The pharmacokinetics and tolerance of oral erythromycin stearate compared with erythromycin ethylsuccinate: implications for preventing endocarditis.

Serum concentrations of erythromycin were monitored in 11 healthy adult volunteers following single dose oral administration of erythromycin stearate, 1.5 g, and erythromycin ethylsuccinate 3.0 g. Peak serum concentrations occurred at 30 min to 2 h after the dose, usually at 1 h. Mean serum peak erythromycin concentrations (standard deviation) were 4.8 mg/l (+/- 2.0) following 1.5 g erythromycin stearate and 2.8 mg/l (+/- 1.4) after 3.0 g erythromycin ethylsuccinate. Both types of erythromycin frequently caused mild gastrointestinal side-effects but there were fewer side-effects associated with erythromycin ethylsuccinate. However, because of the increased serum erythromycin concentrations between 1 and 6 h after the dose of the stearate preparation compared to ethylsuccinate we recommend erythromycin stearate, 1.5 g, as the preferred loading dose, given 1 h before the dental procedure, for preventing endocarditis in susceptible patients allergic to penicillin.