First-pass metabolism of cyclosporin by the gut

Lancet. 1991 Dec 14;338(8781):1488-90. doi: 10.1016/0140-6736(91)92302-i.


Cyclosporin is thought to be exclusively metabolised in the liver. We instilled cyclosporin into the small bowel of 2 patients during the anhepatic phase of liver transplantation; cyclosporin metabolites were readily detected in portal venous blood. Our findings indicate that the small intestine is a major site of cyclosporin breakdown: such intestinal metabolism might help to explain the poor oral bioavailability and drug interactions of cyclosporin.

MeSH terms

  • Biological Availability
  • Cyclosporine / blood
  • Cyclosporine / metabolism*
  • Cyclosporine / pharmacokinetics
  • Humans
  • Intestinal Absorption / drug effects
  • Intestine, Small / metabolism*
  • Liver Transplantation
  • Portal Vein


  • Cyclosporine