title: Effects of antacid formulation on postprandial oesophageal acidity in patients with a history of episodic heartburn.
abstract: BACKGROUND
  Heartburn self-treatment with antacids is extremely common. If the oesophagus is the primary site of antacid action, chewable antacids might raise the oesophageal pH more effectively than swallowable tablets.
  
  
  OBJECTIVE
  To establish a model to assess postprandial acid reflux and to compare the onset and duration of action on oesophageal pH of different antacid formulations.
  
  
  METHODS
  Twenty subjects with a history of episodic heartburn underwent eight pH monitoring sessions each for 5.5 h postprandially. One hour after consuming a meal consisting of chili, cheese, raw onions and cola, subjects received 750 mg, 1500 mg and 3000 mg of either chewable or swallowable CaCO3 tablets, an effervescent bicarbonate solution or placebo. Oesophageal and gastric pH data were collected.
  
  
  RESULTS
  Mean intra-oesophageal pH remained lower than baseline for more than 1 h (pH range 5-5.5) postprandially, indicating reflux of somewhat acidic intragastric contents into the oesophagus. The onset of action on oesophageal pH was similar for all antacids (30-35 min). The duration of action on pH varied: chewable tablets and effervescent bicarbonate had relatively long durations of action (oesophagus, 40-45 min; stomach, 100-180 min); swallowable tablets had little effect.
  
  
  CONCLUSIONS
  The meal model used in this study dependably produced acidic gastro-oesophageal reflux. Antacids increased oesophageal pH independent of gastric pH, demonstrating that chewing antacids controls oesophageal acidity more effectively than swallowing antacid tablets.
authors.affiliation: Oklahoma Foundation for Digestive Research, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
authors.forename: M
authors.initials: M
authors.lastname: Robinson
authors.forename: S
authors.initials: S
authors.lastname: Rodriguez-Stanley
authors.forename: P B
authors.initials: PB
authors.lastname: Miner
authors.forename: A J
authors.initials: AJ
authors.lastname: McGuire
authors.forename: K
authors.initials: K
authors.lastname: Fung
authors.forename: A A
authors.initials: AA
authors.lastname: Ciociola
mesh_terms: D000328:Adult; D000863:Antacids / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D002119:Calcium Carbonate / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D002626:Chemistry, Pharmaceutical; D004304:Dosage Forms; D004942:Esophagitis, Peptic / Q000188:drug therapy*; D005260:Female; D006356:Heartburn / Q000188:drug therapy*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period
chemical_list: D000863:Antacids; D004304:Dosage Forms; D002119:Calcium Carbonate