Psoriasis

Topical Psoriasis Therapy: Vitamin D Analogues, Steroids and the Classics

Psoriasis is a skin that is trying to heal a wound that was never there. The epidermis renews itself at a frantic pace, driven by an inflammatory signal it cannot switch off, and the result is the thick, silvery, stubborn plaque every clinician learns to recognise on sight. For most patients the first — and often the whole — answer is not a pill or an infusion but a cream. The topical shelf is old and new at once: vitamin D analogues that slow the racing skin, potent steroids that quiet the inflammation, and century-old tars and dithranol that still earn their place. Knowing which to reach for, and why, is the foundation on which every later escalation is built.

Phototherapy and the Classic Systemics: Methotrexate, Ciclosporin, Acitretin

Before biologics rewrote the ceiling of what psoriasis treatment could achieve, dermatologists had a ladder — and they still climb it every day, because it is cheaper, faster in a crisis, and sometimes simply the right tool. Light first, then three old drugs, each with a personality: methotrexate the workhorse that also treats the joints, ciclosporin the fire-extinguisher you cannot leave running, and acitretin the retinoid that spares the immune system but scars the future with years of teratogenicity. Knowing when to reach for each — and what blood test protects the patient from it — is the heart of practical psoriasis therapy.

The Biologic Revolution I: TNF and IL-12/23 Blockade

For most of the twentieth century, severe psoriasis was fought with blunt, whole-body weapons — methotrexate, ciclosporin, tar, ultraviolet light — that suppressed the immune system wholesale and taxed the liver, kidney and marrow for the privilege. Then immunology learned the actual language of the disease: a single inflammatory conversation, running from a cytokine called IL-23 through a T-helper cell to a molecule called IL-17. Once you can name the wire, you can cut it. The biologics are monoclonal antibodies that snip one wire of that circuit and leave the rest of the immune system standing — trading blanket immunosuppression for a scalpel. This chapter tells the first half of that story.

The Biologic Revolution II: IL-17, IL-23 and the New Oral Small Molecules

The first biologics proved a point: block the right cytokine and psoriasis melts away. But TNF and ustekinumab left a gap — plenty of patients cleared partly, not completely. The next generation closed it. By aiming at the exact axis that drives the disease — IL-23 up top, IL-17 at the skin — the newer drugs pushed the goalposts from "much better" to "clear or almost clear." And for the first time, a pill could rival an injection. This is the story of how psoriasis therapy went from smearing tar to switching off single cytokines by name.