Prevention of bacterial endocarditis.

To the Editor.— We read with interest the long-awaited update on the recommendations for the prevention of bacterial endocarditis by the American Heart Association.1We were somewhat perplexed by the recommendation of the committee to use erythromycin ethylsuccinate and erythromycin stearate as opposed to the traditional erythromycin base. The authors recommended these products because of more rapid and reliable absorption than other erythromycin formulations, resulting in higher and more sustained serum levels. We would like to comment on the rates of absorption of the various products, interpretation of the serum levels, and, finally, the dosage of the ethylsuccinate ester. The stearate salt is hydrolyzed in the duodenum and then absorbed as the active free base. The biologically inactive erythromycin ethylsuccinate ester is absorbed intact and then hydrolyzed in the bloodstream to the active free base.2While it is true that the rate of absorp