What are the treatment options and doses for psoriasis?

Psoriasis Treatment Options and Dosing Guidelines

The treatment of psoriasis should follow a stepwise approach based on disease severity, with topical therapies for mild disease, phototherapy for moderate disease, and systemic or biologic agents for severe or refractory disease. 1

Disease Classification and Assessment

• Psoriasis severity is categorized as mild (less than 3% body surface area), moderate (3-10% BSA), or severe (greater than 10% BSA), with consideration of location and impact on quality of life 2
• Assessment should include both objective measures (PASI score, BSA) and subjective measures (DLQI) to determine appropriate treatment strategy 1

Treatment Algorithm for Mild Psoriasis

First-Line: Topical Therapies

• Topical corticosteroids: Class 1-7 based on potency

  • Class 1 (ultrahigh-potency): Clobetasol propionate, halobetasol propionate - use for up to 4 weeks 2
  • Class 2-5 (high to medium potency): Use for up to 4 weeks on plaque psoriasis not involving intertriginous areas 2
  • For scalp psoriasis: Any class (1-7) for minimum of 4 weeks for initial and maintenance treatment 2

• Vitamin D analogs: Calcipotriene - can be used alone or in combination with corticosteroids 2

• Topical calcineurin inhibitors: Tacrolimus and pimecrolimus - particularly useful for facial and intertriginous areas 2

Treatment Algorithm for Moderate-to-Severe Psoriasis

First-Line: Phototherapy

• PUVA (Psoralens + UVA): Starting dose 70% of minimum phototoxic dose, increase by 40% if no erythema 2
• Narrowband UVB: Generally considered the phototherapy of first choice with fewer side effects than PUVA 1

Second-Line: Traditional Systemic Agents

• Methotrexate: Initial dose 15 mg weekly, maximum 25-30 mg weekly; response time approximately 2 weeks 2
• Cyclosporine: Dose 2.5-5 mg/kg daily; response time approximately 3 weeks 2
• Acitretin: Dose 25-50 mg daily; response time approximately 6 weeks; particularly effective for pustular psoriasis 2, 3

Third-Line: Biologic Agents

TNF-α Inhibitors

• Etanercept:

  • Starting dose: 50 mg twice weekly for 12 weeks
  • Maintenance: 50 mg weekly (some patients may require 50 mg twice weekly) 2

• Infliximab:

  • Dose: 5 mg/kg at weeks 0,2, and 6, then every 8 weeks
  • Can be administered more frequently (every 4 weeks) or at higher dose (up to 10 mg/kg) for better disease control 2

IL-12/23 Inhibitor

• Ustekinumab:
  • For adults ≤100 kg: 45 mg initially, 4 weeks later, then every 12 weeks
  • For adults >100 kg: 90 mg initially, 4 weeks later, then every 12 weeks
  • Pediatric dosing (6-17 years): Weight-based dosing (<60 kg: 0.75 mg/kg; 60-100 kg: 45 mg; >100 kg: 90 mg) 4

Special Clinical Scenarios

Pustular Psoriasis

• Acitretin is first-line therapy (25-50 mg daily), particularly effective with response seen as early as 3 weeks 3
• Avoid systemic corticosteroids as they can precipitate erythrodermic psoriasis or generalized pustular psoriasis upon discontinuation 3

Psoriatic Arthritis

• TNF-α inhibitors are recommended as first-line biologic therapy for psoriasis with associated arthritis 2
• Infliximab is particularly effective for psoriatic arthritis and inhibits radiographically detected joint damage 2

Combination Therapies

• Topical agents with phototherapy: Combination of topical corticosteroids with phototherapy can enhance efficacy 2
• Biologics with traditional systemic agents: Etanercept may be combined with methotrexate to augment efficacy 2
• Caution with combinations: Toxicity from combination treatments is at least additive, requiring careful monitoring 2

Monitoring Requirements

• Methotrexate: Baseline CBC, liver function tests, serum creatinine; regular monitoring of liver function 2
• Cyclosporine: Baseline serum creatinine, blood pressure; regular monitoring of both 2
• Acitretin: Baseline CBC, lipids, liver function tests; regular monitoring of lipids and liver function 2
• Biologics: Screening for tuberculosis and other infections prior to initiation 4

Common Pitfalls and Caveats

• Avoid systemic corticosteroids in psoriasis management as they can cause disease flare during taper 3
• Pregnancy considerations: All commonly used systemic agents are contraindicated in pregnancy, requiring strict contraception 2
• Long-term phototherapy risks: Increased risk of skin cancer with prolonged PUVA therapy 5
• Combination therapy risks: Use extreme caution when combining systemic agents due to additive toxicity 2, 1