The bioavailability of erythromycin stearate versus enteric-coated erythromycin base when taken immediately before and after food.

1. Erythromycin plasma concentrations were determined in twenty subjects after a single dose, immediately before food, of erythromycin, 500 mg. as: (1) erythromycin stearate (Erythrocin, 500 mg, ovaloid tablets), and (2) erythromycin base (Eryc, 250 mg, capsules containing enteric-coated pellets). 2. Plasma concentrations were again determined in eighteen of the original subjects with the same dose given immediately after food. 3. Maximum Plasma Concentrations (mcg/ml) (See formula in text) 4. Erythromycin stearate was more bioavailable than erythromycin base when administered immediately before food. The preparations were bioequivalent when given immediately after food.