Salicylic Acid (1.15% w/w) + Dithranol (1.15% w/w) + Coal Tar (5.3% w/w) (Medical Monograph)

Overview

A potent, triple-combination topical preparation specifically formulated for the treatment of chronic, stable plaque psoriasis, particularly in the Indian context where cost-effectiveness and efficacy are paramount. This combination leverages the synergistic effects of keratolysis (Salicylic Acid), anti-proliferative and anti-inflammatory action (Dithranol), and anti-pruritic, anti-inflammatory, and anti-proliferative effects (Coal Tar) to manage thick, scaly psoriatic plaques. It is a cornerstone of the Ingram regimen (modified for short-contact therapy) and is primarily used in hospital-based or supervised outpatient settings due to its staining and irritation potential.

The combination works synergistically. Salicylic Acid acts as a keratolytic, breaking down intercellular keratinocyte adhesions in the stratum corneum, facilitating the penetration and efficacy of Dithranol and Coal Tar, and reducing scale. Dithranol (Anthralin) inhibits mitochondrial respiration and enzyme activity (like glucose-6-phosphate dehydrogenase), reduces DNA synthesis, and induces apoptosis in hyperproliferative keratinocytes. It also modulates immune responses by inhibiting neutrophil migration and reducing IL-6 and IL-8. Coal Tar is a complex mixture that reduces epidermal DNA synthesis and mitotic activity, has anti-pruritic effects, and suppresses inflammation, possibly by inhibiting the lipoxygenase pathway.