[Code of Federal Regulations] [Title 21, Volume 5] [Revised as of April 1, 2007] From the U.S. Government Printing Office via GPO Access [CITE: 21CFR346.18] [Page 270] TITLE 21--FOOD AND DRUGS CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) PART 346_ANORECTAL DRUG PRODUCTS FOR OVER-THE-COUNTER HUMAN USE--Table of Subpart B_Active Ingredients Sec. 346.18 Astringent active ingredients. The active ingredient of the product consists of any of the following when used within the concentration range established for each ingredient: (a) Calamine, within a concentration range of 5 to 25 percent by weight per dosage unit (based on the zinc oxide content of calamine). (b) Witch hazel, 10 to 50 percent. (c) Zinc oxide, within a concentration range of 5 to 25 percent by weight per dosage unit. [55 FR 31779, Aug. 3, 1990, as amended at 59 FR 28767, June 3, 1994]