What it's for (Indications)
- Dithranol is indicated for the topical treatment of chronic plaque psoriasis.
- It is particularly effective for thick, well-demarcated plaques on the trunk and extremities, and scalp psoriasis when formulated appropriately.
- Its use extends to treating recalcitrant psoriatic lesions that have not responded adequately to less potent therapies.
- The efficacy of dithranol lies in its ability to normalize epidermal cell proliferation, which is a hallmark of psoriatic disease.
- It can be used as monotherapy or in conjunction with other treatments, always under strict medical supervision and careful monitoring for adverse effects.
Dosage Information
| Type | Guideline |
|---|---|
| Standard | Dithranol is for external use only. The dosage regimen is highly individualized, typically commencing with a low concentration (e.g., 0.05% to 0.1%) and gradually increasing to higher concentrations (e.g., up to 2%) as tolerated and based on clinical response. It is commonly applied using short-contact therapy, where the preparation is applied precisely to the psoriatic lesions for a specified duration, usually ranging from 10 to 30 minutes, before being thoroughly washed off with lukewarm water. For some patients, overnight application may be considered by a clinician, though this carries a higher risk of irritation and staining and requires vigilant monitoring. Precise application to psoriatic plaques, avoiding contact with healthy skin, and adhering strictly to the prescribed contact time are crucial to minimize adverse effects and optimize therapeutic outcomes. Patients must be carefully monitored for signs of excessive irritation or erythema. |
Safety & Warnings
Common Side Effects
- The most common adverse effects associated with topical dithranol therapy include local skin irritation, manifested as erythema, burning, itching, and scaling, particularly in untreated areas of skin if contact occurs.
- A characteristic purple-brown staining of the skin, hair, nails, and clothing is highly probable due to the oxidation of dithranol upon exposure to air and light; this staining is temporary on skin but can be persistent on fabrics and nails.
- Folliculitis may occur if the preparation is applied to hair-bearing areas.
- Rarely, allergic contact dermatitis, photosensitivity reactions, or paronychial inflammation have been reported.
- Systemic absorption leading to adverse effects is generally minimal with proper topical application and adherence to dosage guidelines, though caution is advised with extensive use on compromised or large surface areas of skin.
Serious Warnings
- Black Box Warning: **No FDA Black Box Warning:** Dithranol (e.g., Dithroderm) does not carry a formal FDA-mandated Black Box Warning. However, healthcare professionals and patients should be acutely aware of the significant local irritant potential and potent staining properties associated with its use. These critical safety considerations are detailed extensively in the 'Serious Warnings' section of this clinical information. Careful patient selection, meticulous application techniques, and thorough patient education regarding potential adverse effects and preventive measures (such as protecting healthy skin and avoiding contact with clothing/bedding) are paramount to ensure safe and effective therapy, minimizing the risks of severe local reactions and permanent staining of materials. Adherence to prescribed contact times and concentrations is crucial for patient safety.
- **Serious Warnings:** Dithranol can cause significant local irritation, including severe erythema, burning, and blistering, especially if applied to healthy skin, skin folds, or used in excessive concentrations or for prolonged periods.
- Patients must be carefully instructed on proper application techniques, including precise application to lesions and thorough washing after the prescribed contact time.
- Avoid contact with the eyes, mouth, and other mucous membranes, as severe irritation can occur.
- Due to its potent staining properties, caution must be exercised to prevent contact with unaffected skin, hair, nails, and especially clothing or bedding, as staining is often permanent and difficult to remove.
- Dithranol should not be applied to acute, inflamed, or exudative psoriatic lesions (e.
- g.
- , erythrodermic or pustular psoriasis) as it may exacerbate the condition.
- Use with extreme caution in sensitive areas such as the face, genital region, and skin folds, where irritation is more likely and can be severe.
- While systemic absorption is generally low, historical concerns regarding renal irritation with extensive use or in patients with pre-existing renal impairment suggest a need for caution, particularly with large surface area application.
- Always perform a patch test for tolerance if initiating treatment or changing concentration.
How it Works (Mechanism of Action)
Dithranol, also known as anthralin, is a synthetic trihydroxyanthracene derivative that exerts its therapeutic effects primarily by inhibiting excessive epidermal cell proliferation, a hallmark of psoriatic pathology. Its exact mechanism of action is complex and not fully elucidated but is understood to involve several cellular processes. It is believed to act by reducing DNA synthesis and mitotic activity in hyperproliferative keratinocytes. Additionally, dithranol promotes the generation of reactive oxygen species (ROS) within epidermal cells, which can lead to mitochondrial damage, inhibition of various enzyme systems (such as glucose-6-phosphate dehydrogenase), and ultimately, cell death in rapidly dividing cells. It also possesses anti-inflammatory and immunomodulatory properties, affecting lymphocyte function and reducing inflammatory mediators in psoriatic plaques, contributing to the resolution of lesions. These combined actions lead to the normalization of epidermal turnover.
Commercial Brands (Alternatives)
No other brands found for this formula.