Erythromycin ethylsuccinate, base and acistrate in the treatment of upper respiratory tract infection: two comparative studies of tolerability.

The efficacy and tolerability of erythromycin ethylsuccinate, erythromycin base and erythromycin acistrate were studied in two separate randomized studies in 80 and 82 primary health care patients with upper respiratory tract infections. In Study I, the patients were given either ethylsuccinate 666 mg tid or base 500 mg qid for ten days. Possible side-effects, abdominal pain, nausea, diarrhoea and vomiting, were recorded daily by the patient. Study II followed the same design as Study I with the exception of the side-effect evaluation method. Patients were given in a randomized fashion ethylsuccinate 666 mg tid, or acistrate 400 mg qid. Side-effect evaluation was based on a 10-cm analogue visual scale to record abdominal pain, while nausea, vomiting and diarrhoea were recorded as daily frequencies. These studies indicated that erythromycin ethylsuccinate caused significantly less abdominal pain than the base form (chi 2-test), but there were no significant differences in tolerance between the ethylsuccinate and acistrate forms. Other tolerance parameters revealed no real differences. The clinical response was good with all erythromycin preparations at the doses used in this study.