the concentrations of erythromycin , 2'-acetylerythromycin ( 2'-ae ) and their anhydro forms in plasma and tonsillar tissue were analyzed after a 3-day repeated-dosage regimen of erythromycin stearate ( es ; 500 mg twice a day [ b.i.d ] ) and erythromycin acistrate ( ea ) , a new erythromycin prodrug , at two doses ( 400 and 500 mg b.i.d . ) .
C0059566
erythromycin stearate
C0014806
erythromycin