Acid Suppression Profile of Hydrotalcite in Man. In this randomized, double blind, placebo-controlled cross-over study, the effect of hydrotalcite (CAS 12304-65-3, Talcid), 2 tablets qid (neutralizing capacity 122 mmol) on intragastric 24-h acidity was investigated. 12 healthy male and female volunteers were administered hydrotalcite, 2 tablets qid, or placebo on 2 study days, in each case at 10, 15, 20 and 23 h. Daytime (8-22 h) and nighttime (23-7 h) intragastric H+ concentrations (mmol/l) were significantly reduced by hydrotalcite compared with placebo. The following inhibiton rates were obtained: daytime 37.4%, nighttime 31.5% (p less than 0.05). During the 2-h periods immediately after oral application of hydrotalcite or placebo inhibition rates of up to 65% were observed. These results suggest that hydrotalcite may have also antiulcer activity like other antacids which are used in the treatment of peptic ulcer disease in low daily neutralizing capacities (120-280 mmol/die).