Pepcid AC, acid controller marketed by McNeil Consumer Healthcare, is a combination of the H2-blocker famotidine (10 mg) with the antacids calcium carbonate (800 mg) and magnesium hydroxide (165 mg). It is administered as chewable tablets and used to treat heartburn.An equivalent UK product, Pepcidtwo, has identical quantities of active ingredients and is marketed by McNeil Ltd, a Johnson & Johnson company. It is sold in packs of 6 or 12.