What to Know About Anthralin Cream or Shampoo

Anthralin cream is one of the original psoriasis topical medications. First introduced in 1916, it was applied to the skin as a thick paste to treat severe plaque psoriasis. While effective, anthralin was extremely messy and rarely used outside out of a hospital setting.

Newer incarnations of the drug are more user-friendly but still present challenges in terms of messiness, staining, and the duration of treatment. Even beyond convenience, intensive therapies like anthralin have fallen to the wayside in favor of more bioactive topical drugs, including hydrocortisone cream, tazarotene, and topical vitamin D derivatives.

Nevertheless, anthralin still has a place in treatment if other topical medications prove either ineffective or intolerable.

Anthralin, classified as an anthracene derivative, is typically used for the treatment of stable plaque psoriasis in adults. It appears to inhibit DNA replication and slow the hyperproduction of the skin cells that can lead to the formation of skin plaques.

Anthralin is available by prescription in either cream, gel, or shampoo formulations. The products vary in strength from 0.1% to 2% and are sold in the United States under the brand names Drithocrem, Dritho-Scalp, Psoriatec, Zithranol, or Zithranol-RR.

Anthralin has a slower mechanism of action than topical corticosteroids used to treat psoriasis and may take several weeks before improvement is seen. With that being said, it is less likely to cause steroid withdrawal or skin atrophy (thinning) that commonly occurs with long-term corticosteroid use.

Moreover, because anthralin does not utilize liver enzymes for metabolization, it is less likely to competitively interact with medications that do, including biologic drugs like Tremfya (guselkumab) and Consentyx (secukinumab).

Generally speaking, anthralin is not used unless other standard remedies have failed to provide relief. It is not considered an effective response for severe psoriatic flares but is rather used when chronic plaque psoriasis is either stable or quiescent (dormant).

Precautions and Considerations

Anthralin is classified as a Pregnancy Category C drug, meaning that the safety research is limited but the drug may be warranted despite the possible risks. It is unknown what, if any, harm may be caused by using the drug during breastfeeding.

Speak with your doctor if you are pregnant or are planning to get pregnant so that you are fully appraised of the pros and cons of treatment.

Other Drug Classes

There are other drugs that temper the hyperproduction of skin cells in a way similar to anthralin. These include:

• Coal tar, classified a keratolytic agent
• Tazarac (tazarotene), a topical retinoid

As with anthralin, their exact mechanisms of action are unknown. Coal tar is an attractive option because it can be purchased over the counter and has few side effects. Tazarac, available by prescription, also has few side effects and can be used on an ongoing basis, including on the face.

The anthralin dosage varies by the drug formulation and symptoms. Always read the product instructions carefully before use, and call your doctor or pharmacist if you are unsure how to use the drug.

For mild to moderate psoriasis, a 1% cream or shampoo is generally prescribed. Milder formulations may be used for children 12 and over, while stronger formulations may be prescribed for hard-to-treat lesions on the feet or hands.

How to Apply

To avoid irritation, anthralin is usually applied for shorter periods of time when first starting treatment. As your body adapts to the medication, the duration will gradually be increased as tolerated.

For the treatment of psoriatic skin plaques:

1. Apply a thin layer of anthralin cream once daily to the lesions only. (To prevent irritating surrounding skin, apply a protective layer of petroleum jelly around each lesion.)
2. Leave on the skin for 5 to 10 minutes when first starting treatment.
3. After 5 to 10 minutes, rinse the skin with lukewarm water and wash with soap.
4. After a week, gradually increase the duration until you reach a maximum of 30 minutes.

For the topical treatment of scalp psoriasis:

1. Wash or rinse your hair and towel dry.
2. Apply a thin layer of cream to the lesions once daily while the hair is still damp.
3. Leave for 5 to 10 minutes when first starting.
4. Rinse the scalp with lukewarm water and shampoo.
5. After a week, gradually increase the duration until you reach a maximum of 30 minutes.

For treating scalp psoriasis with anthralin shampoo:

1. Lightly rinse and damp dry your hair.
2. Carefully massage the shampoo into your scalp three to four times weekly. (To protect the surrounding skin, apply petroleum jelly around the hairline and ears and the back of the neck.)
3. Leave for 20 to 30 minutes.
4. Rinse with lukewarm water and wash with a mild regular shampoo.
5. After a week, gradually increase the duration until you reach a maximum of 60 minutes.

How to Store

Anthralin cream, gel, or shampoo can usually be stored at room temperature (between 59^o and 86^o F). Zithronol needs to be stored at a slightly cooler temperature, between 68^o to 77^o F. Keep in a dark, cool room in its original container well away from direct sunlight.

Always check the expiration date, and discard after the use-by date.

Anthralin may cause mild skin irritation when treatment is first started, although this usually resolves with ongoing use.

The bigger concern is staining. Anthralin can temporarily stain the skin a yellowy-brown and permanently stain clothing fabrics, towels, and bathmats. It can even leave permanent stains on ceramic basins and countertops if not cleaned immediately.

There are no known drug-drug interactions associated with anthralin cream, gel, or shampoo. With that being said, always advise your doctor about any medications you are taking, whether they are topical or oral, prescription or OTC, or therapeutic or recreational.

Any drug that causes skin irritation may compound that caused by anthralin. Even high-dose antioxidant supplements have been known to potentiate the effects of anthralin and cause inflammation at the application site.

The only absolute contraindication for anthralin use is a known allergy to anthralin or any of the ingredients in the product.