvement is usually seen within 4-8 weeks. People taking this drug, which is only administered once a week, should avoid alcohol completely as there is a risk of developing liver damage.

The main drawback of therapy is that serious liver damage can occur unbeknownst to the patient and doctor (ie. the blood tests may stay normal until it is too late). Therefore, unless the person is older or there are other contraindications, once it has been established that this drug is effective and well tolerated by a particular person, they will need to have a liver test known as a biopsy. This will be repeated after every 1.5g has been taken, which is approximately every two years.

The drug is usually well tolerated, with the most frequent side effects being nausea, tiredness, mouth soreness, hair loss and, more seriously, a drop in the blood count. Frequent blood tests are necessary. In both sexes conception should be avoided for six months after methotrexate is stopped. No other drugs should be taken at the same time without first checking with your doctor or pharmacist.

Acitretin
Acitretin is another drug which inhibits cell division. It is not as good as methotrexate and is slower to work but is not as toxic either. It cannot be given to women of childbearing age since they must avoid conception for two years after stopping it because of its teratogenic (harmful to the developing foetus) effects.

Side effects include:
• Dry, chapped lips.
• Dry nasal mucosa.
• Increased scaling of the psoriasis.
• Peeling of palms and soles.
• Increased sweating.
• Stickiness of the skin.
• Poor wound healing.
• Hair loss.
• Inflammation of the nail beds.
• Occasionally gastrointestinal (stomach) upset.

However, some people do very well with this, particularly with severe psoriasis of the hands and feet.

Cyclosporin
Cyclosporin is an effective treatment for psoriasis but is very expensive and has many side effects. It is an immunosuppressive drug and acts on the immune system rather than on the skin directly.

The main side effect is the toxic effect on the kidneys and people who are likely to be on this drug long-term should also be monitored by a kidney specialist (nephrologist).
It can cause:
• High blood pressure.
• Nausea.
• Vomiting.
• Swollen gums.
• Headaches.
• Tremor.
• Excessive hair growth.

On a positive note, it is extremely effective and works quickly, an effect being visible in as little as 10-14 days. Regular blood and urine tests, and blood pressure monitoring need to be carried out.

Hydroxyurea
Hydroxyurea is not commonly used but may be tried when all else fails. It may suppress the bone marrow and result in a drop of the blood count so blood tests must be carefully monitored.

Written by Rosemary Coleman, MD FRCPI, Consultant Dermatologist

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