A study was conducted by Savarino and colleagues to determine the effects of single daily doses of placebo, nizatidine 300 mg, ranitidine 300 mg and famotidine 40 mg, administered at 22:00 h. The effects of the study drugs were compared in 16 patients with healed duodenal ulcers. All the study participants were subjected to the said treatment on four different occasions.

• The H2 receptor antagonists were associated with a significantly higher acid inhibition compared to placebo over the entire 24-hour period.
• Famotidine was more effective than nizatidine in reducing circadian acidity.
• The H2 blockers had similar effects on overnight acidity from 23:00 to 07:00 h; however, famotidine and ranitidine were associated with greater anacidity compared to nizatidine during the morning hours, from 07:00 to 12:00 h.
• Famotidine and ranitidine were associated with a significantly longer duration, in consecutive minutes, above 5.0 pH units during drug-related events, in comparison with nizatidine.

The acid suppression with nizatidine appears to be shorter-lasting compared to that with ranitidine and famotidine.

Source: Savarino V, Mela GS, Zentilin P, et al. Comparison of the effects of placebo, ranitidine, famotidine and nizatidine on intragastric acidity by means of continuous pH recording. Digestion. 1989;42(1):1-6.