Comparison of gastric pH with omeprazole magnesium 20.6 mg (Prilosec OTC) o.m. famotidine 10 mg (Pepcid AC) b.d. and famotidine 20 mg b.d. over 14 days of treatment

MINER, P. B. JR
ALLGOOD, L. D.
GRENDER, J. M.

^*Oklahoma Foundation for Digestive Research, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
^†The Procter & Gamble Company, Cincinnati, OH, USA

Correspondence to: Dr P. B. Miner Jr, Oklahoma Foundation for Digestive Research, 1000 North Lincoln Boulevard, Suite 210, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA. E-mail: [email protected]

Publication data Submitted 8 May 2006 First decision 15 May 2006 Resubmitted 16 August 2006 Accepted 17 August 2006

Alimentary Pharmacology & Therapeutics 25(1):p 103-109, January 2007.

SUMMARY

Background

The onset of acid inhibition for proton pump inhibitors is slower than with H₂RAs and generally considered to be at a steady-state after 5 days. Thus, little direct comparison data exists between H₂RAs and proton pump inhibitors for gastric acid suppression on day 1 of therapy. Furthermore, the durability of their acid suppression has not been systematically compared.

Aim

To compare the effects of 20.6 mg omeprazole magnesium o.m. (Ome-Mg 20), famotidine 10 mg b.d. (Fam 10) and famotidine 20 mg b.d. (Fam 20) on intragastric pH on day 1 and throughout 14 days of dosing.

Methods

The study was a randomized, double-blind, three-dosing regimens, three-period crossover. Healthy adults with frequent heartburn (≥2 days/week) underwent 24-h gastric pH monitoring on days 0 (baseline), 1, 3, 7 and 14.

Results

Thirty-one subjects were included in the per-protocol analyses. On day 1, the mean percentage time pH > 4 (pH4%) was higher for Ome-Mg 20, 44.6%, than for Fam 10, 36.7% (P = 0.032), and not different from Fam 20, 46.9% (P = 0.541). The pH4% was higher for Ome-Mg 20 than either famotidine regimen on all subsequent monitoring days (P < 0.001). The 24-h area under the mean intragastric pH curve showed a similar pattern. Furthermore, after day 1, Ome-Mg 20 demonstrated an increasing and sustained effect in contrast to a decreasing effect for famotidine, consistent with H₂RA tolerance.

Conclusion

Gastric acid suppression on Ome-Mg 20 mg o.m. over 14 days was comparable with Fam 10 mg b.d. or Fam 20 mg b.d. on day 1, and superior thereafter.