US lawFederal (United States)RegulationsTitle 21 CFR — Food and DrugsChapter I — FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICESPart 349 — OPHTHALMIC DRUG PRODUCTS FOR OVER-THE-COUNTER HUMAN USESubpart B — Active Ingredients349.1021 C.F.R. § 349.10Ophthalmic astringent.Last amended: 2016Year: 2026Length: 16 wordsOfficial source Cite as 21 C.F.R. § 349.10 (2026)The active ingredient and its concentration in the product is as follows: Zinc sulfate, 0.25 percent.Next21 C.F.R. § 349.12