Effect of combination of antacid and cimetidine on 24-hour intragastric acidity in patients with asymptomatic duodenal ulcer.
By means of a Latin square design, the effect of antacid alone and in combination with cimetidine on a 24-hour intragastric hydrogen ion (H+) activity and serum gastrin profiles was studied in eight patients with duodenal ulcer. Antacid given seven times a day (one and three hours after meals and at bedtime) combined with 600 mg BID of cimetidine (C + A7) achieved greater suppression of H+ after breakfast, overnight, and over the 24-hour period than did antacid alone seven times daily (A7). Antacid given four times a day (one and three hours after lunch and after supper) combined with cimetidine BID (C + A4) maintained the neutralizing capacity during this time, but was less effective than the C  + A7 regimen. However, C + A4 produced more suppression of nocturnal H+ than did A7. A higher percentage of the readings at or above pH 4.0 were obtained with C + A7 than with A7 or C + A4. A greater postprandial integrated gastrin response was obtained with all active treatments as compared with a placebo regimen. The mean peak cimetidine concentration (Cmax) was higher but the time to peak (Tmax) was shorter after the morning than after the evening dose. The area under the cimetidine concentration-time curve and the Cmax and Tmax values after the morning and evening doses of cimetidine were not affected by the coadministration of antacid.


CONCLUSIONS
(1) combination therapy of cimetidine plus antacid is more effective than antacid alone in the reduction of intragastric H+; (2) antacid alone fails to suppress the overnight intragastric acidity; and (3) antacid given concurrently with cimetidine does not interfere with pharmacokinetic determinants of plasma cimetidine concentration.
D000328:Adult; D000368:Aged; D000863:Antacids / Q000008:administration & dosage*; D002927:Cimetidine / Q000008:administration & dosage* / Q000378:metabolism; D002986:Clinical Trials as Topic; D004359:Drug Therapy, Combination; D004381:Duodenal Ulcer / Q000188:drug therapy* / Q000378:metabolism; D005260:Female; D005745:Gastric Acidity Determination; D005755:Gastrins / Q000097:blood; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D013997:Time Factors
D000863:Antacids; D005755:Gastrins; D002927:Cimetidine