CFR > Title 21 - Food and Drugs > CHAPTER I—FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES > SUBCHAPTER D—DRUGS FOR HUMAN USE (parts 300 to 370) > PART 331—ANTACID PRODUCTS FOR OVER-THE-COUNTER (OTC) HUMAN USE > SUBPART B—Active Ingredients (§331.10 to §331.15)