Dithranol (INN) or anthralin (USAN and former BAN) is a hydroxyanthrone, anthracene derivative, and is used in medications applied to the skin of people with psoriasis. It is available as creams, ointment or pastes in 0.1 to 2% strengths (Drithocreme, Dit + some more technical info). Pharmacologically dithranol exerts a local antiproliferative and anti-inflammatory effect thought to involve conversion to active oxidized species that modulate keratinocyte proliferation, mitochondrial function and local cytokine activity; it is lipophilic, partitions into the epidermis and stratum corneum, and is chemically light and oxygen sensitive so formulation pH, antioxidants and opaque primary packaging influence stability. Common pharmaceutical forms include petrolatum-based ointments, water-in-oil creams and vanishing-type pastes; handling considerations include potential for local irritation, temporary staining of skin and fabrics, and the need for dermatologist-directed regimens such as short-contact treatment or controlled overnight application depending on lesion severity and patient tolerance.
Parent: Dithranol
Parent: Dithranol
Technical-grade and finished-product specifications for dithranol monitor a small set of related compounds and degradation products derived from oxidation, dimerization and anthracene/anthraquinone transformation; typical specified related substances include oxidized anthrone derivatives, anthraquinones, anthracene traces and dimeric diarylhydroxy species. As a general manufacturing and quality-control guideline, individual specified impurities are commonly limited in the range of about 0.1 to 0.5 percent by weight and the total of related compounds is commonly controlled to within approximately 1.0 to 2.0 percent, with analytical identification by HPLC, UV-visible profiling and mass spectrometry. Stability testing focuses on increases in anthraquinone-type peaks and colored oxidation products, and suppliers document limits, acceptance criteria and corrective storage or formulation measures to minimize impurity formation during shelf life.
Dithranol is a topical antiproliferative and anti-inflammatory agent used primarily to treat chronic plaque psoriasis; it acts locally in the epidermis rather than systemically and is classified as a topical antipsoriatic.
Use under dermatologist supervision; common approaches include short-contact therapy where a thin layer is applied to plaques for a limited time each day with gradual time escalation, or controlled overnight application for selected patients. Apply only to affected skin, avoid healthy skin margins to reduce irritation and staining, wash off according to the prescribed schedule, and follow instructions on occlusion, duration and emollient use. Patch testing and incremental exposure help manage irritation risk.
Dithranol has not been universally discontinued but availability varies by country and by manufacturer; some branded products have been withdrawn or are less commonly marketed as alternative systemic and biologic therapies expanded, while generic and compounded formulations remain available in many dermatology clinics and pharmacies.
Salicylic acid is a keratolytic that softens and removes scale, improving topical drug penetration; when used with dithranol, salicylic acid helps reduce hyperkeratosis on psoriatic plaques so dithranol can contact viable epidermis more effectively, enhancing overall topical efficacy under clinician guidance.
