Overview of Anthralin

Property	Description
Active ingredient	Anthralin (Dithranol)
Form	Topical preparations (Cream, Ointment, Paste, Gel)
Pharmacological class	Antipsoriatic agent
General use	Managing chronic skin hyperproliferation
Origin	Synthetic compound

What is Anthralin (Dithranol) and Its Classification?

Anthralin, also identified by the International Nonproprietary Name (INN) Dithranol, is a synthetic active pharmaceutical ingredient classified as a specialized topical antipsoriatic agent. This compound is a non-steroidal derivative of the hydroxyanthrone chemical family, specifically known as 1,8,9-anthracenetriol. Anthralin is clinically recognized as a highly effective topical agent for treating hyperproliferative skin conditions, establishing it as a classic, proven therapy.

Composition and Common Topical Forms

Anthralin is employed solely for topical administration and is manufactured as a single active ingredient product. It is formulated into various pharmaceutical preparations, including creams, ointments, pastes, and gels. The compound requires incorporation into specialized lipid-based vehicles to ensure its stability and controlled release, which is a distinguishing formulation feature due to its inherent chemical reactivity. Specific preparations, such as those designed for the scalp, ensure targeted delivery to various patient areas.

High-Level Purpose of Anthralin Therapy

The overall purpose of Anthralin is rooted in its fundamental antiproliferative action, which targets the cellular growth cycle within the skin. The substance works by suppressing the excessively rapid production and division of skin cells (keratinocytes), an abnormal process characteristic of certain chronic skin conditions. This mechanism allows Anthralin to help flatten the thick, raised lesions and improve the overall texture of the affected skin, providing a localized, focused therapeutic benefit.

What side effects are possible with Anthralin?

Possible Side Effects and Safety Information

The official safety profile for topical Anthralin (Dithranol) is defined primarily by local skin and subcutaneous tissue adverse reactions, reflecting its topical application and minimal systemic absorption. The safety information, as documented by regulatory agencies, categorizes possible effects by frequency and system.

Documented Adverse Reactions

The most frequent adverse reactions are local and reversible:

Common / More Common: Local skin irritation, including burning and soreness, in the treated area. The development of erythema (redness) is also a commonly documented safety characteristic

Frequency Not Defined (Widely Documented): The compound is known to cause temporary yellow-brown discoloration of the skin, hair, and nails. This is an expected characteristic of the drug and not typically considered a serious adverse reaction.
Rare: Documented cases include the development of a widespread skin rash or more significant allergic contact sensitivity.

Serious Safety Considerations and Constraints

Although systemic serious adverse reactions are uncommon, regulatory documents highlight specific safety constraints:

Serious Adverse Reactions: The potential for severe allergic reactions (hypersensitivity) and the exacerbation or spread of psoriasis (Koebner phenomenon) are considered clinically significant safety concerns.
Contraindications: Anthralin is strictly contraindicated in patients with known hypersensitivity to the drug and must not be applied to acute, actively inflamed, or pustular psoriatic lesions.
Population Safety Notes: Official labels note that adequate, controlled studies are not available regarding the safety of use during pregnancy, lactation, or for pediatric patients, limiting specific recommendations for these groups.

Overdose and Emergency Response

Overdose Manifestations and Supportive Actions

Overdose involving topical Anthralin is primarily defined by local exposure consequences, as regulatory documents indicate minimal systemic absorption. Excessive application or contact time may result in signs of excessive localized irritation, including profound skin redness (erythema) and an intense burning sensation. Management of these localized effects, as stated in official labeling, involves discontinuing application or reducing the concentration and frequency of use.

When Immediate Medical Help is Required

The most severe documented outcomes relate to accidental severe exposure. Accidental contact with the eyes is categorized as a serious event that can lead to severe conjunctivitis, keratitis, and corneal opacity. In such cases, regulatory guidance mandates that affected areas must be washed with plenty of lukewarm water, and an eye specialist must be contacted immediately.

For accidental ingestion or any manifestation of severe, uncontrolled exposure, the official instruction is to seek immediate medical attention. Patients are directed to contact a Poison Information Centre or proceed directly to the nearest Accident and Emergency department. No specific systemic antidote is known for Anthralin overdose, and systemic management remains symptomatic and supportive. Regulatory documents also note specific population constraints, stating the product is contraindicated in patients with renal insufficiency.

Therapeutic Uses of Anthralin

What Anthralin Treats: Main Uses and Benefits

Anthralin is primarily indicated for the management of chronic plaque psoriasis, which is a condition characterized by persistent, well-defined skin patches. Psoriasis is characterized by symptoms that create noticeable physiological strain. The medication is commonly used to help manage these symptoms that interfere with daily functioning in adult and adolescent patients.

Therapeutic Scope and Patient Benefit

The primary therapeutic benefit of Anthralin is applied in situations involving symptoms related to skin thickening and chronic manifestations. This therapeutic focus is relevant for managing symptom clusters related to heightened physiological activity, such as skin thickening, scaling, and flaking.

The core indications include chronic plaque psoriasis and scalp psoriasis.

“The treatment supports the overall easing of the symptom burden by targeting visible manifestations and supports general well-being during symptomatic phases.”

It is applied in clinical settings where specific management of these long-standing patches is required, and supports patients during periods of heightened discomfort. The medication is used in addressing the visible redness and local inflammation within the affected areas, may assist with maintaining functional stability during symptomatic periods.

Quick Fact: Used for managing persistent skin thickening

Regulatory References

NIH MedlinePlus Medical Encyclopedia

Eligibility and Restrictions for Use

This section summarizes the official population eligibility and non-eligibility for Anthralin (Dithranol) as documented in regulatory labeling.

Eligibility Scope

Category	Official Regulatory Statement
Populations for whom use is allowed	Adults with stable chronic plaque psoriasis.
Populations for whom use is not recommended	Breastfeeding/Nursing Mothers: Caution is advised, as it is not known whether Anthralin is excreted in human milk.
Populations for whom use is contraindicated	Patients with known hypersensitivity to anthralin or any ingredient in the formulation. Patients with acute or actively inflamed psoriatic eruptions.
Age-related eligibility rules	Pediatric patients (Children): Safety and effectiveness have not been established for most topical preparations. Adolescents (12 years of age and older): Use is indicated for specific scalp formulations.
Condition-specific eligibility rules	Contraindicated on blistered, raw, or oozing areas of the skin or scalp.
Pregnancy and lactation eligibility status	Pregnancy: Classified as Pregnancy Category C. Use is restricted to situations where it is clearly needed.
Eligibility-related restrictions	Use is prohibited on sensitive anatomical areas, including the face, eyes, mucous membranes, and intertriginous (skin-fold) areas.

Eligibility Classifications (High-Level)

Category	Regulatory Basis
Eligibility severity classification	Contraindicated (for inflamed skin/hypersensitivity); Not Established (for children); Restricted (for sensitive areas/pregnancy).
Regulatory basis	U.S. Food and Drug Administration (FDA) Labeling.
Eligibility-context constraints	Psoriasis Subtype (Acute vs. Stable), Anatomical Area, and Pediatric/Pregnancy Status.

Resulting Eligibility Structure

Official regulatory documents define Anthralin eligibility by creating clear boundaries based on the patient's existing skin condition, age, and physiological state. The profile primarily allows use in adults with stable, chronic disease while explicitly contraindicating the medication for patients with acute inflammation or known hypersensitivity. Furthermore, specific application site restrictions and the classification of pediatric use as not established collectively define the non-eligible populations.

What should I know about interactions with other medicines?

The official interaction profile for Anthralin (Dithranol) is structured by its status as a topical agent with minimal systemic absorption, a fact reflected in regulatory documentation. This low absorption establishes an absence of anticipated systemic drug-drug interactions involving major metabolic pathways. Specifically, Anthralin is not documented in official sources to inhibit hepatic microsomal enzyme activity, such as CYP enzymes, and no relevant transporter-mediated interactions are listed in prescribing information.

The clinically significant interactions documented by regulatory authorities are strictly localized to the site of application and are pharmacodynamic in nature. Co-administration with certain other topical medicinal products is associated with an additive effect. For instance, the use of topical keratolytic agents, including substances like Salicylic Acid, is documented to enhance the penetration of Anthralin.

This topical exposure modification also extends to other co-administered dermatological treatments. Anthralin is officially stated to increase the local absorption and subsequent exposure of both topical corticosteroids and topical calcineurin inhibitors when applied to psoriatic plaques. Importantly, the profile confirms that no systemic drug combinations are formally listed as contraindicated. Furthermore, regulatory sources document no known interactions with food or drinks, while the effect of alcohol co-use is stated as unknown. No population-specific interaction cautions relating to hepatic or renal clearance are required.

Mechanism of Action

Modulating Cellular Energy and Overgrowth

Anthralin acts primarily on the mitochondria of fast-dividing skin cells, disrupting their electron transport chain and cellular energy supply. This action generates oxidative stress and limits the hyperproliferation (overgrowth) of cells by activating the Intrinsic Apoptotic Pathway, which induces controlled cell death in target cells.

Dampening Local Inflammatory Signaling

The drug’s mechanism extends to influencing inflammatory processes by inhibiting key enzymes like Protein Kinase C (PKC) and modulating signaling within immune cells. This interference suppresses the production and activity of inflammatory mediators and immune cells, resulting in the modulation of local inflammatory processes.

Physiological Consequences of the Mechanism

The combined effect of targeting energy production to slow cell growth and suppressing inflammatory signaling contributes to altered epidermal structure and keratinocyte activity. These actions lead to a regulated state where skin cell turnover is regulated and localized inflammatory signaling is decreased.

Dosage and Administration Information

How to Use Anthralin

Anthralin (Dithranol) is administered exclusively as a topical agent to the skin or scalp, primarily available in formulations such as creams, ointments, and shampoos. Its application is defined by two key principles: dose titration and strictly limited contact time, following established protocols.

Treatment begins with the lowest available concentration, typically 0.1% cream. This strength is then gradually increased over time, often at weekly intervals, until the highest concentration that can be used is determined, with strengths up to 2.0% being utilized in some regimens.

Administration Principle	Official Instructions
Application Frequency	Applied once daily for creams and ointments; shampoos are typically used 3 to 4 times per week.
Contact Time	Standard practice is Short-Contact Therapy (SCT), where a thin layer is applied to lesions and left on for a brief, fixed duration (e.g., 10 to 30 minutes, potentially up to 60 minutes) before complete removal by washing or showering.
Course Duration	The course is typically maintained until the affected areas are clear, a process that may require 4 to 12 weeks of continuous daily treatment.

The preparation must be applied only to the affected area, and a protective agent may be used on surrounding, unaffected skin. If a dose is missed, it should be applied when remembered, but only if it is not almost time for the next scheduled dose. For pediatric patients under 12 years, the safety and effectiveness for certain formulations are not yet established.

Recent Clinical Evidence

Anthralin: Recent Clinical Evidence

Evidence for Use in Chronic Plaque Psoriasis

Research into Anthralin was studied for chronic plaque psoriasis, with studies relevant in trials assessing short-term or episodic symptom patterns. The evidence base consists of Randomized Controlled Trials (RCTs) and Systematic Reviews that aggregate data. Researchers mainly included adult patients and measured outcomes related to physical discomfort using the Psoriasis Area and Severity Index (PASI). Studies also examined outcomes when Anthralin was evaluated in comparison to a placebo or other agents. Follow-up durations were often limited to approximately 4 to 12 weeks. Results apply only to the populations studied, and research provides context but not individual predictions.

Research Findings for Scalp Psoriasis

Anthralin was studied for scalp psoriasis. Research has explored formulations tailored for this specific area, including Comparative Trials. Studies monitored outcomes using specialized tools, such as the Scalp-Specific Global Assessment (ScPGA). The body of dedicated research for the scalp is smaller than that for general plaque psoriasis. Subgroup findings are uncertain, and a smaller number of large-scale dedicated trials have been conducted for this specific location.

Long-Term Studies and Durability of Follow-up

The majority of clinical research available for Anthralin relates to the initial, short-term phase of treatment. Research exploring short-term symptom changes contributes to understanding symptom patterns during this initial period, but long-term effects are not fully established. Evidence is limited regarding outcomes and treatment patterns for conditions characterized by fluctuating manifestations over many months or years.

Evidence in Specific Patient Groups and Key Gaps

Research on Anthralin was observed in adult populations. Studies explored the extent of evidence available for specific age groups where data remains insufficient. For instance, research has explored Anthralin in research involving some adolescent patients, but data for this age group, or for the very young, remain insufficient. Key limitations include the fundamental gap in research detailing the sustained outcomes required for long-term management and the methodological variability across studies.

Key Studies & References

Psoriasis: assessment and management - NICE Guideline (CG153)

Frequently Asked Questions (FAQ)

Common questions about Anthralin (FAQ)

Q: How long does it typically take to see any kind of change when using Anthralin?

A: According to official product information, a course of treatment may be maintained for 4 to 12 weeks until the affected area is clear. The four-week mark is often a key time point, as regulatory documents note a need for re-evaluation by a healthcare professional if no improvement has been observed by then. This duration provides context for the expected timeline of treatment.

Q: Does using more Anthralin make it work faster?

A: Official instructions caution against using more of the medication than the amount prescribed by a healthcare provider. Doing so may not accelerate the desired effects and could increase the chance of local side effects, such as skin irritation or redness. Official instructions describe the need to adhere to the prescribed short-contact application time and concentration.

Q: Are there any specific cosmetic products that should be avoided while using Anthralin?

A: Regulatory guidance recommends that the use of other topical skin products should be discussed with a healthcare professional before applying them to the affected area. This caution exists because using additional products may potentially increase the risk of irritation or alter the absorption of Anthralin.

Q: Can Anthralin be used with moisturizing creams?

A: Official guidance notes that the use of other topical skin products, including moisturizers or emollients, should be discussed with a healthcare professional. This is intended to manage the risk of potential interference with the intended effect or local skin reactions.

Q: Is the purpose of Anthralin to soften or remove scales on the skin?

A: The core purpose of Anthralin, as described in official documents, is its antiproliferative action, meaning it works to suppress the excessively rapid production of skin cells. This cellular regulation is the intended action that contributes to the skin lesions flattening and the potential improvement of overall skin texture.

Q: Is it a common concern that Anthralin might damage healthy skin surrounding the target area?

A: Regulatory documents indicate that Anthralin may cause temporary irritation or redness on normal, unaffected skin surrounding the lesion. Because of this established risk, official instructions often describe the use of a protective agent, such as petroleum jelly, to shield the healthy skin before the medication is applied.

Q: Can I use Anthralin if I have other skin conditions besides the main one it treats?

A: Regulatory information notes that Anthralin may potentially worsen other coexisting skin conditions or problems in the treated area. For this reason, a healthcare professional should review all existing dermatological conditions when assessing the appropriateness of Anthralin use.

Q: Do official sources describe any specific types of skin lesions that respond best to Anthralin?

A: Official labeling defines clear boundaries for appropriate use by specifying the drug is intended for stable, chronic plaque psoriasis. It is also explicitly contraindicated for use on actively inflamed, acute, or pustular lesions, or on skin that is blistered or raw.

Q: Is it possible to be allergic to the ingredients in the Anthralin vehicle (base)?

A: Official safety information states that Anthralin is contraindicated for anyone with a known hypersensitivity or allergy to the active drug or to any of the inactive ingredients used in the specific product formulation (the vehicle or base). The complete list of ingredients is available in the official labeling.

Q: Can Anthralin stain clothing or bedding?

A: Official warnings state that Anthralin is known to stain materials, including fabrics, clothing, and bed linens. Official warnings indicate the need to avoid contact between the preparation and these items, as the discoloration may be permanent.

Q: Why do official documents specify certain areas where Anthralin should not be applied?

A: Official restrictions prohibit the use of Anthralin on sensitive anatomical areas, such as the face, eyes, mucous membranes, and skin-fold areas. This is due to the drug's established safety profile, which includes a high likelihood of causing significant local irritation and redness upon application.

Q: Is it necessary to use gloves when applying Anthralin?

A: While official instructions do not mandate the use of gloves, precautions suggest that users may wear plastic gloves when applying Anthralin. This recommendation is intended to help minimize exposure of the hands to the medication and prevent temporary discoloration or staining.

Q: Are there known interactions between Anthralin and herbal supplements?

A: While no specific interactions with herbal supplements are formally documented in official prescribing information, regulatory guidance notes that it is important that a healthcare professional be informed of any herbal products being used. This is a standard measure to manage potential unknown interactions with concurrent therapies.

Q: Why is Anthralin only available by prescription in some regions?

A: Anthralin is classified as a prescription medicine in many regions due to its potential for causing local skin irritation and the requirement for a dose titration schedule. The prescription status reflects the requirement for use to be overseen by a healthcare professional who guides the treatment and monitors the patient's skin response.

Q: What happens if Anthralin gets into the eyes?

A: Official safety warnings stress that contact with the eyes must be avoided. If the medication accidentally contacts the eyes, the warnings specify that the area requires immediate and thorough flushing with water.

Q: What is the role of the 'reducing agent' property of Anthralin?

A: Pharmacological descriptions indicate that Anthralin's ability to regulate skin cell growth is partially attributed to its function as a reducing agent. This chemical property allows it to interfere with the energy production (mitochondria) and DNA synthesis within hyperproliferative skin cells.

Q: Is there a rebound effect if Anthralin use is stopped suddenly?

A: Pharmacological summaries indicate that Anthralin is generally without the potential for a rebound reaction, which is a sharp worsening of the condition upon stopping treatment. This characteristic has been noted in pharmacological summaries.

How should Anthralin be stored and disposed of?

How to Store and Dispose of Anthralin?

Anthralin must be stored at a controlled room temperature, specifically between 20°C to 25°C (68°F to 77°F), with permitted excursions between 15°C and 30°C. Storage mandates require that the product must be kept from freezing and protected from excessive heat, moisture, and direct light.

Container and Safety

The container must be kept tightly capped when not in use to maintain product integrity. As a mandatory safety constraint, anthralin must be stored out of the reach of children.

Disposal Instructions

To dispose of unused or expired anthralin, regulatory guidance recommends using a drug take-back program. If this option is not available, the product may be mixed with an unappealing substance, placed in a sealed container, and discarded in the household trash. Personal information must be removed or obscured from the packaging before disposal.

Anthralin