Still useful: Coal tar for treating psoriasis

Applying the prescription drug tazarotene (Tazorac) to chronic plaque psoriasis is more effective than using a placebo. But how does it compare to the age-old remedy, coal tar?

Researchers from the All India Institute of Medical Sciences in New Delhi reported their findings during the International Congress of Dermatology.

First, the details.

• 30 patients with stable plaque psoriasis applied 0.1% tazarotene gel on the right side of the body and 5% coal tar ointment on the left.
• The patients had limited disease — less than 20% of body surface area.
• Disease duration averaged about 9 years.
• There was no attempt to disguise the treatments from the patients or researchers.
• Treatment continued for 12 weeks, and patients were assessed every 2 weeks.
• Response was determined by changes in redness, scaling, and ESI (erythema, scaling, induration) score, which averaged about 28 at the start of the study.

And, the results.

• 27 patients completed the study.
• Psoriasis lesions on both sides of the body improved by at least 50% in all patients.
• Both treatments resulted in “marked” or “moderate” improvement in all patients after 12 weeks.
  • The researchers rated the improvement as “marked” in 41% of tazarotene-treated areas and in 59% of areas treated with coal tar.
  • The ratings were reversed for “moderate” improvement.
• The ESI scores didn’t differ significantly between treatments at any time.
  • At 12 weeks, ESI scores averaged 7 with tazarotene treatment vs 6 with coal tar.
  • The average ESI score for lesions treated with coal tar was lower at 6 and 10 weeks, and at the end of the study.

The bottom line?
Yes, coal tar is greasy, unpleasant smelling, and can stain clothing.

On the other hand, “Considering the overall cost/benefit ratio in a chronic disease like psoriasis, coal tar ointment is still an effective treatment modality for patients with stable plaque psoriasis, especially in developing countries where the treatment/healthcare costs are borne by patients themselves,” concluded the authors.

Dr. Kelly Cordoro from the University of California, San Francisco adds, “There is no definitive evidence of an increased risk of skin cancer… from the use of therapeutic tar. Education regarding the favorable safety profile and place in therapy as a steroid-sparing adjunct may increase tolerance and compliance of this excellent and underutilized topical therapy.”

5/28/09 11:31 JR