The Best Time to Take Bismuth-PeptoBismol, H pylori

When is the best time to take bismuth? Traditionally, patients have been advised to take colloidal bismuth (PeptoBismol) on an empty stomach to allow the compound to coat the stomach. However, a double-blind study by Webb et al suggests that bismuth compounds may be more effective when taken on a full stomach. The investigators studied the antimicrobial efficacy of ranitidine bismuth citrate in 40 patients with H pylori infection. Ranitidine bismuth citrate (Tritec/Glaxo) is a combination of ranitidine and bismuth citrate (bismuth 32% w/w). The combination has a dual mechanism of action; the bismuth component protects ulcer craters and is toxic to H pylori, while the ranitidine blocks H2 receptors on the acid-secreting parietal cell.
Patients with H pylori infection -- as indicated by a positive serum test 21 days prior to dosing and a positive urea breath test 60 minutes and 30 minutes prior to dosing -- were randomly assigned to ranitidine bismuth citrate (400 mg twice daily for 7 days). Half the patients took the drug combination 30 minutes prior to morning and evening meals (with a matching placebo taken 30 minutes after these meals), and half the patients took the combination 30 minutes after meals (with a matching placebo taken 30 minutes before meals). Food enhanced drug activity: 90% of patients who took the combination on a full stomach tested negative for H pylori on two consecutive 13C-urea breath tests, compared with only 55% of those who took it on an empty stomach. At follow-up in 3- 10 months, 14% of patients who took the combination on a full stomach were clear of H pylori compared with none of those who took the combination without food.The investigators suggest that food delays gastric emptying, prolonging the time that the bismuth component is in contact with the mucosa. Also, digestion mixes stomach contents, enhancing drug dispersal. The results of this study suggest that bismuth-containing preparations may be more effective when administered with food.

Webb DD et al. Am J Gastroent