Indigo naturalis extract effective for psoriatic nails

By Will Boggs MD

NEW YORK (Reuters Health) - Lindioil, an olive oil extract of indigo naturalis, is an effective treatment for psoriatic nails, researchers from Taiwan report.

"Efficacy and safety are two very important components for medications that treat psoriatic nails because of psoriasis's refractory nature, which requires long-term treatment," Dr. Yin-Ku Lin from Chang Gung University, Taoyuan, Reuters Health by email. "In this study, we found that Lindioil was safe and effective in treating psoriatic nails, that it was superior to calcipotriol solution and was more acceptable to subjects. Hence, we conclude that Lindioil has a great potential to become a safe and effective alternative therapy for psoriatic nails."

Indigo naturalis, a Chinese herb that has been used for centuries, was previously shown by this group to be effective in treating recalcitrant skin psoriasis and severe nail psoriasis.

In this trial, Dr. Lin and colleagues compared Lindioil with topical calcipotriol in 28 patients with psoriatic nails.

Patients applied Lindioil to the fingernails of one hand and calcipotriol to the fingernails of the other hand twice daily for 24 weeks.

At week 24, use of Lindioil brought significantly greater improvements in Nail Psoriasis Severity Index (NAPSI) scores compared with calcipotriol (51.3% versus 27.1%, respectively), according to the March 4 JAMA Dermatology online report.

Half of the participants had NAPSI that improved 50% or more, whereas only a quarter of the participants showed similar improvements with calcipotriol.

Two individuals (6.1%) experienced local irritation with Lindioil, compared with 10 individuals (30.3%) who experienced local irritation with calcipotriol. No serious adverse events occurred.

"Lindioil does not have any significant adverse side effects compared to oral systemic agents and biologics (which have unpredictable side effects)," Dr. Lin said. "In addition, biologics are significantly more expensive than Lindioil."

"I first came across Dr. Lin's work on indigo and nail psoriasis in 2011, and was eager to try the extract in my patients, but my pharmacy provider was unable to comply with my request, and I did not pursue my search with herbal or natural medicine providers," Dr. Luís Puig from the Autonomous University of Barcelona Medical School, Spain, told Reuters Health by email.

"As regards the comparator, potent/ultrapotent corticosteroids, rather than calcipotriol, are usually accepted (in systematic reviews) to be the most effective topical treatment, and indigo might have some advantages from the safety perspective if proven to be similarly effective at 24 weeks and beyond," Dr. Puig said.

"The best available systemic treatments (biologics) are able to produce a 57% improvement in NAPSI scores after 6 months of treatment (the boundary between short-term and medium-term effect)," Dr. Puig said.

"In addition, I wonder if a lacquer might be more suitable than olive oil as an excipient," Dr. Puig said.

Indigo naturalis "can be found in traditional Chinese herbs pharmacy (as qing dai), but one should be careful of counterfeit indigo made from chemical dye," Dr. Lin said.

Several websites sell oil extracts of indigo naturalis, often with other ingredients, but caution is advised regarding their authenticity.

The authors reported no external funding or disclosures.

SOURCE: http://bit.ly/1897rwZ

JAMA Dermatol 2015.

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