Objective: To compare the efficacy of a single dose of doxycycline (200 or 300 mg) with the standard multiple doses of tetracycline in patients with cholera.
Design: Randomised double blind controlled trial. Patients were given a single 200 mg dose of doxycycline, a single 300 mg dose of doxycycline, or multiple doses of tetracycline (500 mg, six hourly intervals).
Setting: Hospital in Bangladesh treating diarrhoea.
Patients: 261 Patients aged over 15 admitted to the hospital with severe dehydration due to acute watery diarrhoea associated with Vibrio cholerae. All vibrios isolated from the stools and rectal swabs of patients, including those patients with prolonged excretion of vibrios, were sensitive to tetracycline. The stools of all patients at admission were negative for shigella and salmonella.
Interventions: All patients received rapid intravenous acetate solution for the first four hours after admission to hospital. They were then entered in the study and randomised. Oral rehydration was started immediately after the intravenous treatment. If signs of severe dehydration reappeared during oral treatment patients were given rapid intravenous acetate solution until dehydration was fully corrected.
Main outcome measures: Stool output in first 24 hours and till diarrhoea stopped, total intake of oral rehydration fluid, duration of diarrhoea, and excretion of vibrio after receiving antibiotic treatment.
Results: The median stool outputs during the first 24 hours (275 ml/kg body weight) and till diarrhoea stopped (296 ml/kg body weight) were significantly higher in patients receiving 200 mg doxycycline as a single dose than in patients receiving either standard tetracycline (242 ml/kg body weight and 254 ml/kg body weight) or 300 mg doxycycline (226 ml/kg body weight and 255 ml/kg body weight). Similarly, median consumption of oral rehydration solution (18.45 l) was significantly higher in patients receiving 200 mg doxycycline than in patients receiving either 300 mg doxycycline (16.10 l) or standard tetracycline (14.80 l). Almost equal numbers of patients in each group required unscheduled intravenous acetate solution to correct dehydration during antibiotic treatment. Patients treated with doxycycline (low or high dose), however, had more prolonged excretion of bacteria.
Conclusions: A single 300 mg dose of doxycycline is as effective as the standard multiple dose tetracycline treatment for cholera in terms of stool output, duration of diarrhoea, vomiting, and requirement for oral rehydration solution.