Management of Psoriasis

Psoriasis is a chronic, non-infectious, proliferative inflammatory skin condition affecting the epidermal and dermal layers of the skin. It is characterised by well-defined erythematous lesions bearing adherent silvery scales. Many patients also often concurrently suffer from psychological and social difficulties as a result and these also need to be addressed by the practitioner.² The disease process follows a fluctuating course of exacerbations and remissions but never completely clears. Therapy aims to decrease the degree of exacerbation and to induce remission.³ There is no definitive cure.

• Treatment is as much guided by the patient's perception of their condition as by the objective severity of it.
• Treatment options have to take into account the patient's ability to understand and follow through with treatment (as there can be issues relating to acceptability of certain treatments).
• Patient education is important: it is just as important for them to know how to apply their treatment as it is for them to be clear about the management steps decided in their particular case.
• Associated psychological problems need to be specifically addressed and if necessary, treated in their own right.
• Most patients with mild or moderate plaque psoriasis responding to topical treatment can safely be managed in the community.
• There are three main categories of treatment: local agents, phototherapy and systemic therapy. These may be used sequentially, in combination or in rotation.
• No active treatment is one of the treatment options.

Emollients

• Nature: these are hydrating agents, which may be aqueous or lipid based. They soothe dry, cracking skin and may also have an anti-proliferative effect.
• Examples: include aqueous cream and soft white paraffin.
• Use: suitable for all forms of psoriasis.
• Safety: no adverse reactions have been reported.
• Patient acceptability: these are highly acceptable.

Coal tar⁴

• Nature: crude coal tar and its distillates have been used for years and are thought to act via the inhibition of DNA synthesis.¹ It also has anti-scaling properties. It is often used in combination with other agents (such as with salicylic acid ointment, zinc and calamine).
• Examples: available as creams, solutions, shampoos, bath preparations with many commercial preparations being available.
• Use: ideal for chronic plaque psoriasis.
• Safety: there has been concern about the carcinogenicity of these products but current opinion suggests that the apparent increased risk in squamous cell carcinoma (amongst others) is due to a number of confounding factors.²
• Patient acceptability: these preparations tend to be smelly and messy and they stain clothes (particularly the crude extracts). Refined products are available but are less effective. Irritation, contact allergy and sterile folliculitis may occur.

Dithranol⁵

• Nature: this is an effective (remission in 85-95% of inpatients), extensively used and inexpensive therapy: it acts by inhibiting DNA synthesis and also through the formation of free radicals.⁶
• Use: chronic plaque psoriasis but it is not appropriate for the flexures and the face.
• Safety: in some patients, low concentrations can cause inflammation, which can lead to unstable psoriasis. Treatment should therefore start at low concentrations (0.1%) and be increased gradually every few days. Discontinue at first sign of inflammation.
• Patient acceptability: it has staining and irritant properties, particularly of normal peri-lesional skin: this can be reduced by application of protective pastes such as zinc paste. It is also tricky to apply (gloves and hand washing are needed to prevent irritation and staining) and therefore not suitable for widespread lesions. It tends to be applied in a hospital setting.

Vitamin D analogues^2,7

• Nature: these are regulators of keratinocyte proliferation and differentiation.
• Examples: include calcipotriol, calcitriol and tacalcitol.
• Use: stable plaque psoriasis. Latter two less irritant and better for face and flexures. Calcipotriol may be effectively used in combination with a moderate potency topical steroid for up to 4 weeks.
• Safety: hypercalcaemia may develop if large quantities are used: avoid in patients with calcium metabolism disorders.
• Patient acceptability: irritants - they can give rise to redness, soreness and pruritis in 20% of patients during a 6 week period of treatment. This can be limited somewhat by alternating treatment with a weak to moderate strength topical steroid. However, they are less irritant and messy than dithranol and free from the disagreeable odour of coal tar.

Topical retinoids⁸

• Nature:⁹ inhibit inflammation through specific retinoid receptor interactions and increase collagen production.
• Example: tazarotene is the standard drug.⁹
• Use: it is suitable for stable plaque psoriasis affecting up to 10% of the skin area.
• Safety: contra-indicated in women who are pregnant or intending to get pregnant. Patients should wash their hands after use and avoid getting it in contact with eyes, face, skin folds and hair-covered areas of the scalp.
• Patient acceptability: it is clean, odorless and only needs to be applied once daily but the treatment is long (12 weeks). Local irritation, pruritis and burning can occur as well as a non-specific rash, contact dermatitis and rebound worsening of the psoriasis (10-15% of patients).

Salicylic acid¹⁰

• Nature: this is a keratolytic - it softens keratin and helps loosen the dry, scaly skin.
• Examples: it is available in combination with coal tar (ointment), dithranol (paste) and zinc (paste).
• Use: it is largely used in combination preparations with other agents as it enhances their penetration.
• Safety: areas being treated with agents containing salicylic acid should be protected from alcohol-containing agents, abrasive soaps and cleaners and cosmetics. Excess use can lead to systemic absorption through the skin.
• Patient acceptability: can cause irritation if left too long and may cause skin reddening/flushing but otherwise usually well tolerated.

Topical corticosteroids¹¹

• Nature: anti-inflammatory agents used to relieve symptoms and suppress signs of the inflammatory condition. They do not bring about cure.
• Examples: these may be of mild, moderate or strong potency and include a range of drugs.
• Use:¹ practice varies somewhat but they particularly have a use in body areas where other topical treatments are not tolerated or have poor effect (e.g. face, hands and feet), for patients who cannot use vitamin D analogues or dithranol and finally, for more minor localised psoriasis. Topical steroids are not suitable as monotherapy for psoriasis.
• Safety: weaker steroids can enable spread or worsening of pre-existing skin infections, skin atrophy, contact dermatitis and mild depigmentation. Use of the more potent steroids can result in rebound relapse and development of generalised pustular psoriasis. Rarely, absorption of potent steroids through the skin can cause adrenal suppression and application around the orbital area can occasionally be associated with glaucoma. Steroid tolerance may occur too. Their prescription needs to be done in a specialist setting particularly in infants and small children because of the large surface area relative to mass.
• Patient acceptability: this will be limited by the side effects.

Coconut oil¹²

• Example: Cocois® is a scalp ointment combining coconut oil, coal tar solution, precipitated sulphur and salicylic acid.
• Use: it may be helpful in scalp psoriasis.
• Safety: not to be used in acute pustular psoriasis or in the presence of infected skin.
• Patient acceptability: may cause local irritation and dermatitis. Rarely, hypersensitivity reactions and photosensitisation can occur.

Essence of phototherapy

Most patients show some improvement in natural sunlight (UVA and UVB; UVC is absorbed in the ozone layer). Treatments are given in specialist settings: they tend to involve exposure several times a week over an interval of several weeks.¹

Natural sunlight¹³

This has a beneficial effect in some patients but they must be reminded of the usual precautions (length and time of day of exposure, head protection, keep self and skin hydrated etc.). They should also wear sunscreen lotions and apply this as non-sufferers would. Sun beds are not recommended as their use without specialist input is dangerous (and a number of them emit pure UVA which has no beneficial effect in the treatment of psoriasis).

UVB¹⁴

• Nature: intermediate wavelength ultraviolet light. May be broad band or narrow band - the latter is more effective and less likely to cause burns. Combination regimes with topical treatments are sometimes used owing to the synergistic effects which decrease the UVB exposure required. Goeckerman regimen (UVB coal tar) is very effective in mild psoriasis. Ingram regimen (UVB dithranol tar bath) is also commonly used.
• Use: chronic stable psoriasis, guttate psoriasis and moderately severe psoriasis where conventional treatment has failed.
• Safety: patients with previous skin malignancy, systemic lupus erythematosis and xeroderma pigmentosum are excluded from this treatment as there is a dose-related risk of increased skin cancer. However, unlike PUVA, can be used in children and pregnant women.
• Patient acceptability: this form of treatment may cause skin burn.

PUVA¹⁴

• Nature: this is photochemotherapy which combines UVA radiation with an oral or topical psoralen (which enhances radiation absorption). If monotherapy is inadequate, it may be combined with vitamin D analogues or retinoids.
• Use: unstable forms of psoriasis, localised palmoplantar pustular psoriasis and failed topical treatment.
• Safety: an accumulation of high dose treatments increases the risk of skin ageing, skin cancer and cataracts.
• Patient acceptability: pre-treatment, patients have to wear photoprotective glasses for 24 hours from the time of psoralen ingestion. There may be acute post-treatment effects including photosensitivity, pruritis, pain and nausea. Chronically, skin ageing and pigmentation may be seen.

Patients requiring these drugs will frequently have been through a series of unsuccessful treatment regimes or will have psoriasis severe enough to warrant specialist supervision at the outset.

Oral retinoids: acitretin¹⁵

• Nature: this derivative of etretinate is effective as monotherapy but treatment may need to be long term (benefit only after ~8 weeks, sometimes longer) as it simply suppresses inflammation. May be combined with PUVA to reduce UVA exposure.
• Use:¹ pustular psoriasis and used to thin down thick hyperkeratotic plaques.
• Safety: frequently causes drying/cracking of the lips and in 20-30% of patients, increased loss of scalp hair. There are numerous side-effects that occur infrequently (e.g. drying of oral mucosae, peeling or stickiness of the skin, itchiness etc.). It is strongly teratogenic (up until 2 years after end of use) and may cause abnormalities in blood liver and lipid profiles, both of which need to be monitored. There is a potential for bone toxicity (so not suitable for children).

Methotrexate¹⁶

• Nature: this immunosuppressant may be used for short or long term treatment. In the former, this may be to gain control over an acute episode before returning to the patient's usual treatment regime.
• Use: generalised pustular psoriasis, psoriatic erythroderma, psoriatic arthritis and poorly controlled extensive plaque psoriasis. It can be used as a short-term agent or, more commonly, for long-term treatment.
• Safety: this folic acid antagonist should be avoided in patients with haematological disorders, renal impairment (particularly in the elderly), liver disease / alcohol problems, lung disease and in fertile women until pregnancy can be excluded and adequate contraception ensured (it is causes abortions and is highly teratogenic). Potential fathers should also be warned that spermatogenicity is affected during treatment and for three months after. Concurrent medication needs to be reviewed as a number of drugs potentiate its effect, particularly NSAIDs. Methotrexate treatment needs to be suspended where dehydration occurs (e.g. diarrhoea in the elderly): patients need to be told about this. Ideally, alcohol should not be consumed at all whilst on methotrexate but some specialists allow up to 6 units a week. It should be avoided where there is active peptic ulceration, active infectious disease (e.g. tuberculosis or immunodeficiency states) and patient unreliability.

Ciclosporin¹⁷

• Nature: this is another immunosuppressant which acts by blocking lymphocyte proliferation and cytokine release.¹
• Use: severe psoriasis and used to thin down thick hyperkeratotic plaques.
• Safety: it may cause reversible renal failure and hypertension. Liver serology abnormalities can occur and this drug is avoided in patients previously infected with the hepatitis B and C viruses. Before a lesion is treated, there should be efforts to exclude malignancy (e.g. atypical looking lesion). It is not recommended in children under 16 years old. It can give rise to a number of less serious side-effects e.g. self-limiting nausea, hypertrichosis (may be problematic in dark-haired women) and gum hypertrophy.

Hydroxycarbamide¹⁸

• Use: this is a second line modality for the treatment of psoriasis, especially generalised pustular.
• Safety: the main risk is that of myelosuppression which may manifest itself as megaloblastic anaemia, thrombocytopenia or leukopenia. Consequently, patients should have their full blood count, including platelet count and differential white cell count, checked prior to commencing the drug and, at least, weekly intervals for at least the first six weeks. Subsequently, the intervals between haematological assessments may be gradually extended, provided there is no cause for concern (no more than three months).

Antimetabolites¹⁸

• Examples: these include mycophenolate mofetil, hydroxyurea and azathioprine.
• Use: psoriasis which is unresponsive to conventional treatment.
• Safety: these tend to affect bone marrow more than the liver.

Biological agents¹⁹

• Examples: etanercept, efalizumab and infliximab.²⁰
• Nature: so called because they are derived from endogenous proteins rather than through entirely artificial chemical manufacture. They act centrally and specifically within the immune system so limiting side-effects. They are expensive to use.
• Use: given the limited experience of these agents to date, there are strict guidelines that are followed but generally, use is limited to severe psoriasis (including plaque not responding to other therapy) and psoriatic arthritis.
• Safety: these are still being evaluated but so far, short-term side effects appear to be minor (such as GI upset and coryzal symptoms).

It is reasonable to try emollients in all cases but certain types of psoriasis (outlined below) are particularly responsive to them.

Stable plaque

• No active treatment: is acceptable in chronic low-grade conditions that the patient feels happy to live with.
• Topical therapy: vitamin D analogues, mild coal tar extracts, dithranol (chronic extensor plaques only) and topical retinoids.
• Phototherapy: UVB enhances effect of topical treatment; PUVA may also be used.
• Systemic treatment: this is rarely required.

Severe plaque / inflammatory

• Topical therapy: emollients. Use of topical vitamin D analogues, coal tar, dithranol and retinoids should be suspended in acute phase as the skin may show general irritancy to topical agents. Localised lesions can be treated with medium potency corticosteroids.
• Phototherapy: UVB where topical treatment has failed or PUVA.
• Systemic treatment: decision to move to systemic therapy is a dermatologist decision.

Guttate

• Topical therapy: this form of psoriasis is generally less tolerant of topical therapy but it is reasonable to start by trying calcipotriol, mild / moderate potency steroids or low concentration tar and dithranol.
• Phototherapy: both UVB and PUVA are suitable.
• Systemic treatment: a number of these patients may have recently had streptococcal infection (confirmed by throat swab serum antistreptolysin O titre) - repeated attacks of guttate psoriasis after confirmed repeated episodes of tonsillitis warrant consideration for tonsillectomy. Dermatologist decision as to whether to treat the psoriasis alone with systemic treatment.

Scalp

• Topical therapy: softening of thick plaques with coconut / olive / arachis oil (ideally applied under a shower cap / cling film) and tar-based shampoo are recommended in the first instance. Emollient cream (which, combined with salicylic acid is keratolytic) or more potent topical corticosteroids can be used and salicylic acid (combined with coal tar extract, sulphur and coconut oil) can be helpful.
• Phototherapy: PUVA is appropriate.
• Systemic treatment: this remains a dermatologist decision.

Facial

• Topical therapy: mild coal tar extracts, mild corticosteroids and vitamin D analogues (with caution) are all suitable agents.
• Phototherapy and systemic treatment: decision to use these is made within a dermatologist clinic.

Flexural

• Topical therapy: mild coal tar extracts, mild corticosteroids and vitamin D analogues (with caution) can be used.
• Phototherapy and systemic treatment: decision to use these is made within a dermatologist clinic.

Palmoplantar

• Topical therapy: emollients, more potent corticosteroids, calcipotriol may help. There may be a possible benefit from coal tar and dithranol.
• Phototherapy: PUVA is appropriate.
• Systemic treatment: this is a dermatologist decision and usually involves acitretin (alone or with PUVA). Disabling disease may be treated with methotrexate.

Acute erythrodermic

These patients need to be admitted to hospital for systemic treatment.

Psoriasis has a knock-on effect in most aspects of the patient's life from their own personal self-image to the social consequences of the disease (jobs, relationships, social life). There is a high rate of anxiety, stress, depression and even suicidal ideation amongst this patient population and these issues need to be addressed explicitly. It is helpful, in addition to any specific psychological or drug treatment required, to offer information relating to support groups as often, it is here that patients will find the solace and support in managing their distressing condition.

The Psoriasis Association A patient-centred but very comprehensive website. The Psoriasis Association, Milton House, 7 Milton Street, Northampton NN2 7JG (T: 0845 676 0076)

The UK Psoriasis Help Forum Internet based patient support group.

Dermatology Meddaid Limited (parent company), Jubilee House, Old Lane, Beeston, Leeds LS11 8BT (T: 0113 277 5556) This organisation provides information on a variety of skin problems (direct link to psoriasis provided) for both sufferers and healthcare professionals.