Pesavento TE, Jones PA, Julian BA, Curtis JJ
Amlodipine increases cyclosporine levels in hypertensive
renal transplant patients: results of a prospective study
J Am Soc Nephrol
(Jun) 7:831-835 1996

Verapamil, diltiazem, and nicardipine, but not nifedipine, are known to
interfere with cyclosporine metabolism and raise cyclosporine levels. The
authors find that amlodipine also increased cyclosporine levels. In 11
patients studied prospectively, a 40% increase in cyclosporine levels was
seen. When amlodipine was withdrawn, cyclosporine levels returned to
baseline. Because of its long half life, steady state levels of amlodipine
may not be achieved until 7-10 days after starting therapy, and the increase
in cyclosporine levels may be delayed.
What is the mechanism whereby amlodipine causes an increase in cyclosporin
levels? Presumably amlodipine is also metabolized by the cytochrome P-450 3A
enzyme system in the liver, which is responsible for metabolism of
cyclosporine. Interestingly, amlodipine i in the dihydropyridine class of
CCBs, but not all dihydropyridines appear to affect cyclosporine levels.
Nifedipine, isradipine, and nitrendipine apparently do not, while nicardipine
and amlodipine do. Caution must be exercised particularly, when converting
patients from long-acting nifedipine (which does not affect cyclo levels) to
amlodipine (which does).
See also a
related discussion on HDCN
by Dr. George Aronoff pertaining to the P-450 enzyme system and cyclosporine
.
(John T. Daugirdas, M.D., University of Illinois at Chicago)