Psoriasis: Basics & Goals - Skin Deep Strategy
- Chronic, immune-mediated inflammatory skin disease; T-cell driven, ↑keratinocyte proliferation.
- Presents as well-demarcated erythematous plaques with silvery scales.
- Key cytokines: TNF-α, IL-23, IL-17.
- Common types: Plaque (vulgaris), guttate, pustular, erythrodermic.
- Severity: Body Surface Area (BSA), PASI score.
- Treatment Goals: ↓lesions, ↑Quality of Life, manage comorbidities (psoriatic arthritis), induce remission, minimize drug toxicity.
⭐ Auspitz sign: pinpoint bleeding observed upon removal of psoriatic scales.
Topical Therapies - Skin's First Aid
First-line for mild-moderate psoriasis.
| Agent | MOA (Simplified) | Key ADRs | Notes |
|---|---|---|---|
| Corticosteroids | Anti-inflammatory, Anti-proliferative | Skin atrophy, Tachyphylaxis | Potency varies (mild to superpotent) |
| Vit D3 Analogs (Calcipotriol) | Inhibit keratinocyte proliferation | Skin irritation, Hypercalcemia (rare) | Good for long-term use, often combined |
| Retinoids (Tazarotene) | Normalize gene expression | Irritation, Photosensitivity | ⚠️ Teratogenic (Pregnancy CI) |
| Calcineurin Inhibitors (Tacrolimus, Pimecrolimus) | Immunomodulatory | Burning, Stinging; malignancy risk? | Off-label; face/intertriginous areas |
Systemic Non-Biologics - Core Systemic Squad
Key systemic agents for moderate-to-severe psoriasis, often used when topical therapy fails or for widespread disease.
| Drug | MOA (Abbrev.) | Key ADRs | Key Monitoring | CIs (Abbrev.) |
|---|---|---|---|---|
| Methotrexate | DHFR inhib. | Hepatotox, myelosupp, mucositis | LFTs, CBC | Preg, liver dis. |
| Cyclosporine | Calcineurin inh | Nephrotox, HTN, neurotox | BP, renal func | Unctrl HTN, renal imp |
| Acitretin | Retinoid | Teratogenic, hyperlipidemia, dryness | LFTs, lipids | Preg (3 yrs post) |
| Apremilast | PDE4 inhib. | Diarrhea, nausea, headache, depression | Weight, mood | - |
⭐ Folic acid (1-5 mg daily, or 5 mg weekly) reduces Methotrexate's hematologic, GI, and hepatic side effects.
Biologic Agents - Targeted Skin Warriors
Advanced therapy for moderate-to-severe chronic plaque psoriasis, targeting key cytokines in its pathogenesis.
- TNF-α Inhibitors: E.g., Infliximab, Adalimumab, Etanercept. Broad immunosuppression, monitor for infections.
- IL-17 Inhibitors: E.g., Secukinumab, Ixekizumab. Target IL-17A, a key pro-inflammatory cytokine. Rapid efficacy.
- IL-12/23 Inhibitors: E.g., Ustekinumab. Targets p40 subunit common to both IL-12 & IL-23.
- IL-23p19 Inhibitors: E.g., Guselkumab, Risankizumab. Highly selective for the IL-23 pathway. ⚠️ Pre-treatment screening for TB is mandatory.
⭐ IL-17 inhibitors like Secukinumab and Ixekizumab are known for their rapid onset of action in clearing psoriatic lesions.
Phototherapy - Healing Light Rays
- UV light for moderate-to-severe psoriasis.
- UVB Therapy:
- NB-UVB: 311-313 nm, preferred. Reduces proliferation, immunomodulates.
- PUVA (Psoralen + UVA):
- Oral/topical psoralen + UVA.
- Inhibits DNA synthesis. Potent for thick plaques; higher risks.
- SE: Burns, photoaging, ↑ skin cancer risk (PUVA > UVB).
⭐ NB-UVB is often first-line due to better efficacy/safety than PUVA.
High‑Yield Points - ⚡ Biggest Takeaways
- Topical corticosteroids & Vitamin D analogs (calcipotriol) are primary for mild-moderate psoriasis.
- Methotrexate, a systemic DMARD, requires LFT monitoring & folic acid; risk of hepatotoxicity.
- Cyclosporine, potent for severe psoriasis, causes nephrotoxicity; monitor renal function.
- Acitretin (oral retinoid) is highly teratogenic; contraindicated in pregnancy.
- Biologics (TNF-α, IL-17, IL-23 inhibitors) treat moderate-severe, refractory psoriasis.
- Apremilast, an oral PDE4 inhibitor, is a non-biologic systemic option.
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