[Code of Federal Regulations] [Title 21 Volume 5] [Revised as of April 1, 2003] From the U.S. Government Printing Office via GPO Access [CITE: 21CFR349.10] [Page 270] TITLE 21--FOOD AND DRUGS CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) PART 349--OPHTHALMIC DRUG PRODUCTS FOR OVER-THE-COUNTER HUMAN USE--Table of Contents Subpart B--Active Ingredients Sec. 349.10 Ophthalmic astringent. The active ingredient and its concentration in the product is as follows: Zinc sulfate, 0.25 percent.