Absorption of rifampicin in gastrectomized patients. Effect of meals.

Rifampicin absorption was studied in six gastrectomized and six non-gastrectomized tuberculous patients who had been on continuous rifampicin therapy for more than 4 weeks. A dose of 450 mg was given on two occasions, first immediately after breakfast and, 2 days later, 1 h before breakfast. In all the gastrectomized and control patients a serum level well above the MIC for M. tuberculosis (0.2-0.5 microgram/ml) was achieved irrespective of whether rifampicin was administered after the meal or during fasting. Gastrectomized patients tended to have more delayed serum concentration peaks postprandially than when fasting. The differences in absorption were not statistically significant, and the serum concentrations remained above the MIC for M. tuberculosis for similar lenghts of time. Individual serum concentrations varied greatly, and this variation may represent a greater problem in the routine monitoring of rifampicin serum levels than administration of the drug with food.