Anthralin is a topical irritant used to treat alopecia areata

Alopecia areata hair loss information for men and women
Alopecia Areata 
Alopecia Areata Biology
Alopecia Areata Treatments

  Anthralin Irritant Treatment of Alopecia Areata

Anthralin is one of the non-specific irritants known for inducing hair growth. Anthralin was discovered as a comparatively effective irritant after earlier topical applications of other potential non-irritants such as croton oil, sodium laureate sulfate and topical tretinoin were not found successful in regenerating hair growth.

There are a few variably controlled studies on treatment of AA with anthralin. It is not known how it works but basically it acts by preventing normal cell growth and differentiation in the skin. In the laboratory it has been demonstrated that anthralin generates free radicals and oxygen radicals. It has been shown to prevent human monocytes from secreting IL-6, IL-8 and tumor necrosis factor but it does not inhibit secretion of IL-1. Anthralin also inhibits epidermal growth factor signaling. However, since anecdotal success of anthralin has been reported in a small proportion of the population, this medication is mostly used as a second line of treatment

Typically, a 0.5% anthralin is applied in liquid or cream form. After a specified duration of treatment the anthralin is washed away. The precise concentration and duration of treatment depends on the nature of the disease and the patient’s response to it.

The first attempt at producing hair growth in patients with alopecia areata, using anthralin, was made by inducing an inflammatory non-allergic dermatitis. Anthralin with a concentration of 0.2% to 0.8% in an ointment base was applied once a day on the affected areas.

In cases of extensive alopecia areata, the anthralin was applied to a small-circumscribed area to prevent spontaneous growth. In most cases dermatitis was observed. In cases of severe itching, blistering or regional lymph node swelling the treatment was discontinued for several days. Treatment went on for several weeks after hair regrowth had been observed. It was after five to eight weeks that hair regrowth was first seen, but as white hair which after sometime became fully pigmented.

Out of 32 patients with patchy alopecia areata 18 showed cosmetically acceptable hair regrowth, 3 had only a short period of hair regrowth and the remaining 3 were treatment failures. Out of 8 alopecia totalis patients two showed cosmetically good hair growth, one had transient hair growth, two had vellus hair growth and three showed no response.

The results of a partly controlled study reported an acceptable cosmetic regrowth after unspecified treatment duration in 75% patients with patchy alopecia areata and in 25% patients with alopecia totalis. They were treated with anthralin once daily, in concentrations enough, to produce erythema and pruritis. New hair growth was observed by 8 weeks. Two patients with extensive alopecia areata, who were given half head treatment showed unilateral effect. The patients were given an application of 0.5% to 1% anthralin cream to bare patches for 20 to 30 minutes, for two weeks. Then the exposure time was gradually increased by 10 to 15 minutes, at two-week interval, up to a total of 1 hour, until low-grade erythema and pruritis developed. After inducing erythema and pruritis, daily treatment was continued at the then exposure time, for 3 months. At this stage, treatment was stopped for those who did not respond.

For those who responded, the treatment was continued until cosmetically acceptable regrowth was seen, which may take up to 6 months. Attempts to gradually lower the frequency of treatment were made thereafter. Some precautions need to be observed during anthralin treatment Hands should be washed well after each application and eye contact with the drug avoided. The treated area should be protected from the sun.

Inflammation-Response Link

Both the studies, described, demonstrate that induction of some kind of a skin irritation and inflammation was essential to get a response. This issue begs two questions.
Firstly, is there a particular degree of irritation required to get a satisfactory response? Secondly, is there a relation between the degree of irritation and the degree of response? To find the answers a small study was made.

10 patients with alopecia, ranging from 4cm or bigger patches to alopecia totalis, were given applications of 0.1%, 0.25%, and 0.5% anthralin cream or 0.4% anthralin scalp unguent once or twice daily, on the affected areas, for 16 weeks. To maintain a mild contact dermatitis, clinically observed as mild erythema, slight tenderness or pruritis, weekly or bi-weekly changes were made in the dosage or frequency of treatment. No difference in hair growth was observed between the treated and control areas. However, since the study was conducted on a small number of patients and since there was no comparison group with a sufficient inflammation response to anthralin, the results of the study must be taken as just suggesting, that extent of inflammation may affect response.

Side Effects of Anthralin

As expected, skin staining and irritation occurred. Other adverse effects observed were fabric staining and fair hair. This whitening of hair makes anthralin treatment unsuitable for some individuals. The serious side effects that may be produced, during anthralin treatment, are folliculitis, regional lymphadenopathy severe itching and blisters.

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