Prevention of travelers' diarrhea by the tablet formulation of bismuth subsalicylate
H. L. DuPont, C. D. Ericsson, P. C. Johnson, J. A. Bitsura, M. W. DuPont and F. J. de la Cabada
Within 48 hours of arrival in Mexico, 182 US students participated in a
study to compare the efficacy of two dosages of bismuth subsalicylate (262
mg per tablet) as a prophylactic agent against diarrhea. The students were
randomly assigned to receive two tablets (high dose) or one tablet (low
dose) of bismuth subsalicylate four times daily or a placebo four times
daily during a three-week period. Among these completing the trial,
diarrhea (four or more unformed stools in 24 hours or three in eight hours,
plus one other symptom) occurred in seven (14%) of 51 receiving the
high-dose regimen compared with 15 (24%) of 63 receiving the low-dose
regimen and 23 (40%) of 58 in the placebo group. Protection rates were 65%
for high-dose and 40% for low-dose bismuth subsalicylate. Diarrhea caused
by enterotoxigenic Escherichia coli was found in one student receiving the
high-dose regimen, in no students receiving the low-dose regimen, and in
seven placebo-treated subjects. Bismuth subsalicylate was well tolerated;
the most common side effects were blackening of tongues and stools. Bismuth
subsalicylate use in both dosages was associated with tinnitus at a low,
clinically insignificant frequency of 1.2 days per 100 days of treatment.
The dosage of two tablets of bismuth subsalicylate four times daily (2.1
g/d) appears to be a safe and effective means of reducing the occurrence of
travelers' diarrhea among persons at risk for periods up to three weeks.
