![]() |
|
|
Vol. 285, Issue 3, 1104-1112, June 1998
Zentrumsabteilung für Lebensmitteltoxikologie,
Tierärztliche Hochschule Hannover, Hannover, Germany (A.L.);
Department of Biopharmaceutical Sciences, School of Pharmacy,
University of California at San Francisco, San Francisco, California
(Y.Z., L.Z.B., U.C.);
Institut für Allgemeine Pharmakologie,
Medizinische Hochschule Hannover, Hannover, Germany (I.H., K.-Fr.S.);
and
Department of Cardiothoracic Surgery, Stanford University,
Stanford, California (U.C.)
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.
This article has been cited by other articles:
![]() |
J. J. Zimmerman, A. Patat, V. Parks, R. Moirand, and K. Matschke Pharmacokinetics of Sirolimus (Rapamycin) in Subjects With Severe Hepatic Impairment J. Clin. Pharmacol., March 1, 2008; 48(3): 285 - 292. [Abstract] [Full Text] [PDF] |
||||
![]() |
N. Picard, N. Djebli, F.-L. Sauvage, and P. Marquet Metabolism of Sirolimus in the Presence or Absence of Cyclosporine by Genotyped Human Liver Microsomes and Recombinant Cytochromes P450 3A4 and 3A5 Drug Metab. Dispos., March 1, 2007; 35(3): 350 - 355. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. G. van de Kerkhof, A.-L. B. Ungell, A. K. Sjoberg, M. H. de Jager, C. Hilgendorf, I. A. M. de Graaf, and G. M. M. Groothuis Innovative Methods to Study Human Intestinal Drug Metabolism in Vitro: Precision-Cut Slices Compared with Ussing Chamber Preparations Drug Metab. Dispos., November 1, 2006; 34(11): 1893 - 1902. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Y. Lau, H. Okochi, Y. Huang, and L. Z. Benet PHARMACOKINETICS OF ATORVASTATIN AND ITS HYDROXY METABOLITES IN RATS AND THE EFFECTS OF CONCOMITANT RIFAMPICIN SINGLE DOSES: RELEVANCE OF FIRST-PASS EFFECT FROM HEPATIC UPTAKE TRANSPORTERS, AND INTESTINAL AND HEPATIC METABOLISM Drug Metab. Dispos., July 1, 2006; 34(7): 1175 - 1181. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. J. Zimmerman, K. C. Lasseter, H.-K. Lim, D. Harper, S. C. Dilzer, V. Parker, and K. Matschke Pharmacokinetics of Sirolimus (Rapamycin) in Subjects With Mild to Moderate Hepatic Impairment J. Clin. Pharmacol., December 1, 2005; 45(12): 1368 - 1372. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. W Neff, P. Ruiz, J. R Madariaga, S. Nishida, M. Montalbano, D. Meyer, D. M Levi, A. G Tzakis, and C. B O'Brien Sirolimus-Associated Hepatotoxicity in Liver Transplantation Ann. Pharmacother., October 1, 2004; 38(10): 1593 - 1596. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. L. Cummins, W. Jacobsen, U. Christians, and L. Z. Benet CYP3A4-Transfected Caco-2 Cells as a Tool for Understanding Biochemical Absorption Barriers: Studies with Sirolimus and Midazolam J. Pharmacol. Exp. Ther., January 1, 2004; 308(1): 143 - 155. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. S. Pang MODELING OF INTESTINAL DRUG ABSORPTION: ROLES OF TRANSPORTERS AND METABOLIC ENZYMES (FOR THE GILLETTE REVIEW SERIES) Drug Metab. Dispos., December 1, 2003; 31(12): 1507 - 1519. [Full Text] [PDF] |
||||
![]() |
J. J. Zimmerman, D. Harper, J. Getsy, and W. J. Jusko Pharmacokinetic Interactions between Sirolimus and Microemulsion Cyclosporine When Orally Administered Jointly and 4 Hours Apart in Healthy Volunteers J. Clin. Pharmacol., October 1, 2003; 43(10): 1168 - 1176. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. J. A. Punt, J. Boni, U. Bruntsch, M. Peters, and C. Thielert Phase I and pharmacokinetic study of CCI-779, a novel cytostatic cell-cycle inhibitor, in combination with 5-fluorouracil and leucovorin in patients with advanced solid tumors Ann. Onc., June 1, 2003; 14(6): 931 - 937. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Matysiak-Budnik, M. Heyman, C. Candalh, D. Lethuaire, and F. Megraud In vitro transfer of clarithromycin and amoxicillin across the epithelial barrier: effect of Helicobacter pylori J. Antimicrob. Chemother., December 1, 2002; 50(6): 865 - 872. [Abstract] [Full Text] [PDF] |
||||
![]() |
V. J. Wacher, J. A. Silverman, S. Wong, P. Tran-Tau, A. O. Chan, A. Chai, X.-Q. Yu, D. O'Mahony, and Z. Ramtoola Sirolimus Oral Absorption in Rats Is Increased by Ketoconazole but Is Not Affected by D-alpha -Tocopheryl Poly(Ethylene Glycol 1000) Succinate J. Pharmacol. Exp. Ther., October 1, 2002; 303(1): 308 - 313. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. F. Paine, L. Y. Leung, H. K. Lim, K. Liao, A. Oganesian, M.-Y. Zhang, K. E. Thummel, and P. B. Watkins Identification of a Novel Route of Extraction of Sirolimus in Human Small Intestine: Roles of Metabolism and Secretion J. Pharmacol. Exp. Ther., April 1, 2002; 301(1): 174 - 186. [Abstract] [Full Text] [PDF] |
||||