ATC Group: D05A Antipsoriatics for topical use

Calcipotriol is a derivative of vitamin D for topical use on psoriasis. It probably works by suppressing keratinization. Advantage of substance or absence of odor and non-coloring of clothing.

Calcitriol is the most active known form of vitamin D₃ in stimulating intestinal calcium transport. In physiological amounts it augments the intestinal absorption of calcium and phosphate and plays a significant part in the regulation of bone mineralisation.

Coal tar is an antipruritic and keratoplastic. It is used in eczema, psoriasis and other skin conditions. Tar acids have also been shown to have disinfectant properties. Coal tar may be used alone, or as part of a more extensive treatment regimen.

Dithranol has been used in the treatment of sub-acute and chronic psoriasis for over 70 years and, during that time it has become established as a safe and effective form of therapy. Its precise mode of action is still to be confirmed, although it has been shown to inhibit DNA replication, cellular respiration and key cellular enzymes eg glucose-6-phosphate dehydrogenase.

Methoxsalen, upon photoactivation, conjugates and forms covalent bonds with DNA which leads to the formation of both monofunctional (addition to a single strand of DNA) and bifunctional adducts (crosslinking of psoralen to both strands of DNA). Reactions with proteins have also been described. The formation of photoadducts results in inhibition of DNA synthesis, cell division and epidermal turnover.

Roflumilast is a PDE4 inhibitor, a non-steroid, anti-inflammatory active substance designed to target both the systemic and pulmonary inflammation associated with COPD.

Tacalcitol is a vitamin D₃ derivative, which inhibits keratinocyte hyper-proliferation and induces differentiation of these cells. The normalisation of these mechanisms is the basis for the efficacy in the treatment of psoriasis.

Tapinarof is an aryl hydrocarbon receptor (AhR) agonist. The specific mechanisms by which tapinarof cream exerts its therapeutic action in psoriasis patients are unknown.

Tazarotene, a member of the acetylenic class of retinoids, is a prodrug which is converted to its active free form, tazarotenic acid, by de-esterification in the skin area. Tazarotenic acid is the only known metabolite of tazarotene to have retinoid activity.