Gosset Coal tar Overview
Coal tar is **not a single molecule or receptor**, but rather a complex mixture derived from coal processing that contains phenols, polycyclic aromatic hydrocarbons, heterocyclic compounds, and other chemicals. Medically it is used topically for chronic inflammatory skin conditions such as psoriasis and seborrheic dermatitis. Its main therapeutic effects are attributed to its ability to slow down excessive proliferation of epidermal keratinocytes by suppressing DNA synthesis. Coal tar also exhibits anti-inflammatory actions—possibly via inhibition of pro-inflammatory cytokines like IL‑12—and can reduce itching due to its antipruritic properties. Despite being one of the oldest treatments for psoriasis with proven efficacy especially in combination regimens like Goeckerman therapy (coal tar plus UV light), it is not considered a molecular target but rather an active pharmaceutical ingredient composed of many substances acting together on multiple pathways relevant to hyperproliferative skin diseases[1][2][3][4][5]. **Note:** The entry "Coal Tar Antiproliferative effect on skin cells" does not refer to an individual molecule or receptor but describes the pharmacological action/effect produced by coal tar preparations—a drug product—not a specific biological target. Therefore, *is_target* should be marked false, *is_incorrect* should be marked true, and *canonical_name* should be "Coal tar".
Mechanism of Action
Coal tar acts by **slowing the rapid growth of skin cells** through suppression of DNA synthesis in keratinocytes, leading to reduced scaling and plaque formation in psoriasis. It also has anti-inflammatory, antipruritic, antibacterial, antifungal, and mild antiseptic properties[1][2][3][4][5][6]. Some components inhibit STAT3-mediated transcription involved in psoriasis pathophysiology[4].
Biological Functions
Disease Associations
Safety Considerations
- Skin irritation or allergic reactions[5]
- Photosensitivity; increased risk of sunburn—patients should use sunscreen and protective clothing when exposed to sunlight[3][5]
- Staining and odor may be undesirable for some users[3]
- Listed as a known human carcinogen due to polycyclic aromatic hydrocarbons content; however, cancer risk from topical use at therapeutic concentrations remains debated[5]