Trimethoprim prophylaxis of acute exacerbations in chronic obstructive pulmonary diseases

A double-blind randomized trial was carried out to study the efficacy and tolerance of trimethoprim with a daily single dose of 300 mg in long-term prophylaxis of acute exacerbations of chronic obstructive pulmonary diseases (COPD). The patients, 13 in the trimethoprim group and 11 in the placebo group, were followed up at fixed intervals and checked for respiratory functions and haematological parameters for six months. The number of exacerbations were significantly lower than during the previous winter in both groups: 0.6 compared to 3.8 in the trimethoprim group, and 0.6 to 3.0 in the placebo group. Tolerance of trimethoprim was good and did not differ from that of placebo. The necessity of double-blind trials in evaluating the prophylactic value of antibiotics in COPD is emphasized, since the exacerbations are also dependent on many unknown factors. There were no statistically significant differences in blood counts of folate levels.