Treatment of respiratory tract infections with erythromycin acistrate and two formulations of erythromycin base.

Erythromycin acistrate (EA)--a new ester of erythromycin--was compared with erythromycin base as enterocoated pellets in capsules (EB enterocapsules) and enterocoated tablets of erythromycin base (EB enterotablets) in the treatment of respiratory tract infections. The present double-blind, multicentre study, conducted in eight occupational health centres, included 474 patients; 236 treated with EA, 117 with EB enterocapsules and 121 with EB enterotablets. The diagnoses included tonsillitis, sinusitis, otitis media, bronchitis and pneumonia. The patients were examined on admission and at the end of the treatment. The dosage of EA was 400 mg tid and that of the two erythromycin base preparations 500 mg tid. The treatment was given for seven to 14 days. In the EA-group, 97% of patients were clinically cured by the end of the treatment, while the cure rates for EB enterocapsules and EB enterotablets were 95% and 94%, respectively. Gastrointestinal side effects were reported by 36% of the patients on EA, 54% on EB enterocapsules and 50% on EB enterotablets. Discontinuations due to adverse effects occurred in 8% in the EA, in 21% in the EB enterocapsule and in 12% in the EB enterotablet groups. All three preparations were thus equally effective, but EA caused statistically significantly less gastrointestinal side effects overall (P less than 0.01), especially nausea (P less than 0.01) and abdominal pain (P less than 0.05), than the two formulations containing erythromycin base. Also discontinuations due to side effects occurred statistically significantly less frequently in the EA-group.