What is "seirogan"

is a pharmaceutical drug marketed in Japan, sold as a treatment of the digestive tract (especially as an antidiarrhoeal), whose main active ingredient is "wood creosote" (also wood-tar creosote, or beechwood creosote.)

The name is nominally a registered trademark of based in Suita, Osaka which is still the major market-share holder, but the enforceability of the tradename has been voided by the Supreme Court of Japan, which ruled seirogan to be a common generic name. The ruling only recognizes proprietary use of the bugle logo by Taiko, but not protection of its characteristic packaging. As a result, dozens of extremely similar packaged drugs are being manufactured and sold in the market.