Evaluation of the intestinal absorption of erythromycin in man: absolute bioavailability and comparison with enteric coated erythromycin

Pharm Res. 1995 Jan;12(1):149-54. doi: 10.1023/a:1016215510223.


To determine the role of acid hydrolysis on the gastrointestinal absorption of erythromycin, six healthy subjects received erythromycin as a 240 mg intravenous dose, a 250 mg oral solution administered via endoscope directly into the duodenum and bypassing the stomach, and an enteric-coated 250 mg capsule. Blood samples were collected for 6 hours and serum erythromycin quantified by a microbiological method. The time to achieve maximum serum concentrations for the solution was 0.25 +/- 0.08 (mean +/- SD) hours and for the capsule was 2.92 +/- 0.55 hours. The absolute bioavailability of erythromycin from the capsule was 32 +/- 7% and for the duodenal solution 43 +/- 14%. The ratio of the areas under the serum erythromycin concentration-time curve of capsule to solution was 80 +/- 28% (range 38 to 110%). There is substantial loss of erythromycin apart from gastric acid hydrolysis, which cannot be accounted for by hepatic first-pass metabolism. Attempts to further improve the oral bioavailability of erythromycin beyond 50% by manipulation of formulation are likely to be futile.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Adult
  • Biological Availability
  • Capsules
  • Chemistry, Pharmaceutical
  • Drug Administration Routes
  • Duodenum
  • Erythromycin / administration & dosage*
  • Erythromycin / analogs & derivatives
  • Erythromycin / blood
  • Erythromycin / pharmacokinetics*
  • Evaluation Studies as Topic
  • Female
  • Humans
  • Injections, Intravenous
  • Intestinal Absorption*
  • Male
  • Solutions


  • Capsules
  • Solutions
  • erythromycin lactobionate
  • Erythromycin