Calcium channel antagonists and cyclosporine metabolism: in vitro studies with human liver microsomes

Br J Clin Pharmacol. 1989 Sep;28(3):362-5. doi: 10.1111/j.1365-2125.1989.tb05439.x.


The effects of four Ca2+ channel antagonists on the metabolism of cyclosporine (CsA) by human liver microsomes (n = 4) in vitro have been examined. Nicardipine produced marked inhibition of both M17 and M21 (IC50 = 7.0 microM) formation. In contrast nifedipine produced less than 20% inhibition of M17 and M21 even at the highest concentration examined (50 microM). Diltiazem data were comparable to those for nifedipine. Verapamil (50 microM) produced 30 and 28% inhibition of M17 and M21 formation, respectively. These findings give a basis to the increase in CsA blood concentrations seen in transplant patients who are also given nicardipine.

MeSH terms

  • Adult
  • Calcium Channel Blockers / metabolism*
  • Chromatography, High Pressure Liquid
  • Cyclosporins / metabolism*
  • Diltiazem / metabolism
  • Female
  • Humans
  • In Vitro Techniques
  • Male
  • Microsomes, Liver / metabolism*
  • Middle Aged
  • Nicardipine / metabolism
  • Radioimmunoassay
  • Verapamil / metabolism


  • Calcium Channel Blockers
  • Cyclosporins
  • Verapamil
  • Nicardipine
  • Diltiazem