Treatment of Psoriasis

For mild to moderate psoriasis, start with moderate to high potency topical corticosteroids (classes 2-5) for a maximum of 4 weeks, combined with vitamin D analogs (calcipotriol) for synergistic effect. 1

Assess severity using two components: the patient's perception of disability (need for treatment) and objective assessment of body surface area involvement 2, 1
Diagnosis is clinical and does not require laboratory investigations 2, 1
Identify any triggering medications: avoid or discontinue lithium, chloroquine, and mepacrine (can cause severe, life-threatening deterioration); use caution with beta-blockers and NSAIDs 2, 3
Never use systemic corticosteroids as they precipitate severe flares upon discontinuation 1

Apply moderate to high potency corticosteroids (classes 2-5) such as clobetasol propionate 0.05% or betamethasone dipropionate 0.05% twice daily for 2-4 weeks maximum 1, 4
Combine with vitamin D analog (calcipotriol) for synergistic effect—more effective than either agent alone 1
Use fixed combination products (calcipotriol + corticosteroid) for convenience and improved adherence 1
Limit moderate potency preparations to maximum 100g per month 2, 1

Use low potency corticosteroids to avoid skin atrophy 1
Topical calcineurin inhibitors (tacrolimus 0.1%) are preferred for these sensitive areas as they don't cause atrophy 1, 5

Apply topical corticosteroids (classes 1-7) for at least 4 weeks in solution, foam, or shampoo formulations 1, 5
Clobetasol propionate 0.05% in alcoholic solution applied twice daily is highly effective for severe scalp psoriasis 6, 7

Coal tar (0.5-1.0% crude coal tar in petroleum jelly, increasing to maximum 10%) is extremely safe and particularly appropriate for elderly patients, though messier 2, 1, 3
Dithranol (anthralin) starting at 0.1-0.25% with doubling concentrations as tolerated—requires patient education about irritancy and staining 2, 3
Tazarotene (topical retinoid) combined with moderate to high potency corticosteroids reduces irritation while enhancing efficacy 1

After initial control, use weekend-only corticosteroid application while using vitamin D analogs on weekdays 1
Plan mandatory periods each year using alternative non-corticosteroid treatments to prevent tachyphylaxis 1, 3
Require regular clinical review every 4 weeks with no unsupervised repeat prescriptions 2, 1, 4
Very potent (grade I) or potent (grade II) preparations should only be used under dermatological supervision 2, 3

Body surface area involvement exceeds 5% 4, 3
Inadequate response to optimized topical therapy after 8 weeks 4
Generalized pustular or erythrodermic psoriasis 4, 3
Severe psoriatic arthropathy 2, 3
Extensive chronic plaque psoriasis in elderly or infirm patients is a specific indication even when topical treatments have not been exhausted 2, 3

For moderate to severe psoriasis (>5% body surface area):

Methotrexate is especially useful for extensive chronic plaque psoriasis with response time of 2 weeks 2, 3
- Maximum dose should not exceed 0.2 mg/kg body weight, especially in patients over 70 years 2, 3
- Require weekly monitoring initially (full blood count, liver function, renal function) then every 1-2 months once stable 2, 3
- Absolutely contraindicated during pregnancy and breastfeeding; avoid conception for at least one menstrual cycle after stopping 2, 4
- Avoid combining with alcohol, salicylates, NSAIDs, co-trimoxazole, trimethoprim, and other interacting drugs 2
Cyclosporine 3-5 mg/kg/day is preferred for short-term "interventional" courses (3-4 months) for unstable psoriasis, pustular psoriasis, or erythroderma 2, 3
- Monitor renal function and blood pressure carefully 2
Biologics (TNF blockers such as adalimumab) for moderate to severe chronic plaque psoriasis when candidates for systemic therapy 8
- Adalimumab: 80 mg initial dose, followed by 40 mg every other week starting one week after initial dose 8
- Screen for latent tuberculosis before starting; monitor for serious infections 8

Do not delay systemic therapy in extensive disease—topical treatments alone are insufficient for most patients with extensive chronic plaque psoriasis in elderly or infirm individuals 3
Perceived "tachyphylaxis" to topical corticosteroids is often due to poor adherence rather than receptor down-regulation 1
For unclear reasons, some patients who fail one topical agent will respond to another—try alternative topical agents before escalating 2, 1
Avoid abrupt corticosteroid withdrawal—taper frequency gradually after clinical improvement to prevent rebound flare 3
Patients requiring systemic agents should be under continuing supervision of a consultant dermatologist due to potential toxicity 2, 3