Following a 1-week , open-label run-in phase to document baseline heartburn frequency , subjects were randomly assigned to receive treatment with one tablet of either ranitidine , 75 mg ( n = 537 ) ; ranitidine , 25 mg ( n = 539 ) ; or placebo ( n = 544 ) , to be taken as needed up to four times daily for 2 weeks for the relief of heartburn .
