What is the treatment for plaque psoriasis?

Treatment of Plaque Psoriasis

Initial Treatment Approach

For mild plaque psoriasis (<5% body surface area), start with topical corticosteroids of class 2-5 (moderate to high potency) combined with vitamin D analogs (calcipotriene) for up to 4 weeks. 1, 2 This combination provides synergistic effects and is more effective than either agent alone. 2

Topical Therapy Algorithm

First-Line Topical Treatment:

• For thick plaques on trunk/extremities: Use class 1 (ultrahigh-potency) corticosteroids like clobetasol or halobetasol propionate for up to 4 weeks 1
• For moderate plaques: Apply class 2-5 corticosteroids (e.g., triamcinolone 0.1%) combined with calcipotriene 1, 2
• For face and intertriginous areas: Use low-potency corticosteroids or topical calcineurin inhibitors (tacrolimus 0.1%) to avoid skin atrophy 1, 2
• For scalp: Apply class 1-7 topical corticosteroids for at least 4 weeks 1

Combination Strategies:

• Apply calcipotriene/betamethasone dipropionate fixed combination products to simplify regimen and improve adherence 2, 3
• For maintenance after initial control, use weekend-only corticosteroid application while applying vitamin D analogs on weekdays 2
• Tazarotene (topical retinoid) can be combined with moderate-to-high potency corticosteroids to reduce irritation while enhancing efficacy 1, 2

Critical Precautions:

• Do not exceed 4 weeks of continuous high-potency corticosteroid use without physician supervision 1
• Use beyond 12 weeks requires careful monitoring for skin atrophy, striae, and telangiectasia 1, 4
• Avoid applying more than 100g of moderate-potency corticosteroid per month 2, 3
• Never use systemic corticosteroids as they can precipitate severe flares upon withdrawal 2, 3

Moderate-to-Severe Psoriasis (≥5% BSA)

For moderate-to-severe plaque psoriasis, escalate to phototherapy (narrowband UVB or PUVA) before considering conventional systemic agents. 1, 3 Phototherapy should be offered before oral systemic therapy for chronic plaque psoriasis that has not responded adequately to topical treatments. 1

Phototherapy Options:

• Narrowband UVB: First-line phototherapy option 1, 3
• PUVA (psoralen plus UVA): Consider if narrowband UVB fails or for especially thick/extensive plaques 1
• 308-nm excimer laser: For localized resistant areas 3

Conventional Systemic Agents (Third-Line):

When phototherapy is insufficient, contraindicated, or unavailable, use conventional systemic agents: 1

• Methotrexate: 15-25 mg weekly (oral, subcutaneous, or intramuscular) 1, 5
• Cyclosporine: 2.5-5 mg/kg daily 1, 5
• Acitretin: 25-50 mg daily 1, 5
• Fumaric acid esters 5, 6

Important: These agents require at least 3 months at therapeutic doses to determine adequate response (defined as <50% improvement in PASI or <5-point improvement in quality of life measures). 1

Biologic Therapy (Fourth-Line)

For patients who fail conventional systemic therapy or have contraindications, biologic agents targeting specific immune pathways are highly effective. 1

Biologic Agent Hierarchy (Based on PASI 90 Achievement):

Most Effective (First Choice Biologics):

1. Ixekizumab (anti-IL17): Most effective biologic with 32-fold improvement over placebo in achieving PASI 90 6
2. Secukinumab (anti-IL17): 26-fold improvement over placebo 6
3. Brodalumab (anti-IL17): 25-fold improvement over placebo 6
4. Guselkumab (anti-IL23): 21-fold improvement over placebo 6
5. Ustekinumab (anti-IL12/23): 19-fold improvement over placebo 6

Anti-TNF Alpha Agents (Alternative Biologics):

• Infliximab: 5 mg/kg at weeks 0,2, and 6; 87% achieve PASI 75 by week 10 1
• Adalimumab 1
• Etanercept: 50 mg subcutaneous twice weekly for 12 weeks, then 50 mg once weekly maintenance; 47% achieve PASI 75 at 3 months with 50 mg twice weekly 1, 7
• Certolizumab 6

Etanercept Specific Dosing (FDA-Approved):

• Induction: 50 mg subcutaneous twice weekly for 12 consecutive weeks 1, 7
• Maintenance: 50 mg once weekly (though 50 mg twice weekly may be required for better disease control in some patients) 1, 7
• Efficacy: 47% achieve PASI 75 at 3 months; median time to PASI 75 is approximately 2 months 7

Biologic Combination Therapy:

Biologics can be combined with topical agents to augment efficacy: 1

• Etanercept + high-potency corticosteroids with or without vitamin D analogs (Strength A recommendation) 1
• Etanercept + methotrexate (Strength B recommendation) 1
• Etanercept + acitretin (Strength B recommendation) 1
• Etanercept + narrowband UVB (Strength B recommendation) 1

Special Situations

Scalp Psoriasis:

• Etanercept is recommended as monotherapy for moderate-to-severe scalp involvement 1
• Topical options include calcipotriene foam or calcipotriene/betamethasone gel for 4-12 weeks 3

Nail Psoriasis:

• Etanercept is recommended as monotherapy 1
• Intralesional triamcinolone acetonide up to 20 mg/mL every 3-4 weeks for localized lesions 1

Palmoplantar Psoriasis:

• When intensive topical therapy fails, use methotrexate, cyclosporine, or oral retinoids 1
• Soak PUVA (15-30 minutes in methoxsalen solution) is effective 1
• Quality of life impact justifies systemic therapy despite small body surface area involved 1

Psoriatic Arthritis:

• Etanercept is recommended for plaque psoriasis of any severity when associated with significant psoriatic arthritis 1

Pustular or Erythrodermic Psoriasis:

• Etanercept can be used (Strength B recommendation) 1
• Infliximab shows efficacy in severe unstable psoriasis and generalized pustular psoriasis 1

Safety Considerations

Methotrexate has the best safety profile among systemic agents regarding serious adverse events, though evidence certainty is moderate. 6 However, all interventions showed no significant difference from placebo in short-term trials (12-16 weeks), likely due to low event numbers and inadequate follow-up duration. 6

Common pitfalls to avoid:

• Abrupt withdrawal of topical corticosteroids can cause rebound flares 1
• Long-term potent corticosteroid use on face, forearms, and intertriginous areas causes atrophy and telangiectasia 1, 4
• Drugs that worsen psoriasis include alcohol, beta-blockers, NSAIDs, lithium, chloroquine, and mepacrine 2, 3
• Do not apply salicylic acid simultaneously with calcipotriene as acidic pH inactivates calcipotriene 2

Treatment Selection Based on Efficacy-Safety Trade-off

Ustekinumab, infliximab, and certolizumab appear to have the best balance between high efficacy (PASI 90 achievement) and acceptable safety profiles. 6 While anti-IL17 agents (ixekizumab, secukinumab, brodalumab) show superior efficacy, they have slightly higher serious adverse event rates compared to anti-IL12/23 agents. 6