24 HOUR CONTROL OF GASTRIC-ACIDITY BY TWICE-DAILY DOSES OF PLACEBO, NIZATIDINE 150 MG, NIZATIDINE 300 MG, AND RANITIDINE 300 MG

This study was carried out to assess the effects on gastric acidity of placebo twice daily (bid), nizatidine 150 mg bid, nizatidine 300 mg bid, and ranitidine 300 mg bid by means of continuous 24-hour intragastric pH monitoring. Twelve patients with duodenal ulcer in remission were randomized to receive in single-blind fashion the above medications on four separate occasions, at least 1 week apart. The three active regimens produced higher pH values (P < .001) and maintained gastric pH above 3.0 units for a longer period (P < .001) than placebo in all time intervals but evening. Nizatidine 150 mg bid caused a lower rise in pH than nizatidine 300 mg bid (P < .01) and ranitidine 300 mg bid (P < .05) during both the daytime and the whole 24 hours. In these time windows also the time spent above 3.0 pH units was significantly shorter for the former regimen than for 300 mg bid of both nizatidine (P < .01) and ranitidine (P < .05). There was no difference between the latter two dosing schedules in terms of both potency and duration of action in all the time intervals considered. It is concluded that twice daily doses of H-2 blockers are more effective than placebo in reducing gastric acidity. Three hundred milligrams twice daily of both nizatidine and ranitidine produce a significantly greater and longer-lasting acid suppression than 150 mg bid of nizatidine. Our study also confirms the greater effectiveness of H-2 antagonists during nighttime than during day-time.