Linked Life Data

9618413

Source:http://linkedlifedata.com/resource/pubmed/id/9618413

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1998-7-2
pubmed:abstractText
Small intestinal metabolism and transport of sirolimus, a macrolide immunosuppressant with a low and highly variable oral bioavailability, were investigated using small intestinal microsomes and intestinal mucosa in the Ussing chamber. After incubation of sirolimus with human and pig small intestinal microsomes, five metabolites were detected using high performance liquid chromatography/electrospray-mass spectrometry: hydroxy, dihydroxy, trihydroxy, desmethyl and didesmethyl sirolimus. The same metabolites were generated by human liver microsomes and pig small intestinal mucosa in the Ussing chamber. Anti-CYP3A antibodies, as well as the specific CYP3A inhibitors troleandomycin and erythromycin, inhibited small intestinal metabolism of sirolimus, confirming that, as in the liver, CYP3A enzymes are responsible for sirolimus metabolism in the small intestine. Of 32 drugs tested, only known CYP3A substrates inhibited sirolimus intestinal metabolism with inhibitor constants (Ki) equal to those in human liver microsomes. The formation of hydroxy sirolimus by small intestinal microsomes isolated from 14 different patients ranged from 28 to 220 pmol.min-1.mg-1 microsomal protein. In the Ussing chamber, >99% of the sirolimus metabolites reentered the mucosa chamber against a sirolimus gradient, indicating active countertransport. Intestinal drug metabolism and countertransport into the gut lumen, drug interactions with CYP3A substrates and inhibitors in the small intestine and an 8-fold interindividual variability of the intestinal metabolite formation rate significantly contribute to the low and highly variable bioavailability of sirolimus.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0022-3565
pubmed:author
pubmed:issnType
Print
pubmed:volume
285
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1104-12
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Metabolism and transport of the macrolide immunosuppressant sirolimus in the small intestine.
pubmed:affiliation
Zentrumsabteilung für Lebensmitteltoxikologie, Tierärztliche Hochschule Hannover, Hannover, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't