Response to the Letter by Frumkin Regarding the Article, "Dramatically Improved Severe Pulmonary Arterial Hypertension Caused by Qing-Dai (Chinese Herbal Drug) for Ulcerative Colitis"

Abstract

We deeply thank Dr. Frumkin for the comments on our case report. 1) We completely agree with Dr. Frumkin that drug and toxin-induced pulmonary arterial hypertension (PAH) according to the guidelines should be classified to be associated with "indigo naturalis (Chinese herb Qing-Dai)" administration instead of "indirubin (Chinese herb Qing-Dai)". As Dr. Frumkin pointed out, Qing-Dai comprises various ingredients and its formulation widely varies depending on where and by whom it is prescribed. Thus, determining which ingredients are more associated with PAH could be difficult. In our case, the Qing-Dai that the patient received was prescribed by a specific clinic. 2) However, indigo naturalis itself is a substance commonly available as a dye used for jeans and other clothing materials. In Asian countries, some patients with ulcerative colitis (UC) could purchase indigo naturalis on the Internet and self-administer it. Since these indigo naturalis formulations are not sold as drugs, currently regulating their use under the Pharmaceutical Affairs Law is difficult. Therefore, there is a need to more clearly warn patients with UC and physicians that indigo naturalis or Qing-Dai could pose a risk of causing PAH.