Pharmacokinetic, bacteriological and clinical aspects on the use of doxycycline in patients with active duodenal ulcer associated with Campylobacter pylori.

Seven patients with active duodenal ulcer and positive cultures for Campylobacter pylori were given anti-ulcer treatment for 28 days with the addition of doxycycline for the last nine days. Repeated endoscopy with biopsy for culture and doxycycline concentration determinations from the mucosa at the end of doxycycline therapy showed that five of seven patients remained positive in culture. The concentrations of doxycycline in biopsy material were 0.1 to 0.3 mg/kg in four patients; in three patients the level of antibiotic was not measurable. The serum concentrations of doxycycline in six patients varied between 0.5 and 2.7 mg/l. One patient had less than 0.5 mg/l. The two patients with C. pylori negative cultures at the end of therapy had serum concentrations of doxycycline of 2.4 and 1.0 mg/l. These patients were positive in biopsy culture for C. pylori 12 weeks after therapy. In conclusion, doxycycline does not eradicate C. pylori when given in recommended dosage for 9 days.